This article reviews the contemporary clinical modalities for rectal cancer tumor response assessment following neoadjuvant treatment(s), including physical exam, endoscopy, biopsy, biomarkers, and dedicated rectal cancer imaging. Some patients obtaining a complete or near-complete clinical response following neoadjuvant treatment(s) may safely defer or avoid major pelvic surgery.Local tumor response evaluation following neoadjuvant treatment(s) in rectal adenocarcinoma requires a multi-modality approach including physical and endoscopic evaluations, rectal protocoled MRI, and cross-sectional imaging. Clinical tumor response exists on a spectrum from complete clinical response (cCR), defined as the absence of clinical evidence of residual tumor, to near-complete response (nCR), which assumes a significant reduction in tumor burden but with increased uncertainty of residual microscopic disease, to incomplete clinical response (iCR), which incorporates all responses less than nCR that is not progressive disease. This article aims to review the clinical tools currently routinely available to evaluate treatment response and offers a potential management approach based on the extent of local tumor response. Over the last decades, a significant number of patients diagnosed with non-metastatic locally advanced rectal adenocarcinoma (LARC) have avoided or deferred radical proctectomy with mesorectal excision following neoadjuvant treatment(s). Largely driven by patients wishing to avoid the life-altering sequelae of major pelvic surgery, patients considered suitable for rectal preservation nonoperative management (NOM), or a Watch and Wait (WW) approach, are often cured without the need for a proctectomy. The decision to pursue NOM or a WW approach is based on clinical and radiographic criteria upon completion of neoadjuvant treatment(s). The magnitude of benefit for a patient otherwise facing a permanent colostomy or coloanal anastomosis able to pursue a high-intensity surveillance approach rather than proctectomy is difficult to quantify but clinically significant. Apart from preserving quality of life by avoiding proctectomy, when studied through Markov modeling comparing WW to radical resection , WW has been shown to be significantly more cost-effective than radical resection .Some patients with LARC may accept a lower likelihood of cure if able to avoid rectal surgery, though it remains uncertain whether there is potential oncologic harm to a patient later identified with a local regrowth and requiring a deferred total mesorectal excision (TME) . Recent For these reasons, it is necessary to understand how best to evaluate rectal cancer patients following neoadjuvant therapy. Given the limited ability to predict tumor response to neoadjuvant treatment(s) currently, patients must be thoughtfully reassessed after neoadjuvant treatment(s) ,7. CurreThe evidence reviewed in this manuscript is a summation of relevant scientific publications and current practice guidelines. This review provides expert opinion on the evolving literature reporting clinical assessment of rectal cancer in the context of organ preservation and also provides a management decision algorithm for tumor response extent interpretation. We believe this review is timely and of high clinical importance, as rectal cancer management is rapidly changing and clinical decision-making increasingly complex.Neoadjuvant treatment sequences and strategies have evolved over the last several decades, with varying permutations of pelvic (chemo) radiation and systemic chemotherapy. The heterogeneity of tumor responsiveness to these treatments demonstrates the major gap in understanding rectal cancer tumor biology . Most paTreatment intensification or escalation in the form of radiation dose boosting, novel radiosensitizers applied during long-course chemoradiation, or multi-agent systemic chemotherapy regimens are active areas of research. The intent of treatment escalation is twofold: to improve long-term oncologic prognosis and maximize the likelihood of a pathologic complete response (pCR). On the other hand, the PROSPECT trial studied the de-escalation of pelvic radiation in the hope of avoiding its related toxicity within the overarching tri-modality treatment paradigm of LARC . Schrag Total neoadjuvant treatment (TNT) strategies are considered a standard treatment paradigm in the US, reserving rectal resection as the last in the sequence of treatment, if necessary. Re-assessment throughout neoadjuvant treatment(s) allows for response-based decision-making rather than empirically prescribed management strategies. The superiority of any given TNT approach over another has yet to be firmly determined; however, all increase the proportion of LARCs reaching a pCR when compared to either neoadjuvant (chemo) radiation or chemotherapy alone prior to resection. The rate of pCR is relatively consistent across published cohorts receiving TNT and ranges between 25% and 38% ,14,15. AWhich patients should receive treatment intensification (or de-intensification) and for what intent ,17? EffoAssessing tumor response to neoadjuvant treatment(s) is ultimately subjective and suggests the probability of the presence or absence of a residual tumor. Because a cCR does not necessarily equate to a pCR, and similarly, a patient with a pCR may not satisfy clinical criteria for a cCR, WW must be cautiously approached for each patient. Patients pursuing WW should be closely monitored with CEA, clinical DRE, endoscopic examination, and imaging, including rectal protocoled MRI, at regularly defined, frequent intervals following receipt of neoadjuvant treatment(s). The factor of time from cCR designation heavily influences the conditional risk for a patient, with over 90% of local regrowth occurring within the first 2 years and over 98% within 3 years . A fundamental limitation of WW is imperfect patient selection. Because DRE, endoscopic inspection of the luminal mucosa, and functional rectal MRI sequences cannot alone detect cancer cells remaining within the bowel wall and mesorectal lymph nodes, clinicians must understand the findings from these evaluations as an association, or clinical probability, of the pathologic gold standard . Local regrowth following an apparent clinical complete response (cCR) pursuing WW surveillance ranges between 15 and 40% . These mAs experiences with WW mature, the combination of clinical, endoscopic, and rectal MRI assessment remains the most accurate modality for the identification of tumor response after TNT(s) ,27,28,29As part of the usual rectal surveillance, CEA (carcinoembryonic antigen) is monitored post-receipt of neoadjuvant treatment(s) and trended for patients following a WW approach. The frequency of checking CEA is usually paired with each endoscopy, initially every 3 to 4 months after clinically establishing a cCR (or nCR). There is no clear correlation between the pre-treatment CEA cut-off value and the probability of a favorable tumor response to neoadjuvant treatment(s). Nor is there consistent evidence that post-neoadjuvant CEA levels predict the extent of tumor regression, specifically pCR or non-pCR ,33. The There are no biomarkers available for clinical use with the accuracy needed to reliably predict or identify pCR or cCR . MoleculTactile examination by digital rectal exam (DRE) may detect subtle irregularities not apparent endoscopically or radiographically, yet suspicious for residual tumors. DRE is only possible for lower rectal cancers and is subjective to the examiner. The tumor may not be in reach of the examiner’s reach, particularly in patients with a long anal canal. When assessing tumor response, a cCR is satisfied when the mucosa is regular and smooth fibrosis or normal mucosa is palpated, although thickening and extra-rectal fibrosis are commonly appreciated. A near-complete response (nCR) may have smooth induration or minor mucosal abnormalities or irregularities, including a non-critical or clinically asymptomatic stenosis. In addition, abnormalities on DRE do not preclude a pCR . In a stEndoscopy remains the primary modality to assess the degree of rectal tumor response to neoadjuvant treatment(s). Since morphologic changes following neoadjuvant treatment(s) visualized at the time of endoscopic assessment presumedly represent varying degrees of histologic regression, the endoscopic exam is often considered the most reliable method to evaluate the completeness of tumor response. However, a lack of simple and reproducible endoscopic criteria and variability in the perception of endoscopic features characterizing tumor response limit optimal patient selection for WW ,39. AlthEndoscopic evaluation provides a magnified view of the mucosa, allowing a detailed inspection of post-treatment mucosal changes. These findings, including edema, proctitis, stenosis, and reduced elasticity on insufflation, along with other visual characteristics and cues, suggest the extent of tumor response to neoadjuvant treatments. Diagnostic accuracy may be improved by ascribing the presence or absence of reproducible visual features and patterns. The Sao Paulo group was the first to provide formal criteria for classifying endoscopic findings into a binary treatment response assessment—complete or incomplete clinical tumor response . CurrentResidual mucosal abnormalities (RMA) describe mucosal irregularities present endoscopically or on surgical pathologic specimens after neoadjuvant treatment. Several retrospective series have attempted to correlate RMA to the final pathologic stage ,46. ThesThe application of pre-specified endoscopic criteria has been associated with improved objectivity in endoscopic assessment and, consequently, accurate tumor response degree classification ,39. Pre-Since a considerable proportion of patients may reach a nCR at initial endoscopic restaging, the question of whether to observe, pursue a biopsy, locally excise, or radically resect is less clear but must be considered . A near-A routine endoscopic biopsy should not be performed, but rather selectively. Endoscopic forceps allow for a limited superficial biopsy and carry a high risk of false-negative sampling. A biopsy may fail to detect persistent malignancy in 25% of cT2 tumors and up to 40% of cT3/T4 tumors ,51. ThisA biopsy is most useful when suspicion is high for viable disease to confirm its presence pathologically . Van der Sande et al. reported a significant change in the endoscopic confidence level of tumor response extent following endoscopic biopsy in 4% to 13% of patients, suggesting the uncertain but likely limited role of endoscopic biopsy in determining the completeness of tumor response . In caseA potential alternative to the shortcomings of a superficial endoscopic biopsy is full-thickness rectal wall local excision (FTLE), allowing the pathologic T-stage to be confirmed. This is especially helpful when there is an equivocal clinical and radiologic interpretation of the degree of tumor response. In this way, FTLE may overcome the inherent subjectivity of clinical, endoscopic, and radiologic assessments, allow the selection of patients for WW, and provide tailored surveillance, particularly when a near clinical complete response is present. Currently, neither the expert consensus of the NCCN nor the ASCRS Clinical Practice Guidelines consider LE an acceptable therapeutic option for a fit patient with LARC pursuing a rectal organ preservation strategy ,52.In addition to the inability of FTLE to adequately sample mesorectal nodes, the phenomenon of non-uniform ‘tumor scatter’ beyond the visible residual endoluminal mucosal abnormality has been posed as a limitation when determining local excision lateral margins ,54,55,56There are clear benefits to obtaining accurate diagnostic pathologic data; however, FTLE is not widely pursued in part due to the risk of severe postoperative toxicities. Significant wound healing morbidity has been associated with FTLE in the irradiated rectum and has tempered its application as a diagnostic and/or therapeutic management tool . Perez eNot only can wound healing complications compound difficulties in subsequent rectal interpretation during surveillance, but FTLE may also compromise the quality of the mesorectal excision specimen’s integrity if radical surgery is later recommended following pathologic T-stage confirmation. Patients recommended to undergo short interval total mesorectal excision following FTLE pathologically confirming more than limited disease or containing unexpectedly higher risk histology  have been shown to have inferior quality of mesorectal specimens, higher rates of non-sphincter sparing resections, and greater perioperative complications ,61,62,63When highly suspected to fulfill criteria for a cCR, FTLE should not be routinely performed to confirm ypT0 pathologically due to the risks for acute and long-term anorectal and bowel impairment when compared to patients observed with a sustained cCR and followed by WW . FTLE miRadiographic local rectal tumor response assessment is currently best performed with rectal protocoled MRI and is the currently accepted standard of care . Rectal Imaging Regression Schema: For each type of response, we see pre-therapy imaging to the left and post-treatment to the right.Complete Clinical Response (cCR): cCR highlights a complete response through imaging. For T2 response, cCR has a dark T2 signal, which is well demonstrated on post-therapy images (arrow). Lymph nodes with a cCR show complete or near-complete resolution, which is demonstrated by both cases (arrow). For DWI, cCR displays no signal on high-B value DWI, and for ADC, cCR highlights no low signals (arrows).Near-Complete Clinical Response (nCR): nCR shows findings of response to therapy with some concern for a small amount of residual disease. nCR has both a dark and intermediate signal on T2 imaging. This patient had a mid-rectal mass with an intermediate signal (arrow) on pre-contrast imaging that extended beyond the muscularis propria (chevron). On post-therapy imaging, there is a combination of dark and intermediate T2 signals with fibrotic tethering but no clear extension beyond the muscularis propria. For lymph nodes, nCR demonstrates regression (arrows). For DWI and ADC maps, nCR demonstrates minimal to low residual signals (arrows). Note that the signal on DWI post-therapy imaging is difficult to detect, but the persistent intermediate signal on T2w imaging confirms the nCR designation.Incomplete Response (iCR): iCR demonstrates distinct imaging findings of recurrent/residual disease. For T2 response, iCR shows a predominance of intermediate T2 signal with no dark scar. There has been some reduction in the extent of the lower rectal mass (arrow), but post-treatment imaging illustrates clear intermediate T2w signal with no signs of a dark fibrotic response. The chevron details the right side of the puborectalis sling which abuts the mass but with no clear signs of tumor invasion. Regarding lymph nodes, iCR generally demonstrates no change in imaging features. There has been a decrease in the size of the IMA lymph node (arrow) which suggests some response, but an overall conclusion of iCR is still governed by the T2w and DWI features of the mass. For DWI, iCR displays no loss of signal on high b value DWI (arrow). For ADC, iCR illustrates clear loss of signal which is best demonstrated on pre-therapy and post-therapy images.Despite improvements in technology and experience interpreting post-treatment rectal MRI, accurately distinguishing fibrosis from viable disease remains a challenge. In a randomized, prospective multi-institutional total neoadjuvant treatment trial, the positive predictive value of MRI interpreting a pathologic complete response was only 40%, despite three highly specialized radiologists centrally reviewing and agreeing on the findings. Conversely, the negative predictive value of identifying residual tumor as determined by restaging MRI and confirmed by pathology reached up to 90% . In a DuSimilar to endoscopic evaluation, this may be in part due to the tendency to err on the side of caution when interpreting any area of abnormalities, including fibrosis, at risk of containing a small volume of viable microscopic disease. These data are consistent with other series, highlighting the need to combine MRI morphologic and DWI response patterns with DRE and endoscopy to most accurately assess the extent of local tumor response to neoadjuvant treatment ,29,72.The role of FDG–PET for local evaluation, treatment response, and/or surveillance is not well studied. Combining PET with MRI may overcome the limitations of both modalities; however, microscopic residual disease and post-treatment inflammation still result in diagnostic uncertainty .Currently, the most accurate strategies to assess the extent of rectal tumor response to neoadjuvant treatment(s) include a combination of digital rectal exam, endoscopy, and MRI imaging utilizing T2 weighted and DWI sequences. Despite ongoing refinements of these tools, there remains a moderately high rate of local regrowth, highlighting the shortcomings of recognizing microscopic residual local disease admixed with treatment-related fibrosis. Advances in sophisticated imaging techniques and computational data processing segmentation, along with increasingly sensitive biomarkers for low-volume microscopic residual disease, may enhance the ability to discriminate between a scar and an incomplete response to neoadjuvant treatment(s) to best select rectal cancer patient for nonoperative management.


Recent large-scale sequencing efforts have shed light on the genetic contribution to the etiology of congenital heart defects (CHD); however, the relative impact of genetics on clinical outcomes remains less understood. Outcomes analyses using genetics are complicated by the intrinsic severity of the CHD lesion and interactions with conditionally dependent clinical variables.Bayesian Networks were applied to describe the intertwined relationships between clinical variables, demography, and genetics in a cohort of children with single ventricle CHD.As isolated variables, a damaging genetic variant in a gene related to abnormal heart morphology and prolonged ventilator support following stage I palliative surgery increase the probability of having a low Mental Developmental Index (MDI) score at 14 months of age by 1.9- and 5.8-fold, respectively. However, in combination, these variables act synergistically to further increase the probability of a low MDI score by 10-fold. The absence of a damaging variant in a known syndromic CHD gene and a shorter post-operative ventilator support increase the probability of a normal MDI score 1.7- and 2.4-fold, respectively, but in combination increase the probability of a good outcome by 59-fold.Our analyses suggest a modest genetic contribution to neurodevelopmental outcomes as isolated variables, similar to known clinical predictors. By contrast, genetic, demographic, and clinical variables interact synergistically to markedly impact clinical outcomes. These findings underscore the importance of capturing and quantifying the impact of damaging genomic variants in the context of multiple, conditionally dependent variables, such as pre- and post-operative factors, and demography. Single ventricle congenital heart disease is a birth defect. In these children, the heart has only one effective blood-pumping chamber instead of two. Surgery can reroute the blood to use only one chamber, but multiple risk factors influence how well a child develops afterwards. Studying these risk factors can be challenging because they are interconnected, i.e. children with a genetic birth defect may be more likely to have a lower birthweight, and hence more likely to spend longer in hospital after surgery. Here, we used a statistical approach not commonly applied to study congenital heart disease and describe that whether a genetic variant  is important for how a child with single ventricle heart disease develops and grows after surgery depends on the presence of other risk factors. Miller, Hernandez et al. demonstrate a modest genetic contribution to neurodevelopmental and growth outcomes in single ventricle heart disease, and a markedly synergistic effect of genetic, demographic, and clinical variables. This shows the importance of quantifying the impact of genomic variants in the context of conditionally dependent variables. Despite improvements in standardized care, neurodevelopmental and growth outcomes vary substantially in children with SV-CHD2. Identifiable syndromes and chromosomal abnormalities are associated with worse outcomes for multiple forms of complex CHD6. Predicted damaging genetic variants in genes related to CHD may contribute to poor outcomes, irrespective of whether the patient has syndromic CHD. Outside of aneuploidy and other known syndromes, the genetic architecture of CHD includes high-impact, rare variants across many loci. Thus, many variants that contribute to CHD have a small population-attributable risk (PAR)8. This low PAR makes determination of the association of variants with outcomes difficult, especially when studying relatively small numbers of individuals with SV-CHD. As a result, the relative contribution of genomic variation to neurodevelopment and growth outcomes remains poorly described, especially in the context of clinical variables and other comorbidities, which can combine with one another in a conditionally dependent manner to create a constellation of influence on any given outcome9. Two clinical variables are conditionally dependent if the probability of encountering both variables is not equal to the multiplication of their individual probabilities. For example, sex and bicuspid aortic valve (BAV) are conditionally-dependent, in that the probability of encountering an individual with bicuspid aortic valve is greater for males versus females10.While survival for infants with single ventricle congenital heart disease (SV-CHD) has improved dramatically, significant healthcare utilization, morbidity, and mortality persist8. Compared to traditional regression models, Bayesian Networks offer many advantages to risk prediction, as a single network can be used to evaluate multiple outcomes based upon any combination of variables or exposures12. Moreover, Bayesian Networks provide improved means to quantify the synergistic impacts of demographic, clinical, and genomic variables. In this context, we apply Bayesian Networks in an exploratory, proof-of-principle analysis to explore the landscape of damaging genotypes on neurodevelopmental and linear growth outcomes in the Pediatric Heart Network’s (PHN) Single Ventricle Reconstruction (SVR) trial and Infant Single Ventricle (ISV) trial participants.We recently reported the conditionally dependent relationships between genotypes, gene functions, and phenotypes in a large CHD cohort using Bayesian Networks, an Artificial Intelligence (AI) solution17. Both trials excluded participants with known chromosomal abnormalities or syndromic features at the time of enrollment. Institutional Review Boards for all centers participating in the SVR and ISV trials gave ethical approval for the human subjects research in this work and written informed consent was obtained. Data Use Agreements between the PHN and the Pediatric Cardiac Genomics Consortium (PCGC) allowed for the de-identified sharing of genetic and limited clinical data between the two consortia. All SVR and ISV participants who had whole exome sequencing (WES) and neurodevelopmental follow-up at 14 months of age were included in this cohort. Sub analyses were performed on those who had complete matching clinical and demographic variables.Participants in the PHN’s SVR and ISV trials who had blood or saliva collected for DNA extraction were included in this study. The original study design, descriptive characterization of the cohort, and primary results of the SVR (NCT00115934) and the ISV (NCT 00113087) trials have previously been publishedz-score, LAZ) for both the SVR and ISV trials at 14 months of age. BSID-II subdomain scores included the Psychomotor Developmental Index (PDI) and Mental Developmental Index (MDI), wherein the standardized mean scores are 100. While it is true that MDI and PDI are assessed at the same time, we consider these variables within the Bayesian Networks as both outcomes and risk factors, in order to highlight the ability of our approach to capture and quantify synergistic (non-additive) relationships between variables under study. An advantage of our approach is that the use of a Bayesian network allows us to employ a single model to explore the impact of highly correlated variables singly or jointly, as outcomes and as risk factors to generate the results shown here. Additional pre- and post-operative clinical and demographic variables were available for a subset of 179 SVR participants, including birthweight, duration of mechanical ventilation following the Stage I palliation surgery, gestational age, and US census socioeconomic scores.Outcomes included the Bayley Scales of Infant Development (BSID-II) and length measurement , ventilation following the Stage I palliation surgery , gestational age , and US census socioeconomic score .In order to optimally discretize continuous variables, we used a grid search to evaluate the performance of the nascent Bayesian Network, using receiver operating characteristic (ROC) curves  using the Burrows-Wheeler Alignment (BWA) Tool and the MEM algorithm (http://bio-bwa.sourceforge.net/bwa.shtml#13). Variants were called using the best practice protocol of the Genome Analysis Toolkit (GATK) pipeline (http://www.broadinstitute.org/gatk/guide/best-practices). All exomes were jointly-genotyped together with ~190 European individuals  from the 1000 Genomes Project. This was followed by Variant Quality Score Recalibration (VQSR), which uses known, high-quality variant sites from HapMap3 and 1000 Genomes to identify and filter potential false positive variant calls. Both variant calling and VQSR were performed separately on INDELs and single nucleotide variants (SNVs). Tranche values were set to 99.5 and 99.0 for SNPs and INDELs, respectively. Variant consequences and annotations were obtained with VEP v.95 (uswest.ensembl.org/info/docs/tools/vep/script/vep_download.html) utilizing ENSEMBL transcripts version 95 (excluding non-coding transcripts) and selecting the canonical transcript for analysis. Transcript-specific prediction for evaluating variant deleteriousness was calculated with VVP20, which were also used as input for VAAST (VVP and VAAST: [github.com/Yandell-Lab/VVP-pub])21. Variants were annotated with ClinVar (20200419) ensuring exact position and base match. Gene-conditions were extracted from the Online Mendelian Inheritance in Man (OMIM) catalog (2020_07)22 and the Human Phenotype Ontology (HPO) database 23. Gene symbols were harmonized using ENSEMBL and HGNC databases controlling for synonymous gene symbols.Raw sequencing data in the form of fastq files (Illumina 101 bp paired-end reads) for each individual were aligned to the human genome reference sequence . GEM inputs are genetic variant calls in VCF format and proband phenotypes in the form of HPO terms. GEM aggregates inputs from multiple variant prioritization algorithms  with genomic and clinical database annotations, using Bayesian means to score and prioritize potentially damaged genes and candidate diseases. The prior probability for the model is based upon known disease associations in the Mendelian conditions databases OMIM and/or HPO with the gene in question. In order to capture a broad category of genes related to heart development, we selected the HPO term Abnormal Heart Morphology (HP:0001627).AI-based prioritization and scoring of candidate disease genes and diagnostic conditions were performed using GEM25, representing the log10 ratio between the posterior probabilities of two models, summarizing the relative support for the hypothesis that the prioritized genotype damages the gene in which it resides and explains the proband’s phenotype versus the hypothesis that the variant neither damages the gene nor explains the proband’s phenotype. We used a Bayes factor of ≥0.69 to represent a likely deleterious genetic variant, based on a recent retrospective analysis of critically ill newborns whereby a Bayes factor threshold ≥0.69 successfully achieved a diagnostic rate of 95% for cases solved using a standard clinical diagnostic approach24. Each variant that passed the 0.69 threshold was evaluated using the graph-based adjudication tool Graphite, which constructs a variant graph that permits the exclusion of false positives due to errors in variant calling (github.com/dillonl/graphite)8. Gene penetrance for GEM calculations was set to 0.95 to enforce strict consideration of known dominant and recessive disorders.GEM’s gene scores are Bayes Factors26 which provides a Bayesian Information Criterion (BIC)-based exact structure search algorithm )27. The exact search algorithm explores the entire applicable space of conditional dependencies in order to discover the optimal network structure for the data. Parameter learning for this optimal network and multimorbidity risk calculations were accomplished using the loopy belief propagation algorithm from the R gRain package28. The conditional dependencies in the dataset are presented as a directed acyclic graph. Risk estimates derived from Bayesian Networks are maximum likelihood estimates given the optimal structure under the BIC and uniform prior probability. Relative risk was calculated in the following manner: Probability /Probability . Confidence intervals  for the mean values for these estimates were obtained by creating 1000 nets from bootstrap replicates of the same data.Bayesian Network structure was learned using the R package “bnstruct”Differences in testing scores (MDI and PDI) and LAZ for those with and without damaging genetic variants in various gene categories were assessed using independent non-parametric Mann-Whitney U Test, correcting for multiple comparisons using a Bonferroni correction.17. Of those that underwent WES, there were 21 individuals who were enrolled in both SVR and ISV trials. For this study, a total of 304 participants underwent WES, neurodevelopmental assessment, and length measurement at 14 months of age and form the primary study cohort. Patient-parent trio WES was available for 86 participants. Additionally, the selected pre- and post-operative clinical and demographic variables were available for a subset of 179 SVR participants. Distribution of sex, race, ethnicity, cardiac anatomy, gestational age, and birthweight were similar across the various cohorts N = 41), X-linked recessive (N = 4), X-linked dominant (N = 1) and autosomal recessive (N = 1) inheritance modes , NOTCH1 , ANKRD11 (N = 3 KBG Syndrome), MED12 , SHANK3 , and SRCAP . While there was a trend toward lower MDI and PDI scores for participants with versus without a damaging variant in the syndromic CHD gene list, the differences were not significant after correction for multiple testing . A damaging de novo genetic variant in the HPO-term derived gene list was identified in 10 probands, representing 12% of the cohort with trio WES data , each harboring a mean of 1.8 damaging variants/proband . When combined with normal linear growth (LAZ > 0) and MDI ( > 100) scores, the absence of a damaging CHD syndromic genetic variant increased the probability of a normal PDI score by 16.5-fold.The contribution of genetics to PDI score was most impactful when considering predictors of a favorable PDI outcome  are underestimated by the initial exclusion of known syndromic patients. The power of this Bayesian approach is that we can tease apart the contribution of syndromic genes (or other gene classes) to clinical outcomes and thereby predict risk across all patients.Our analyses reveal a modest genetic contribution to poor neurodevelopmental outcomes in probands harboring a damaging variant in abnormal heart morphology genes versus syndromic CHD genes. In the context of predicting a favorable outcome, absence of a damaging variant in the syndromic CHD gene list was more impactful. Although individuals with known syndromic disorders were excluded from enrollment in the SVR and ISV trials, we found that 14% of the SV-CHD cohort harbored a damaging genetic variant in a gene known to cause syndromic CHD, including 29.An advantage of Bayesian Networks is the ability to capture and quantify the joint contributions of multiple conditionally dependent variables, all within a single probabilistic graphical model. Traditional techniques, such as regression analyses, have limited ability to capture the conditional dependencies between clinical variables. While mixture and generalized linear models can overcome these weaknesses, they require the design of a new model to address each individual question. Neural nets, while capable of capturing conditional dependencies, lack explainability in that the contributions of different variables on a given output are often unclear. By contrast, Bayesian Networks provide an explainable AI solution9.Our Bayesian Network approach allowed us to start to describe the landscape of clinical, genetic and demographic variables in children with SV-CHD, capturing and quantifying the impacts of synergistic relationships between these variables and outcomes of interest. Genetic variables interacted synergistically with duration of post-operative mechanical ventilation to increase the probability of a poor or favorable MDI score by 10- and 59-fold, respectively. Likewise, genetic variables interacted synergistically with SES to increase the likelihood of a favorable PDI score by 53-fold. Our analyses here were limited to the relatively small number of individuals with complete clinical variables; precluding further exploration of the impact of a damaging genetic variant on pre- and post-operative variables, as well as SES. Expanding the analysis to the wider range of clinical variables associated with this well-phenotyped cohort and increasing the number of genotyped probands will provide greater insight into the genetic contribution to clinical outcomes in SV-CHD. In a broader sense, the current work supplements our efforts using Bayesian Networks as an explainable AI solution for understanding the joint impacts of diagnoses, medications, and medical procedures on cardiovascular health outcomes30. Our rationale for defining a damaging variant was based on a recent study benchmarking the AI tool against clinically solved cases24. Stricter criteria for a damaging classification will allow for fewer false positives, but at the expense of false negatives and vice versa. However, the expectation is that false positives will dilute genetic signals, but truly benign variants are a priori not positively correlated with negative outcomes. Thus, the magnitudes and statistical significance of the associations between damaging genotypes and clinical variables reported here should be thought of as lower bounds. Finally, the goal of this study was to highlight the advantages of an AI-based Bayesian Networks approach as a proof-of-principle analysis, leveraging existing ISV and SVR clinical and genetic data. In this context, the risk predictions are directly relevant to the study cohort, but cannot be more widely applied without a validation cohort.There are several limitations inherent to this study. For example, DNA collection was not a requirement for participation and thus, sample procurement was inconsistent across the cohort. Moreover, DNA samples were not obtained at enrollment, but rather at subsequent time points in these longitudinally followed cohorts, thereby introducing survival bias. Some DNA samples were collected at a few years of age which would have been well after the 14-month clinical endpoints included in these analyses. Thus, patients who died early may have harbored highly damaging genotypes that are not accounted for in this cohort of infants that survived at least until the 14-month endpoint. The later DNA analysis also highlights the limitations of the original exclusion criteria, as some individuals in SVR were later found (during enrollment in SVR extension studies) to have syndromes, such as Kabuki Syndrome, consistent with our variant analysis. Additionally, we recognize the relatively small sample size of patients limited the ability to include all potential peri-operative, clinical, and socio-economic predictors of outcomes in this proof-of-principal analysis. Future efforts by the PHN consortium to sequence more patients with rich clinical datasets as well as by the PCGC to obtain richer clinical data on their sequenced patients, will allow for more robust analyses of the genetic contribution to clinical outcomes in children with complex forms of CHD. The definition of a “damaging” genetic variant is a topic of intense debateCollectively, our findings highlight how genetics, demography, and clinical variables interact synergistically to impact neurodevelopmental outcomes and underscore the importance of capturing and quantifying these synergies. We have also demonstrated the utility of Bayesian networks for conditional risk analyses. Moving forward, large-scale collaborations between genetic and clinical consortia will provide more extensive datasets to better understand the synergistic impacts of genetic and clinical variables on clinical outcomes in children with CHD.Further information on research design is available in the Peer Review FileSupplementary InformationDescription of Additional Supplementary FilesSupplemental data 1NR reporting summary


The past decade has seen significant advances in dynamic imaging of the aorta. Today’s vascular surgeons have the opportunity to choose from a wide array of imaging modalities to evaluate different aortic pathologies. While vascular ultrasound and aortography are considered to be the bread and butter imaging modalities, newer dynamic imaging techniques provide time-resolved information in various aortic pathologies. However, despite growing evidence of their advantages in the literature, they have not been routinely adopted. In order to understand the role of these emerging modalities, one must understand their principles, advantages, and limitations in the context of various clinical scenarios. In this review, we provide an overview of dynamic imaging techniques for aortic pathologies and describe various dynamic computed tomography and magnetic resonance imaging protocols, clinical applications, and potential future directions. Dynamic imaging is a rapidly evolving yet not fully adopted technique in the realm of medical imaging modalities. Most aortic pathologies have a dynamic component, such as aortic dissection, and any imaging technique must be nimble enough to capture this dynamic nature—not only to enable better diagnosis but also to aid in determining optimal treatment options. To account for cardiac motion-related artifacts, especially in the ascending aorta and aortic arch, an electrocardiogram (ECG)-gated imaging protocol typically is performed. The word “dynamic” in dynamic imaging can be broadly interpreted as introducing time as the fourth dimension to evaluate the dynamics of contrast enhancement in the aorta—for example, time-resolved angiography. In addition, such novel dynamic imaging techniques can enable one to assess and quantify the direction, velocity, and volume of blood flow to impact clinical decision-making, patient management, and optimal post-interventional surveillance.Most cardiovascular imaging modalities have a dynamic component, including vascular ultrasound with contrast enhanced ultrasound, echocardiography, intravascular ultrasound, x-ray angiography, dynamic computed tomography angiography (d-CTA), and dynamic magnetic resonance angiography (MRA), such as 4-dimensional (4D) flow magnetic resonance imaging (MRI).Although each of the above-mentioned modalities can provide “dynamic” information during the evaluation of aortic pathologies, we limit the scope of this article to discussing the three most commonly used noninvasive dynamic 3D cross-sectional imaging techniques: dynamic CTA, dynamic MRA, and 4D flow MRI. Herein we provide an overview of dynamic aortic imaging techniques, describing various CT/MRI protocols, clinical applications, and potential future prospects.1 In addition, ECG-gated CTA can be used to evaluate cardiac, ascending aortic, and arch pathologies by acquiring a series of CTA datasets (approximately10 scans) across different points of the cardiac cycle.2 These two techniques also can be combined to provide time-resolved contrast kinetics and ECG gating for cardiac motion, especially in the setting of post endograft surveillance in the ascending aorta and aortic arch.3 The technical details and our institutional CT aortic imaging protocols are summarized in Like conventional CTA imaging, d-CTA involves acquiring a series of CTA datasets (approximately 5-12 scans) across different points of the contrast enhancement curve after a bolus of iodinated contrast injection , 2, 3.1 Unlike CTA imaging, MRI can provide better insights into aortic pathologies by imaging vessel wall characteristics without any additional radiation exposure. However, its clinical utilization is still evolving due to relatively longer acquisition times, the need for a dedicated setup, a steeper learning curve, and understanding and optimizing multiple MR imaging sequences. The technical details and our institutional MR aortic imaging protocols are summarized in Aortic pathologies cover a broad spectrum of vascular diseases of the aorta, spanning from the aortic valve to the distal abdominal aorta. In this section, we provide a descriptive overview of clinical applications of the dynamic imaging technique across various aortic pathologies and its impact on treatment planning and guidance based on our early clinical experience.5 Transthoracic echo (TTE) is considered to be the mainstay of diagnosis and classification of disease severity, providing information on peak jet velocity, mean transvalvular pressure gradient, and aortic valve area. Contrast-enhanced CTA imaging is also a standard-of-care imaging technique to facilitate better aortic morphometry and plan for potential transcatheter therapies. In the setting of AS, cardiac MRI is performed in select situations to study any other associated cardiac anomalies and to provide better noninvasive hemodynamic information. Adriaans et al.6 compared TTE and 4D flow and found the latter to improve concordance between AS parameters regarding peak jet velocity, mean transvalvular pressure gradient, and aortic valve area. The study suggested the potential of 4D flow MRI as a comprehensive noninvasive quantitative technique, especially in patients with inconsistent findings on TTE.In developed countries, aortic stenosis (AS) ranks as the most common valvular heart disease, occurring in 12.4% of elderly patients.8 CTA adds the anatomical information required for invasive treatment planning. In addition, cardiac MRI is considered to be a complementary imaging technique, although it gives more accurate information on left ventricle volume, mass and function as well as aortic dilatation compared with TTE.10Aortic regurgitation (AR) can occur with or without AS, and TTE is the gold standard modality for diagnosis and evaluation based on current guidelines.Acute aortic syndrome is an umbrella term referring to aortic dissection, intramural hematoma, and penetrating aortic ulcer. All three conditions are considered potentially lethal and may overlap with each other.Since acute type A dissection presents as an imminent life-threatening condition, MRI currently is not considered an option for preoperative planning given its time-consuming nature, nor is dynamic CTA due to its limited field of view.11 and blood flow enters the space between the intimal and medial layers of the aorta, creating true and false lumen throughout the length of the affected aortic segment. The intimal flap may compromise blood supply via the aortic branches by causing either dynamic or static obstruction. In general, standard operative strategy for complicated TBAD includes primary entry tear coverage with a stent graft to facilitate false lumen collapse and positive aortic remodeling, although dynamic imaging may uncover a more distal tear as the one supplying the false lumen. Failure of culprit fenestration coverage could lead to subsequent interventions, increasing the risk for perioperative morbidity such as access-related complications, progression of aortic dissection, or spinal cord ischemia. Moreover, dynamic imaging could also aid in discerning between dynamic and static obstruction of visceral vessels, consequently affecting operative planning. While d-CTA is capable of the latter, given the limited field of view, it does not allow for imaging of the entire aorta, which excludes d-CTA from initial TBAD assessment. In fact, it can be preserved for follow-up imaging to address specific questions, such as determining residual static versus dynamic occlusion of the aortic branches.Type-B aortic dissection (TBAD) occurs when a tear develops in the intimal layer distal to the origin of the innominate artery,16 Apparently, 4D flow MRI seems comparable to triphasic CTA in terms of fenestration detection in TBAD patients based on the study conducted by Allen et al.12 Another study concluded that 4D flow MRI image quality is comparable to CTA for TBAD assessment.13 A third paper evaluated false lumen pressure analysis in chronic TBAD patients and identified false lumen ejection fraction and absolute pressure difference between distal false lumen and aortic root as independent factors for aortic growth.14 Ruiz-Muñoz et al. examined false lumen flow dynamics and biomechanics and identified in-plane rotational flow, pulse wave velocity, and false lumen thrombus as factors positively related to aortic growth in chronic aortic dissection patients.16Overall, several studies have been published regarding 4D flow MRI in TBAD patients, yet each of them lacks long-term follow-up and an appropriate number of cases.On the whole, the concept of 4D flow MRI imaging in TBAD patients seems to be established ; however17 On the other hand, dynamic MRA affected the treatment plan for 10 out of 19 patients, which underlines the importance of dynamic imaging in this particular aortic pathology  to high-resolution contrast-enhanced MRA in acute aortic dissection patients. On one hand, they have found the latter as significantly more sensitive and even comparable to CTA in terms of image quality.athology .19Intramural hematoma (IMH) occurs when blood enters the intimal/medial layer without visible entry tear. Penetrating aortic ulcer (PAU) develops in the aortic wall as a focal outpouching to the internal elastic lamina due to atherosclerotic plaque erosion and inflammatory changes.21 however the role of dynamic imaging is not yet established in the setting of these types of aortic pathologies. Although in theory dynamic imaging could provide additional information on the feeding vessel and blood pool in cases of acute/subacute IMH, further research is necessary to acquire sufficient evidence-based data.In general MRI is an excellent modality to assess and follow IMH and PAU lesions,22 Berczeli et al. recently highlighted that d-CTA imaging can help in understanding the pathophysiology behind these blood pools by identifying flow direction and their source.23IMH is a dynamic phenomenon, thus addressing it with time-resolved imaging can help to better identify influencing factors. IMH has several imaging features, such as intramural blood pools, which are considered a benign prognostic factor and may favor conservative management.24 CoA is responsible for 5% to 7% of congenital heart disease cases and predisposes to hypertension, aortic insufficiency, aortic dissection, and aortic aneurysm.26 Based on the location of the narrowing, CoA is classified as preductal, ductal, or postductal, the latter being the most common type in adults.27 Treatment is based on pressure gradient through the stenosis and post-stenotic pressure loss.28 When the systolic pressure gradient exceeds 20 mm Hg, intervention is recommended according to current guidelines.26 The pressure gradient could be measured either by invasive catheterization or by TTE. 4D flow MRI offers a noninvasive alternative to measure flow proximal and distal to the coarctation in all three dimensions, addressing the shortcomings of the previous two modalities, namely invasiveness in case of catheterization and the lack of time-resolved 3D information on part of TTE. Additionally, 4D flow MRI provides information about the collateral flow as well.29 Riesenkampff et al. compared 4D flow MRI and catheterization, in terms of pressure measurement at 5 different locations on the aorta and concluded a good agreement between the two modalities, suggesting that 4D flow MRI could potentially replace invasive catheterization in the evaluation of CoA.26Aortic coarctation (CoA) is a congenital cardiovascular condition in which the aorta is narrowed, most commonly around the level of the ligamentum arteriosum.Overall 4D flow MRI is a promising technique regarding CoA assessment, which may guide the perioperative management of patients with CoA in the future.3 The descending thoracic and abdominal aorta have not been studied extensively in terms of dynamic imaging, to date. Based on the data published on 4D flow MRI performed on ascending aortas, wall shear stress and oscillatory shear index (instantaneous WSS fluctuation) play an important role in ascending aorta dilation.32 These findings are probably applicable to the descending thoracic aorta, although further studies are required to explore the role of 4D flow MRI at the level of the descending thoracic aorta.The term “aneurysm” refers to a localized dilation involving all 3 layers of the vessel, which exceeds the normal caliber by more than 150%. The most common thoracic aortic aneurysms are located on the ascending aorta (40%), followed closely by descending thoracic aortic aneurysms (35%). The aortic arch (15%) and the thoracoabdominal localization (10%) are considered less frequent. Due to recent advancements in aortic graft development, in specific scenarios, the ascending aortic stent graft implantation offers a feasible alternative to open repair. However, follow-up of these grafts presents a challenge with traditional d-CTA, given the frequent occurrence of cardiac motion related artefacts. In these instances, dynamic electrocardiography-gated CTA offers a viable solution and optimizes imaging sensitivity for endoleak detection.33 Endovascular aneurysm repair (EVAR) is the mainstay of infrarenal abdominal aortic aneurysm (AAA) treatment due to its superior perioperative survival rate compared to open surgical repair,37 type II endoleak (T2EL) being the most common endoleak following EVAR procedures.38 T2EL is caused by retrograde filling of the aneurysm sac after stent graft implantation, usually from lumbar branches and/or the inferior mesenteric artery (IMA). Although dynamic imaging may not provide additional information compared to triphasic CTA and MRA in the preoperative evaluation of infrarenal AAAs, it presents a unique option during the course of postoperative follow-up in terms of diagnosing and differentiating between the various types of endoleaks and determining the culprit vessel(s) feeding the aneurysm sac in the setting of T2EL.39The infrarenal aorta is considered the most common predilection location for aneurysmal disease.42 Additionally, Berczeli et al.42 demonstrated the applicability of d-CTA in intraoperative image guidance as well, underlining the versatility of this particular imaging modality. However, as tempting as it seems to perform d-CTA for routine follow-up after EVAR, in our day-to-day practice we tend to reserve it for cases where findings on triphasic CTA are inconclusive regarding the origin of the endoleak . Also, 4D flow MRI acquisition must become faster and more accurate to offer an alternative to CTA in acute cases and to reach widespread recognition. Additionally, the general knowledge of this modality must be established to take full advantage of it. One approach to these challenges could be the introduction of compressed sensing, more robust automated segmentation, and utilization of computational fluid dynamics with adaptive mesh refinement.Currently, dynamic imaging in general is used sporadically without a uniform disease-tailored protocol, which is natural given the lack of large cohort longitudinal trials. Therefore, more large-scale studies are required to establish evidence in dynamic imaging of the aorta. Time-resolved cross-sectional imaging modalities carry great potential and may open the door to a new era in vascular surgery, where we can offer patient-tailored treatment for a variety of aortic pathologies to an extent never seen before.


Bifid condyle is a rare developmental anomaly that results from an obstructed blood supply during its development. Bifid condyle is more often unilateral, although bilateral. A case of a bifid condyle is evaluated three-dimensionally in three orthogonal planes namely coronal, sagittal and axial sections. The etiology, clinical features, diagnostic, non-surgical and surgical treatment modalities of bifid condyle are discussed. A bifid condyle is a rare developmental anomaly affecting the temporomandibular joint's condyle . A bifidA 26-year-old male reported to the dental outpatient department with a chief complaint of pain in his left temporomandibular joint region for the past two days. History revealed the patient had clicking of the temporomandibular joint for the past six months during movements of the mandible, and there was no history of trauma to the temporomandibular joint. Further probing of his family history revealed he was born between parents of a non-consanguineous marriage. His medical history was non-contributory. On probing, his past surgical history among his family members revealed he was born of non-forceps delivery. In addition, extraoral examination revealed the absence of facial asymmetry due to any swelling or any visible scars near the temporomandibular joint Figure .On further examination, the mandible deviates to the left side during the initial mouth opening and returns to the centric relation position during maximum mouth opening Video .On palpation, no tenderness present on temporomandibular joint regions. The intraoral examination did not reveal any occlusal derangements. However, intrinsic chalky white enamel areas and discrete enamel mottling are present on all teeth Figure .The provisional diagnosis was made as internal derangement of the articular disc of the left temporomandibular joint (TMJ) region and dental fluorosis. The anterior disc displacement with reduction type of internal derangement is also associated with a second reciprocal click, which is not appreciable in clicking of TMJ caused by bifid mandibular condyle. Magnetic resonance imaging (MRI) of TMJ with 3 Tesla helps to study the finer details and changes in the articular disc in such instances. Sagittal section cone-beam computed tomography (CBCT) revealed two condylar heads on the left temporomandibular joint  image revealed a bifid condyle involving the left temporomandibular joint (TMJ) Figure .A final diagnosis of the bifid condyle was made. The patient was counseled for surgical procedures but was afraid to undergo surgery, so he refused surgical treatment. Instead, the patient has been prescribed a tablet of ketorolac tromethamine 10 mg twice daily for three days to provide symptomatic pain relief. In a follow-up after a week, the patient was relieved from his pain over the left temporomandibular joint (TMJ).DefinitionBifid condyle is a rare developmental anomaly that affects the condylar head of the temporomandibular joint (TMJ), resulting in bifid (two) condylar heads resembling heart-shaped condyle .SynonymsThe bifid condyle is also known as the double-headed condyle.EtiologyThe etiology of the bifid condyle is unknown and controversial. The embryonic theory states that bifid condyles occur when the blood supply to the condyle is blocked or when fibrous septa persist. Some authors attribute the formation of bifid condyle due to underlying trauma . Trauma,EpidemiologyThe prevalence of bifid condyle is 0.31% to 1.82%. No age predilection exists. However, bifid condyle occurs in age groups of six to 35 years . The stuClassificationBifid condyle is also known as double-headed condyles. The classification of the bifid condyle is enumerated in Table Clinical featuresThe clinical features of bifid condyle vary from asymptomatic cases to progressive pain over the temporomandibular joint (TMJ), facial asymmetry, stuck disc, progressive deterioration with a reduction in mouth opening and lateral mandibular excursions . A bifidDiagnosisBifid condyles are better appreciated more commonly by specialized radiographic techniques like computed tomography, magnetic resonance imaging and cone-beam computed tomography imaging techniques than conventional orthopantomography. Computed tomography and cone-beam computed tomography provide three-dimensional visualization of condyles in three orthogonal planes namely the coronal, sagittal and axial sections. In conventional radiographs like panoramic radiography, bifid condyle may not be apparent sometimes, since orthopantomography is a two-dimensional imaging technique, where the presence of an aberrant extra condyle is masked by superimposition or overlapping of the functional posteriorly placed condyle over the anterior head .TreatmentThe treatment modalities for bifid condyle depend on the clinical signs and symptoms . No treaThe uniqueness of the case report is that it describes a rare TMJ developmental anomaly, which usually goes unnoticed and is mostly discovered incidentally by routine radiographic evaluation. The case describes a bifid condyle in the absence of any occlusal derangement. This case report enumerates light on the etiology, clinical features, diagnostic and treatment modalities of bifid condyle that every dentist must know. A non-surgical pharmacotherapeutic treatment modality was provided for this rarest developmental anomaly affecting the condyle in our case. Hence, invasive surgical treatment, which can also be prone to infection, is prevented.Bifid condyle is a rarest developmental variation resulting in a bifid condylar head resembling a heart-shaped condylar head. Bifid condyle is diagnosed chiefly by incidental radiological evaluation by conventional radiographs like orthopantomography, trans-pharyngeal projection of temporomandibular joint and specialized radiographic techniques like computed tomography (CT), magnetic resonance imaging and cone-beam computed tomography (CBCT). A careful radiological evaluation by cone-beam computed tomography helps diagnose cases of bifid condyle. Bifid condyle, if left untreated, can cause pain or clicking of TMJ, reduced mouth opening and permanent luxation. Therefore, dentists must be aware of the clinical features of the bifid condyle to diagnose this rare anomaly and also provide earlier treatment.


Aging is associated with a progressive loss of skeletal muscle mass and strength, resulting in frailty and lower quality of life in older individuals. At present, a standard of clinical or pharmacological care to prevent the adverse effects of aging does not exist. Determining the mechanism(s) responsible for muscular atrophy in disused aged muscle is a required key step for the development of effective countermeasures. Studies suggest an age-related differential response of genes and signalings to muscle disuse in both rodents and humans, implying the possibility that effective countermeasures to prevent disuse muscle atrophy may be age-specific. Notably, exercise preconditioning can attenuate disuse-induced muscular atrophy in rodent and human skeletal muscles; however, information on age-specific mechanisms of this exercise-induced protection remains limited. This mini-review aimed to summarize the protective effects of acute exercise preconditioning on muscular atrophy in aged muscle and provide potential mechanisms for its preventive effect on skeletal muscle wasting. Aging is associated with frailty, impaired health span, and lower quality of life . Aging iAlthough various countermeasures have been developed as potential therapeutic treatments to protect against disuse skeletal muscle atrophy, endurance exercise preconditioning is one of the most practical countermeasures currently available. Even a single bout of preconditioning exercise can attenuate disuse muscle atrophy induced by hindlimb unloading in rats . This evAging affects gene and signaling responses to skeletal muscle disuse in rodents and humans, and investigators have demonstrated that some apoptotic responses to disuse are age-specific –6. Interl, calpain, caspase-3, and E3 ubiquitin ligases) in 9- to 10-week-old male Wistar rats. This suggests that a single bout of preconditioning exercise may effectively suppress the upregulation of protein degradation during disuse in aged skeletal muscle. Additionally, we recently demonstrated that a bout of exercise could suppress Gadd45α upregulation in the gastrocnemius muscle of old rats [Until now, a variety of countermeasures have been investigated as potential treatments to protect against disuse skeletal muscle atrophy in humans. Physical strategies, such as resistance exercises and maximal voluntary contractions, which can be performed both isometrically and dynamically, are feasible during most immobilization situations and represent powerful tools for preventing muscle atrophy . Moreoveold rats . As Gaddold rats . This stAlthough the precise mechanisms of acute exercise preconditioning-induced protection against muscle atrophy are still unknown, there are some candidate mechanisms that indicate exercise can prevent HDAC4/Gadd45α pathway upregulation in aged muscle Fig. . First, The evidence suggests that acute exercise preconditioning is an effective countermeasure against a reduction in muscle mass in aged skeletal muscle, and the mechanisms of exercise-induced protection against skeletal muscle loss may be age-specific. Moreover, this protective effect in the aged muscle may be partially mediated by the HDAC4/Gadd45α axis and subsequent protein degradation systems. Currently, supporting evidence in this area is limited, especially regarding the age-specific effects of chronic exercise on disuse-induced muscle atrophy. Therefore, future studies should clarify mechanisms of exercise-induced protection on muscular atrophy in aged muscle and lead to developing therapeutic approaches to prevent muscle wasting.


Bicuspid aortic valve (BAV) is the most common congenital heart disease, with a prevalence of 1–2% and occurring in >20% of octogenarians referred for aortic valve replacement. However, BAV patients have been systematically excluded from pivotal randomized trials. Since TAVI indications are moving toward low-risk patients, an increase in the number of BAV patients who undergo TAVI is expected. BAV represents a challenge due to its unique morphological features  and the lack of consensus about the accurate sizing method. The role of multi-slice computed tomography (MSCT) in the planification of the TAVI procedure is well-established, being useful to define the optimal valve sizing and the implantation strategy. New-generation devices, more experience of the operators and better planification of the procedure have been associated with similar clinical outcomes in bicuspid and tricuspid patients undergoing TAVI. Bicuspid aortic valve (BAV) is the most common congenital heart disease, with a prevalence of 1–2% in the general population [Despite transthoracic echocardiography (TTE) often being the first imaging modality when evaluating a patient for suspected BAV, it can lead to severe BAV underestimation when used solely. Its accuracy is reported to be around 87%, or even lower when the study is of limited quality or there is heavy valve calcification . Multi-stype 0 (no raphe); type 1 , which is the most common phenotype; and type 2 (two raphes)  .tricommissural type, bicommisural raphe type and bicommissural non-raphe type  and a higher rate of mean transprosthetic gradient ≥ 20 mmHg  in type 0 vs. type 1 BAV, potentially in relation to the more elliptical configuration of the transcatheter heart valves (THVs) [Regardless of the classification used, to date, no clear correlation has been demonstrated between BAV phenotypes and clinical outcomes after TAVI. A subgroup analysis from the BEAT Registry revealed a trend toward lower VARC-2 device success  .MSCT plays a central role in TAVI preprocedural planning, and it is even more crucial in patients with BAV. Several studies have demonstrated that MSCT before TAVI can improve procedural results in this anatomical setting ,10,11. CIn the tricuspid anatomy, the aortic annulus is the narrowest part of the aortic root where the prosthetic valve will be sealed; hence, it is recommended that the THV should be sized based on annular dimensions, the so-called virtual basal ring (VBR). On the contrary, in a non-negligible proportion of BAV patients (approximately 13.8%), the tightest part of the aortic root may be situated above the annulus .BAVARD Registry [Tchétché et al. first developed the concept of the BAV landing zone. According to the Registry , the evaLIRA) method [In 2020, another BAV-specific sizing strategy was proposed by Iannopollo et al. The Level of Implantation at the Raphe  method  suggests) method .CASPER  [Petronio et al. elaborated a completely different sizing method called h Raphe) , which fcircle method [Last, the e method  is anothThe concept of supra-annular sizing remains debated and poorly standardized, with significant variability across operators. Recent evidence from the prospective BIVOLUT-X registry , comparip = 0.821) and clinical outcomes up to 1 year [p = 0.043). Specific data on SEV (Evolut R/PRO) have recently been published in the BIVOLUTX Registry [The selection of the most appropriate valve for each patient should be based on device-specific features and patient-specific anatomical aspects. The Sapien platform allows very stable deployment and predictable positioning. Its great radial force usually permits circular THV frame expansion, at the cost of higher risk of annular rupture, especially in heavily calcified anatomy. The flexibility of the delivery system and the short stent frame can reduce the risk of aortic injury in the case of aortic dilatation. On the other hand, in self-expanding valves (SEVs), the possibility of repositioning and recapturing allows one to achieve an accurate positioning. The supra-annular design provides a better hemodynamic performance in constrained anatomy. Yet, the lower radial force might lead to THV underexpansion and a higher degree of PVL. To date, the BEAT Registry  is the oo 1 year . Better Registry , which rRegistry .Gentle pre-dilatation with a semi-compliant balloon sized according to the smaller annular diameter is highly recommended in BAV patients, especially when using SEV or in patients with heavy valve calcifications. It can facilitate THV crossing through the stenotic native valve, offer useful information for valve sizing and positioning and allow the risk of coronary occlusion to be anticipated. In “gray zone” cases, valvuloplasty with simultaneous aortography could be used to confirm the most appropriate valve size and identify the best implantation depth according to the sealing point . Oversizing must be avoided, especially in severe calcified anatomies, to prevent intraprocedural complications.Two different landing zones can be identified according to the three possible BAV configuration patterns. In tubular and flared configurations, the annulus plane is the optimal landing zone, while in the tapered pattern, a supra-annular landing zone is recommended. Higher implants have been associated with lower rates of permanent pacemaker implantation (PPI) (reducing the interaction of the THV frame with the conduction system), but at the cost of increased risk of THV embolization and coronary obstruction ,16,20. OConsidering the younger age of BAV patients, when using SEV platforms, commissural alignment is strongly recommended as it can facilitate coronary reaccess for future revascularization, even in the case of TAVI-in-TAVI.double coplanar view” alignment (both the cusp and the THV) represents the optimal deployment projection [While cusp-overlap projection is the preferred deployment view for SEV platforms such as Evolut R/PRO and Navitor, the coplanar (or three-cusp) view is the gold-standard deployment projection for BEV. The alignment of the cusp in BAV anatomies can be challenging in case of severe cusp asymmetry, especially in type 0 BAV. In this case, the coplanar view is not feasible and “ojection . To achiIn BAV patients, a higher implantation depth should be attempted, while balancing the risk of THV malpositioning and embolization . It is sflare the inflow” technique [THV underexpansion with a residual high gradient and significant PVL can be quite a common complication in BAV patients, especially when using SEV ,22. Thisechnique  can be vthe flare outflow” technique [In BAV anatomy, the prevalence of large annuli outside the range of currently available THVs is not rare. In these cases, overexpanding and overfilling remains a safe alternative ,20. The When applying the previous concepts, in “gray zone” annular sizing, a smaller or bigger THV could be chosen. In the first case, deployment with intentional overexpansion could be put into practice. Postdilatation following the “flare the inflow” technique with additional filling allows for achieving overexpansion (and reduces the risk of PVL) without increasing the pressure on the annulus. If a bigger THV is chosen, the deployment should be carried out with intentional underexpansion. Intentional underfilling of the deployment balloon is required, followed by postdilatation using the “flare the inflow” technique with a nominal volume.SAVR is considered the gold-standard treatment for BAV stenosis ,24. BAV Comparisons between outcomes deriving from TAVI in BAV and TAV patients are limited to retrospective registries’ data, and the highest level of evidence is limited to propensity-matched analyses and meta-analyses.p = 0.63), but a higher rate of conversion to surgery occurred in BAV patients treated with BEV, and there was a greater incidence of significant PVL and need for reintervention in BAV patients treated with SEV. The latest evidence has demonstrated favorable clinical outcomes after TAVI in selected low-risk patients. A propensity-matched analysis including patients from the Evolut Low Risk Bicuspid study revealed no difference in all-cause mortality, stroke and echocardiographic results at 1-year of follow-up [p = 0.80) [In an early TAVI experience of using first-generation THV in high-risk patients, the authors reported similar mortality to TAV patients, but a lower rate of device success, greater need for conversion to surgery and higher incidence of significant PVL . Since tollow-up . An equi = 0.80) .Ultimately, the outcomes after TAVI in BAV patients appear to be strongly dependent on specific anatomical features. Thus, appropriate patient selection is crucial to obtain satisfactory results, as underscored by a recent meta-analysis from Montalto .Among these features, the calcification amount and distribution should be important considerations before valve treatment. Severe calcifications are commonly observed in BAV anatomy and both the amount and, above all, distribution of calcium can predict procedural complications. In particular, the presence of a calcified raphe can affect prosthesis expansion and can increases the risk of PVL and THV malpositioning. Heavy calcifications in the commissural zones entail higher risk of annular rupture. Finally, bulky leaflet calcifications can be associated with stroke and coronary obstruction. This is even though BAV patients usually have wide sinuses of Valsalva, which protect them from acute coronary occlusion during TAVI.Yoon et al. identified a calcified raphe and excess leaflet calcification as independent predictors of procedural complications and 2-year all-cause mortality. Patients with both morphological characteristics had higher rates of aortic root injury, moderate-to-severe PVL and 30-day mortality  Figure .p = 0.003) [Significant PVL was originally a major limitation of TAVI, especially in BAV patients, who showed an even higher rate of PVL when first-generation devices were used  . HoweverConversely, the rate of PPI has not significantly decreased, despite the introduction of new-generation devices. This complication is traditionally higher when using SEV as compared to BEV. Despite the Bivolut X Registry and TAVR Low Risk Bicuspid Study  reportedThe embolization of small debris during valve implantation can lead to periprocedural stroke. High valve calcification and additional procedural manipulation (pre-/postdilatation) can further increase the risk. According to the TVT Registry, the incidence of cerebral ischemic events was not significantly different among BAV and TAV patients treated with last-generation BEV ; howeverAfter the publication of the results of the PROTECTED TAVR trial , the rolTHV underexpansion in hostile BAV anatomy can affect THV durability and increase the risk of leaflet thrombosis due to accelerated prosthetic degeneration, a matter of particular concern in younger BAV patients. Long-term data beyond 1 year of follow-up are still scarce and highly awaited.Since TAVI indications are moving toward young and low-risk patients, the number of BAV patients evaluated for percutaneous treatment is expected to increase.Accurate imaging-based preprocedural planning has been proved to enhance outcomes after TAVI. It appears even more crucial in BAV anatomy to identify the appropriate valve size and the intended implantation level according to the landing zone configuration. This also enables identifying unfavorable anatomical features that can predict potentially dramatic complications and poor outcomes.Experienced TAVI operators can now offer similar procedural and short-term clinical outcomes to selected BAV patients as compared to TAV patients. However, favorable results after TAVI remain strictly dependent on careful patient selection. Long-term evidence is highly awaited.


Immune cells within the tumor microenvironment (TME) significantly contribute to the composition and dynamics of the TME, thereby influencing cancer pathogenesis and therapeutic response. The dynamic balance of interactions among immune cells and between immune cells and tumor cells has been identified as a promising therapeutic strategy for treating various cancers. Several therapies have been demonstrated to alleviate such immune disorders and restore immune cell homeostasis. Therefore, it is urgently necessary to deeply explore the significant implications of immune cell homeostasis in cancers, and to unravel the underlying molecular mechanisms and biological functions of this interplay, with the goal of improving treatment efficacy.This Research Topic aims to explore the Frontier research in the context of immune cell homeostasis in the TME, with a spotlight on 1) immune cell-based strategies for cancer research and treatment; 2) the interaction between cancer cells and immune cells; 3) the molecular mechanisms of tumor-infiltrating immune cell regulation; 4) underlying roles of cancer-associated molecules in immune cell infiltration; 5) clinical or bioinformatics analyses to explore immune cell-based therapeutic targets.Huang et al. focused their research on the integration of artificial intelligence with immunosignals for the precision treatment of liver diseases associated with Hepatitis B Virus (HBV). They identified CLST and aCD4, two immunosignals integral to the virus’s pathogenesis, as key players in the inflammation, fibrosis, and hepatocellular carcinoma triggered by HBV. Using gene set variation analysis, they developed immunogenomic signatures that streamlined the creation of robust diagnostic and prognostic models. The clinical application of CLST and aCD4 as indicators could significantly improve the precision management of hepatocellular carcinoma. This study provides an in-depth understanding of the gene characteristics tied to the immune microenvironment in HBV infection and offers subtle insights for the clinical management of HBV-related hepatocellular carcinoma, thereby establishing a strong foundation for precision medicine. Liu et al. successfully integrated machine learning to build classifiers related to aberrant alternative splicing (AS) events. These classifiers are designed to predict prognosis and the response to immunotherapy in patients with hepatocellular carcinoma. They found that AS can be instrumental in classifying HCC subtypes, as it alters the activity of tumor-related pathways through differential splicing effects. This, in turn, impacts the TME and plays a role in immune reprogramming. The authors have outlined the clinical and molecular characteristics, offering a fresh approach for personalized treatment of HCC patients.Li et al. reveal that the transcription factor ZBTB42 is highly expressed in glioma, it could be regarded as a promising prognostic factor for glioma. Moreover, ZBTB42 appears to be linked to immune cell infiltration, potentially playing a role in the immune-suppressive TME. Notably, the study also found a correlation between ZBTB42 and stem cell markers, indicating a positive association with glioma stemness. Therefore, the research identifies ZBTB42 as a prognostic biomarker for glioma, with its function tied to both the suppressive TME and the stemness of glioma. Fang et al. found that URB2 is also significantly overexpressed in glioma, and has a potential oncogenic role, as evidenced by the substantial impairment of cell viability upon its knockdown. Its expression level can independently predict overall survival. Interestingly, a strong link between URB2 and immune responses has been discovered, with the URB2 phenotype possibly contributing to immune suppression in GBM. This study indicated URB2 may serve as a crucial tool for prognosis prediction and immunotherapy guidance in glioma treatment. Luo et al. conducted a bioinformatic analysis of IL-15, a cytokine with diverse roles in immune regulation and tumorigenesis, as a potential prognostic biomarker across various cancers and its link to exercise’s anti-cancer effects. They discovered that IL-15 is generally downregulated in most cancers, with its high expression predicting better survival outcomes. Amplification emerged as the most common mutation type in IL-15’s genome. Additionally, IL-15 expression correlated with the infiltration levels of different immune cells and positively associated with ferroptosis/cuproptosis-related genes (ACSL4 and LIPT1) across various cancers. This study underscores IL-15’s potential as a prognostic biomarker for patient outcomes, immune responses, and ferroptosis/cuproptosis in pan-cancer, shedding light on exercise’s anti-cancer effects.Glioma is one of the most common types of primary brain tumor. Li et al. found that tissues resistant to TPF chemotherapy, a regimen comprising Docetaxel, Cisplatin, and Fluorouracil, in HPSCC patients exhibited upregulated T cell activation and downregulated glycolysis. They identified SEC61G as a key gene negatively correlated with CD8+ T cells and involved in glycolysis. Their findings suggest that while enhanced glycolysis may promote immune escape, it may also increase TPF chemotherapy response. Targeting the E2F1/SEC61G pathway could potentially boost MHC-I expression, offering a new therapeutic avenue.Zeng et al. analyzed the link between TGF-β signaling pathway-related genes (TSRGs), clinical prognosis, the TME, and immunotherapy in gastric cancer. This study discerned two unique TGF-β subgroups in gastric cancer, with one subgroup showing an immunosuppressive environment and reduced survival. A new TGF-β-related prognostic model was developed, indicating that patients with lower risk scores have improved prognosis and are more responsive to immunotherapy. These insights emphasize the role of TSRGs in shaping the tumor immune microenvironment and tailoring immunotherapy for gastric cancer patients. Interestingly, TGF-β has also been explored as a potential prognostic biomarker for glioma. Chen et al. have identified a crucial connection between serine and glycine metabolism-related genes (SGMGs) and both the prognosis and immune microenvironment of glioma. They’ve constructed a unique SGMG signature that holds promise in predicting patient prognosis and immune responses. This research implies that SGMGs could potentially steer the choice of immunotherapy in treating glioma. Qi et al. analyzed the genomic and transcriptomic profiles of 34 anoikis-related genes (ARGs), which are crucial for maintaining immune cell balance. The researchers found significant differences in ARG expression between soft-tissue sarcoma and normal tissues, suggesting a potential disruption of immune homeostasis in cancer. Their anoikis scoring system, which effectively predicted immune cell infiltration and immunotherapy response, could serve as a tool for assessing immune status and guiding personalized immunotherapy in cancer treatment. Meng et al. identified two molecular subtypes in uveal melanoma (UM) based on matrix-remodeling associated genes (MAGs), which showed significant differences in clinical outcomes. They developed a risk score system involving six MAGs that effectively predicted prognosis and immune activity. Their findings suggest that this MAGs-based system could enhance prognosis assessment and guide clinical decision-making in UM, highlighting the role of immune cell homeostasis in cancer therapy response.Clearly, these research findings will serve as a critical source of information to benefit all stakeholders involved in understanding the impact of immune cell homeostasis in cancer and their potential therapeutic responses.


Down syndrome, also known as trisomy 21, is associated with congenital cervical spine abnormalities, including atlantoaxial instability with or without os odontoideum, atlanto-occipital instability, and hypoplasia of the atlas. Herein, we report a case of Down syndrome complicated by congenital atlanto-occipital dislocation. The patient presented with severe cervical myelopathy at 13 years of age after a 10-year follow-up. Radiography and computed tomography revealed os odontoideum protruding into the foramen magnum and congenital anterior atlanto-occipital dislocation. Additionally, a bifurcated internal occipital crest with a thinned central portion of the occipital bone was noted. Magnetic resonance imaging revealed kyphotic alignment of the spinal cord with severe compression at the foramen magnum level. As the neurological impairment was partially improved by halo vest immobilization, we performed in situ O-C2 fusion with an iliac autograft and decompression of the foramen magnum and posterior arch of C1. An improvement was observed immediately after surgery. Two years after surgery, radiography and computed tomography showed solid O-C2 segment fusion. The accumulation of similar cases is essential for determining the prognosis or optimal treatment for this rare congenital condition. Down syndrome OMIM 190685) is caused by trisomy of all or a critical portion of chromosome 21 and can be associated with congenital cervical spine abnormalities, including atlantoaxial instability with or without os odontoideum, atlanto-occipital instability, and hypoplasia of the atlas 90685 is . Herein,The patient first presented to our department at 3 years of age for abnormal cervical radiography findings. He was diagnosed with Down syndrome at birth. His family history was unremarkable. Radiography showed basilar invagination and kyphotic O-C2 alignment Fig. a, b. SagThe neurological impairment was partially attributed to upper cervical instability associated with os odontoideum because of partial neurological symptom improvement by the halo vest immobilization. Hence, we performed in situ O-C2 fusion using an iliac autograft and decompression of the foramen magnum and posterior arch of C1, in lieu of reducing the congenital atlanto-occipital dislocation. Due to a bifurcated internal occipital crest with a thinned central portion of the occipital bone, we bilaterally placed the occipital plates separately Fig. a, b. TheThere are no reports describing congenital atlanto-occipital dislocation; most reported cases have been trauma-related –6. Down The optimal treatment for this congenital atlanto-occipital condition will be the subject of future studies. In this case, preoperative dynamic radiography of the cervical spine revealed limited cephalocaudal motion of the atlanto-occipital joint; therefore, reduction of the atlanto-occipital dislocation was presumed to be technically demanding. Hence, we conducted an in situ fusion and decompression, which was motivated by the partial neurological recovery from external halo vest immobilization alone. Although the short-term clinical course was favorable in our case, long-term follow-up and accumulation of similar cases are essential for determining the optimal treatment for this condition.Additionally, it remains to be determined whether surgery before the development of myelopathy is recommended in patients with congenital atlanto-occipital dislocation, because the prognosis or natural course of this congenital condition is completely unknown. Retrospectively, our case may have benefitted from prophylactic surgery, given the preoperative severe and rapid neurological deterioration. However, determining the significance of prophylactic surgery for this congenital condition may be premature as neurological impairment in this case may have been affected by concomitant os odontoideum, a well-known predictive factor for neurological deterioration and a proposed indicator for prophylactic surgery due to its high-grade instability –17. NeveA bifurcated internal occipital crest, which is reported in approximately 3% of the normal population, was identified in this case . TherefoIn conclusion, we have reported the first case of Down syndrome complicated by congenital atlanto-occipital dislocation that demonstrated progressive myelopathy and was successfully treated surgically. Although this condition seems to be extremely rare, we provided detailed information about the clinical course, including surgical treatment for future cases with congenital atlanto-occipital dislocation. The accumulation of similar cases is essential to determine the prognosis or optimal treatment for this congenital condition.


Peptide-based nanoparticles (PBN) for nucleotide complexation and targeting of extrahepatic diseases are gaining recognition as potent pharmaceutical vehicles for fine-tuned control of protein production (up- and/or down-regulation) and for gene delivery. Herein, we review the principles and mechanisms underpinning self-assembled formation of PBN, cellular uptake, endosomal release, and delivery to extrahepatic disease sites after systemic administration. Selected examples of PBN that have demonstrated recent proof of concept in disease models in vivo are summarized to offer the reader a comparative view of the field and the possibilities for clinical application. Recent advances in the clinical application and regulatory approval of nucleotide therapeutics have launched a veritable avalanche of new research and commercial activity in the design of RNA species and delivery vectors for a myriad of diseases. Following initial excitement around the discovery of RNA interference , a decadN-Acetylgalactosamine  moieties, which are amino sugar derivatives of galactose . Th. ThH in H load perhaps might establish a lower limit for certain cationic amphipathic peptides as a necessary condition for endosomal pH-based polyplex disassembly, which is critical to the release of complexed RNA and biological efficacy. In other peptide structures with higher H loads, proton buffering and the osmotic sponge effect perhaps could dominate.Hou et al., around the same time had postulated a similar behavior for the cationic amphipathic p5RHH system that incorporates only two histidines ,52. TheyW) is felt by many authors to play an important role in cellular uptake through their noncovalent interactions with membrane lipids and cholesterol and in stabilizing nucleotide interactions through pi-bonding of the aromatic indole groups such as in WRAP peptides . W is asequence . Once meulations . Zieglerulations  and Bechulations  showed tR/W nonapeptides, Walrant et al. determined that these cationic peptides bind to model lipids  and heparin (a glycosaminoglycan mimic) with increasing binding enthalpy as the peptide content of W increases . Th. Th76]. Enhanced Permeability and Retention) before encountering a desired cellular target . A. A129]. Other recent in vivo studies of cancer in mouse models have been completed against various tumor driver molecular targets. In pancreatic cancer, wild type KRAS was targeted with siRNA(unmodified)-p5RHH polyplexes administered systemically in serial doses to subcutaneous KPC-1 PDAC xenografts. KRAS siRNA uptake was observed in >85% of cancer cells isolated from the tumor mass, and tumor growth was suppressed by ~80% . Deep peLung and sarcoma tumor xenografts were shown to be susceptible to siRNA polyplexes against factors that control tumor angiogenesis (ETV-2 and MYCT1) and the immunosuppressive tumor microenvironment ,171. In Other broad-ranging in vivo studies using siRNA polyplexes have included metabolic syndrome, necrotizing enterocolitis (NEC), and atherosclerosis. In fat-fed mice that develop obesity, targeting ASXL2 that drives white fat inflammation, macrophages were converted from inflammatory to resolving phenotypes; adipose inflammation was reduced, and weight gain was inhibited . In mousAdditional studies of mRNA delivery with p5RHH polyplexes have been reported. Ex vivo studies in explanted cartilage from patients with OA utilized mRNA to enhance production of WNT16 (~1100 nt), which itself antagonizes the WNT3/beta-catenin inflammatory pathway that has been implicated in the development of OA . In thisKip1 mRNA in a mouse model of vascular endothelial damage and restenosis sought to attenuate vascular smooth muscle cell participation in intimal-medial hyperplasia . C. C192]. A follow up study on the complexation of mRNA (GFP) to BAPCs revealed biodistribution primarily to lung and liver early but clearance by 24 h in normal mice . These pThese peptides combine a branched polyarginine structure and reducible S-S disulfide bonds with the use of interposed cysteines linkers (mR9: Cys-R9-Cys-R9-Cys)  xenograft murine model , fine tuning of adaptive personalized therapeutics may become a reality.Herein, we have reviewed a selection of promising recent reports on PBN that appear to meet the objectives of extrahepatic delivery. In view of the growing interest in the field of RNA therapeutics beyond vaccines, we anticipate that some of these agents and other new ones will emerge in full development and clinical testing programs over the next few years. In particular, the applications of PBN mRNA promise to enable engagement of the missing factor in the pharmacopeia equation, the overexpression of critical proteins that have been


We present a rare case in which a 63-year-old male with a history of hypertension, diabetes mellitus, hyperlipidemia, and previous coronary artery bypass graft (CABG) presented with bilateral external iliac artery near occlusion. We describe the utilization of lithotripsy balloon angioplasty as opposed to the traditional double-barrel stenting method or modified endovascular repair (EVAR) to treat the occlusion. Pre-operative computed tomography (CT) angiography demonstrated a 90 percent occlusion of both the distal aorta and right external iliac artery, and 99 percent occlusion of the left external iliac. The patient remains symptom-free three years post-intervention with normal right and left ankle-brachial indices, 1.34 and 1.32 respectively. We review the available literature regarding aortoiliac occlusive disease (AIOD) and discuss the advantages and disadvantages of novel and traditional treatment modalities. Understanding all treatment options is crucial for physicians who are presented with similar cases. The descending aorta bifurcates and gives rise to the common iliac arteries, which bifurcates once more to give rise to the external and internal iliac arteries. The larger external iliac artery forms the main blood supply to the lower extremity, while the internal iliac artery primarily supplies reproductive organs, the pelvis, pelvic organs, and the medial thigh. Any change in diameter or disease at the iliac arteries plays an important role in planning an endovascular intervention due to the possible complications that a blood flow restriction may produce .Many patients with aortoiliac occlusive disease (AIOD) and peripheral artery disease are asymptomatic. While this makes determining the exact prevalence of the diseases in the general population difficult, estimates range from 3.56 percent to greater than 14%. Presenting severity and onset dictate the management and treatment of AIOD . There are a few techniques used to repair iliac artery and aorta lesions, one of them being angioplasty. Angioplasty, performed with or without stenting, is a percutaneous procedure used to widen occluded arteries due to underlying atherosclerosis . The proCurrently, double-barrel stenting or modified endovascular aneurysm repair has been commonly utilized in the treatment of visceral artery dissecting aneurysms and bilateral iliac artery aneurysms ,6. A comWe present a rare case in which the use of lithotripsy balloon angioplasty alone in a patient with bilateral iliac near occlusion with severe distal aortic closure was performed, opposing the conventional stenting approach. Traditional successful patency outcomes due to open repair have been replaced with endovascular stenting for short proximal lesions. In the setting of aortoiliac obstruction, it is, however, not the only treatment modality, and balloon angioplasty with lithotripsy was considered due to clinical expertise and the surgeon’s comfort.A 63-year-old male with a history of hypertension, hyperlipidemia, DM, 35-pack year smoking history, and coronary artery disease (CAD) status post coronary artery bypass graft (CABG) presented to an outpatient clinic for bilateral leg pain during exertion and at rest. Physical exam revealed absent right popliteal pulse and bilateral hypoesthesia of lower shins and feet. Chronic limb ischemia was suspected and Doppler ultrasound was used to measure pulse volume waveform at segmental locations in the leg arteries. To confirm the diagnosis further, computed tomography (CT) angiography was performed revealing a 90% distal aorta, 99% left external iliac artery, and 90% right external iliac artery stenosis Figure . The patNo contraindications for surgery were present and due to the diagnosis of AIOD and the multilevel nature of occlusion, operative intervention was planned with the goal of revascularization. After obtaining bilateral femoral access, a 0.35 glidewire advantage micro-catheter was used to cross the lesions. Angiogram images were obtained to visualize the lesions. 8.0 lithotripsy balloon was used for three cycles each at distal aorta to external iliac arteries, at 4 atm of pressure. Then bilateral kissing 8 mm balloons were used at 8 atm of pressure used for after. CT angiography demonstrated significantly improved flow with some residual stenosis in the left iliac artery Figure . HoweverThree years post-operation, the patient remains symptom-free with the most recent Doppler ultrasound demonstrating bi/triphasic flow in lower extremities with a normal ankle-brachial index (ABI) of 1.34 on the right and 1.32 on the left. The patient remains on clopidogrel and aspirin dual therapy and is symptom-free. In patients with severe iliac artery stenosis involving the distal aorta, double-barrel stenting or modified utilization of endovascular aortic aneurysm repair devices have been used traditionally as a percutaneous approach for intervention. However, in this case, we describe the utilization of lithotripsy balloon angioplasty at low pressure to take severe calcified stenosis to mild to moderate stenosis with no pressure gradient after. Further three years post-intervention, the patient remains symptom-free with essentially normal ABI. Understanding the advantages and disadvantages of both options is crucial for physicians who are presented with similar cases specifically when the distal aorta is involved.Double-barrel stenting is a technique in which stents with a common origin and different outflow targets are deployed in parallel. Long-term complications can be noted if intravascular ultrasound is not performed. Further limitations with interventions arise as a new iliac bifurcation is formed with balloon expandable stents which can be crushed and create new ostial stenosis . To avoiPercutaneous old balloon angioplasty (POBA) is a technique that has been used since 1963 to treat arterial occlusions, in particular obstructive coronary artery disease and atherosclerosis. POBA is generally considered to be safe and quick, and patients are reported to have faster recovery times ,6. The pLithotripsy balloons have been recently introduced to address and minimize these risks specifically with calcified vessels utilized at very low pressures. Intravascular lithotripsy (IVL) consists of a balloon-based system with lithotripsy emitters that create cracks in calcified or atherosclerotic obstructions . Data haWhile traditional approaches to bilateral iliac artery stenosis have reported favorable short-term outcomes, continued improvement in the long-term through the use of novel techniques such as lithotripsy balloon angioplasty has the potential to mold the way patients are treated for years to come. The patient discussed was a candidate for several treatment options, including double-barrel stenting and intravascular lithotripsy (IVL) balloon angioplasty. Given the heightened risk of long-term complications and based on the surgeon's comfort, the decision was made to perform IVL angioplasty. Three years later, the patient is symptom-free and shows no signs of restenosis while on continued medical management. This case highlights the value in analyzing all treatment options and selecting which is most suitable for the individual patient, as opposed to utilizing conventional approaches based on history, specifically beneficial in distal aorta-iliac pre-ostial stenosis.