Relation between heart rate variability and spontaneous and induced @entity943 in XXXX with @entity453 .

@entity1 @entity1165 @entity591 @entity1540 @entity1167 @entity453 @entity943
OBJECTIVES: The aim of this study was to determine the relation between autonomic control of heart rate and the spontaneous occurrence and inducibility of @entity943 in @entity1 with @entity453 . BACKGROUND: Low heart rate variability increases the risk of arrhythmic events. It is not known whether impaired autonomic heart rate control reflects alterations in functional factors that contribute to the initiation of spontaneous @entity943 or whether it is the consequence of an anatomic substrate for reentrant @entity591 . METHODS: Fifty-four @entity1 with @entity453 with a history of sustained @entity1165 (n = 25) or @entity1167 (n = 29) were studied by 24-h ambulatory electrocardiographic recording and by programmed electrical stimulation. Heart rate variability was compared among the @entity1 with and without spontaneous @entity943 and with and without inducibility of sustained @entity1165 . RESULTS: Eight @entity1 had a total of 21 episodes of sustained @entity1165 on Holter recordings. Standard deviation of RR intervals and low frequency and very low frequency components of heart rate variability were significantly blunted in @entity1 with sustained @entity1165 compared with those without repetitive @entity1540 (p < 0.05, p < 0.01 and p < 0.05, respectively). However, no significant alterations were observed in heart rate variability before the onset of 21 episodes of sustained @entity1165 . Heart rate variability did not differ between the @entity1 with or without nonsustained episodes of @entity1165 . In @entity1 with frequent @entity1540 , low frequency and very low frequency power components were significantly blunted compared with those with infrequent @entity1540 (p < 0.01 and p < 0.001, respectively). Heart rate variability did not differ significantly between the @entity1 with and without inducible sustained @entity1165 . CONCLUSIONS: Impaired very low and low frequency oscillation of heart rate reflects susceptibility to the spontaneous occurrence of @entity943 but may not reflect the instantaneous triggers for life-threatening @entity943 or a specific marker of the arrhythmic substrate for @entity1165 .
