Electrocardiographic differentiation of typical XXXX from @entity16992 mediated by concealed accessory pathway in @entity1 .

@entity1 @entity2917 @entity308 @entity6391 @entity591 @entity16992 @entity4710 @entity943
The value of the electrocardiogram (ECG) in @entity1 with @entity4710 ( @entity4710 ) is unclear. The noninvasive differentiation of typical @entity2917 ( @entity2917 ) and @entity16992 ( @entity16992 ) mediated by concealed accessory pathway conduction is clinically important, as it helps in counseling and potentially facilitates ablation procedures. One hundred forty-eight ECGs showing narrow QRS complex @entity4710 were obtained from @entity1 before successful radiofrequency catheter ablation. An initial 102 ECGs were analyzed by 3 blinded observers to assess the utility of various electrocardiographic findings. No electrocardiographic criteria were found to discriminate between @entity4710 mechanisms on 1- to 3-channel Holter/event recorder tracings (n = 32); their interpretation mainly (55%) resulted in an incorrect @entity4710 diagnosis. On 12-lead ECGs (n = 70), the 2 @entity943 were accurately diagnosed in 76% of @entity1 ; 5 findings were found to be discriminators of @entity591 mechanism. Predictors of @entity16992 were visible P waves in 74% of cases (sensitivity 92%; specificity 64%), @entity6391 intervals of > or =100 ms in 91% (sensitivity 84%; specificity 91%), and ST-segment @entity308 of > or =2 mm in 73% of cases (sensitivity 52%; specificity 82%). Pseudo r' waves in lead V(1) and pseudo S waves in the inferior leads during @entity591 predicted @entity2917 in 100% of cases (sensitivity 55% and 20%, respectively; specificity 100% for both). Based on these results, we developed a new diagnostic 12-lead electrocardiographic algorithm for pseudo r'/S waves, @entity6391 duration, and ST-segment @entity308 during @entity591 . Two observers tested the algorithm in 46 (21 @entity2917 ; 25 @entity16992 ) additional cases; they correctly diagnosed the @entity4710 mechanism in 91% and 87%, respectively. Thus, the stepwise use of diagnostically relevant 12-lead electrocardiographic parameters helps to more accurately differentiate mechanisms of reentrant @entity4710 .
