Electrocardiographic characteristics of patients with Ebstein's anomaly before and after ablation of an accessory atrioventricular pathway

The abnormal development of the tricuspid valve in patients with Ebstein's anomaly results in several activation abnormalities including delayed intraatrial conduction, right bundle branch block (RBBB), and ventricular preexcitation. The aim of the present study was to define the ECG characteristics before and after ablation of an accessory A-V pathway (AP) in patients with Ebstein's anomaly.

METHODS

A series of 226 consecutive patients with Ebstein's anomaly was studied. Sixty-four patients (28%) had documented tachycardia. Thirty-three patients with recurrent tachycardia were found to have a single right-sided AP that was successfully ablated (study group). Thirty patients without tachycardia served as the control group.

RESULTS

Only 21 of 33 patients (62%) had a typical ECG pattern of preexcitation. In addition, none of the patients had an ECG pattern of RBBB during sinus rhythm. In contrast, 28 of 30 (93%) patients in the control group had RBBB (P < 0.001). Radiofrequency catheter ablation resulted in appearance of RBBB in 31 of 33 (94%) patients. The absence of RBBB in patients with Ebstein's anomaly and recurrent tachycardia had a 98% sensitivity and 92% specificity for the diagnosis of an AP. The positive predictive value was 91% (0.77, 0.97 CI 95%) and the negative predictive value was 98% (0.85, 0.99 CI 95%).

CONCLUSION

One-third of patients with Ebstein's anomaly and symptomatic tachyarrhythmias have minimal or absent ECG features of ventricular preexcitation. In these patients, the absence of RBBB pattern is a strong predictor of an AP.

Dynamic electrocardiographic changes after aborted sudden death in a patient with Brugada syndrome and rate-dependent right bundle branch block

A 37-year-old man with Brugada syndrome and dynamic changes of the ST-segment morphology observed after an episode of aborted sudden death is described. On admission, after 3 syncopal episodes during nighttime, his electrocardiogram showed right bundle branch block (RBBB) with a J-point elevation of 0.6 mV in lead V 2 . Changes observed in the following days included a diminished J-point elevation and intermittent "saddle-back" type of morphology. During a previous 2-year follow-up, intermittent, complete, acceleration-dependent RBBB was documented. Right ventricular intracavitary tracings showed an RS pattern with a broad S wave in the unipolar electrogram; the time of onset of intrinsic deflection in this electrogram was 60 milliseconds. To our knowledge, this is the first report of an intracavitary demonstration of complete RBBB in Brugada syndrome.