This report describes a catheter technique for ablating the His bundle and its application in nine patients with recurrent supraventricular tachycardia that was unresponsive to medical management. A tripolar electrode catheter was positioned in the region of the His bundle, and the electrode recording a large unipolar His-bundle potential was identified. In the first patient, two shocks of 25 and 50 J, respectively, were delivered by a standard cardioversion unit to the catheter electrode, resulting in an intra-His-bundle conduction defect. Subsequent delivery of 300 J resulted in complete heart block. In the next eight patients, an initial shock of 200 J was used. The His bundle was ablated by this single shock in six of these patients and by an additional shock of 300 J in one. In the remaining patient, conduction in the atrioventricular node was modified, resulting in alternating first and second-degree atrioventricular block. A stable escape rhythm was preserved in all patients. The procedure was well tolerated, without complications, and all patients have remained free of arrhythmia, without medication, for follow-up periods of two to six months.
Accessory atrioventricular pathways, the anatomical structures responsible for the preexcitation syndromes, may result from a developmental failure to eradicate the remnants of the atrioventricular connections present during cardiogenesis. To study whether preexcitation syndromes could also be transmitted genetically, we determined the prevalence of preexcitation in the first-degree relatives of 383 of 456 consecutive patients (84 percent) with electrophysiologically proved accessory pathways. We compared the observed prevalence of preexcitation among the 2343 first-degree relatives with the frequency reported in the general population (0.15 percent). For 13 of the 383 index patients (3.4 percent), accessory pathways were documented in one or more first-degree relatives. At least 13 of the 2343 relatives identified (0.55 percent) had preexcitation; this prevalence was significantly higher than that in the general population (P less than 0.0001). Identification of affected relatives may have been incomplete because clinical information was obtained only about symptomatic relatives. Patients with familial preexcitation have a higher incidence of multiple accessory pathways and possibly an increased risk of sudden cardiac death. Our data suggest a hereditary contribution to the development of accessory pathways in humans. The pattern of inheritance appears to be autosomal dominant.
SUMMARY During reciprocating tachyeardia in patients with accessory atrioventricular pathways, the observation of changes in ventriculoatrial (VA) intervals with bundle branch block (BBB) aberration has been used to localize the site of the pathway and prove the participation of the pathway in the tachycardia. In this report we present the changes observed during BBB in 93 patients with single atrioventricular pathways in whom the site of their pathways was subsequently proved at the time of their surgical interruption. In patients with left or right free wall pathways, the minimum VA interval (VA min) increased by 61 + 19 msec with ipsilateral BBB, whereas no change occurred with contralateral BBB. The smallest increase in the VA interval was 35 msec. In 14 patients, shortening of the AH intervals resulted in changes in overall cycle length that were less than 35 msec. Patients with septal pathways all had changes in VA min of 25 msec or less with either right or left bundle branch block (RBBB or LBBB), which suggests that a clear differentiation between septal and free wall pathways can be made on the basis of changes in VA min. In patients with anteroseptal pathways, VA min intervals frequently prolonged with RBBB (16 ± 9 msec) but not with LBBB. In patients with posteroseptal pathways, VA min frequently prolonged with LBBB (13 ± 8 msec) but not with RBBB. Therefore, the observed changes in VA min with BBB may serve as an important indicator of the site of an accessory pathway and may provide guidance in the choice of surgical therapy.IN PATIENTS with accessory atrioventricular pathways, the observation of bundle branch block (BBB) aberration during reciprocating tachycardia (RT) may help locate the site of the accessory pathway in RT. IX In a previous report from this laboratory, Pritchett et al.6 described preliminary observations in 22 patients with BBB and RT who subsequently underwent epicardial mapping and surgical interruption of their accessory pathways. In 11 of 18 patients with free wall pathways, BBB on the side ipsilateral to the pathway prolonged the ventriculoatrial (VA) conduction interval by more than 25 msec, whereas in four patients with septal pathways, BBB caused no change.Discriminating between posterior septal and paraseptal free wall pathways during endocardial mapping is frequently difficult. This differentiation is important because the surgical approach and the potential risk of interrupting the normal atrioventricular connections are different in these two locations. In these cases, we rely heavily on observations made during functional BBB during RT.In this report, we describe patients in whom BBB was induced during electrophysiologic study and who subsequently underwent surgical interruption of their pathways guided by intraoperative mapping. A correlation of the preoperative findings with the surgically proved site of the pathway permitted a more precise delineation of the relationship of the effect of BBB to the site of the accessory pathway.
Methods
Patient PopulationNinety-thr...
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