Abstract
The outcome of posteroseptal accessory pathway ablation by direct current (DC) shocks delivered just outside the os of the coronary sinus was studied in 21 patients. Electrocardiographic and electrophysiological parameters as well as phase image patterns of equilibrium multiple-gated blood-pool scintigrams were studied to determine their usefulness in predicting the success of ablation. A second free-wall pathway was documented by electrophysiological or surgical findings in six patients, and the value of phase images in detecting this second pathway was studied as well. Ablation was successful in 57%. The cumulative mean energy of DC shocks amounted to 524 +/- 170 joules and was not predictive of ablation outcome, neither was the mean ventriculoatrial (VA) conduction time. The predictive value of the 12-lead maximally preexcited electrocardiogram was poor in the 15 patients with a single posteroseptal bypass tract. A new method to triangulate the site of the earliest phase angle on the atrioventricular (AV) valve plane successfully localized the bypass pathway in 14 of those patients. No specific phase pattern predicted successful ablation except for a symmetrical, concentric peripheral phase progression found to be predictive of ablation success in the four patients who showed this pattern. Phase analysis was able to localize the second, nonposteroseptal pathway in four of six patients. This study showed that a concentric peripheral phase progression in the gated blood-pool scintigrams is predictive for ablation success in patients with posteroseptal pathways. A free-wall localization of the earliest phase angle is suggestive of a second bypass tract in this area.
Highlights
Fifteen patients showed a typical pattern for a posteroseptal pathway in the standard 12-lead electrocardiogram with no R waves in leads III and avF and a delta wave progression of 1.03 ± 0.8 mV between Vi and V^ with an initial delta wave amplitude of 0.12 ± 0.1 mV in Vi [Fig. 1)
Four of the 15 patients had dual accessory pathways, and the electrocardiogram showed no evidence for ventricular activation through the second bypass tract
Four patients with only a single posteroseptal accessory pathway had an atypical pattern with absence of delta wave progression from Vi to V2 in the chest leads [# 9 and 20] or preexcitation associated with a positive delta wave in lead II [# 13 and 21)
Summary
Catheter ablation of the atrioventricular (AV) junction using direct current (DC) energy has been. Dr Oeff was awarded a grant by the Deutsche Forschungsgemeinschaft. Dr Dae is the recipient of an NIH First Award. Received September 5, 1990; revision January 31, 1991; accepted February 14, 1991
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