Supraventricular tachycardia originating from the posterior atrioventricular node in the univentricular heart with single atrium.

Supraventricular tachycardia (SVT) was observed in a 13-year-old male patient with complex clinical features that included univentricular heart with single atrium, pulmonary atresia, and polysplenia syndrome. During electrophysiologic study, atrial burst stimuli reproducibly induced and terminated the SVT, while the occurrence of ventriculoatrial block did not interrupt the SVT. His bundle electrograms (HBEs) were recognized both in the anterior and posterior regions on the common atrioventricular (AV) valve annulus.

Site of the arrhythmogenic focus and cardiac vulnerability to ventricular fibrillation.

The aim of this study was to test the hypothesis that a subendocardial arrhythmogenic focus makes the heart more susceptible to VF due to electrical interaction with the Purkinje network. Monofocal ventricular tachycardia (mVT) was created by injecting 5-microg aconitine into the left ventricular subepicardium (EPI-mVT, n = 8) or subendocardium (ENDO-mVT, n = 13) in anesthetized dogs. Despite the similar cycle length of mVT, the incidence of VF was significantly different between EPI-mVT and ENDO-mVT (100 [8/8] vs 46% [6/13], P <0.