Electrophysiology of ventricular inversion.

Electrophysiological studies were carried out in 7 subjects with angiographically proven ventricular inversion in order to determine if this technique could be used in the study of arrhythmias in such subjects. Three subjects with normal PR intervals on the electrocardiogram had normal low right atrium to His (LRA-H) and His to ventricle (HV) intervals at rest. With atrial pacing, I of these 3 with normal PR interval developed Mobitz II second-degree atrioventricular block. Of 2 subjects with first-degree atrioventricular block r was found to have prolonged LRA-H and HV intervals, and the other had only LRA-H prolongation. In both subjects with complete atrioventricular block, the block was below the His bundle recording site. One of these patients with complete AV block wasfound to be able to conduct through his AV conducting system during the supernormal period. This study found that useful information can be obtained by recording the His bundle potential in patients with ventricular inversion. Conduction abnormalities were found from the AV node through the His-Purkinje system. This technique may be useful in making clinical decisions in patients with ventricular inversion and complex arrhythmias.