Electrophysiologic Effects of Disopyramide in Patients

Seventeen patients with first-degree or Mobitz I atrioventricular (AV) block and narrow QRS complexes underwent electrophysiologic drug testing before and after i.v. administration of disopyramide. Disopyramide did not significantly change the mean sinus cycle length (895 131 vs 877 119 msec), mean maximal sinuss node recovery time (1134 + 169 vs 1133 13 msec), mean atrial effective refractory period (314 + 72 vs 307 54 msec), mean AV nodal conduction time (187 ± 79 vs 180 ± 73 msec) or the mean paced cycle length at which AV nodal Wenckebach conduction occurred (545 ± 144 vs 497 ± 130 msec) after disopyramide. The mean AV nodal effective refractory period decreased significantly (from 535 137 to 521 ± 122 msec), and both infranodal conduction time and the paced ventricular cycle length producing ventriculoatrial block increased significantly (from 56 ± 12 to 63 ± 13 msec and from 625