Electrophysiological effects of disopyramide in patients with bundle branch block.

Our findings relating to small but significant increases in H-Q support previous observations by Marrott et al.31

J M Desai; M Scheinman; R W Peters; J O'Young


Scholarcy highlights

  • Twenty-two patients with right or left bundle branch block and 1: 1 AV conduction were included in the study
  • Our work confirms the observations of Josephson et al., Spurrell et al., Birkhead and Vaughan Williams, and Marrott et al. in that disopyramide results in small but statistically significant increases in atrial or ventricular effective refractory periods
  • Cardiac refractory periods in the present study were obtained in only 16 of the 22 patients. These findings differ from the observations of Befeler et al., who found no significant change in atrial refractoriness after disopyramide
  • In contrast to our previous studies of procainamide in which a substantial lag was often observed between H-Q prolongation and serum blood levels, the data for disopyramide suggest that this drug rapidly equilibrates with cardiac tissue producing maximal effects within minutes after drug infusion
  • For the group as a whole, mean control H-Q increased by 18% 5 minutes after disopyramide
  • Our findings support the concept that the electrophysiological effects of disopyramide in man are similar to those of other so-called type I antiarrhythmic agents, in that atrial, His-Purkinje system, and ventricular refractoriness were prolonged as was infranodal conduction time
  • This study does not address the important issue of the long-term safety of chronic oral disopyramide therapy, for those patients with markedly prolonged infranodal conduction time

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