[The electrophysiological effects of the Ca-antagonists gallopamil (D 600), dimeditiapramine (Ro 11-1781) and verapamil in man (author's transl)].

The electrophysiological effects of D 600 (D) (0.03 mg/kg i.v., 10 pts) and Ro 11-1781 (Ro) (1.0 mg kg i.v., 10 pts) were compared with those of verapamil (V) (0.1 mg/kg i.v., 20 pts). All three Ca-antagonists caused a slight shortening of the cycle length which was only significant after verapamil. There was practically no change in SNRT. As a consequence, the SNRT corrected for heart rate (CNSRT) increased insignificantly in all three groups (control C): 359.7 +/- 174.8 ms, V: 397.1 +/- 204.6 ms; C: 362.5 +/- 125.2 ms, Ro: 420.8 +/- 179.0 ms; C: 339.5 +/- 93.6 ms, D: 407.7 +/- 272.0 ms). In addition, the calculated "sinoatrial conduction time" increased insignificantly (C: 84.3 +/- 23.0 ms, V: 101.3 +/- 39.4 ms; C: 105.2 +/- 35.1 ms, Ro: 114.8 +/- 31.9 ms) or did not change (C: 105.9 +/- +/- 20.6 ms, D: 101.6 +/- 32.2 ms). The conduction time from high-to-low right atrium (HRA-A) as well as the His-ventricle time (HV) and the conduction interval from the septum to the right ventricular apex (V RVA) did not change. In contrast, the conduction time through the AV node (A-H) was significantly prolonged by all three drugs (C: 78.1 +/- 16.0 ms, V: 88,4 +/- 19.5 ms; C: 92.9 +/- 16.2 ms, Ro: 104.3 +/- 19.1 ms; C: 88.5 +/- 20.0 ms, D: 102.5 +/- 22.6 ms). The effective refractory period of the AV node (ERP AVN) was significantly prolonged by verapamil (C: 290.0 +/- 77.6 ms, V: 360.5 +/- 93.3 ms) and by D 600 (C: 266.7 +/- 72.6ms, D: 380.0 +/- 112.7 ms). Ro 11-1781 did not show any effect on this parameter. As a consequence, the Wenckebach point during high rate atrial pacing was significantly lowered by Verapamil and D 600, but only insignificantly by Ro 11-1781. The refractoriness of the right atrium and ventricle was not altered by any of the drugs. The results show that all three Ca-antagonists have similar electrophysiological effects in man after acute i.v. application. In the dose given, D 600 and verapamil are equipotent, whereas Ro 11-1781 is less effective.

RCT Entities:   Population Interventions Outcomes