Untitled research work

The hemodynamic effects of mexiletine, lidocaine, procainamide and disopyramide were compared using 12 healthy volunteers.We used physiological saline as control. Twenty ml of saline (control), 100 mg of mexiletine, 100 mg of lidocaine, 500 mg of procainamide and 100 mg of disopyramide, respectively, were injected intravenously in the time span of 5 min. to the same subjects at an interval of one week. Lidocaine was found to be prone to increase heart rate, but showed hardly any effects upon cardiac index or total peripheral vascular resistance. Procainamide increased heart rate and showed reduction in systolic blood pressure and a trend of decrease in total peripheral vascular resistance slightly. Disopyramide exhibited hardly any effects upon the systolic blood pressure, but elevated the diastolic blood pressure remarkably. Despite the increased heart rate, a tendency of reduction in the cardiac index was noted and the stroke volume index decreased appreciably.The pre-ejection period (PEP) was increased and the ratio of ejection time (ET) versus pre-ejection period was decreased. Hardly any changes were noted in the QTc on EKG with mexiletine and lidocaine, whereas the QTc in procainamide and disopyra mide tended to be lengthened.It is clearly shown by the above findings that the intravenous injection of 100 mg of mexiletine for 5 min. caused no adverse effects upon the hemodynamics. On the other hand, it was found advisable to take precaution in the use of disopyramide for patients with cardiac dysfunction, since its intravenous injection in a dose of 100 mg for 5min. showed the decrease in cardiac index and in stroke volume index and the increase in total peripheral vascular resistance.