Effects of quinidine and amiodarone on blood pressure during rapid ventricular pacing in coronary artery disease

The hemodynamic response to ventricular tachycardia is an important determinant of prognosis.¹ Many factors determine the hemodynamic response to ventricular tachycardia, including (1) the rate of the ventricular tachycardia,^2,3 (2) systolic and diastolic ventricular function,^4,5 and (3) the neurohumoral response to the arrhythmia.^6,7 Antiarrhythmic drugs such as quinidine and amiodarone may either improve hemodynamics during ventricular tachycardia by slowing the rate of the tachycardia, or may impair the hemodynamic response to ventricular tachycardia by decreasing ventricular contractility, blunting the neurohumoral response to the tachycardia, or by causing vasodilation.^8-14 No prior studies have evaluated the effect of antiarrhythmic drugs on the hemodynamic response to ventricular tachycardia independent of their effects on the rate of the tachycardia. The objective of this study was to determine the relative effects of quinidine and amiodarone on the blood pressure (BP) response to rapid ventricular pacing in humans. Previous studies have demonstrated that the BP response during ventricular tachycardia and during ventricular pacing are similar.² Therefore, in this study ventricular pacing was used to assess the effects of antiarrhythmic drugs on the BP response independent of heart rate.