[Short and long term hemodynamic effects of amiodarone in patients with hypertrophic obstructive myocardiopathy....

Amiodarone is an antiarrhythmic drug with negative inotropic effect; therefore an study of hemodynamic effects of this drug in obstructive hypertrophic cardiomyopathy was performed. Seven consecutive patients with hypertrophic cardiomyopathy were studied prospectively. Intraventricular pressure gradient was determined at rest and during the Valsalva manoeuver during left heart catheterization; traces were obtained before (control) and at 10, 20 and 40 minutes after amiodarone, 10 mg/kg of body weight, was given IV. Simultaneously a mode M echocardiogram and carotid pulse were registered, Internal diameters, ejection time, percentual shortening, systolic anterior motion of the mitral valve, and mesosystolic aortic closure were measured. Afterwards oral amiodarone was administered to the same patients for 3 months. In this chronic phase the same phono-echocardiographic parameters and isovolumetric relaxation time were measured at 6 and 12 weeks. Parenteral administration of amiodarone reduced intraventricular gradient from 48.3 to 6.2, 8.7, and 1.3 mmHg. at 10, 20 and 40 minutes (p less than 0.001); mean pressure with Valsalva decreased from 78 to 19.6, 20.4, and 22.5 mmHg. (p less than 0.001). In four patients there was a reduction of left ventricular end diastolic pressure, Ejection time percent shortening and aortic closure intensity were reduced, systolic diameter and the distance septum, forward movement increased. The maximal effect was found 40 minutes after the injection of amiodarone. In the chronic phase the negative inotropic effect returns to near control values, but there is an increase in ventricular volumes with a significant shortening of the isovolumetric relaxation time. Amiodarone IV, decreases the intraventricular gradient in obstructive hypertrophic cardiomyopathy probably by a negative inotropic influence. This action almost disappears with oral amiodarone but there is a notorious improvement of left ventricular compliance.