Combined invasive and noninvasive study of left ventricular systolic and diastolic function following acute administration of cicloprolol to subjects with normal cardiac function.
Cicloprolol is a new beta-blocking agent with high selectivity for beta 1 receptors and high intrinsic sympathomimetic activity. We studied the acute hemodynamic effects of cicloprolol in nine subjects with no evidence of left ventricular dysfunction who underwent cardiac catheterization for the evaluation of chest pain. All patients had normal coronary angiography and left ventriculography. Left ventricular pressure was determined throughout the cardiac cycle using a Millar 8Fr Minotip catheter; an echocardiogram, phonocardiogram, and ECG were simultaneously recorded to obtain left ventricular pressure-diameter loops. All the measurements were repeated before and after the intravenous administration of cicloprolol. Cicloprolol was administered at increasing doses of 0.05, 0.10, and 0.25 mg/kg until a cardiac output increase of at least 15% over basal values was achieved. A decrease of mean arterial pressure or cardiac output after cicloprolol was not observed in any patient. Cicloprolol administration significantly increased cardiac output (24%), stroke volume (22%), and peak positive dP/dt (25%); no significant changes in heart rate, systemic blood pressure, right atrial pressure, or pulmonary artery pressures were observed. No significant change in the echocardiographic parameters occurred. Among the indices of left ventricular diastolic function, the time constant of isovolumetric relaxation was significantly decreased (-43%) after cicloprolol; moreover, the left ventricular pressure-diameter loop in the protodiastolic phase was shifted to the left following cicloprolol infusion. This study confirms that in subjects with normal left ventricular function cicloprolol can improve resting left ventricular systolic function, and it shows that this action can also be attended by a more rapid isovolumetric relaxation, similar to what has been observed with other sympathomimetic amines.