Effect of verapamil on left ventricular function: a randomized, placebo-controlled study

Cardiovascular effects of verapamil enantiomer combinations in conscious dogs

We examined the systemic and coronary hemodynamic effects of five combinations of R- and S-verapamil enantiomers (R/S; 100/0, 90/10, 80/20, 50/50, and 20/80%, respectively) in conscious dogs chronically instrumented for measurement of aortic and LV pressure, +dP/dt, subendocardial segment length, coronary blood flow velocity, and aortic blood flow. Dogs received escalating doses (0.1, 0.2, and 0.4 mg kg(-1)) of each verapamil combination over 2 min at 30 min intervals on different experimental days and peak changes in hemodynamics were recorded 2 min after each dose. All verapamil combinations increased heart rate, mean aortic blood flow, and coronary blood flow velocity and decreased calculated systemic and coronary vascular resistance. Alterations in coronary hemodynamics were most pronounced with 20/80 R/S verapamil. Racemic and 20/80 R/S verapamil decreased mean arterial and left ventricular systolic pressure, in contrast to combinations with greater concentrations of the R enantiomer. Left ventricular function was unchanged during administration of 100/0, 90/10, and 80/20 R/S verapamil. Direct negative inotropic and lusitropic effects occurred with 50/50 and 20/80 R/S verapamil. The high dose of 20/80 R/S verapamil also increased left ventricular end-diastolic pressure and the regional chamber stiffness constant, consistent with diastolic dysfunction. The results indicate that combinations of R- and S-verapamil produce differential hemodynamic and left ventricular functional effects in conscious, unsedated dogs that are dependent on the relative ratio of these enantiomers.

Verapamil. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension

Although verapamil is a well-established treatment for angina, cardiac arrhythmias and cardiomyopathies, this review reflects current interest in calcium antagonists as anti-hypertensive agents by focusing on the role of verapamil in hypertension. Verapamil is a phenylalkylamine derivative which antagonises calcium influx through the slow channels of vascular smooth muscle and cardiac cell membranes. By reducing intracellular free calcium concentrations, verapamil causes coronary and peripheral vasodilation and depresses myocardial contractility and electrical activity in the atrioventricular and sinoatrial nodes. Verapamil is well suited for the management of essential hypertension since it produces generalised systemic vasodilation resulting in a marked reduction in systemic vascular resistance and, consequently, blood pressure. Evidence from clinical studies supports the role of oral verapamil as an effective and well-tolerated first-line treatment for the management of patients with mild to moderate essential hypertension. Clinical studies have shown that verapamil is more effective the higher the pretreatment blood pressure and some authors have found a more pronounced antihypertensive effect in older patients or in patients with low plasma renin activity. Sustained release verapamil formulations are available for oral administration which, as a single daily dose, are as effective in lowering blood pressure over 24 hours as equivalent doses of conventional verapamil formulations given 3 times daily. As a first-line antihypertensive agent, oral verapamil is equivalent to several other calcium antagonists, beta-blockers, diuretics, angiotensin-converting enzyme (ACE) inhibitors and other vasodilators, and is not associated with many of the common adverse effects of these treatments. Verapamil may be preferred as an alternative first-line antihypertensive treatment to diuretics in elderly patients because it has similar efficacy in these patients without causing the adverse effects commonly linked with diuretic treatment. Furthermore, because verapamil does not cause bronchoconstriction, it may be used in preference to beta-blockers in patients with asthma or chronic obstructive airway disease. Reflex tachycardia, orthostatic hypotension or development of tolerance is not evident following verapamil administration. As a second- or third-line treatment for patients refractory to established antihypertensive regimens, verapamil produces marked blood pressure reductions when combined with diuretics and/or ACE inhibitors, beta-blockers and vasodilators such as prazosin.(ABSTRACT TRUNCATED AT 400 WORDS)

The haemodynamic effects of nifedipine, verapamil and diltiazem in patients with coronary artery disease. A review

Of the 3 most widely used calcium antagonists--nifedipine, verapamil and diltiazem--nifedipine is the most potent arterial vasodilator. Increases in cardiac output and coronary blood flow following nifedipine administration result in part from the afterload reduction. Reflex adrenergic stimulation produces an increase in heart rate and masks a direct inhibitory effect on myocardial contractility. The negative inotropic action of nifedipine is observed during intracoronary administration or may be made apparent by concurrent beta-blocker therapy. While verapamil is also a potent vasodilator, negative inotropic and dromotropic properties are more apparent in therapeutically used dosages. Reflex sympathetic activation is also triggered by verapamil, with an offsetting of the negative inotropic effects such that little change in cardiac output results. A decrease in myocardial oxygen consumption, with or without a decrease in coronary sinus blood flow, has regularly been observed following verapamil administration. Reduced oxygen demand appears to be a major mechanism of its antianginal effect. The heart rate X systolic pressure product is decreased both by the fall in arterial pressure and, particularly after oral administration, by a decrease in heart rate. Diltiazem produces similar haemodynamic and electrophysiological effects to those of verapamil but has less potency in inducing arterial dilatation and more of a tendency to slow the heart rate. Diltiazem does not appear to cause significant increases in coronary blood flow or bring about improvement in ejectional and isovolumic indices of myocardial contraction - evidence of its intrinsic negative inotropic effect.

Hemodynamic effects of verapamil in left ventricular valvular volume overload

The hemodynamic consequences of aortic and mitral insufficiency may be influenced by the high systemic vascular resistance often seen in these patients. Since the calcium antagonists have been shown to reduce systemic vascular resistance, we evaluated the effects of intravenous verapamil in 23 patients. In 11 patients with aortic insufficiency, verapamil resulted in a 20% increase in cardiac index (p less than 0.001), 18% increase in forward stroke volume index (p less than 0.001), and a 24% decrease in regurgitant fraction (p less than 0.005). In the 12 patients with mitral insufficiency, verapamil resulted in a 19% increase in both cardiac index (p = 0.004), and forward stroke volume index (p less than 0.001), while there was a 19% decrease in regurgitant fraction (p less than 0.02). Left ventricular end-systolic stress decreased significantly in both groups as did end-diastolic stress in the mitral insufficiency group. There was no significant change in several measures of contractile performance, though the end-systolic stress-to-volume index ratio fell significantly (p less than 0.04) in the mitral insufficiency group. Our findings suggest that the vasodilatory effects of intravenous verapamil predominate over the negative inotropic effects in patients with aortic and mitral insufficiency. Verapamil may be of use in patients intolerant to other vasodilators, patients with concomitant ischemic heart disease, or those with supraventricular arrhythmias.

Improvement in regional wall motion and left ventricular relaxation after administration of diltiazem in patients with coronary artery disease

To assess the effect of diltiazem on left ventricular systolic regional wall motion and diastolic function in patients with coronary artery disease (CAD), 22 patients underwent biplane left ventricular cineangiography before and after intravenous diltiazem (plasma concentration 154 +/- 12 ng/ml). Left ventricular and right ventricular pressures were measured by micromanometer-tipped catheters. Regional wall motion was assessed quantitatively with an area ejection fraction technique. Diltiazem decreased mean arterial pressure 11.5% (p less than .0001) and heart rate 6.8% (p less than .005); it increased cardiac index 8.8% (p less than .025) and global ejection fraction 9.1% (p less than .0001). However, left ventricular end-diastolic pressure increased 14.2% (p less than .001) and the left ventricular end-systolic pressure-volume (P-V) ratio decreased 8.8% (p less than .02). Diltiazem decreased the time constant of left ventricular relaxation by 14.3% (p less than .002), despite lack of change in the left ventricular diastolic P-V relationship, in 16 patients. Diltiazem caused a significant increase in area ejection fraction in 53% of hypokinetic areas supplied by diseased arteries compared with 13% of normokinetic areas supplied by diseased arteries (p less than .0001). Response of ejection fraction to diltiazem in areas supplied by normal coronary arteries was less (p less than .05) than that in hypokinetic areas supplied by arteries affected by disease. In conclusion, diltiazem improves regional wall motion abnormalities in patients with CAD and the improvement is associated with better left ventricular relaxation but not with a change in the diastolic P-V relationship. Global indexes of left ventricular systolic performance are favorably influenced by diltiazem, despite a mild negative inotropic effect.

Hemodynamic effects of intravenous bepridil in patients with normal left ventricular function

Calcium-channel blockers are known to have depressant effects on atrioventricular (AV) nodal conduction and myocardial contractility. Because of these known depressant effects, bepridil hydrochloride, a new, long-acting, antianginal and antiarrhythmic calcium-channel blocker, was administered intravenously to patients without heart failure to determine acute hemodynamic effects. The patients studied had normal ventricular function, were without electrocardiographic conduction disturbances and were taking no drug except sublingual nitroglycerin for at least 24 hours before bepridil infusion. The study protocol included right- and left-sided cardiac catheterization with infusion of bepridil at 2 mg/kg for 15 minutes followed by 1 mg/kg for 15 minutes in 10 patients, and infusion of bepridil at 3 mg/kg for 15 minutes followed by 1 mg/kg for 15 minutes in 8 patients. Pressures, Fick cardiac output, resistances, left ventricular (LV) dP/dt, LV stroke work index and rate-pressure product of the left ventricle were monitored. There were no significant changes during bepridil infusion at either dose for cardiac output, systemic vascular and pulmonary vascular resistances, LV stroke work index, heart rate, arterial blood pressure and rate-pressure product. There was mild depression of LV dP/dt during bepridil infusion. Further, LV end-diastolic pressure, pulmonary capillary wedge pressure and pulmonary arterial pressures were significantly increased during bepridil infusion. There were no apparent changes in AV nodal or intraventricular conduction during bepridil infusion. We conclude that bepridil appears to be a safe drug for intravenous administration despite mild depression of myocardial function in patients with normal baseline hemodynamic function who are not receiving concomitant beta-blocker therapy.

Randomized, placebo-controlled study of the effect of verapamil on exercise hemodynamics in coronary artery disease

At cardiac catheterization, 16 patients with coronary artery disease (14 men and 2 women) were allocated by a random, double-blind method to intervention with placebo (saline solution) or verapamil (0.2 mg/kg total by bolus and by 10-minute infusion). In all patients, resting and exercise (3 minutes with a bicycle at 150 kg X m/min) hemodynamic values were obtained during a control period and after intervention. Subsequent left ventriculography and coronary arteriography revealed a mean ejection fraction of 52 and 53% and the mean number of diseased vessels (3-vessel scale) of 2.1 and 1.5 in the placebo and verapamil groups, respectively. In both groups of patients, exercise induced significant increased heart rate, mean arterial pressure, left ventricular end-diastolic pressure and cardiac index. Verapamil increased the heart rate and decreased the mean arterial pressure at rest and the arterial pressure during exercise. It did not affect exercise-induced increases in left ventricular end-diastolic pressure or cardiac index. These results support a role for peripheral mechanisms mediating the antianginal effects of verapamil.