Hemodynamic effects of sublingual nifedipine in congestive heart failure

Calcium antagonists and heart failure

The systemic vasodilatory actions of the calcium antagonists make them potentially attractive for use as afterload reducing agents in patients with left ventricular failure. However, unlike other vasodilator drugs, these drugs also exert a direct negative inotropic effect on the myocardium. Clinical data suggest a limited role for the calcium antagonists as vasodilator therapy in patients with heart failure.

Effects of a new second generation calcium channel blocker, nilvadipine (FR34235), on exercise-induced hemodynamic changes in stable angina pectoris

The mechanism of the antianginal actions of nilvadipine was investigated in 11 patients with effort angina pectoris. Hemodynamic data were obtained by angina-limited supine multistage bicycle ergometer exercise testing before and after a single 6 mg dose of nilvadipine. Compared with chest pain during control exercise testing, pain at peak exercise disappeared or abated and the ST segment at peak exercise also showed less significant depression after administration of nilvadipine. At rest and at peak exercise, mean blood pressure, pulmonary artery wedge pressure and systemic vascular resistance decreased significantly, whereas heart rate and cardiac index increased significantly after nilvadipine. Rate-pressure product and stroke volume index did not change significantly. Coronary sinus flow at peak exercise increased significantly and total coronary vascular resistance at rest and at peak exercise decreased significantly after nilvadipine. The plasma concentrations of nilvadipine 1.5 hours after administration ranged from 1.15 to 8.23 ng/ml. These data suggest that the principal factors in the antianginal actions of nilvadipine are an increase in myocardial oxygen supply due to increased coronary blood flow and a reduction in myocardial oxygen demand mainly by a decrease in afterload and additionally by a decrease in preload.

Characterization of the dose-concentration-dependent hemodynamic effects of nifedipine in heart failure

The hemodynamic effects of increasing oral doses of nifedipine (10 to 30 mg) were studied in 12 patients who had low output heart failure. With each set of hemodynamics, serum concentrations of nifedipine were measured to determine the concentration/response relationships. Eleven of twelve patients responded acutely to nifedipine, defined as a reduction in systemic vascular resistance (SVR), and an augmentation in cardiac index (CI) and stroke volume index (SVI). The differential dose effects (X +/- SD) for SVR and SVI for baseline (N = 11), 10 mg (N = 10), 20 mg (N = 3) and 30 mg (N = 4) were: 1913 +/- 486, 1102 +/- 221, 1128 +/- 166, 803 +/- 176 and 17.9 +/- 4.8, 23.8 +/- 4.5, 31 +/- 0.42, 33 +/- 3.5, respectively. All nifedipine doses reduced SVR and increased CI and SVI compared with baseline (P less than .001). The increase in CI and SVI was significantly correlated to the mg/kg dose of nifedipine (r = 0.79; P less than .001). Nifedipine administration resulted in no significant change in central venous pressure, pulmonary capillary wedge pressure, or pulmonary vascular resistance. No relationship could be demonstrated between serum concentrations of nifedipine and any hemodynamic effect. Conclusions drawn were: (1) the afterload reduction effects of nifedipine are acutely efficacious in a large portion of patients with heart failure and this activity supercedes the negative inotropic effects of the drug at doses between 10 and 30 mg; (2) the magnitude of the hemodynamic effects are dose dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Experience with calcium antagonist drugs in congestive heart failure

Several clinical studies have demonstrated beneficial hemodynamic effects of calcium antagonist drugs when used as arterial vasodilators in the treatment of certain patients with moderate to severe congestive heart failure. These drugs usually decrease systemic vascular resistance and improve ejection phase indexes of left ventricular function in such patients. However, calcium antagonists have intrinsic negative inotropic effects and other vasodilators such as nitroprusside, hydralazine and captopril appear to be more beneficial when used in the treatment of severe congestive heart failure.

Usefulness of calcium antagonists for congestive heart failure

In patients with congestive heart failure (CHF) due to dilated cardiomyopathy, nifedipine, diltiazem and several of the newer calcium antagonists including nicardipine, nitrendipine, felodipine and PN 200-110 (isradipine) improve left ventricular function. Because of its relatively more pronounced negative inotropic and chronotropic actions, verapamil is generally not tolerated by patients with left ventricular failure. In addition, even relatively vascular-selective agents such as nifedipine can occasionally cause significant left ventricular depression, particularly if combined with beta-adrenergic blocking agents. Comparative studies using nitroprusside to cause an equivalent decrease in arterial pressure indicate that nifedipine acts predominantly on the arterial vasculature, and that a small but significant decrease in contractility occurs, apparently due to a direct myocardial action. Although diltiazem causes a depression in myocardial contractility in dogs with volume overload heart failure, limited data show no significant negative inotropic action in patients with heart failure. The negative inotropic effects, if any, of newer and possibly more vascular-selective agents are not yet known. Calcium antagonists appear to act predominantly on the limb and coronary vasculature, with relatively less effect on renal and hepatic vessels. In patients with CHF, nifedipine causes an increase in coronary blood flow and a decrease in the aorto-coronary sinus oxygen difference indicating an improvement in myocardial energetics. Although nifedipine causes an increase in cardiac index and decreases in systemic vascular resistance and pulmonary capillary wedge pressure during exercise, the limited data available fail to show a short- or long-term increase in exercise capacity. Nifedipine causes an increase in plasma renin activity, possibly due to a direct action on the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nifedipine on forearm vascular resistance and venous capacitance in normal subjects and in patients with congestive heart failure

The effects of oral nifedipine on limb hemodynamics were studied in 7 normal subjects, 8 patients with congestive heart failure and 2 patients who underwent sympathectomy of unilateral limb. Forearm venous capacitance remained unchanged both in normal subjects and in patients with congestive heart failure. In normal subjects, systemic vascular resistance decreased without change in forearm vascular resistance. On the other hand, both systemic and forearm vascular resistance decreased simultaneously in patients with congestive heart failure. In 2 patients with normal left ventricular function undergoing sympathectomy, limb vascular resistance decreased in the denervated side and increased in the contralateral innervated side. These findings indicate that the effects of nifedipine on forearm vascular resistance are dependent upon the circulatory state of the patient at the time the drug is administered, while venous dynamics were not changed by nifedipine, and that the difference in the density of sympathetic innervation results in a reordering of territorial blood flow by modifying the vasodilatation due to the calcium antagonistic action of nifedipine.

Sublingual nifedipine: acute effects in severe chronic congestive heart failure secondary to idiopathic dilated cardiomyopathy

Nine patients with chronic, severe (New York Heart Association class III to IV) congestive heart failure were studied to determine the acute effects of 10 mg of sublingual nifedipine on left ventricular (LV) function. Hemodynamic and echocardiographic data were obtained at rest and 30 minutes, 1, 2, 4 and 6 hours after nifedipine. Measurements at rest reflected LV dysfunction with elevation of end-diastolic volume index (102 +/- 46 ml/m2), pulmonary capillary wedge pressure (17 +/- 8 mm Hg), systemic vascular resistance (1,547 +/- 439 dynes s cm-5) and reduction of cardiac index (2.8 +/- 0.5 liters/min/m2). There were no adverse effects noted with administration of sublingual nifedipine. Initial changes through 1 hour reflected an unloading effect of nifedipine with reduction in pulmonary capillary wedge pressure (11 +/- 5 mm Hg) (p less than 0.05), systemic vascular resistance (1,179 +/- 289 dynes s cm-5) (p less than 0.01), end-diastolic volume index (91 +/- 37 ml/m2 [difference not significant]) and an increase in cardiac index (3.6 +/- 0.7 ml liters/min/m2) (p less than 0.01). Subsequently the cardiac index, systemic vascular resistance and end-diastolic volume index returned toward baseline. Only the pulmonary capillary wedge and pulmonary artery pressures demonstrated a sustained reduction through the 6-hour study period suggesting an effect of nifedipine on LV relaxation. Thus, sublingual nifedipine administered acutely to patients with clinical congestive heart failure is a safe and efficacious vasodilator.

Inotropic, vascular and neuroendocrine effects of nifedipine in heart failure: comparison with nitroprusside

To evaluate the short-term hemodynamic and neuroendocrine effects of nifedipine in heart failure, it was compared with nitroprusside, a balanced vasodilator without known inotropic effect, in equihypotensive doses during right and left heart catheterization in nine patients with heart failure. Mean arterial pressure decreased from 89 +/- 12 to 76 +/- 14 mm Hg with nitroprusside, and from 90 +/- 12 to 75 +/- 13 mm Hg with sublingual nifedipine. Right atrial, pulmonary artery, pulmonary capillary wedge and left ventricular end-diastolic pressures decreased significantly with nitroprusside, but not with nifedipine. Cardiac index and stroke volume index increased to a similar extent with both drugs; in contrast, stroke work index increased significantly with nitroprusside, but not with nifedipine. Peak rate of left ventricular pressure development (dP/dt) (measured with a micromanometer-tipped catheter in seven patients) was unchanged with nitroprusside, but decreased significantly with nifedipine (747 +/- 292 to 639 +/- 238 mm Hg/s; p less than 0.002). There was no change in heart rate with either medication. Plasma norepinephrine and epinephrine concentrations were not altered significantly by either drug. Plasma renin activity was not changed by nitroprusside infusion, but was increased after the administration of nifedipine. Thus, in contrast to the balanced vasodilator action of nitroprusside, the effect of nifedipine is predominantly on the arterial circulation. In these patients with heart failure, reflex sympathetic stimulation did not occur in response to a decrease in systemic arterial pressure by either vasodilator. A negative inotropic effect occurred after the administration of nifedipine, but not nitroprusside.

Hemodynamic effects of intravenous diltiazem with impaired left ventricular function

The acute hemodynamic effects of intravenous diltiazem were studied in 8 patients with coronary artery disease, left ventricular (LV) failure (New York Heart Association functional class III), a rest ejection fraction (EF) less than 40% or a cardiac index less than 2.4 liters/min/m2. Hemodynamic measurements and LV angiograms were performed at rest before and after the administration of diltiazem, 0.5 mg/kg, administered at a speed of 5 mg/min. Diltiazem treatment induced a decrease in heart rate from 68 +/- 12 to 55 +/- 9 beats/min (p less than 0.001). Mean aortic pressure decreased from 94 +/- 14 to 81 +/- 15 mmHg (p less than 0.05). Thus, the pressure-rate product significantly decreased under the influence of the drug, from 8,791 +/- 2,465 to 6,342 +/- 1,808 beats mm Hg/min, (p less than 0.001). Diltiazem induced no significant change of LV end-diastolic pressure, pulmonary wedge pressure, cardiac index and LV stroke work index. Systemic vascular resistance decreased (p less than 0.01), whereas pulmonary vascular resistance showed no change. End-systolic volume diminished (p less than 0.02), which accounts for the increase of stroke volume and ejection fraction (p less than 0.001). Disorders of regional contractility were not aggravated by diltiazem, and even improved in individual cases. Thus, intravenous diltiazem may be used safely in patients with heart failure. However, in view of the marked bradycardic effects seen in some cases, heart rate should be carefully monitored.

Beneficial hemodynamic effects of intravenous and oral diltiazem in severe congestive heart failure

Concern persists about the potential negative inotropic effects of calcium channel blockers in patients with severely depressed myocardial function. Therefore, intravenous diltiazem (100 to 200 micrograms/kg per min infusion) was administered for 40 minutes followed by oral diltiazem (90 to 120 mg/8 hours) for 24 hours to patients with advanced congestive heart failure (New York Heart Association class III to IV, mean ejection fraction 26 +/- 4 [SD]). Intravenous diltiazem (eight patients) increased cardiac index 20% (2.05 +/- 0.8 to 2.47 +/- 0.8 liters/min per m2, p less than 0.01), stroke volume index 50% (22 +/- 9 to 33 +/- 12 ml/m2, p less than 0.001) and stroke work index 27% (19 +/- 10 to 24 +/- 10 g-m/m2, p less than 0.05); while reducing heart rate 23% (97 +/- 18 to 75 +/- 11 beats/min, p less than 0.01), mean arterial pressure 18% (95 +/- 13 to 78 +/- 7 mm Hg) and pulmonary wedge pressure 34% (29 +/- 9 to 19 +/- 7 mm Hg), without altering maximal first derivative of left ventricular pressure (dP/dtmax). Oral diltiazem (seven patients) produced equivalent hemodynamic effects. Transient junctional arrhythmias were observed in three of eight patients with intravenous diltiazem and one of seven patients with oral diltiazem. It is concluded that intravenous and short-term oral diltiazem improve left ventricular performance and reduce myocardial oxygen demand by heart rate and afterload reduction without significantly depressing contractile function in severe congestive heart failure. Caution should be exercised to avoid potential adverse, drug-induced electrophysiologic effects in such patients.

Differential effects of diltiazem and nitroprusside on left ventricular function in experimental chronic volume overload

To compare the hemodynamic effects of a calcium-channel blocker with those of a conventional vasodilator in the awake preinstrumented dog, diltiazem and nitroprusside were administered in equihypotensive infusions before (decrease in mean aortic pressure by 10%; p less than .001, n = 6) and after (decrease in mean aortic pressure by 12%; p less than .001) chronic volume overload (CVO) produced by an infrarenal aortocaval fistula. Diltiazem had no effect on preload either before or after CVO. The maximal rate of change in left ventricular pressure (dP/dtmax) was unaffected by diltiazem before the aortocaval fistula (decrease in dP/dtmax by 6%; p = NS) but was significantly reduced by calcium-channel blockade after CVO (decrease in dP/dtmax by 22%; p less than .001). By contrast, at matched aortic pressures nitroprusside significantly reduced left ventricular end-diastolic dimension (LVEDD) and pressure (LVEDP) in the same animals before (decrease in LVEDD by 10%, p less than .05; decrease in LVEDP by 7 +/- 2 mm Hg, p less than .001) and after CVO (decrease in LVEDD by 7%, p less than .05; decrease in LVEDP by 5 +/- 2 mm Hg, p less than .001) without altering dP/dtmax. We conclude that the calcium entry blocker diltiazem, unlike conventional vasodilators, may depress left ventricular function in CVO by direct negative inotropic properties in amounts that are without myocardial depressant effects in the presence of normal left ventricular performance.

Effect of calcium antagonists on cardiac performance in patients with dilatative cardiomyopathy evaluated by noninvasive methods

We present 14 patients with dilatative cardiomyopathy, proven by hemodynamic and angiographic assessment who received in a single-blind, randomized study, equipotent doses of the three calcium blockers: verapamil (0.1 mg/kg i.v., followed by an infusion of 0.01 mg/kg/min), nifedipin (20 mg sublingually), or diltiazem (0.2 mg/kg i.v., followed by infusion of 0.02 mg/kg/min). Before and after treatment in 8 patients systolic time intervals were recorded with an AVL-Myocard-Check (Q-S2, pre-ejection period, left ventricular ejection time, and pre-ejection period/left ventricular ejection time) and end-systolic and end-diastolic diameter, fractional shortening, and circumferential fiber shortening velocity were measured by M-mode echocardiography. In another 6 patients radionuclide ventriculography was performed before and after each treatment (ejection fraction, cardiac index). PEP/LVET increased slightly after verapamil (+ 15%) and decreased after nifedipin (-5%) and diltiazem (-3%), the changes being not significant. Fractional shortening and circumferential fiber shortening velocity however, decreased after verapamil (-5%, resp. -15%) and increased after nifedipin (+ 14%, resp. + 25%) and after diltiazem (+ 23%, resp. + 16%). In the radionuclide studies ejection fraction increased after verapamil (+ 9%), nifedipin (+ 14%), and diltiazem (+ 13%), while cardiac index remained unchanged with verapamil and nifedipin and increased with diltiazem (+ 14%). In conclusion there are no significant changes in myocardial performance with the calcium blockers verapamil, nifedipin, and diltiazem. However, under verapamil there is a tendency to deterioration of myocardial performance, while it was slightly improved after nifedipin and diltiazem. Calcium antagonists may be used safely, therefore, also in patients with impaired myocardial performance.

Hemodynamic effects of dibutyryl cyclic AMP in congestive heart failure

To evaluate the hemodynamic effects of dibutyryl cyclic AMP (DBcAMP) in congestive heart failure (CHF), right-sided cardiac catheterization was performed in 11 patients with CHF, and hemodynamic variables were investigated before and after infusion of various doses of DBcAMP at a rate of 0.025 to 0.2 mg/kg/min (mean 0.14 +/- 0.077 [standard deviation]). DBcAMP reduced total systemic vascular resistance index from 3,171 +/- 1,158 to 1,880 +/- 554 dynes s cm-5 X m2 (mean +/- standard deviation) and pulmonary arterial end-diastolic pressure from 23 +/- 13 to 20 +/- 11 mm Hg, and increased cardiac index from 2.24 +/- 0.60 to 3.41 +/- 1.02 liters/min/m2. Mean arterial blood pressure decreased from 91 +/- 14 to 84 +/- 13 mm Hg, and heart rate increased from 91 +/- 16 to 99 +/- 13 beats/min. The increase in cardiac index was accompanied by a proportional decrease in total systemic vascular resistance index in all patients except 1. In 8 patients the decrease in pulmonary arterial end-diastolic pressure was accompanied by an increase or no change in the left ventricular stroke work index. In 6 patients, DBcAMP was given in incremental doses of 0.05, 0.1, and 0.2 mg/kg/min every 20 minutes, and 5 of 6 patients tolerated the full dose and showed dose-related hemodynamic changes for the incremental doses of DBcAMP. These data suggest that DBcAMP has powerful vasodilating effects on resistance vessels in patients with CHF; hence, it can be a useful vasodilating agent for treatment of CHF.

Clinical applications of slow channel blocking compounds

The slow-channel blockers constitute a structurally diverse group of drugs with varying mechanisms of action, propensities for site of greatest cardiovascular activity, and clinical efficacy. They share however the property of blocking the slow inward channel in heart muscle and of inhibiting calcium fluxes in smooth muscle. Their in vivo and in vitro actions must be distinguished. The overall actions represent a balance of direct and autonomically-mediated reflex actions interacting with the compounds' varying degrees of intrinsic non-competitive sympathetic antagonism. A knowledge of the pharmacodynamic differences between these drugs allows the physician to select the most appropriate agent for a given clinical situation. The central role of calcium in the cellular processes in the heart and the vascular system forms the basis for the utility of this class of drugs in a wide variety of cardiovascular disorders. Current intensive experimental and clinical investigations are likely to further define the roles of nifedipine, verapamil and diltiazem and their congeners in cardiovascular therapeutics. The prospect of development of newer compounds with greater selectivity of action is real. As pointed out by Braunwald (1982 a,b), with further clarification of the mechanisms of actions of these compounds and elucidation of the role of calcium fluxes throughout the body, more specific and potent agents may be developed. The apparent efficacy of the nifedipine congener nimodipine, in the treatment of cerebral vasospasm associated with subarachnoid hemorrhage (Allen et al., 1983) may simply be the first of a large number of 'specific' or targeted slow channel blockers. The development of such compounds may offer further therapeutic possibilities in the control of a variety of cardiocirculatory diseases.

The effects of calcium channel blocking agents on cardiovascular function

The hemodynamic effects of calcium blocking agents are a composite of the various direct and indirect cardiac and peripheral vascular actions of these drugs on the individual determinants of left ventricular pump function. Calcium antagonists have been shown to have a direct negative inotropic effect, a direct negative chronotropic effect and a direct effect to produce relaxation of vascular smooth muscle and vasodilation. These agents may also elicit important indirect effects by an anti-ischemic action referable to both coronary arterial dilation and reduction in myocardial oxygen demand, as well as a baroreceptor-mediated reflex increase in beta adrenergic tone in response to vasodilation. The net result of these direct and indirect actions on cardiocirculatory dynamics is also dependent upon the individual calcium blocking agent administered, the dose and route of administration, and the underlying status of left ventricular function. Available data do not lead to a clear definition of the hemodynamic effects referable to calcium blocking agents that may be produced by the interaction of all variable factors. At present, however, it would appear that the direct negative inotropic and chronotropic actions of the calcium antagonists are offset by the reflex increase in beta adrenergic tone, in combination with the reduction in afterload produced by the peripheral vascular effects of these agents. Preliminary data suggest that certain calcium inhibiting agents may be useful in the vasodilator therapy of congestive heart failure. Nevertheless, the direct negative inotropic effects of these agents have resulted in clinically evident decompensation in cardiac performance in patients with advanced left ventricular dysfunction, and caution is warranted in the application of calcium blocking agents in this setting.