Prevention of nifedipine of abnormal coronary vasoconstriction in patients with coronary artery disease

Comparative effects of diltiazem, propranolol, and placebo on exercise performance using radionuclide ventriculography in patients with symptomatic coronary artery disease: results of a double-blind, randomized, crossover study

The effects of oral diltiazem (120 mg), propranolol (100 mg), and placebo on exercise performance and left ventricular function were compared before and during symptom-limited supine bicycle exercise by means of multigated radionuclide ventriculography in 12 patients with documented, symptomatic coronary artery disease; a double-blind, randomized crossover protocol was used. Diltiazem increased ejection fraction (EF) at submaximal exercise (+7.0 absolute percentage points, p less than 0.02) and maximal exercise (+8.1 percentage points, p less than 0.01). Exercise EF was increased by 13.6 percentage points (p less than 0.02) in patients with decreased ventricular function (resting EF less than 50%). Propranolol had no effect on exercise EF at any stage, even when patients with EF less than 50% were excluded. The increase in total exercise time was significant after diltiazem (+27%, p less than 0.01) but not after propranolol (+16%, p = NS). As expected, propranolol decreased both resting (-9 bpm, p less than 0.01) and exercise heart rates (-27 bpm, p less than 0.001), whereas diltiazem had no significant effect. Propranolol decreased resting diastolic blood pressure (-8 mm Hg, p less than 0.02), exercise systolic (-27 mm Hg, p less than 0.001) and diastolic (-9 mm Hg, p less than 0.01) blood pressures, and rest (p less than 0.01) and exercise (p less than 0.001) double product. Diltiazem decreased resting systolic blood pressure (-9 mm Hg, p less than 0.01) and both resting (-8 mm Hg, p less than 0.001) and exercise (-9 mm Hg, p less than 0.01) diastolic blood pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty in patients with stable and unstable angina pectoris: analysis of early and late results

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 50 patients with stable and in 50 patients with unstable angina pectoris, each patient showing an isolated stenosis of more than 80% of the cross-sectional area of a single coronary artery. The technical success rate was 66% in the stable groups (26 of 37 patients [70%] with left anterior descending artery [LAD], 7 of 12 patients [58%] with right coronary artery [RCA]) and 74% in the unstable group (27 of 34 patients [79%] with LAD, 10 of 15 patients [67%] with (RCA). The increase in stenotic area in the unstable group exceeding that in the stable group for LAD stenoses (41.5 +/- 15.1% vs 32.3 +/- 14.5%, p less than 0.03), while in RCA stenoses the results in the stable group were better (45.1 +/- 17.6% vs 32.7 +/- 12.3%, n.s.). One acute vessel occlusion necessitating an emergency bypass operation occurred in each group (2%). The patient in the stable group died (total mortality rate 1%). Sixty-three of the successfully treated patients were routinely restudied 6 months later. According to clinical symptoms, 23% of the stable and 36% of the unstable group were in functional classes III and IV. From the anatomical viewpoint, a restenosis (greater than 85%) was found in 17% of the stable and in 24% of the unstable group. A further spontaneous decrease (greater than 10%) of the vessel obstruction was found in 47% of the stable group and in 12% of the unstable group.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium-entry blockers and cardiovascular disease

The beneficial effects of calcium-entry blockers in the treatment of ischemia in the heart and in other tissues can be explained by (1) relaxation of venous smooth muscle, in particular that of the splanchnic veins; (2) negative inotropic effect on the myocardial cells; (3) negative chronotropic effects on the heart; (4) inhibition of vasospastic episodes in coronary and other large arteries; (5) depression of myogenic activity and responsiveness to vasconstrictor stimuli in precapillary resistance vessels; (6) inhibition of platelet aggregation; (7) possible increases in the deformability of hypoxic red blood cells; (8) protection of endothelial integrity and function; and (9) protection of the body cells, in particular myocardial cells, from prolonged exposure to anoxia and from massive entry of calcium during reperfusion. In the case of angina pectoris, the effects on the myocardial cells themselves, the decrease in preload and afterload, and the improvement of coronary perfusion combine to allow the heart to perform more work before an imbalance is reached between the metabolic demands of the myocardial cells and their blood supply. The increased myocardial performance may favor collateral circulation and withdrawal of the reflex load upon the heart, originating from the ischemic myocardium. The available calcium-entry blockers vary in their potency to affect the different components of the cardiovascular system.

Relation of therapeutic response to nifedipine to coronary anatomy and motion of S-T segment during unstable angina pectoris

Of 77 patients hospitalized for unstable angina pectoris and failure of oral, dermal, or intravenous nitrates and/or beta blockade, 81 percent with negligible or single-vessel disease and 55 percent with two- or three-vessel disease showed response (p less than 0.05) to nifedipine therapy. Patients with either S-T elevation or no change during pain responded better (31 of 45) than those with any S-T depression (16 of 32; p less than 0.05). Patients with negligible or single-vessel disease had a higher prevalence of S-T elevation (13 of 16) than patients with two- or three-vessel disease (15 of 31; p = 0.004). S-T motion did not predict response in patients with two- or three-vessel disease, but did predict response in patients with negligible or single-vessel disease. On follow-up study at 9 +/- 8 (range one to 33) months, 39 of 42 who had shown response were free from pain. Three died from infarction without unstable angina. (range one to 33) months, 39 of 42 who had shown response were free from pain. Three died from infarction without unstable angina. Five who showed response had elective bypass surgery. The addition of nifedipine abolished or reduced pain episodes by more than 50 percent in 61 percent of patients with refractory unstable angina pectoris. Patients with negligible or single-vessel disease with S-T elevation benefit most. In patients with two- or three-vessel disease, the type of S-T motion did not predict response. Follow-up of all those with response indicated sustained amelioration by nifedipine therapy. Failure of nifedipine therapy should not be accepted until a dose of 120 mg per day has been achieved, or until intolerable side effects appear.

Prevention by nifedipine of cold pressor-induced decrease in left ventricular ejection fraction

To examine the effects of nifedipine on changes in ventricular function produced by cold, the cold pressor test was administered to eight patients with angiographically documented coronary artery disease. Radionuclide ventriculograms were obtained at baseline and during the cold pressor stimulus both before and after administration of nifedipine, 10 mg buccally; thus, four serial radionuclide ventriculograms were obtained per patient. The cold pressor stimulus did not produce any significant difference in the mean (+/- standard deviation) peak rate-pressure product during the control or nifedipine test (10,900 +/- 3,390 versus 10,600 +/- 3,700). However, the increase in systolic blood pressure (p = 0.05) and the peak systolic blood pressure achieved (p less than 0.001) were greater during the control (134 +/- 19 to 160 +/- 25 mm Hg) than during the nifedipine (125 +/- 18 to 145 +/- 21 mm Hg) cold pressor test. The mean global left ventricular ejection fraction decreased during the control cold pressor test from a baseline value of 0.60 +/- 0.08 to 0.52 +/- 0.08 (p = 0.004). After nifedipine, this variable did not change during the repeat cold pressor test (0.63 +/- 0.09) compared with the repeat baseline value (0.63 +/- 0.11). Therefore, the difference in left ventricular ejection fraction response during control versus nifedipine cold pressor testing was highly significant (p less than 0.0001). In patients with obstructive coronary artery disease, nifedipine abolished the decrease in left ventricular ejection fraction observed during the control cold pressor test and may be of value to protect patients from cold-induced left ventricular dysfunction. The mechanism may be a combination of coronary artery vasodilation and systolic unloading of the left ventricle.

Effects of verapamil on coronary hemodynamic function and vasomobility relative to its mechanism of antianginal action

The effect of intravenous verapamil on systemic and coronary hemodynamic function was studied at cardiac catheterization in 12 patients with coronary artery disease. Verapamil was administered as a 2-minute bolus (0.145 mg/kg) followed by an infusion (0.005 mg/kg/min). Cardiac output and coronary sinus blood flow were measured by thermodilution techniques. Caliber of the large coronary arteries and of diseased segments was determined from the coronary angiogram using a computer-assisted method. Verapamil reduced mean arterial pressure 14% (p less than 0.001), systemic vascular resistance 21% (p less than 0.01), and stroke work index 16% (p less than 0.001). Coronary vascular resistance decreased 24% (p less than 0.01) with a small increase in coronary sinus blood flow (+13%, difference not significant [NS]). Myocardial oxygen consumption determined in 5 patients showed no significant change with verapamil. Luminal area in 39 coronary lesions was measured in the "normal" portion of the diseased segment and at its maximal constriction, and an estimate of flow resistance in the stenosis was computed. Overall, 50% of "normal" and of diseased coronary segments dilated significantly with verapamil. Stenosis dilation resulted in an average 14% reduction (p less than 0.01) in estimated flow resistance. In 8 patients, the luminal changes (n = 27) induced by sublingual nitroglycerin were compared with those induced by verapamil. Nitroglycerin induced a significantly greater increase in coronary caliber in both normal and diseased segments; estimated stenosis flow resistance decreased 28% with nitroglycerin compared with 14% with verapamil (p less than 0.01). Thus, verapamil moderately dilates the systemic and coronary small vessel resistance bed without apparently increasing myocardial metabolic demand. Furthermore, verapamil mildly dilates large coronary conductance vessels in both "normal" and diseased segments, although significantly less than does nitroglycerin.

Prolactin response to the cold pressor test in patients with panic attacks

Recent advances in psychiatric nosology have provided a clearer clinical description of panic disorder and agoraphobia with panic attacks. This clinical improvement has yet to result in a better understanding of the basic mechanisms involved in these conditions. The present study compares the effects of the cold pressor test on blood pressure changes and prolactin levels in patients with panic disorder and agoraphobia with panic attacks to its effects in normal controls. Because the effects of the cold pressor test were similar in patients and normal controls, it appears that alpha-adrenergic function is normal in the patient group. The results also suggest that prolactin hypersecretion does not occur in pathological anxiety states.

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.

Patients with myocardial infarction and normal coronary arteriogram

Eighteen patients who survived an acute myocardial infarction were found to have a normal coronary arteriogram. Seven patients were younger than 35 years and six were female. The myocardial infarction was nontransmural in 11 cases. The mean follow-up was 21.6 months. Eleven patients developed residual chest pain at rest early after myocardial infarction. One, treated by beta-blockers, suffered a recurrent myocardial infarction. Eight became asymptomatic, and two improved under antispastic therapy. Another patient developed a severe form of variant angina three months after myocardial infarction; she died following plexectomy. Finally, two patients experienced rare episodes of angina at rest. The stress ECG was negative in all cases. Provocative test for spasm was positive in three out of nine patients. Diffuse narrowing associated with chest pain was demostrated in two patients at angiography. Thus, myocardial infarction and subsequent normal coronary angiogram are mainly found in young female patients, and infarction is often nontransmural. Clinical evidence of vasospastic phenomena and increased vasomotor tone are found in most patients. Whenever residual chest pain is controlled by antispastic therapy, the follow-up course seems benign.

Calcium antagonists in the treatment of individuals with ischemic heart disease

The so-called calcium antagonists--verapamil, nifedipine, diltiazem, and perhexiline--are pharmacologic agents that will have a dramatic impact on the medical therapy of individuals with ischemic heart disease. They have been used extensively in Europe and Japan for over 15 years, and more recent studies from this country have demonstrated their efficacy in the treatment of patients with Prinzmetal's "variant" angina pectoris, stable (exertional) angina pectoris, and unstable angina pectoris. In addition, they appear effective in protecting ischemic myocardium both in patients with acute myocardial infarction as well as in those undergoing cardiopulmonary bypass. The purpose of this review is twofold: (a) to describe the mechanism of action and pharmacology of these agents and (b) to delineate their role in the treatment of individuals with ischemic heart disease.

Regional coronary angiographic observations during cold stimulation in patient with exertional chest pain: comparison of diameter responses in normal and fixed stenotic vessels

In 12 patients with exertional chest pain, coronary angiography was performed and quantitative measurements coronary artery (CA) diameters were made before and during cold stimulation (four normal CA patients and eight fixed CA stenosis patients). The left main CA; proximal, middle and distal anterior descending and circumflex segments; and small intramyocardial CAs (0.4 to 1.0 mm) usually showed only minimal and similar degree of vasoconstriction (average diameter reduction 6%) during cold stimulation in both normals and CA disease (CAD) patients. Magnitude of vasoconstriction differed among some CA segments measured; the left main CA segment (0 +/- 2%, mean +/- SD) usually did not change while distal segments (-10 +/- 10%) usually demonstrated greatest percentage vasoconstriction. Coronary stenoses and CAs filled by collaterals did not demonstrate increased magnitude of vasoconstriction compared to other CAs. Results of other CA segments were also similar comparing patients with and without CAD. The minimal degree of vasoconstriction observed in these CA segments does not appear to account for the large increase in coronary resistance reported during cold stimulation in CAD patients.

Nifedipine in the treatment of cardiovascular disease

Nifedipine, a calcium channel blocking agent, has been shown safe and effective in the treatment of various cardiac disorders. In Prinzmetal's variant angina, nifedipine relieves the acute spasm of a large coronary artery, and thereby reverses the sudden decrease in myocardial oxygen supply. In chronic stable angina, the efficacy of nifedipine stems from an interplay of direct and reflex effects. A decrease in systemic vascular resistance, and thus, myocardial oxygen demand, is considered the most important effect. Although this is partially offset by baroreceptor-mediated reflex increases in blood pressure and heart rate, the net effect is a decrease in myocardial oxygen consumption. The importance of nifedipine-induced increases in coronary blood flow in relieving stable angina remains controversial. Numerous clinical trials in patients with chronic angina have demonstrated that nifedipine increases exercise tolerance by lowering the heart rate-blood pressure product (an approximation of myocardial oxygen consumption). The maximal double product during exercise, however, does not increase, suggesting that the drug does not importantly improve myocardial oxygen supply. Nifedipine may also be of value in the therapy of unstable angina, acute myocardial infarction, and hypertension, as well as in the protection of the myocardium at risk during open heart surgery. However, definite recommendations on the use of the drug for these indications must await results of ongoing randomized studies. The effects of nifedipine are dose-related. Larger doses have been shown more effective than smaller doses, as long as an appropriate blood pressure is maintained. The side effects of nifedipine are mild and related to its vasodilating action.