Contrasting hemodynamic responses in severe heart failure: comparison of captopril and other vasodilator drugs

Current perspectives on hydralazine and nitrate therapies in heart failure

The origins of the hydralazine/isosorbide dinitrate (H+ISDN) combination therapy are rooted in the first large-scale clinical trial in heart failure: V-HeFT I. Initially utilized for the balanced vasodilatory properties of each drug, we now know there is "more to the story." In fact, the maintenance of the nitroso-redox balance may be the true mechanism of benefit. Since the publication of V-HeFT I 30 years ago, H+ISDN has been the subject of much discussion and debate. Regardless of the many controversies surrounding H+ISDN, one thing is clear: therapy is underutilized and many patients who could benefit never receive the drugs. Ongoing physician and patient education are mandatory to improve the rates of H+ISDN use.

Effect of captopril on cardiac parasympathetic activity in chronic cardiac failure secondary to coronary artery disease

Thirty-two patients with chronic cardiac failure underwent 24-hour ambulatory electrocardiographic monitoring on 2 separate occasions: 20 patients before and during treatment with captopril, and 12 acting as controls. Heart rate variability was calculated by counting the number of times successive RR interval differences were greater than 50 ms (this measurement being a reliable index of cardiac parasympathetic activity). During treatment with captopril, group mean total counts increased to 1,032 (range 48 to 7,437) from 482 (range 23 to 6,120) (p = 0.002). There was no change in mean hourly waking or sleeping heart rates. In the control group, no changes were seen: group mean total counts on the first occasion were 340 (range 120 to 3,255) and on the second occasion 400 (range 154 to 3,300) (p = not significant). These results show that treatment with angiotensin-converting enzyme inhibitors increases cardiac parasympathetic activity in patients with chronic cardiac failure. This may be relevant to the improved prognosis of this group of patients when treated with angiotensin-converting enzyme inhibitors.

Effect of captopril, an angiotensin-converting enzyme inhibitor, in patients with angina pectoris and heart failure

The effects of captopril and placebo were compared in 18 patients with chronic heart failure and angina pectoris with use of a double-blind crossover trial design. Symptoms were assessed by patient treatment preference, visual analogue scores and nitroglycerin consumption. Exercise performance was assessed using two different treadmill protocols of different work intensity with simultaneous measurement of oxygen consumption and by supine bicycle exercise and simultaneous radionuclide ventriculography. Arrhythmias were assessed by 48 h ambulatory electrocardiographic monitoring. Patients generally preferred placebo to captopril, and this appeared to be due to an increase in symptoms of angina with captopril. Treadmill exercise time on a high intensity protocol was shorter with captopril than with placebo; on a low intensity protocol, angina became a more frequent limiting symptom even though overall exercise performance was not changed. The heart rate-blood pressure product was reduced, but largely because of a reduction in blood pressure rather than in heart rate. During supine bicycle exercise, no differences in symptoms, exercise performance, ejection fraction or changes in blood pressure were noted and ventricular arrhythmias were reduced. Captopril does not appear to be clinically useful in alleviating angina pectoris in patients with heart failure, and this effect may be related to a decrease in coronary perfusion pressure. Nonetheless, desirable metabolic effects, a reduction in arrhythmias and potential effects on survival require further study of captopril in patients with both angina and heart failure.

Cardiac effects of angiotensin converting enzyme inhibitors

ACE inhibitors have provided a major advance in cardiovascular therapeutics. The rationale for their use in hypertension and heart failure, and their cardiac effects are well documented. Further information is required on the relevance of their direct myocardial and other tissue effects, and it is likely that their use in hypertension and heart failure will increase further over the next several years.

Functional infarct expansion, left ventricular dilation and isovolumic relaxation time after coronary occlusion: a two-dimensional echocardiographic study

Left ventricular dilation and infarct expansion after acute myocardial infarction are associated with an increased morbidity and mortality. The purpose of this study was to determine whether angiotensin-converting enzyme inhibition could reverse left ventricular dilation and improve the diastolic properties of the left ventricle very early after coronary occlusion. The acute time course of left ventricular dilation and infarct expansion (as determined by two-dimensional echocardiography) and early diastolic isovolumic relaxation time were studied in 20 dogs subjected to 3 h of coronary occlusion. End-diastolic area before occlusion was 8.4 +/- 0.5 and 8.9 +/- 0.7 cm2 (p = NS) in the captopril- and the saline-treated group, respectively. At 30 min after occlusion (pretreatment), end-diastolic area increased to 12.6 +/- 0.8 cm2 in the captopril-treated group (p less than 0.01) and 11.3 +/- 0.9 cm2 (p less than 0.05) in the saline-treated group. Three hours after occlusion and after captopril treatment, end-diastolic area decreased to 9.4 +/- 0.6 cm2 (p less than 0.05 versus 30 min after occlusion), whereas it was unchanged in the saline-treated group. Functional infarct expansion (as assessed by end-systolic anterior to posterior endocardial segment length ratio) occurred early after occlusion, and captopril reduced this expansion. Pretreatment values for early diastolic isovolumic relaxation time increased from 29.1 +/- 2.4 to 50.5 +/- 2.9 ms in captopril-treated dogs (p less than 0.01) and from 34.3 +/- 3.4 to 46.9 +/- 2.7 ms in saline-treated dogs (p less than 0.01) after coronary occlusion, implying a worsening of diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of a single dose of captopril on pulmonary haemodynamics and right ventricular function in mitral stenosis with pulmonary hypertension

The response of the pulmonary circulation to captopril 75 mg has been examined in 21 patients with pulmonary hypertension secondary to mitral stenosis. The effects of captopril were measured every 15 min up to 2 h by recording pressures in the pulmonary and systemic circulations and by measuring cardiac output. Pulmonary artery systolic pressure fell significantly by 21.6% (from means = 54.6 to 42.8 mm Hg), pulmonary artery diastolic pressure by 23.3% (from 26.2 to 20.1 mm Hg), and the pulmonary artery mean pressure by 23.2% (from 36.9 to 28.3 mm Hg). Right ventricular end-diastolic pressure also fell significantly by 7% (8.1 to 7.5 mm Hg). Heart rate decreased by 6.5% (from 76.3 to 71.3 beats.min-1). Cardiac index and stroke volume index did not change. The total and vascular pulmonary resistance dropped significantly by 23.2% (from 721 to 553.7 dyn.s.cm-5) and 40% (from 287.2 to 172 dyn.s.cm-5), respectively. The right ventricular stroke work index fell by 33% (from 15.1 to 10.1 g/beat/m2). Systemic systolic pressure decreased by 10.5% (from 124.5 to 111.4 mm Hg). Thus, captopril lowered pulmonary pressures and resistances and no deterioration in right ventricular function was observed.

Hemodynamic effects of BTS 49465, a new long-acting systemic vasodilator drug, in patients with severe congestive heart failure

The hemodynamic effects of BTS 49465, a new oral, direct-acting systemic vasodilator drug, were investigated in 10 patients with severe chronic congestive heart failure. One to 2 hours after the administration of 1.5 mg/kg orally, BTS 49465 produced significant increases in cardiac index, stroke volume index, and stroke work index (26%, 27%, and 23%, respectively, p less than 0.01 to 0.001) and marked decreases in left ventricular filling pressure (-12.6 mm Hg, 44%), mean pulmonary artery pressure (-13.2 mm Hg, 31%), and mean right atrial pressure (-7.7 mm Hg, 63%), all p less than 0.001, without significant changes in heart rate. These hemodynamic responses were accompanied by notable declines in systemic vascular resistance (-28%, p less than 0.001) and pulmonary arteriolar resistance (-24%, p less than 0.05). These effects persisted throughout the 24-hour period of observation. The decline in left ventricular filling pressure in our patients ranged in magnitude from 8 to 21 mm Hg, and varied linearly and directly with pretreatment values for left ventricular filling pressure (r = 0.69). The decrease in systemic vascular resistance ranged in magnitude from 3% to 40% and varied linearly and directly with pretreatment values for systemic vascular resistance (r = 0.85). These data indicate that BTS 49465, a new oral, direct-acting vasodilator agent, exerts balanced cardiocirculatory effects in patients with severe chronic heart failure, which may be sustained with once-daily oral administration.

Comparative hemodynamic and clinical effects of long-term treatment with prazosin and captopril for severe chronic congestive heart failure secondary to coronary artery disease or idiopathic dilated cardiomyopathy

Short- and long-term hemodynamic and clinical responses to sequential therapy with prazosin (15 mg/day for 3 to 12 weeks) and captopril (75 to 300 mg/day for 2 to 15 weeks) were compared in 22 patients with severe chronic congestive heart failure. First doses of prazosin produced marked increases in cardiac index and stroke volume index (p less than 0.01), but these effects were lost during long-term treatment. First doses of captopril produced only modest increases in both variables, but these persisted without attenuation during prolonged therapy. Both drugs produced immediate decreases in left ventricular filling pressure, mean arterial pressure, mean right atrial pressure and systemic vascular resistance; these changes became significantly attenuated (p less than 0.01) with prazosin but not with captopril. At the end of treatment, stroke volume index was significantly higher and right and left ventricular filling pressures were significantly lower with captopril than with prazosin (p less than 0.05 to 0.01). Only 8 of the 22 patients (36%) treated with prazosin benefited clinically, whereas 14 of 19 patients (74%) treated with captopril felt that they had improved (p less than 0.05). These differences could not have been predicted by comparing responses to first doses of the 2 drugs. These findings indicate that the choice of 1 vasodilator drug over another in patients with congestive heart failure should be based on studies that compare their long-term rather than short-term hemodynamic and clinical effects.

Comparative immediate hemodynamic and hormonal effects of amrinone and captopril in patients with severe chronic heart failure

To compare the responses to oral inotropic and vasodilator drugs, maximally effective doses of amrinone (300 mg over 3 hours) and captopril (25 mg orally) were administered to 21 patients with severe chronic heart failure, who had not received either agent previously. Despite similar decreases in systemic vascular resistance with both drugs, amrinone produced greater increases in cardiac index (+ 0.56 vs. + 0.41/min/m2, p less than 0.05) and smaller decreases in mean arterial pressure (-11.1 vs. -15.2 mm Hg, p less than 0.05) than did captopril; three patients became symptomatically hypotensive with captopril, but none did so after amrinone. These differences were due to a significant decrease in heart rate with captopril (-6.3 beats/min, p less than 0.01), whereas heart rate increased with amrinone (+ 4.3 beats/min, p less than 0.01); the increases in stroke volume index with both drugs were similar. Despite similar decreases in left ventricular filling pressures, the decrease in mean right atrial pressure with amrinone was greater than with captopril (-5.6 vs. -3.2 mm Hg, p less than 0.01). This difference was the result of the greater decrease in pulmonary arteriolar resistance, and hence in right ventricular afterload, with amrinone than with captopril, (-33% vs. -16%, respectively), p less than 0.01. Despite these superior hemodynamic responses to amrinone, when patients received sequential long-term treatment with both drugs during the follow-up period, only 12% of patients benefitted during therapy with amrinone, whereas 64% improved clinically with captopril.(ABSTRACT TRUNCATED AT 250 WORDS)

Controlled trial of enalapril in congestive cardiac failure

Twenty five patients with chronic congestive cardiac failure had enalapril (n = 13) or placebo (n = 12) added to their existing regimen of digoxin and frusemide in a randomised double blind trial. Four hours after the first 5 mg dose, the enalapril group showed significant falls in blood pressure, heart rate, and concentrations of plasma angiotensin II, angiotensin converting enzyme, and noradrenaline. During the 12 week trial heart failure became worse in one enalapril treated patient (8%) and in seven placebo treated patients (58%). There were no significant changes in cardiac ejection fraction or exercise duration in either group. Plasma noradrenaline response to graded exercise and maximum exercise rate-pressure product were significantly reduced after four and 12 weeks of active treatment but unchanged with placebo treatment. There was a sustained increase in plasma potassium and a slight rise in plasma creatinine in the enalapril group. Plasma concentrations of the active drug, enalaprilate, were dose related and log enalaprilate correlated significantly with percentage of plasma angiotensin converting enzyme activity (r = -0.66). Enalapril was well tolerated and produced no adverse effects. The drug appears to be superior to placebo and offers considerable promise for the treatment of this condition.

Angiotensin converting enzyme inhibition. Unique and effective therapy for hypertension and congestive heart failure

Major developments in the use of angiotensin converting enzyme (ACE) inhibition for the treatment of hypertension and congestive heart failure have occurred since the discovery of captopril in June 1975. Early in the past decade, this oral ACE inhibitor was restricted to refractory and severe cases of hypertension. By July 1985, the Food and Drug Administration approved its use not only for all degrees of hypertension but also for the initial treatment of hypertensive patients with uncomplicated disease. New information has confirmed the effectiveness of twice-daily administration (which favorably influences compliance) and the lack of a need to monitor blood or urine levels to assure safety. The renin-mediated and non-renin-mediated mechanisms of action of captopril-induced ACE inhibition have been fully delineated, as has its side effect profile, which does not include various CNS, sympathetic reflex, and metabolic side effects seen with other antihypertensive agents. As the first vasodilator to prove its efficacy in the acute and chronic treatment of congestive heart failure to the FDA, captopril is now widely used throughout the United States. ACE inhibition reduces symptoms, enhances exercise capacity, and favorably affects sodium, water, and potassium homeostasis in patients with heart failure. Also, recent but as yet unconfirmed evidence suggests that ACE inhibition may prolong survival in these patients. The success of captopril, the first oral agent of this class, promises to hold true for other ACE inhibitors (such as enalapril), which have similar activities but differing pharmacokinetic properties and will soon be available for clinical use. Further information on these newer agents is anxiously awaited. In the near future, the clinician will undoubtedly be able to choose from a large selection of ACE inhibitors for the treatment of hypertension and heart failure. Therefore, it is important to learn about any meaningful differences among ACE inhibitors and to contrast this class of agents with older, standard therapies. This learning process is crucial as we assess whether newer agents offer clinical advantages over the old.

Comparative effects of captopril and isosorbide dinitrate on pulmonary arteriolar resistance and right ventricular function in patients with severe left ventricular failure: results of a randomized crossover study

We compared the short-term hemodynamic effects of isosorbide dinitrate (40 mg orally) and captopril (25 mg orally) in 18 patients with severe chronic heart failure in a randomized, crossover study conducted on consecutive days. Captopril and isosorbide dinitrate produced similar decreases in systemic vascular resistance, but whereas nitrate therapy decreased pulmonary arteriolar resistance significantly, captopril did not; the difference between the two drugs was highly significant (-25% vs -5%, p less than 0.001). Left ventricular filling pressures declined similarly with both captopril (-10.5 mm Hg) and with isosorbide dinitrate (-9.3 mm Hg), but because pulmonary arteriolar resistance fell significantly with nitrate therapy, mean right atrial pressure decreased more with isosorbide dinitrate than with captopril (-5.4 vs -2.8 mm Hg, respectively; p less than 0.001). Although systemic resistance declined similarly with both drugs, cardiac index increased more with nitrate therapy than during converting-enzyme inhibition (+0.47 vs +0.23 L/min/m2) (p less than 0.01), and therefore mean arterial pressure fell less with isosorbide dinitrate than with captopril (-10.5 mm Hg vs -16.7 mm Hg); p less than 0.05); two patients developed symptomatic hypotension with captopril, whereas none did so with the nitrate. The difference in the effects of the two drugs on cardiac index was not due to differences in their effects on heart rate, since heart rate fell similarly with both drugs, and thus both drugs produced similar increases in stroke volume index. These data indicate that, in patients with severe chronic heart failure, nitrates exert favorable dilating effects on the pulmonary circulation not shared by captopril.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II levels, hemodynamics, and sympathoadrenal function after low-dose captopril in heart failure

The angiotensin converting enzyme inhibitor captopril improves the altered hemodynamics in many patients with chronic heart failure, but the first dose may precipitate hypotension. Ten patients with chronic heart failure were studied, nine with high plasma concentrations of renin and one with a low concentration. Frequent measurements of plasma concentrations of angiotensin II, renin, and catecholamines were made over 60 minutes after a small dose (6.25 mg) of captopril and related to concurrently measured hemodynamic variables. Captopril caused a decrease in systemic and pulmonary artery pressure and an increase in cardiac index, and these changes coincided with reductions in the plasma concentrations of angiotensin II and increases in plasma concentrations of renin. The hemodynamic changes were accompanied by reductions in the plasma concentrations of norepinephrine but transient increases in plasma concentrations of epinephrine in patients in whom vasomotor syncope developed. The patient with a low plasma renin concentration showed little hemodynamic response to the drug. It is concluded that vasomotor syncope occurs quite frequently in patients with severe chronic heart failure after captopril in a small dose and is associated with a selective increase in epinephrine secretion from the adrenal medulla.

Clinical applications of angiotensin-converting enzyme inhibitors

Although only recently introduced, angiotensin-converting enzyme inhibitors have been utilized to treat a wide variety of clinical disorders. Their uses to date, approved by the Food and Drug Administration, have been in the treatment of refractory hypertension and congestive heart failure. However, they have been evaluated with mixed results in numerous other conditions in which the renin-angiotensin-aldosterone system may play a role. Their current status in the treatment of hypertension, congestive heart failure, and these other conditions is reviewed.

Angiotensin converting enzyme inhibition in heart failure

Captopril, the first orally effective converting enzyme inhibitor, was administered to 14 patients with chronic heart failure for 6 week periods, in a double-blind crossover comparison with placebo. Captopril improved symptoms and exercise performance, while left ventricular internal dimensions were reduced. The fall in blood pressure induced by captopril was well tolerated. Glomerular filtration rate was reduced and effective renal plasma flow increased on captopril. No decline in body weight or total body sodium was seen, suggesting that a natriuresis had not occurred. Serum and total body potassium rose. Ventricular arrhythmias declined.