Hemodynamic characterization of tolerance to long-term hydralazine therapy in severe chronic heart failure

The First Dedicated Comprehensive Heart Failure Program in the United States: The Division of Circulatory Physiology at Columbia Presbyterian (1992-2004)

The first dedicated multidisciplinary heart failure program in the United States was founded as the Division of Circulatory Physiology at the Columbia University College of Physicians & Surgeons in 1992. The Division was administratively and financially independent of the Division of Cardiology and grew to 24 faculty members at its peak. Its administrative innovations included (1) a comprehensive full-integrated service line, with 2 differentiated clinical teams, one devoted to drug therapy and the other to heart transplantation and ventricular assist devices; (2) a nurse specialist/physician assistant-led clinical service; and (3) a financial structure independent of (and not supported by) other cardiovascular medical or surgical services. The division had 3 overarching missions: (1) to promote a unique career development path for each faculty member to be linked to recognition in a specific area of heart failure expertise; (2) to change the trajectory and enhance the richness of intellectual discourse in the discipline of heart failure, so as to foster an understanding of fundamental mechanisms and to develop new therapeutics; and (3) to provide optimal medical care to patients and to promote the ability of other physicians to provide optimal care. The major research achievements of the division included (1) the development of beta-blockers for heart failure, from initial hemodynamic assessments to proof-of-concept studies to large-scale international trials; (2) the development and definitive assessment of flosequinan, amlodipine, and endothelin antagonists; (3) initial clinical trials and concerns with nesiritide; (4) large-scale trials evaluating dosing of angiotensin converting-enzyme inhibitors and the efficacy and safety of neprilysin inhibition; (5) identification of key mechanisms in heart failure, including neurohormonal activation, microcirculatory endothelial dysfunction, deficiencies in peripheral vasodilator pathways, noncardiac factors in driving dyspnea, and the first identification of subphenotypes of heart failure and a preserved ejection fraction; (6) the development of a volumetric approach to the assessment of myocardial shortening; (7) conceptualization and early studies of cardiac contractility modulation as a treatment for heart failure; (8) novel approaches to the identification of cardiac allograft rejection and new therapeutics to prevent allograft vasculopathy; and (9) demonstration of the effect of left ventricular assist devices to induce reverse remodeling, and the first randomized trial showing a survival benefit with ventricular assist devices. Above all, the division served as an exceptional incubator for a generation of leaders in the field of heart failure.

Aspects on "traditional" vasodilators in the treatment of chronic heart failure

Vasodilator therapy of heart failure has through the last 5-10 years become a well established treatment. Traditionally these drugs have been classified after their primary site of action on the vascular beds. Thus drugs primarily acting on the arteriolar bed are called afterload-reducing agents and are exemplified by hydralazine. Drugs primarily acting on the venous bed have been called preload-reducing reducing agents and the typical example is nitroglycerin. Other drugs, like prazosin, act on both the arteriolar and venous vascular beds. The classification is, however, not as sharp as originally believed since preload- and afterload-reducing activities mix with each other. Treatment with vasodilators for chronic heart failure has mainly been advocated in patients with valvular regurgitation, ischemic heart disease and various types of dilated cardiomyopathies. It seems appropriate today to put some questions concerning vasodilator therapy for heart failure. Among such questions are: When in the natural history of congestive heart failure should vasodilator therapy be commenced? How effective is long-term administration of vasodilating drugs? May vasodilator therapy decrease mortality in congestive heart failure? What about the efficacy of new vasodilating drugs compared to more traditional ones? In the review of vasodilating drugs besides ACE inhibitors, these questions will be addressed.

Treatment of congestive heart failure

The past decade has improved our understanding of the pathophysiological mechanisms underlying the congestive heart failure syndrome. The same decade has seen a considerable expansion in modes of therapy for this syndrome. A review of the present forms of treatment is given.

Hydralazine decreases sodium nitroprusside-induced rat aortic ring relaxation and increased cGMP production by rat aortic myocytes

Association of hydralazine with nitrova-sodilators has long been known to be beneficial in the vasodilator treatment of heart failure. We previously found that hydralazine appeared to reduce the increase in cGMP induced by sodium nitroprusside in cultured rat aortic myocytes. In order to further explore this seemingly paradoxical interaction, we extended our initial observations in rat aortic myocytes and also determined the influence of hydralazine on sodium nitroprusside-induced relaxation of rat aortic rings. Hydralazine produced a concentration-dependent inhibition of sodium nitroprusside stimulation of cGMP production and caused a rightward shift of concentration-relaxation curves in aortic rings. A possible mechanism of the hydralazine-nitroprusside interaction could be the interference with bioactivation of the nitro-vasodilator to release nitric oxide. Recent evidence indicates that vascular NADH oxidase, an enzyme known to be inhibited by hydralazine, could be involved in this process. Accordingly, hydralazine was found to inhibit NADH oxidase activity in rat aortic myocytes at concentrations similar to those reducing sodium nitroprusside responses. It was concluded that antagonism of sodium nitroprusside action by hydralazine could be a consequence of interference with bioactivation of the former, apparently through inhibition of vascular NADH oxidase.

BNP in hormone-guided treatment of heart failure

The pharmacotherapy of heart failure has become complex. Angiotensin-converting enzyme inhibitors (or angiotensin II receptor blockers), beta-blockers, spironolactone, diuretics and digoxin can be prescribed concurrently. Endothelin antagonists and combined inhibitors of converting enzyme and neutral endopeptidase are under investigation. Optimal dosing will become increasingly difficult to judge. Plasma brain natriuretic peptide (BNP) indicates the severity of left ventricular dysfunction. The C-terminal bioactive peptide and N-terminal BNP (N-BNP) circulate at concentrations related to cardiac status. We proposed that plasma levels of N-BNP would provide an index to guide drug treatment in established heart failure. Sixty-nine patients were randomized to treatment adjusted according to clinical criteria or plasma N-BNP. Hormone-guided therapy resulted in fewer clinical end points than did clinical management. This encourages further exploration of hormone guidance of anti-heart failure therapy, which could be extended to patients with preserved ejection fraction, in addition to those with established systolic dysfunction.

Brain natriuretic peptide-guided therapy for heart failure

The drug treatment of heart failure, once simple, has become complex. Apart from a loop diuretic and digoxin, most patients should now be receiving an angiotensin-converting enzyme inhibitor (or angiotensin II receptor blocker), a beta-blocker and spironolactone. Newer drugs, such as endothelin-receptor antagonists and combined blockers of converting-enzyme and neutral endopeptidase, might soon become available. When to introduce these drugs and what dose is optimal for any individual, are questions that currently vex clinicians. We proposed that plasma levels of the cardiac hormone brain natriuretic peptide (BNP, or better, its 1-76 amino-acid N-terminal fragment, N-BNP), would provide an objective index for guiding drug treatment in patients with established, stable cardiac failure. In a pilot study, 69 patients were randomized to drug treatment based on clinical criteria, or based on plasma levels of N-BNP. After a median follow-up of 9.6 months, those in the N-BNP group had fewer clinical end-points than those in the group managed by clinical criteria alone (19 vs 54; P= 0.02). These preliminary data encourage the concept that the increasingly complex pharmacotherapy for heart failure, both chronic (as in this trial) and acute, might best be guided by an objective measure such as plasma levels of BNP or N-BNP.

Reduced liver function is the trigger for renal sodium retention following portal vein ligation in the rat

Sodium retention along with peripheral vasodilation are features of prehepatic portal hypertension. In several models of experimental liver damage, sodium retention occurs only when hepatic function, measured by the aminopyrine breath test (ABT-k), falls below a critical threshold. The relationship between renal sodium handling, ABT-k and systemic and renal haemodynamics in partial portal vein ligated (PVL) rats was examined to test hypothesis that peripheral vasodilation was responsible for initiating sodium retention. Haemodynamic measurements were conducted early after surgery in portal hypertensive rats with and without sodium retention and in sham-operated controls. Compared with control, both PVL groups of rats had elevated portal pressure and lower peripheral vascular resistance (P < 0.05). Sodium retaining-PVL rats had both lower ABT-k (0.95 +/- 0.05 vs 1.38 +/- 0.06 x 10(-2)/min; P < 0.05) and higher sodium balance (1.38 +/- 0.09 vs 0.43 +/- 0.09 mmol/day; P < 0.05) than non-sodium retaining PVL rats. No differences in plasma renin activity or noradrenaline concentrations were observed. In a separate group of rats, hydralazine-induced pheripheral vasodilation did not induce sodium retention. These results suggest that the presence of peripheral vasodilation alone is not sufficient to trigger a sodium-retaining status. A factor, probably liver function-dependent, acting directly on renal tubules may be necessary for changes in renal sodium handling in this model.

Can further benefit be achieved by adding flosequinan to patients with congestive heart failure who remain symptomatic on diuretic, digoxin, and an angiotensin converting enzyme inhibitor? Results of the flosequinan-ACE inhibitor trial (FACET)

BACKGROUND

Angiotensin converting enzyme inhibitors, diuretics, and digoxin are each effective in treating congestive heart failure, but many patients remain symptom-limited on all three medications. This trial was designed to determine whether the addition of oral flosequinan, a new direct-acting arterial and venous vasodilator with possible dose-dependent positive inotropic effects, improves exercise tolerance and quality of life in such patients.

METHODS AND RESULTS

In a randomized, double-blind multicenter trial, 322 patients with predominantly New York Heart Association class II or III congestive heart failure and left ventricular ejection fractions of 35% or less, who were stabilized on a diuretic, angiotensin converting enzyme inhibitor, and digoxin, were treated with 100 mg flosequinan once daily, 75 mg flosequinan twice daily, or matching placebo. Efficacy was evaluated with serial measurements of treadmill exercise time, responses to the Minnesota Living With Heart Failure Questionnaire (LWHF), and clinical assessments during a baseline phase and a 16-week treatment period. After 16 weeks, 100 mg flosequinan once daily produced a significant increment in median exercise time (64 seconds at 16 weeks) compared with placebo (5 seconds), whereas the higher-dose flosequinan group did not show a statistically significant increase. Flosequinan (100 mg once daily) also improved the overall LWHF score significantly compared with placebo; both active therapies decreased the physical component, but 75 mg flosequinan twice daily was associated with a trend toward worsening of the emotional component. Most clinical assessments tended to improve on active therapy.

CONCLUSIONS

These results indicate that additional symptomatic benefit can be attained by adding flosequinan to a therapeutic regimen already including a converting enzyme inhibitor. Because in the future most patients will fall into this category, flosequinan is a potential adjunctive agent in the management of severe congestive heart failure. However, because recent evidence indicates that the flosequinan dose studied in the present trial has an adverse effect on survival, the benefit-to-risk ratio must be assessed in individual patients.

Double-blind, placebo-controlled study of the efficacy of flosequinan in patients with chronic heart failure. Principal Investigators of the REFLECT Study

OBJECTIVES

The aim of this study was to assess the efficacy of flosequinan in chronic heart failure.

BACKGROUND

Flosequinan is a new vasodilator drug that acts by interfering with the inositol-triphosphate/protein kinase C pathway, an important mechanism of vasoconstriction. The drug dilates both peripheral arteries and veins, is orally active and has a long duration of action that permits once-daily dosing. Previous studies have shown that flosequinan produces sustained hemodynamic benefits in heart failure, but large scale studies evaluating its clinical efficacy have not been reported.

METHODS

One hundred ninety-three patients with chronic heart failure (New York Heart Association functional class II or III and left ventricular ejection fraction < 40%) receiving digoxin and diuretic drugs were randomly assigned (double-blind) to the addition of flosequinan (100 mg once daily, n = 93) or placebo (n = 100) for 3 months. The clinical status and exercise tolerance of each patient was evaluated at the start of the study and every 2 to 4 weeks during the trial while background therapy remained constant.

RESULTS

After 12 weeks, maximal treadmill exercise time increased by 96 s in the flosequinan group but by only 47 s in the placebo group (p = 0.022 for the difference between groups). Maximal oxygen consumption increased by 1.7 ml/kg per min in the flosequinan group (n = 17) but by only 0.6 ml/kg per min in the placebo group (n = 23), p = 0.05 between the groups. Symptomatically, 55% of patients receiving flosequinan but only 36% of patients receiving placebo benefited from treatment (p = 0.018). In addition, fewer patients treated with flosequinan had sufficiently severe worsening of heart failure to require a change in medication or withdrawal from the study (p = 0.07). By intention to treat, seven patients in the flosequinan group and two patients in the placebo group died.

CONCLUSIONS

These findings indicate that flosequinan is an effective drug for patients with chronic heart failure who remain symptomatic despite treatment with digoxin and diuretic drugs. The effect of the drug on survival remains to be determined.

Which vasodilator drug in patients with chronic heart failure? A randomised comparison of captopril and hydralazine

1. Fifty patients with symptoms due to chronic heart failure despite diuretic therapy were randomised to receive additional treatment with either hydralazine or captopril. The dose was titrated; 24 received hydralazine and 26 captopril up to a maximum daily dosage of 225 mg and 75 mg respectively. Forty-three patients had coronary heart disease and seven dilated cardiomyopathy. 2. Dyspnoea and tiredness were assessed using a visual analogue scale (0-100) before and during 12 weeks' treatment. Captopril produced a significantly greater reduction in breathlessness (F = 31.6, P less than 0.001) and tiredness (F = 65.8, P less than 0.001) compared with hydralazine. 3. There was an increase in treadmill exercise time during treatment with both hydralazine (from 5.5 (3.47-7.53) min to 6.9 (4.87-8.93) min), and captopril (from 5.0 (3.05-6.95) min to 7.8 (5.85-9.75) min), but the degree of improvement was significantly greater in the patients treated with captopril (F = 7.4, P less than 0.001). 4. There was no significant change in right ventricular ejection fraction (from 27.9 (19.3-36.5)% to 28.7 (20.1-37.3)%) or left ventricular ejection fraction (from 22.2 (14.2-30.2)% to 23.9 (15.9-31.9)%) during treatment with hydralazine. However, both right and left ventricular ejection fraction increased significantly during treatment with captopril (from 27.1 (18.9-35.3)% to 32.0 (23.8-40.2)%, P less than 0.05; and from 25.0 (17.2-32.8)% to 29.6 (21.8-37.4)%, P less than 0.05 respectively). 5. These results suggest that in patients with symptoms due to chronic heart failure despite diuretic therapy, treatment with captopril produces a greater symptomatic and haemodynamic improvement than treatment with hydralazine.

A prospective, randomized, double-blind, crossover study to compare the efficacy and safety of chronic nifedipine therapy with that of isosorbide dinitrate and their combination in the treatment of chronic congestive heart failure

We performed a prospective, randomized, double-blind, crossover study to compare the efficacy and safety of vasodilation with the calcium entry blocker nifedipine with that of isosorbide dinitrate (ISDN) and their combination as treatment for heart failure. Twenty-eight patients with New York Heart Association Functional class II or III chronic heart failure due to left ventricular systolic dysfunction were studied. All patients were maintained on a constant dose of digitalis and diuretics throughout the study. Eight weeks of therapy with nifedipine alone or in combination with ISDN resulted in a significantly higher incidence of heart failure deterioration necessitating hospitalizations and/or additional diuretics. Twenty-four percent of patients required hospitalization during nifedipine therapy and 26% required hospitalization during nifedipine-ISDN combination therapy in comparison to 0% requiring hospitalization during ISDN therapy alone. The total number of heart failure-worsening episodes was nine among patients on nifedipine, three among patients on ISDN (p less than 0.09 versus nifedipine), and 21 among patients on nifedipine-ISDN combination (p less than 0.001 versus nifedipine, p less than 0.0001 versus ISDN). Premature discontinuation of drug administration due to clinical deterioration or other side effects occurred in 29% of patients during nifedipine therapy, 5% of patients during ISDN therapy (p = 0.05 versus nifedipine), and 19% of patients during the combination therapy. A comparison of eight patients who demonstrated clinical deterioration on nifedipine with the remainder of the patients demonstrated no significant difference in left ventricular ejection fraction (0.24 +/- 0.06 versus 0.23 +/- 0.07) or maximal oxygen uptake during exercise (13 +/- 3 versus 14 +/- 2 ml/kg/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Medical management of chronic heart failure: inotropic, vasodilator, or inodilator drugs?

On the basis of pathophysiologic mechanisms, the medical therapy of today for chronic heart failure is reviewed. The advantages and disadvantages of the vasodilator drugs and the inotropic drugs are presented. Finally, the therapeutic value of the inodilator drugs, which combine the central myocardial effects of positive inotropic agents with those of peripheral vasodilators, is discussed. In particular, the orally available dopaminergic agents, such as ibopamine, which interact with beta-receptors in the heart (mediating a positive inotropic effect) as well as with dopaminergic receptors in the peripheral vessels (mediating a systemic vasodilator effect) and in the kidneys (potentiating the natriuretic effect of diuresis), seem to be an advancement in the modern medical therapy of chronic heart failure. Data are shown during long-term treatment with ibopamine, in which the sustained clinical benefit in heart failure was not diminished, despite a decrease of the adrenergic receptors in blood cells. Dopamine plasma concentration was permanently normalized during long-term treatment. The discrepancy between clinical improvement and the measured adrenergic downregulation may be due to the interference of the inodilator with neurohormonal systems at multiple sites and is probably independent of receptor activation. It is suggested that the biosynthesis of noradrenaline is improved by increasing intracellular dopamine transport.

Endocrinologic Warfare: The Role of Angiotensin-Converting Enzyme Inhibitors in Congestive Heart Failure

The angiotensin-converting enzyme (ACE) inhibitors represent the gold standard of vasodilator therapy for congestive heart failure through blunting of the endocrinologic manifestations of heart failure. The future role of these agents may be in the asymptomatic and mild stages of heart failure. ACE inhibitors have been shown to decrease morbidity and mortality with the natural history of this disease being altered. The future will bring many new ACE inhibitors to market, with the challenge for physicians and pharmacists to understand the important distinctions of each specific agent. © 1990 by W.B. Saunders Company.

Assessment of hemodynamic tolerance from a 24-hour intravenous infusion of fenoldopam mesylate in congestive heart failure

To determine the maintenance of pharmacodynamic effects of fenoldopam mesylate, a dopamine-1 agonist, the invasive hemodynamic profiles of 33 patients with New York Heart Association functional class III to IV congestive heart failure were examined. Fenoldopam mesylate was initiated at 0.1 micrograms/kg/min and titrated to a cardiac index greater than or equal to 25% above baseline. Upon achievement of optimal hemodynamics, maintenance infusion was begun (mean dose 0.6 micrograms/kg/min). Fenoldopam mesylate (baseline vs maximal effect) decreased systemic vascular resistance by 37% (p less than 0.001), left ventricular filling pressure by 16% (p less than 0.05) and mean arterial pressure by 11% (p less than 0.05), with an associated augmentation in cardiac index and stroke volume index by 27% (p less than 0.001). Attenuation of hemodynamic effect (maximal effect vs time) was noted in cardiac index (14% p less than 0.001), systemic vascular resistance (13% p less than 0.05) and stroke volume index (13% p less than 0.05). None of the parameters exhibited complete attenuation to baseline values. Fenoldopam mesylate improves cardiac output and lowers systemic vascular resistance with relative attenuation of pharmacodynamic effect during a 24-hour intravenous infusion.

Vasodilator and inotropic drugs for the treatment of chronic heart failure: distinguishing hype from hope

During the past 10 years, more than 80 orally active vasodilator and inotropic agents have been tested in the clinical setting to evaluate their potential utility in the treatment of chronic heart failure. Although the initial reports of all of these drugs suggested that each represented a major therapeutic advance, only three agents--digoxin, captopril and enalapril--have produced consistent long-term hemodynamic and clinical benefits in these severely ill patients. Most of the other drugs that have been tested have not (to date) distinguished themselves from placebo therapy in large-scale, controlled trials, even though these agents produce hemodynamic effects that closely resemble those seen with digitalis and the converting-enzyme inhibitors. These observations suggest that the hemodynamic derangements that characteristically accompany the development of left ventricular dysfunction cannot be considered to be the most important pathophysiologic abnormality in chronic heart failure. Although cardiac contractility is usually depressed in this disease, positive inotropic agents do not consistently improve the clinical status of these patients. Similarly, although the systemic vessels are usually markedly constricted, drugs that ameliorate this vasoconstriction do not consistently relieve symptoms, enhance exercise capacity or prolong life. Hence, correction of the central hemodynamic abnormalities seen in heart failure may not necessarily provide a rational basis for drug development, and future advances in therapy are likely to evolve only by attempting to understand and modify the basic physiologic derangements in this disorder.

The effects of long term methyldopa in patients with hypoxic cor pulmonale

Methyldopa (alpha-methyldopa) was given to patients with cor pulmonale secondary to chronic obstructive airways disease (COAD) to determine its effect on pulmonary haemodynamics. Twenty-five patients were randomly allocated to methyldopa (750 mg daily) or placebo. Pulmonary haemodynamics were measured twice, 12 months apart. Conventional therapies were continued unchanged. The effects of the drug on pulmonary haemodynamics were inconclusive when considered overall, but total pulmonary vascular resistance (TPVR) fell in all patients on active therapy in whom measurements were obtained both at rest and upon exercise. Only one patient in the placebo group achieved this. Over the trial period there was one death in the active but five in the placebo group. Survival was unrelated to abnormalities in pulmonary haemodynamics at the commencement of the trial in this study although the numbers of patients was small. Postural hypotension developed in patients receiving methyldopa and limited the dose that could be administered. The problems involved in long term trials of vasodilators in hypoxic cor pulmonale are discussed.

Clinical pharmacokinetics in heart failure. An updated review

Pharmacokinetics is the study of the effect that the body has on drug absorption, distribution, metabolism and excretion. The pharmacokinetics of a specific drug are assessed by the volume of distribution, bioavailability, clearance and elimination half-life. Elimination half-life is directly related to the volume of distribution and inversely related to clearance. Any 1 or more of these parameters may be altered by physiological changes such as ageing, or disease states such as congestive heart failure. Congestive heart failure is associated with hypoperfusion to various organs including the sites of drug clearance, i.e. the liver and kidneys. It also leads to organ congestion as seen in the liver and gut. The main changes in drug pharmacokinetics seen in congestive heart failure are a reduction in the volume of distribution and impairment of clearance. The change in elimination half-life consequently depends on whether both clearance and the apparent volume of distribution change, and the extent of that change. Pharmacokinetic changes are not always predictable in congestive heart failure, but it seems that the net effect of reduction in the volume of distribution and impairment of clearance is that plasma concentrations of drugs are usually higher in patients with congestive heart failure than in healthy subjects. The changes in pharmacokinetics assume importance only in the case of drugs with a narrow therapeutic ratio (e.g. digoxin) and some of the antiarrhythmics such as lignocaine (lidocaine), procainamide and disopyramide. This necessitates reduction in both the loading and maintenance doses. Prolongation of the elimination half-life leads to delay in reaching steady-state, and therefore dose increments must be made more gradually. Plasma concentration measurements of the drugs concerned are a good guide to therapy and help to avoid toxicity. Pharmacokinetic changes are of less importance in the case of drugs with immediate clinical response, e.g. diuretics and intravenous vasodilators such as nitrates and phosphodiesterase inhibitors. The dose in the latter group can be titrated to the desired effect. Not all adverse reactions to drugs that may occur in heart failure are the result of alterations in pharmacokinetics; rather, some may be due to important drug interactions. An interaction may occur directly e.g. reduction of renal clearance of digoxin by captopril and quinidine; or indirectly, e.g. through diuretic-induced hypokalaemia, which exacerbate arrhythmias associated with digoxin and antiarrhythmics such as quinidine and procainamide.

Efficacy of felodipine in chronic congestive heart failure: a placebo controlled haemodynamic study at rest and during exercise and orthostatic stress

A vascular selective calcium antagonist, felodipine, was evaluated in a randomised, double blind, crossover trial in 18 patients with chronic congestive heart failure of ischaemic cause. Felodipine (10 mg twice daily) or a corresponding placebo was added to conventional treatment. After three weeks haemodynamic function was assessed at rest, during a standard supine leg exercise, and during 45 degrees passive upright tilt. In patients in the supine resting position, felodipine reduced the mean arterial pressure (9%) and systemic vascular resistance (24%) and increased the stroke volume (25%) and cardiac index (23%). The heart rate and right and left ventricular filling pressures were unchanged. During felodipine treatment the standard exercise was accomplished at a similar cardiac index but at a substantially lower heart rate (7%), arterial pressure (10%), systemic vascular resistance (17%), and left ventricular filling pressure (19%), and a higher stroke volume (13%). During both placebo and felodipine administration there were substantial reductions in cardiac filling pressure during upright tilting. Upright tilting during the placebo phase did not increase the heart rate. It also caused a greater fall in systemic vascular resistance while the arterial pulse pressure but not the mean pressure was maintained and the cardiac index and stroke volume increased. The reduced cardiac filling pressures during the felodipine upright tilt were accompanied by reductions in arterial pulse pressure and stroke volume and the patients were able to maintain the mean arterial pressure by an increase in both the heart rate and systemic vascular resistance. Thus three weeks treatment with felodipine improved haemodynamic function at rest and during standard exercise and normalised the baroreflex mediated haemodynamic response in patients with congestive heart failure. The haemodynamic efficacy of the drug in such patients may be associated with a baroreceptor mediated effect as well as direct vasodilatation.

Long term use of enalapril in the treatment of patients with congestive heart failure

Fifty-five patients of both sexes, aged 39-72, suffering from congestive heart failure of varying aetiology were admitted to a double blind study in which enalapril given in a dose of 5-10 mg twice daily or placebo was added to existing medication. A significant increase in exercise performance (P less than 0.004) was seen in the group treated with enalapril, an improvement which was still evident after 24 weeks of therapy. No significant difference was seen between the mean ejection fractions but subjective assessment suggested improvement in the enalapril-treated group.

Pharmacotherapy of congestive heart failure. An evaluation of recent advances

Vasodilator therapy represents an important step forward in the treatment of chronic left ventricular failure. Angiotensin converting enzyme (ACE) inhibitors appear to be the most versatile vasodilators, but selected direct-acting vasodilators, sympathetic inhibitors (prazosin), and possibly calcium channel antagonists (nifedipine and diltiazem) may be useful in certain situations. The bipyridine derivatives possess potent inotropic and vasodilating properties. The efficacy of intravenously administered amrinone and milrinone has been proven in the treatment of refractory left ventricular failure. Whether oral administration of milrinone or other bipyridine derivatives will prove to be safe and effective in the long-term treatment of chronic left ventricular failure remains uncertain.

Early tolerance to hemodynamic effects of high dose transdermal nitroglycerin in responders with severe chronic heart failure

Transdermal systems for delivery of nitroglycerin have been shown to provide sustained blood levels of the drug for at least 24 hours. Investigations of hemodynamic effects of transdermal nitroglycerin in patients with heart failure have demonstrated a transient reduction in pressure lasting less than the expected 24 hours. These findings could be due to the development of circulatory tolerance to the vasodilatory effects of nitroglycerin or to insufficient drug dosing. In the present study, we compared the hemodynamic effects of the first and the second doses of high dose (120 mg) transdermal nitroglycerin given 24 hours apart in 11 responders (greater than or equal to 20% reduction in mean pulmonary artery wedge pressure lasting greater than or equal to 2 hours). Initiation of nitroglycerin therapy resulted in a significant reduction in mean right atrial pressure lasting for 14 hours and in a reduction in mean pulmonary artery and mean pulmonary artery wedge pressures lasting 24 hours. After administration of the second dose, mean right atrial pressure at 2 hours (9 +/- 5 versus 7 +/- 4 mm Hg), 4 hours (8 +/- 5 versus 6 +/- 4 mm Hg) and 8 hours (8 +/- 5 versus 6 +/- 3 mm Hg) was higher than after the first dose (p less than 0.05). Both mean pulmonary artery and mean pulmonary artery wedge pressures were significantly higher after the second nitroglycerin dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term indoramin therapy in congestive heart failure: a double-blind, randomized, parallel placebo-controlled trial

Twenty-one patients with moderately severe congestive heart failure participated in a double-blind, randomized, parallel placebo-controlled trial designed to evaluate the effects of long-term (2 months) indoramin therapy on rest and exercise hemodynamics, exercise capacity and clinical status of patients with this clinical syndrome. The long-term administration of indoramin in patients (mean dose 50 mg every 12 hours) caused a mild reduction from baseline values in supine rest mean systemic blood pressure and, after dosing, elicited a significant reduction in systemic and pulmonary vascular resistances, pulmonary capillary wedge pressure and heart rate as well as a mild increase in stroke volume. Long-term indoramin therapy caused a small decrease, as compared with baseline exercise responses, in systemic and pulmonary vascular resistance and pulmonary capillary wedge pressure at submaximal levels of exercise. It did not alter hemodynamic variables at maximal exercise, exercise capacity or overall clinical status, compared with findings at baseline or with placebo.

Hemodynamic effects of PN 200-110 (isradipine) in congestive heart failure

PN 200-110 (isradipine), a dihydropyridine derivative, is a newly available calcium antagonist with potent vasodilatory properties. To determine if PN 200-110 might benefit patients with congestive heart failure (CHF), its acute hemodynamic effects were evaluated in a group of 12 patients with severe CHF. Measurements of cardiac performance were obtained after oral administration of placebo and 15 mg of PN 200-110. Placebo resulted in no significant changes in any of the variables. PN 200-110 decreased mean arterial pressure from 94 +/- 14 (mean +/- standard deviation) to 77 +/- 7 mm Hg (p less than 0.001) and increased both cardiac index from 2.1 +/- 0.4 to 2.8 +/- 0.6 liters/m2 (p less than 0.01) and stroke volume index from 26 +/- 7 to 36 +/- 10 ml/m2 (p less than 0.001). Systemic vascular resistance was reduced from 1,726 +/- 563 to 1,099 +/- 370 dynes s cm-5 (p less than 0.01). Neither heart rate nor pulmonary artery wedge pressure changed significantly. Of the 7 patients discharged receiving PN 200-110, 6 improved clinically and there was evidence of a substantial reduction in cardiothoracic ratio on chest x-ray in some patients. No serious side effects were encountered. Vasodilation with PN 200-110 can improve cardiac performance acutely in patients with CHF. Although this clinical experience is encouraging, carefully performed long-term trials must be done to determine the value of this drug in the management of patients with CHF.

Hemodynamic effects of hydralazine in infants with idiopathic dilated cardiomyopathy and congestive heart failure

We evaluated the acute hemodynamic responses to hydralazine during cardiac catheterization in 13 infants with idiopathic dilated cardiomyopathy. Ages ranged from 2 to 13 months (6.7 +/- 4.0 months, mean +/- SD). Each infant had congestive heart failure and angiographic evidence of markedly depressed left ventricular ejection fraction (0.24 +/- 0.11; normal = 0.58-0.78) with left ventricular dilation (left ventricular end-diastolic volume = 349 +/- 125% of normal). Hydralazine (0.5 to 1.0 mg/kg administered intravenously) acutely decreased systemic arteriolar resistance from 21.1 +/- 3.3 to 12.0 +/- 2.7 U/m2 (p less than 0.001). This 41 +/- 14% decrease in systemic resistance was accompanied by a 45 +/- 16% increase in cardiac index (3.24 +/- 0.53 to 4.71 +/- 0.99 L/min/m2; p less than 0.001). Mean arterial blood pressure declined from 70 +/- 8 to 60 +/- 11 mm Hg (p less than 0.001). Hydralazine also increased heart rate (122 +/- 19 to 138 +/- 18 bpm; p less than 0.001), but this increase did not account entirely for the change in cardiac index as evidenced by a rise in stroke volume index (26.9 +/- 4.9 to 34.5 +/- 7.5 ml/beat/m2; p less than 0.001). Pulmonary arteriolar resistance and pulmonary capillary wedge pressure fell slightly in response to hydralazine. Subsequently, oral hydralazine was included in the treatment regimen of 10 infants followed for 3 to 38 months (mean = 15 months). Of these, eight demonstrated sustained clinical improvement. We conclude that hydralazine may be a beneficial adjunct to the management of congestive heart failure in young infants with a dilated cardiomyopathy.

Angiotensin inhibitors and other vasodilators with special reference to congestive heart failure

ACE inhibitors have emerged as important pharmacologic agents for treatment of hypertension and heart failure. Attenuation or inhibition of angiotensin mediated vasoconstriction appears to be the principal mechanism for the reduction of arterial pressure and systemic vascular resistance.

Congestive heart failure

A review of the epidemiology, pathophysiology, and treatment of congestive heart failure is presented, with particular attention given to newer modalities of therapy.

Is inotropic therapy appropriate for patients with chronic congestive heart failure? Or is the digitalis leaf withering?

The appropriateness of inotropic therapy in chronic heart failure was examined by critically reviewing five assumptions upon which this form of therapy has been justified. Only the first, that cardiac performance can be acutely improved by inotropic therapy, has been empirically proven. That such acute improvement is sustained appears to be true with non-catecholamine agents whereas the chronic haemodynamic efficacy of oral catecholamines remains in doubt. That any inotropic agent can improve exercise tolerance, make the patient feel better, or effect a change without deleteriously affecting the myocyte is very much in doubt. Thus, although the prospect of using powerful inotropic therapy in the patient with heart failure is theoretically appealing, its utility remains to be proven.

Vasodilator therapy

Vasodilators are a group of drugs with various degrees of arteriolar or venous dilatation used in the treatment of congestive heart failure when symptoms persist after digoxin and diuretic therapy. Nitrates and captopril provide the most consistent improvement in symptoms. Reduced mortality rates in congestive heart failure with vasodilator therapy has not been demonstrated, and prediction of clinical response to therapy is difficult.

The role of vasodilator therapy in the treatment of severe chronic heart failure

The rationale for the use of vasodilating agents in the treatment of congestive heart failure is to reverse the systemic vasoconstriction that characterises patients with this disorder, and which may further limit cardiac performance. Nitrates were the first vasodilators used, followed by arterial vasodilators (hydralazine, minoxidil), alpha-adrenergic blockers (prazosin, trimazosin) and, more recently, calcium antagonists, ACE inhibitors, beta-agonists and phosphodiesterase inhibitors. The choice of vasodilator should be based on consideration of overall benefit-risk profiles. Consideration of pharmacological action together with classification of patients into haemodynamic subsets has been used as a basis from which to initiate vasodilator therapy. However, such a classification may not lead to a logical choice of drug and there is no evidence to suggest that patients so selected do better when given long term treatment with peripherally specific drugs than with agents that are not tailored to pretreatment haemodynamic variables. Moreover, changes in central haemodynamics after administration of specific vasodilator drugs may differ from those expected on the basis of their presumed actions on the peripheral vasculature. Dosage requirements are difficult to predict with many vasodilator drugs. Traditionally, such requirements have been established by titrating vasodilating drugs to achieve an arbitrarily defined haemodynamic response. However, there is little correlation between haemodynamic end-points and clinical efficacy in patients with heart failure, and short and long term haemodynamic responses to vasodilator drugs are not necessarily related. Drug-specific haemodynamic and clinical tolerance occurs during the course of treatment with all vasodilator drugs; the extent and frequency with which it develops differs between agents. Tolerance is thought to arise from a reduction in drug receptor affinity and/or density or activation of counter-regulatory forces (mainly neurohormonal) that limit the magnitude of vasodilatation that can be achieved. Development of tolerance to a single agent does not usually preclude efficacy of other agents. ACE inhibitors have been associated with a relatively low incidence of tolerance. This may relate to their natriuretic effect and ability to decrease the degree of neurohormonal activation, actions not shared by other vasodilators. Tolerance is the principal reason for failure of prazosin and nitrates as therapeutic agents in severe chronic heart failure.(ABSTRACT TRUNCATED AT 400 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.

Acute and long-term effects of enalapril on the cardiovascular response to exercise and exercise tolerance in patients with congestive heart failure

Enalapril is a recently developed angiotensin-converting enzyme inhibitor that improves cardiac function at rest in patients with congestive heart failure. This study investigated the acute effects of enalapril on the cardiovascular response to exercise, and then evaluated the long-term effects of enalapril on exercise capacity and functional status during a 12 week placebo-controlled trial in patients with heart failure. Ten patients underwent hemodynamic monitoring while at rest and during incremental bicycle exercise before and after 5 to 10 mg of enalapril orally. At rest, enalapril decreased mean blood pressure 13% (p less than 0.01) and systemic vascular resistance 20% (p less than 0.05) and increased stroke volume index 21% (p less than 0.01). During maximal exercise, enalapril decreased systemic vascular resistance and increased both cardiac and stroke volume indexes. Enalapril acutely increased exercise duration (p less than 0.05) and maximal oxygen consumption (p less than 0.001). These 10 patients and an additional 13 patients were then randomized to either placebo or enalapril treatment and followed up for 12 weeks. Of the 11 patients assigned to active treatment, 73% considered themselves improved compared with 25% of the patients assigned to placebo treatment (p less than 0.02). During long-term treatment, exercise capacity increased in patients receiving enalapril (p less than 0.001) but was unchanged in patients receiving placebo (intergroup difference, p less than 0.05). During long-term treatment, no adverse effects of enalapril occurred. Thus, enalapril improves cardiac function at rest and during exercise. Compared with placebo, maintenance therapy with enalapril results in symptomatic improvement and increased exercise capacity.

Clinical importance of the renin-angiotensin system in chronic heart failure: double blind comparison of captopril and prazosin

Nineteen patients with chronic heart failure participated in a double blind crossover trial of captopril and prazosin--two drugs with differing neuroendocrine effects--to determine whether neuroendocrine changes could explain clinical and haemodynamic responses to treatment. Patients were assessed before and after acute and long term (four weeks') treatment with each drug given in random order. Sixteen patients completed the study. During captopril haemodynamic improvement was maintained by inhibition of the renin-angiotensin system. Breathlessness was relieved in 15 patients and exercise capacity increased. During prazosin a reduction in systemic vascular resistance was maintained, but plasma renin activity and aldosterone and noradrenaline concentrations increased, fluid retention developed, and clinical benefit did not occur. These results suggest that clinical and haemodynamic responses to long term vasodilator treatment for chronic heart failure are related to neuroendocrine changes. In patients with chronic heart failure inhibition of the renin-angiotensin system results in clinical benefit, whereas inhibition of the alpha adrenergic system does not.

Inotropic therapy for refractory congestive heart failure with oral fenoximone (MDL-17,043): poor long-term results despite early hemodynamic and clinical improvement

Thirteen male patients with NYHA class IV congestive heart failure refractory to conventional therapy were treated with oral fenoximone, a new imidazole compound with inotropic and vasodilator effects, for a mean duration of 11 weeks (range 2 to 34). On initial hemodynamic evaluation, the effects of oral fenoximone were comparable to those of the intravenous form and included a significant (p = .0001) increase in cardiac index (mean +/- SD) (1.7 +/- 0.4 to 3.0 +/- 0.7 liters/min/m2) and a significant (p = .0001) but modest decrease in pulmonary capillary wedge pressure (27 +/- 6 to 23 +/- 6 mm Hg), with only minor overall changes in heart rate and arterial blood pressure. Symptomatic improvement by at least one NYHA class was observed in all patients during the first week of therapy with fenoximone; however, severe and symptomatic congestive heart failure recurred in seven patients within an average of 8 weeks after initiation of therapy, resulting in death in all seven. Of the remaining six patients, two died suddenly at home within 3 weeks of initiation of therapy, one died from ventricular fibrillation in the hospital 7 weeks after initiation of therapy, and two died from noncardiac causes. One patient is currently alive with NYHA class II heart failure 21 weeks after the initiation of therapy. Partial or complete attenuation of hemodynamic efficacy of oral fenoximone during long-term administration was demonstrated during repeat hemodynamic evaluation in six of eight patients. We conclude that despite short-term hemodynamic and clinical benefits, oral fenoximone therapy in patients with NYHA class IV congestive heart failure does not produce sustained clinical or hemodynamic benefit and is associated with a high mortality.

Role of vasodilators in the treatment of congestive heart failure

Appreciation of the important role played by peripheral vasoconstriction in the pathophysiology of congestive heart failure (CHF) has led to the widespread use of vasodilators as treatment. Short-term studies show that, regardless of the vasodilator used, the arterial and venous dilatation produced invariably results in improvement in the hemodynamic status of patients. This short-term response, however, does not automatically translate to long-term clinical improvement. The reasons for this are not well understood but such factors as differing mechanisms of action, development of tolerance and unique patterns of regional redistribution of blood flow may all play a modifying role in differentiating one vasodilator from another. Nevertheless, a number of controlled trials have demonstrated sustained symptomatic and functional improvement when vasodilators such as the converting enzyme inhibitors or nitrates are given to patients with CHF.

Methodologic problems in clinical trials in heart failure

Trials designed to establish the effectiveness of pharmacologic therapy in chronic heart failure illustrate methodologic problems associated with intervention trials in chronic disease. Early improvement in hemodynamic status or exercise capacity does not predict long-term changes, and hemodynamic variables do not correlate with exercise capacity. Mortality may not be a feasible outcome, suggesting that an adequate measure of quality of life is necessary to establish patient benefit. Care must be taken to ensure that subjects recruited are representative of the underlying population with respect to drug response. Need for cointervention can be dealt with by comparing only periods of comparable treatment, treating need for cointervention as a treatment failure, or using changes in non-study drugs as a measure of outcome. While cross-over designs can improve feasibility, the investigator runs the risk of inadequate followup and a time-treatment interaction. These issues must be considered in planning intervention trials in chronic disease.

Effect of hydralazine on serial measurements of exchangeable sodium and blood pressure in spontaneously hypertensive rats

Hydralazine was dissolved in 0.5% drinking saline (40 mg/1000 ml) labelled with isotope 22Na and given to spontaneously hypertensive rats for four weeks. Another group of rats were given isotope labelled saline only and served as control. Measurements of total exchangeable sodium, blood pressure, pulse rate and weight were performed before and repeatedly during treatment. Before treatment exchangeable sodium, blood pressure, pulse rate, and weight were no different between the groups. The antihypertensive effect of hydralazine was marked and maintained throughout the experiment. No significant changes were found in pulse rate. Both groups gained weight similarly. Exchangeable sodium increased at the same rate in both groups along with the weight increase. Thus, chronic hydralazine treatment effectively reduces blood pressure in spontaneously hypertensive rats without causing measurable sodium or fluid retention.

Hemodynamic and clinical limitations of long-term inotropic therapy with amrinone in patients with severe chronic heart failure

To determine the hemodynamic and clinical effects of long-term positive inotropic stimulation on the myocardium, we treated 31 patients with severe chronic heart failure with oral amrinone (600 mg daily) and performed invasive hemodynamic studies during short- and long-term treatment with the drug. Stroke volume and stroke work indexes increased markedly during the first 48 hr of therapy (p less than .01) but returned to pretreatment values after 2 to 10 weeks; upon drug withdrawal, both variables deteriorated rapidly to values significantly lower than those observed before treatment with amrinone (p less than .01), despite similar values for left ventricular filling pressure, mean arterial pressure, and systemic vascular resistance. This pattern of response indicated that progression of the underlying heart disease had occurred during treatment with amrinone and contributed importantly to its failure to produce long-term benefits. Progression of left ventricular dysfunction was associated with a progressive increase in heart rate and plasma renin activity and a decline in serum sodium concentration. Clinically, amrinone therapy was complicated by sustained symptomatic ventricular tachycardia in four patients, worsening myocardial ischemia in four patients, and worsening congestive heart failure in eight patients, all of whom had been stable before entry into the study; only three of the 31 patients improved clinically. Ten patients died during the first 2 weeks of treatment, and 16 (52%) were dead within 3 months, a mortality rate twice as great as that seen during comparable trials with vasodilating drugs. Although noncardiac adverse effects were frequent, they were not the primary reason for drug failure. In conclusion, long-term therapy with amrinone may accelerate progression of left ventricular dysfunction, exacerbate myocardial ischemia, and provoke life-threatening ventricular tachyarrhythmias, thereby shortening survival in patients with severe chronic heart failure. Prolonged administration of inotropic drugs may achieve short-term gains at the expense of long-term detrimental effects on the myocardium.

Antidepressant tachyphylaxis

We report eleven patients in whom tachyphylaxis to antidepressants, lithium or ECT occurred. These cases are a small sample of patients we have encountered in whom an initial good response to mood regulating drugs was not sustained. We suspect that systematic studies would reveal that tachyphylaxis is a common phenomenon with antidepressant therapies.

Long-term beneficial effects of endralazine, a new arteriolar vasodilator at rest and during exercise capacity in chronic congestive heart failure

Hemodynamic measurements were made at rest and during submaximal and maximal exercise in 12 patients with chronic congestive heart failure before and after oral endralazine (EN). After acute assessment, patients received endralazine, twice daily, for a mean of 2.8 months, when hemodynamic measurements were repeated. The drug was withdrawn for 3 to 4 days and subsequently reintroduced. Three patients with greatly elevated pulmonary wedge pressures were assessed after 30 mg of isosorbide dinitrate, which was also chronically administered. Resting mean cardiac and stroke volume indexes increased by 44 and 33%, respectively (p less than 0.01), with concomitant reduction of the systemic resistance. This improvement was maintained on a long-term basis in 8 of the 11 surviving patients. Withdrawal and subsequent reintroduction of EN confirmed that there was worsening of left ventricular dysfunction in the other 3 subjects. Chronic but not acute therapy produced a modest reduction in wedge pressure. At maximal exercise, cardiac and stroke volume indexes increased by 29 and 18%, respectively (p less than 0.01), after EN; the duration of exercise increased in 7 of the 10 subjects after acute therapy and this was maintained on a long-term basis. Mean creatinine clearance increased by 34% (p less than 0.01). The results confirm that EN produces acute and long-term hemodynamic and functional improvement without tolerance in congestive heart failure.

Amrinone therapy in patients with heart failure. Lack of improvement in functional capacity and left ventricular function at rest and during exercise

Short-term amrinone therapy has been shown to exert beneficial hemodynamic effects in patients with heart failure. To determine whether this improvement persists longer, the effects of maximally tolerated doses of amrinone on exercise duration, oxygen consumption, and left ventricular function and volumes were examined during maintenance therapy. After four weeks of amrinone therapy, 75 to 150 mg three times a day (mean 292 +/- 70 mg daily), treadmill exercise duration, maximal oxygen consumption, and functional class were unchanged from control values. Radionuclide-derived ejection fraction and end-diastolic and end-systolic volumes were not altered at rest or during maximal supine exercise. Similarly, significant changes in echocardiographic end-systolic and end-diastolic dimensions did not occur. This lack of clinical benefit on functional capacity and left ventricular function, together with frequent adverse reactions, will limit the application of amrinone in the treatment of heart failure. These findings are relevant to the investigation of amrinone-like derivations presently being studied for the treatment of heart failure. Before their release, these agents will require careful evaluation and demonstration of a therapeutic action during maintenance therapy, together with a low incidence of adverse reactions.

Hydralazine therapy in chronic congestive heart failure. Sustained central and regional hemodynamic responses

Central and regional hemodynamic parameters were evaluated at baseline and following three months of placebo or hydralazine therapy (100 mg orally every eight hours) in 20 patients with idiopathic dilated cardiomyopathy. Both control (placebo) and hydralazine groups were comparable with respect to functional classification (New York Heart Association classes III and IV) and baseline hemodynamic variables. In the hydralazine group, cardiac index increased 25 percent (2.4 +/- 0.4 to 3.0 +/- 0.5 liters/minute/m2), renal blood flow increased 26 percent (648 +/- 199 to 815 +/- 229 ml/minute), and limb blood flow was augmented by 35 percent (6.8 +/- 3.0 to 9.2 +/- 4.6 ml/dl/minute) with long-term therapy. These changes were significant (all p less than 0.05) when compared with both baseline values and values in the control group. Both central and regional hemodynamic parameters remained unaltered in the control group. Long-term hydralazine therapy (three months) elicited a favorable circulatory response in this group of patients with chronic congestive heart failure. Central or regional hemodynamic tolerance to oral hydralazine failed to develop in the majority of patients.

Conceptual dilemmas in the classification of vasodilator drugs for severe chronic heart failure. Advocacy of a pragmatic approach to the selection of a therapeutic agent

Two distinct systems of classifying vasodilator drugs have been developed over the past decade in an attempt to guide the choice of a therapeutic agent for the patient with severe heart failure, but the merits and utility of these systems have not been critically evaluated. Vasodilator drugs may be categorized according to their peripheral site of action: an agent may exert its effects preferentially on systemic arteries, systemic veins, or on both circulations. However, changes in the peripheral circulation cannot be directly translated into an improvement in central hemodynamic variables; furthermore, immediate hemodynamic responses may not be predictive of long-term clinical efficacy. Hence, there is no evidence that characterization of patients into hemodynamic subsets determined by the findings of right heart catheterization improves the clinical outcome of vasodilator therapy in chronic heart failure. An alternative classification system groups vasodilator drugs according to their mechanism of action: an agent may possess direct vasodilating effects or may exert its actions via selective neurohumoral inhibition. However, attempts to identify patients who might be most responsive to neurohumoral antagonism by measuring plasma renin activity or circulating levels of catecholamines before treatment have not been successful in predicting the clinical responses to therapy. Because neither system of drug classification provides the clinician with useful therapeutic guidelines, patients with severe heart failure appear to be best managed using a pragmatic approach in which specific drugs that produce predictable therapeutic benefits with a low frequency of side effects are utilized preferentially. Among presently available vasodilator agents, only captopril and oral isosorbide dinitrate have been shown to produce consistent hemodynamic and clinical improvement with an acceptable degree of adverse reactions.