Systemic and coronary hemodynamic and neurohumoral effects of levodopa in chronic congestive heart failure

Renal effects of L-DOPA in heart failure

We examined whether low-dose L-DOPA treatment induces natriuresis and diuresis in patients with congestive heart failure who have cardiac decompensation despite treatment with digoxin, a diuretic, and an angiotensin-converting enzyme inhibitor and who respond acutely to intravenously infused dopamine. In a randomized, double-blind, placebo-controlled crossover study, 11 patients with severe congestive heart failure received L-DOPA (0.10 g, p.o., t.i.d., for 1 day and then 0.25 g, p.o., t.i.d., for 2 days after a washout period of > or = 1 day), with assessments of plasma and urinary levels of catechols, urinary volume, and sodium content, and clinical and laboratory measures of improvement of congestive heart failure. L-DOPA elicited short-term, dose-related increases in urinary volume and sodium excretion. At the 0.10-g dose, L-DOPA increased plasma L-DOPA levels and urinary L-DOPA excretion by about fivefold, whereas at the 0.25-g dose, L-DOPA increased plasma and urinary L-DOPA by >50-fold. Twenty-four-hour urinary dopamine excretion increased by about fivefold after the low dose of L-DOPA and approximately 50-fold after the high dose. The results demonstrate that oral L-DOPA treatment can produce beneficial natriuretic and diuretic effects in selected patients with congestive heart failure. The bioavailability of oral L-DOPA appears to vary with the dose. These results support findings from previous studies about beneficial cardiac functional effects of L-DOPA in patients with refractory heart failure.

Hemodynamic and clinical effects of oral levodopa in children with congestive heart failure

OBJECTIVES

This study was undertaken to evaluate the safety, efficacy and pharmacodynamic variables of oral levodopa in pediatric patients with congestive heart failure refractory to standard therapy.

BACKGROUND

Therapeutic options for children with congestive cardiomyopathies are limited to digoxin, diuretic agents and angiotensin-converting enzyme inhibitors. Previous work in adults with congestive heart failure has shown a short-term effectiveness of levodopa and improvement of cardiac function.

METHODS

Baseline two-dimensional and M-mode echocardiography, surface electrocardiography, Holter monitoring and exercise testing, when applicable, were performed. Levodopa was administered in a dose escalation scale from 8 mg/kg body weight per dose to 20 mg/kg per dose over 3 days with concomitant metoclopramide and pyridoxine. Catecholamine levels at initiation of the trial and throughout dose escalation were measured, with echocardiographic and electrocardiographic correlation. After 24-h drug washout, cardiac catheterization was performed both before and after administration of levodopa.

RESULTS

Between February 1992 and December 1995, nine children (age 10 +/- 1.7 years, weight 27.8 +/- 4.3 kg) were enrolled in this study. At cardiac catheterization, serum dopamine levels rose from 108.5 +/- 59.2 pg/ml to 1,375.8 +/- 567.9 pg/ml (p = 0.03) at 100 +/- 14.8 min after levodopa administration without a significant change in serum norepinephrine or epinephrine levels. Paralleling these increases, there were significant changes in the cardiac index (1.7 +/- 0.3 to 3.2 +/- 0.7 liters/min per m2), stroke volume index (16.1 +/- 3.2 to 31.2 +/- 7.0 ml/m2 per min), oxygen consumption (138.6 +/- 24.4 to 188.3 +/- 30.8 ml/min per m2) and systemic vascular resistance (36.8 +/- 8 to 21.9 +/- 5.5 indexed Wood's units; all p < 0.01). There was a significant reversal of the daily fluid volume output/input ratio from 0.8 +/- 0.1 to 1.2 +/- 0.1 (p < 0.01). Levodopa administration was complicated by hypertension or tachycardia, or both, requiring a dose reduction in three patients, and by significant gastrointestinal distress in one. There was sustained symptomatic improvement a median of 19.5 months after drug initiation in seven of the patients.

CONCLUSIONS

These preliminary data support the hemodynamic value of oral levodopa in the treatment of severe congestive heart failure in children.

A randomized crossover trial of levodopa in congestive heart failure

BACKGROUND

The short- and long-term effects of levodopa (L-dopa), an oral dopaminergic prodrug, were assessed in patients with severe left ventricular dysfunction.

METHODS AND RESULTS

Initially, 26 patients were included in the study group. After clinical, radiographic, and radionuclide examination, each patient underwent right heart catheterization (Swan-Ganz thermodilution catheter). Plasma noradrenaline levels were measured. In two patients, a favorable hemodynamic response to L-dopa was not observed, another two required permanent pacemaker implantation. These four patients were excluded from the study. Two patients required permanent pacemaker implantation. The remaining 22 patients with favorable hemodynamic response to L-dopa (increase in cardiac index, stroke volume index, reduction in total systemic resistance) were randomized in a nonblinded fashion to the conventional (11 patients) or conventional plus L-dopa (11 patients) treatment groups. During the study period, two patients, one from each group, died. They were excluded from the analysis. The final analyzed study group consisted of 20 men, aged 33-69, in New York Heart Association functional class IV (9 patients) and III (11 patients). The cause of congestive heart failure was primary dilated cardiomyopathy in 11 patients and ischemic heart disease in 9 patients. After 3 months' treatment, all patients were crossed over. Clinical, radiographic, radionuclide, and hemodynamic evaluation was repeated at the end of the 3-month treatment period. After 3 months of therapy with L-dopa in each group (covariance analysis), there was improvement in clinical, radiographic (relative heart volume, -128 mL/m2), radionuclide (left ventricular ejection fraction, +4.6; right ventricular ejection fraction, +4.8%), hemodynamic (mean pulmonary wedge pressure, -8 mmHg; total systemic resistance, -1.8 Wu; total pulmonary resistance, -3.5 Wu), and neurohumoral (noradrenaline, -218 pg/mL) measures.

CONCLUSIONS

The addition of L-dopa to conventional therapy has beneficial short- and long-term effects in patients with severe left ventricular dysfunction.

Refractory Heart Failure: A Therapeutic Approach

Optimal “triple therapy” for patients with chronic congestive heart failure (CHF) includes diuretics, digoxin, and either angiotensin-converting enzyme inhibitors or hydralazine plus nitrates. Refractory CHF is defined as symptoms of CHF at rest or repeated exacerbations of CHF despite “optimal” triple-drug therapy. Most patients with refractory CHF require hemodynamic monitoring and treatment in the intensive care unit. If easily reversible causes of refractory CHF cannot be identified, then more aggressive medical and surgical interventions are necessary. The primary goal of intervention is to improve hemodynamics to palliate CHF symptoms and signs (i.e., dyspnea, fatigue, edema). Secondary goals include improved vital organ and tissue perfusion, discharge from the intensive care unit, and, in appropriate patients, bridge to cardiac transplantation. Medical interventions include inotropic resuscitation (e.g., adrenergic agents, phosphodiesterase inhibitors, allied nonglycoside inodilators), load resuscitation (e.g., afterload and preload reduction with nitroprusside or nitroglycerin; preload reduction with diuretics and diuretic facilitators, such as dopaminergic agents or ultrafiltration), and electrical resuscitation (e.g., prevention of sudden death, correction of new or rapid atrial fibrillation, or dual chamber pacing in the setting of relative prolongation of the PR interval and diastolic mitral/tricuspid regurgitation). Surgical interventions are temporizing (e.g., intra-aortic balloon pump and other mechanical assist devices) or definitive (e.g., coronary artery revascularization, valvular surgery, and cardiac transplantation). Although these interventions may improve immediate survival in the short term, only coronary artery revascularization and cardiac transplantation have been shown to improve long-term survival.

Inotropic therapy of the failing myocardium

The clinical syndrome of congestive heart failure remains a therapeutic dilemma and challenge for the physician in 1992. This is a disease process that appears to be increasing in frequency and continues to carry an unacceptably high mortality rate. For years it has been well recognized that the combination of digoxin, Lasix and vasodilator therapy improved symptoms in these patients and decreased hospitalization, but did not increase survival. It was not until 1986 that the combination of digoxin, Lasix, Isordil, and hydralazine was shown to increase survival. Further significant improvement in quality of life and survival has recently been established in three large clinical trials, and it is now safe to say that the standard of care for symptomatic congestive heart failure in 1992 is digoxin, furosemide, and an ACE inhibitor, with the survival trials favoring the ACE inhibitor enalapril. The IV inotropic drug dobutamine remains the mainstay of pharmacological therapy for the treatment of severely refractory heart failure. Unfortunately, the phosphodiesterase inhibitors--amrinone, milrinone, and enoximone--have demonstrated unacceptable clinical side effects and have been withdrawn from further clinical study. In spite of these promising developments, the mortality and morbidity of congestive heart failure remains unacceptably high, and continued investigation in the new fields of pharmacology and the pathophysiology of congestive heart failure still must be aggressively pursued.

Effects of dopaminergic agents on cardiac and renal function in normal man and in patients with congestive heart failure

Dopamine is an effective drug in the management of acute congestive heart failure. Its beneficial action is due to both cardiovascular--peripheral vasodilation and positive inotropy--and renal effects. Dopexamine is one of the newer dopamine agonists. Like dopamine, however, it can only be administered intravenously, and its value in the chronic treatment of congestive heart failure is limited. For this reason, dopamine analogs were developed with oral bioavailability, including levodopa, fenoldopam and biopamine. Although both levodopa and fenoldopam have shown beneficial hemodynamic effects, these agents cannot be recommended for general use in patients with congestive heart failure. Levodopa frequently causes side effects, especially nausea, and fenoldopam induces an increase in neurohumoral activity, which limits its long-term efficacy. Ibopamine has vasodilatory, mild inotropic and diuretic properties and it lowers plasma norepinephrine levels. Since ibopamine is usually well tolerated, it appears to have the most interesting profile of these oral dopaminergic agents.

Current status of non-digitalis positive inotropic drugs

Considerable effort and resources have been directed at the development and study of positive inotropic drugs over the past 10-15 years. Much has been learned about the physiology and pharmacology of myocardial contraction, the application of agents to augment contractility, and, importantly, the general and specific limitations of positive inotropic therapy. Studies on acute inotropic intervention have now shown that a drug's ability to augment overall cardiac performance is heavily dependent on its effects on vasculature, vascular control, and ventricular-vascular coupling. The clinical research on new agents has served to remind us how difficult it is to formulate the "ideal" positive inotropic or cardiovascular support drug for the critical care setting. The vast effort to develop a chronically and orally administrable drug to replace or even supplement digitalis has generally been disappointing. The dopaminergic agents (e.g., ibopamine, levodopa) act primarily via vasodilation and their effectiveness and role in managing heart failure remain unresolved. The initial excitement about the phosphodiesterase III inhibitors (e.g., amrinone, milrinone, enoximone) has been tempered by the results of large well-designed trials indicating variable effectiveness and a prominent adverse effect profile. During long-term oral administration none of these agents has been shown to improve clinical status or exercise capacity beyond that achieved by digoxin, when administered either separately or in combination with digoxin. The Prospective Randomized Milrinone Survival Evaluation (PROMISE) trial, showing that repeated oral administration of milrinone can increase mortality in heart failure, is having a devastating effect on the further development of this class of drugs.(ABSTRACT TRUNCATED AT 250 WORDS)