Untreated heart failure: clinical and neuroendocrine effects of introducing diuretics

Angiotensin-converting enzyme inhibitors, left ventricular dysfunction, and early heart failure

A study was undertaken to examine the effects of the angiotensin-converting enzyme inhibitor lisinopril on exercise performance in 18 patients with major impairment of left ventricular systolic function. The study was a randomized, double-blind, crossover design, and patients received treatment with either once-daily lisinopril (2.5-10 mg) or placebo for a period of 6 weeks. A total of 15 patients completed the study. Compared with placebo, lisinopril had no significant effect on supine or standing blood pressure or heart rate. Although lisinopril had no effect on exercise duration during a low-intensity exercise protocol, in patients undergoing a high-intensity exercise protocol, there was a trend toward improved exercise time and peak oxygen consumption improved significantly. In addition, treatment with lisinopril resulted in an increase in renal blood flow and a reduction in glomerular filtration rate. Moreover, administration of once-daily lisinopril 10 mg resulted in a decrease in plasma concentrations of angiotensin II, aldosterone, and atrial natriuretic peptide, and an increase in plasma concentrations of active renin.

Atrial natriuretic peptide in severe heart failure: response to controlled changes in atrial pressures during intravenous nitroglycerin therapy

Atrial natriuretic peptide (ANP) levels were measured in 17 patients with severe congestive heart failure (New York Heart Association functional class IV), and the response of the peptide was studied during changes in cardiac filling pressures induced by a 24-hour infusion of nitroglycerin. In the control state plasma ANP levels (687 +/- 551 pg/ml) were 10-fold normal. During the administration of nitroglycerin, natriuretic peptide levels decreased (p less than 0.005) with changes matching very closely the decreases in pulmonary arterial wedge and right atrial pressures, a 1% mean decrease in the peptide level for every 1.5 to 2% mean change in atrial filling pressures. In patients with hemodynamic tolerance to constant-dose nitroglycerin infusion, the resulting increase in atrial pressures was accompanied by an appropriate secondary increase in the plasma ANP level. During the 24-hour study period there was a direct linear relationship between both wedge (r = 0.93, p = 0.007) and right atrial (r = 0.93, p = 0.008) pressures and the plasma ANP level, with a zero-pressure ANP intercept near normal (69 pg/ml for wedge, 174 pg/ml for right atrial pressure). The findings were no different in a subgroup of five patients receiving simultaneous treatment with captopril, except that plasma renin activity was higher and the aldosterone level lower than in the control group by a factor of approximately 2.5. The close relationship and tracking of atrial pressure and natriuretic peptide curves suggested that the sensitivity of the atrial stretch response to changes in atrial filling pressures was maintained in severe congestive heart failure.

Lack of correlation between the acute haemodynamic response to intravenous captopril and plasma concentrations of angiotensin II in patients with chronic cardiac failure

We have given a series of incremental intravenous injections of captopril to ten patients with chronic cardiac failure. Small doses of captopril produced significant changes in pulmonary artery end-diastolic pressure and right atrial pressure, up to a total cumulative dose of captopril of 2.5 mg, after which further injections had no significant effect. There were large changes in systemic vascular resistance and blood pressure up to a cumulative dose of captopril of 5.0 mg, after which the injection of larger doses caused no further significant changes. Small doses of intravenous captopril produced large increases in plasma renin activity and plasma angiotensin I concentrations up to a total cumulative dose of captopril of 1.25 mg, after which there were no significant further changes in either plasma renin activity or plasma angiotensin I concentration. However the plasma concentration of angiotensin II fell more slowly, no further change being recorded after a total cumulative dose of captopril of 10 mg. These results suggest that plasma renin activity is not the only determinant of plasma angiotensin II concentrations.

Blood flow and skeletal muscle in patients with heart failure

The factors that contribute to the symptoms of breathlessness and fatigue, and that limit exercise capacity in patients with chronic heart failure are poorly understood. Recent evidence suggests that the major mechanism is not related to central hemodynamics but to a reduction of skeletal muscle mass and diminished blood flow to skeletal muscle on exercise.

Impact of converting enzyme inhibition on progression of chronic heart failure: results of the Munich Mild Heart Failure Trial

OBJECTIVE

Neurohormonal activation has major impact on the pathophysiology of congestive heart failure. The Munich Mild Heart Failure Trial was designed to test the hypothesis that interference with the renin-angiotensin system by angiotensin converting enzyme inhibition favourably influences the natural history of heart failure.

DESIGN AND PATIENTS

170 patients, median New York Heart Association (NYHA) class II, were randomised to double blind treatment with 25 mg captopril twice a day or placebo in addition to standard treatment for a median observation period of 2.7 years.

MAIN OUTCOME MEASURES

Progression of heart failure to NYHA class IV on an optimally adjusted standard treatment, death due to progressive heart failure, and sudden death.

RESULTS

Heart failure progressed to class IV in nine patients (10.8%) treated with captopril and in 23 patients (26.4%) treated with placebo (p = 0.01). The mean survival time until this end point was 223 days longer in the captopril group (Kaplan-Meier life table analysis; p = 0.02). Also, progressive deterioration to severe heart failure was a powerful predictor of total mortality and death from heart failure; 80% of deaths due to progressive heart failure occurred after this end point. There were fewer deaths caused by progressive heart failure in the captopril group than in the placebo group (4 v 11; p = 0.10) but similar numbers of sudden deaths (11 v 10). Progressive heart failure was the cause of death in 18.2% of all deaths in the captopril group and 50% in the placebo group. Total heart failure events (the end point on which power calculation was based) were also more common in the placebo group (19 v 32 events) but not significantly so. Total mortality was similar to both groups (22 of 83 v 22 of 87).

CONCLUSIONS

Angiotensin converting enzyme inhibition in conjunction with standard therapy early in the course of congestive heart failure slowed the progress of heart failure and thus favourably altered the natural history of the disease.

Predictors of prognosis in severe chronic heart failure

A total of 127 patients with chronic heart failure referred to our exercise laboratory were studied retrospectively to identify parameters predictive of prognosis. Patients were followed for a mean of 14.6 months. The group as a whole had severe ventricular dysfunction with a median ejection fraction of 17% and a median peak rate of oxygen consumption of 13.7 ml/kg/min. During the follow-up period 23 patients (18%) died and 18 (14%) underwent cardiac transplantation. The effect of the following variables on outcome (death or transplantation) were examined: age, cause of heart failure, cardiothoracic ratio on chest radiography, left ventricular end-systolic dimension on echocardiography, left ventricular ejection fraction on radionuclide ventriculography, mean dose of diuretic, plasma sodium and urea concentrations, and peak oxygen consumption during exercise. Although all variables except cause of heart failure affected outcome on univariate analysis, multivariate analysis identified three variables that were statistically significant and independent predictors of outcome. In order of importance these were plasma sodium level, left ventricular ejection fraction and peak oxygen consumption. Even in this group of patients with severe heart failure, these variables were predictive of outcome.

The influence of right heart catheterisation on pulmonary arterial pressure in chronic heart failure: relationship to neuroendocrinal changes

Continuous ambulatory measurement of pulmonary arterial pressure was used to investigate changes following right heart catheterisation in patients with chronic heart failure. Ten males, mean age 56 years, with chronic heart failure, underwent 24 hour pressure recording using a micromanometer tipped catheter with in vivo calibration and frequency modulated recording. Eight patients were taking diuretics and 3 vasodilators. Blood was drawn for catecholamines, plasma renin activity and atrial natriuretic peptide 1 hour before catheterisation (-1 h), at the time of catheterisation (0 h) and 1, 2, 3, 4 and 6 hours later and aldosterone, cortisol and growth hormone at -1, 0 and 6 hours. Analysis of variance was used to determine changes in pulmonary arterial pressure, heart rate and hormones from the time of catheterisation in lying, sitting and standing postures. There was no significant change in pulmonary arterial pressure or heart rate over the 12 hours following or 24 hours after catheterisation in any posture. In the majority of patients plasma noradrenaline, plasma renin activity, atrial natriuretic peptide, aldosterone and cortisol were elevated. There was no significant change in hormone levels during the 6 hours following catheterisation. These findings suggest that the effect of invasive haemodynamic monitoring and chronic medical therapy on central haemodynamics is minor, and that a delay between insertion of catheters and measurement of pressure is unnecessary.

Differences in first dose response to angiotensin converting enzyme inhibition in congestive heart failure: a placebo controlled study

OBJECTIVE

To compare the first dose responses to low dose angiotensin converting enzyme inhibitors (captopril, enalapril, and perindopril) in elderly patients with stable chronic heart failure.

DESIGN

Double blind, randomised, placebo controlled, parallel, group prospective study of elderly patients with stable chronic heart failure.

SETTING

General hospital in-patient admissions for supervised diuretic withdrawal (24-48 hours) and the introduction of angiotensin converting enzyme inhibitor therapy.

PATIENTS

48 unselected elderly (58-85 years) patients with symptomatic but stable chronic heart failure (New York Heart Association grades II-IV) confirmed by clinical history, examination, and cardiological investigations. Patients gave their written and informed consent to receive their initial treatment under double blind conditions; blood pressure was monitored and blood samples taken to measure the pharmacokinetic and neurohormonal responses.

INTERVENTION

Patients were randomised to receive a daily oral dose of placebo, captopril (6.25 mg), enalapril (2.5 mg), or perindopril (2 mg).

MAIN OUTCOME MEASURES

Blood pressure and heart rate responses, drug concentration, and plasma renin and ACE activities. Differences between treatment groups were analysed by analysis of variance.

RESULTS

The four randomised groups of patients had similar age, severity of heart failure (NYHA class), pretreatment diuretic dosage, plasma renin activity, and serum electrolyte state. Placebo treatment caused a modest but significant diurnal fall in blood pressure. Captopril produced a significant early (1.5 hours) and brief fall in blood pressure. The blood pressure fall with enalapril was later (4-10 hours), longer lasting, and was associated with significant slowing of supine heart rate. Though perindopril produced a similar plasma ACE inhibition to that produced by enalapril, it only caused changes in blood pressure that were similar to those caused by placebo.

CONCLUSIONS

This controlled study is the first to indicate a qualitative difference in the acute response to angiotensin converting enzyme inhibitors with similar structure and metabolism (that is, enalapril and perindopril). Low dose perindopril seems to be less likely to cause hypotension in patients with heart failure. The explanation for the differences is unclear but may reflect differential effects on local tissue angiotensin generation.

A large-scale trial of captopril for mild to moderate heart failure in the primary care setting

A large-scale, prospective, 8-week, office-based study was conducted to evaluate the effects of adding captopril to a therapeutic regimen of diuretic and digoxin or diuretic alone in the management of patients with mild to moderate congestive heart failure (CHF). A total of 2218 primary care physicians evaluated 6669 patients over the study period for efficacy parameters, which included changes in a modified New York Heart Association (NYHA) functional classification, symptomatology, and daily activity levels. Overall, 63.8% of evaluated patients improved with regard to functional ability, with 19% improving two or more modified NYHA classes. Symptoms of CHF, including dyspnea on exertion, fatigue, and orthopnea and signs, including rales and peripheral edema, were reduced in 86% of these patients: 41.5% demonstrated mild improvement; 30.0%, moderate improvement; and 14.5%, marked improvement. Three parameters, with which patients reported having difficulty at study entry, were assessed serially to evaluate changes in functional capacity; 78.5% of patients reported an increased walking distance, 72.3% had increased capacity for climbing stairs, and 60.2% had improved capacity for individual recreational activities. Adverse experiences were reported in 18.1% of all patients; 4.9% of patients withdrew from the study because of an adverse effect. Combination therapy with captopril and diuretic for CHF was shown to be safe and effective regardless of patient age (less than 70 years vs. greater than or equal to 70 years), duration of heart failure (less than 1 year vs. greater than 1 year), presence of digoxin treatment, or the dosing schedule employed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of long-term enalapril therapy on cardiopulmonary exercise performance in men with mild heart failure and previous myocardial infarction

Forty-one men with documented myocardial infarction greater than 6 months previously were randomized to long-term (48 weeks) therapy with placebo or enalapril on a double-blind basis. All patients were receiving concurrent therapy with digitalis and a diuretic drug for symptomatic heart failure (functional class II or III). The mean age was 64 +/- 7.3 years and no patient suffered from exertional chest pain. Patients underwent maximal cardiopulmonary exertional chest pain. Patients underwent maximal cardiopulmonary exercise testing to exhaustion on an ergometer cycle nine times over the course of 48 weeks. Gas exchange data were collected on a breath by breath basis with use of a continuous ramp protocol. In the placebo group (n = 21), the mean (+/- SD) peak oxygen consumption (VO2) at baseline was 18.8 +/- 5.2 versus 18.5 +/- 5.5 ml/kg per min at 48 weeks (-1.4%, p = NS). In the enalapril group (n = 20), the corresponding values were 18.1 +/- 3.1 versus 18.3 +/- 2.6 ml/kg per min (+2.8%, p = NS). The mean VO2 at the anaerobic threshold for the placebo group at baseline study was 13.1 +/- 3.5 versus 12.8 +/- 2.1 ml/kg per min at 48 weeks (-2.2%, p = NS). The corresponding values for the enalapril group were 11.8 +/- 2.3 versus 11.8 +/- 2.4 ml/kg per min (+1.4%, p = NS). The mean total exercise duration in the placebo group at baseline study was 589 +/- 153 versus 620 +/- 181 s at 48 weeks (+5.4%, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Interrupting the adaptive changes in congestive heart failure

Circulating plasma concentrations of norepinephrine, renin, angiotensin and vasopressin are increased in congestive heart failure. By increasing ventricular afterload, heart failure is further worsened, which in turn--in a vicious cycle--stimulates neurohumoral vasoconstrictor mechanisms. Furthermore, because of the compensatory but excessive stimulation of the sympathomimetic system, a down-regulation and desensitization particularly of the myocardial beta 1 receptors and depletion of myocardial catecholamine occurs in chronic heart failure. These defects may be restored toward normal by interventions that attenuate the activity of the sympathetic nervous system. A direct approach to modify the excessive vasoconstriction is to administer systemic vasodilator drugs, but despite favorable short-term effects, tolerance developed to most of these drugs during long-term treatment. One reason for the loss of effectiveness is the reflex activation of the sympathetic system, which increases vasoconstrictor hormone concentrations. Activation of the renin-angiotensin system can be modified effectively by angiotensin-converting enzyme inhibitors that have shown favorable responses in patients with chronic heart failure. Beta-blocking agents interfere with endogenous sympathetic activation and have produced beneficial effects in patients with congestive cardiomyopathy. Long-term treatment is associated with up-regulation of the number of beta receptors and an improved responsiveness to catecholamines. Owing to the negative inotropic effects of beta-blocking agents, some of the patients with severe heart failure deteriorated hemodynamically and clinically. Theoretically, it should be advantageous to have a substance that combines protection against excessive beta stimulation with a mild inotropic support to prevent cardiac decompensation. This may be achieved by a selective beta 1-partial agonist like xamoterol.

Neuroendocrine activation in congestive heart failure

Several changes in neuroendocrine activity follow failure of cardiac function to satisfy peripheral requirements and contribute to the clinical syndromes of heart failure. Afferent pathways are poorly understood and triggers are both central and peripheral, involving attenuation of atrial and arterial baroreceptor activity. Efferent sympathetic activity is generally increased with resulting vasoconstriction, but responses are organ-specific and differ among heart, kidney, lung and skeletal muscle. Changes in cardiac sympathetic activity are inadequately understood. Enhanced cardiac norepinephrine spillover contrasts with reduced tissue concentration and impaired activity of synthetic enzymes and neuronal catecholamine uptake. Beta-receptor down-regulation further complicates overall adrenergic responsiveness and the balance between enhancement of contractile function and reduction in arrhythmia threshold. Activation of the renin-angiotensin system is potentiated by the sympathetic nervous system and may contribute to vasoconstrictor hyporesponsiveness. Angiotensin II may in turn facilitate the central and peripheral effects of sympathetic activation and the release of vasopressin from the pituitary. Our understanding of the role of vasodilator peptides in heart failure remains rudimentary. It is likely that vasoconstrictor neuroendocrine response adversely influences optimal cardiac function in heart failure and may promote arrhythmogenesis. The neuroendocrine response in individual organs, however, requires intensive study.

Neuroendocrine activity in untreated heart failure

Neuroendocrine activity was studied in 60 consecutive untreated patients with dyspnoea and a clinical suspicion of heart failure. On the basis of the so-called Boston clinical criteria the diagnosis of heart failure was regarded as unlikely in 26 patients, possible in 15 patients, and definite in 19 patients. These groups were studied before any drug treatment was started and were compared with a control group of 69 healthy individuals. Plasma atrial natriuretic peptide concentration was clearly raised in patients with definite heart failure and slightly raised in patients with possible heart failure. Plasma adrenaline concentration was somewhat raised in patients with definite or possible heart failure, whereas plasma noradrenaline concentration was raised only in patients with definite heart failure. Plasma renin activity was not increased in any of the patient groups and plasma aldosterone concentration was slightly increased only in patients with definite heart failure. In the total patient series there were significant correlations between plasma atrial natriuretic peptide concentration and markers of the severity of left ventricular dysfunction. There was some evidence of neuroendocrine activation in untreated heart failure: plasma concentrations of atrial natriuretic peptide and catecholamines were increased but the renin-angiotensin-aldosterone system showed little or no activation.

Resolved and unresolved issues in the prevention and treatment of coronary artery disease: a workshop consensus statement

Advances in cardiovascular research during the past two decades have resulted in an improved understanding of the chain of events that lead to end-stage coronary artery disease. These developments have been paralleled by therapeutic advances that now make it possible to intervene at virtually every stage in the development of advanced cardiac disease, from asymptomatic persons at risk of developing coronary atherosclerosis to patients with end-stage heart failure. By interrupting this chain of events, perhaps at multiple sites, it may be possible to prevent or slow the development of symptomatic heart disease and hopefully prolong life. Many opportunities exist for obtaining further information regarding the underlying pathophysiology, the fundamental mechanisms of action of interventions designed to prevent and/or treat the development of myocardial ischemia and cardiac failure and for effecting favorably the natural history of various forms of heart disease.

Comparative effects of angiotensin converting enzyme inhibition (perindopril) or diuretic therapy on cardiac hypertrophy and sympathetic activity following myocardial infarction in rats

The long-term effects of perindopril or chlorothiazide therapy were studied in rats after the induction of myocardial infarction by coronary artery ligation. Rats with infarction developed marked cardiomegaly, indicating the presence of chronic left ventricular dysfunction. The ratio of the norepinephrine metabolite, 3,4-dihydroxyphenylethylene glycol (DHPG) to norepinephrine (NE) was elevated in the right ventricle of rats with infarction, suggesting a chronic increase in cardiac sympathetic activity. Perindopril therapy commenced either immediately following infarction or 4 weeks following infarction reduced DHPG/NE ratios toward normal levels, and prevented or reversed cardiac hypertrophy. In contrast, chlorothiazide therapy significantly reduced DHPG/NE ratios but did not decrease cardiac hypertrophy. Perindopril reverses or prevents cardiac hypertrophy and chronic cardiac sympathetic hyperactivity following myocardial infarction, while chlorothiazide reduces cardiac sympathetic activity without influencing cardiomegaly.

Tissue and plasma angiotensin converting enzyme and the response to ACE inhibitor drugs

1. There is a body of circumstantial and direct evidence supporting the existence and functional importance of a tissue based RAS at a variety of sites. 2. The relation between circulatory and tissue based systems is complex. The relative importance of the two in determining haemodynamic effects is unknown. 3. Despite the wide range of ACE inhibitors already available, it remains unclear whether there are genuine differences related to tissue specificity. 4. Pathological states such as chronic cardiac failure need to be explored with regard to the contribution of tissue based ACE activities in generating acute and chronic haemodynamic responses to ACE inhibitors. 5. The role of tissue vs plasma ACE activity may be clarified by study of the relation between drug concentration and haemodynamic effect, provided that the temporal dissociation is examined and linked to circulating and tissue based changes in ACE activity, angiotensin peptides and sympathetic hormones.

Acute and long term effects of loop diuretics in heart failure

Diuretics, together with digitalis glycosides and vasodilators are of prime importance in the medical treatment of patients with congestive heart failure (CHF). Diuretics provide quick symptomatic relief in these patients. Their beneficial effect is related to the promotion of sodium and water excretion via the kidney, thus reducing extracellular fluid volume expansion and mitigating the increase in preload and afterload caused by sodium and water retention. Loop diuretics administered intravenously are indispensable in the management of pulmonary oedema; thiazides and loop diuretics in low doses are effectively used in the oral treatment of mild to moderate heart failure. Torasemide is a new loop diuretic which differs from furosemide (frusemide) and related loop diuretics by virtue of its longer elimination half-life and longer duration of action, with almost complete bioavailability. The efficacy and tolerability of torasemide have been compared with furosemide in several studies. Once daily oral administration of torasemide (starting with 5mg) or furosemide 40mg reduce bodyweight, oedema and symptoms of heart failure to a similar extent. Mean New York Heart Association class is consistently reduced by 0.5 to 0.7. Intravenous administration attenuates the increase in intracardiac pressures during exercise in patients with CHF, and produces acute improvements in cardiac haemodynamics in patients with high grade left heart failure. A beneficial effect on both pulmonary and cardiac haemodynamics has been demonstrated during chronic oral treatment of patients with previously untreated CHF. Torasemide was well tolerated with only mild and transient adverse effects reported in a small number of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurohumoral activation in congestive heart failure

This article reviews the evidence that congestive heart failure is accompanied by an increased plasma norepinephrine concentration and that this is due not only to a reduced tissue clearance of the substance but also to a marked increase in sympathetic nerve activity. It also reports data that indicate that the sympathetic activation is associated with an activation of the renin-angiotensin system and an increased plasma level of vasopressin. At which degree of congestive heart failure these phenomena become manifest is not clear, but some studies suggest that the sympathetic and renin-angiotensin systems may be normal in asymptomatic congestive heart failure but already somewhat activated when this condition reaches New York Heart Association class II. There is also evidence that this activation, though initially compensatory, is eventually responsible for a number of adverse cardiovascular effects that account for the negative relationship between this event and survival. Finally, the article discusses the inability of the increased plasma level of atrial natriuretic peptide that characterizes congestive heart failure to offset the adverse effects of the neurohumoral activation and the variable influence of drug treatment on this phenomenon. This is not impossible to achieve, however, because heart transplantation appears to rapidly normalize a major factor in the increased sympathetic activity observed before surgical intervention, that is, impairment of the arterial baroreflex.

Comparison of neuroendocrine activation in patients with left ventricular dysfunction with and without congestive heart failure. A substudy of the Studies of Left Ventricular Dysfunction (SOLVD)

Neuroendocrine activation is known to occur in patients with congestive heart failure, but there is uncertainty as to whether this occurs before or after the presence of overt symptoms. In the Studies of Left Ventricular Dysfunction (SOLVD), a multicenter study of patients with ejection fractions of 35% or less, we compared baseline plasma norepinephrine, plasma renin activity, plasma atrial natriuretic factor, and plasma arginine vasopressin in 56 control subjects, 151 patients with left ventricular dysfunction (no overt heart failure), and 81 patients with overt heart failure before randomization. Median values for plasma norepinephrine (p = 0.0001), plasma atrial natriuretic factor (p less than 0.0001), plasma arginine vasopressin (p = 0.006), and plasma renin activity (p = 0.03) were significantly higher in patients with left ventricular dysfunction than in normal control subjects. Neuroendocrine values were highest in patients with overt heart failure. Plasma renin activity was normal in patients with left ventricular dysfunction without heart failure who were not receiving diuretics and was significantly increased (p less than 0.05) in patients on diuretic therapy. We conclude that neuroendocrine activation occurs in patients with left ventricular dysfunction and no heart failure. Neuroendocrine activation is further increased as overt heart failure ensues and diuretics are added to therapy.

Hormones regulating cardiovascular function in patients with severe congestive heart failure and their relation to mortality. CONSENSUS Trial Study Group

There is a varying hormonal activation in heart failure. To be able to evaluate this activation and relate it to prognosis, we took blood samples at baseline and after 6 weeks from 239 patients with severe heart failure (all in New York Heart Association class IV) randomized to additional treatment with enalapril or placebo. In this study (CONSENSUS), which has previously been reported, there was a significant reduction in mortality among patients treated with enalapril. The present data show in the placebo group a significant positive relation between mortality and levels of angiotensin II (p less than 0.05), aldosterone (p = 0.003), noradrenaline (p less than 0.001), adrenaline (p = 0.001), and atrial natriuretic factor (p = 0.003). A similar relation was not observed among the patients treated with enalapril. Significant reductions in mortality in the groups of patients treated with enalapril were consistently found among patients with baseline hormone levels above median values. There were significant reductions in hormone levels from baseline to 6 weeks in the group of patients treated with enalapril for all hormones except adrenaline. There were no correlations between these changes in hormone levels. Summarily, there is a pronounced but variable neurohormonal activation in heart failure even in patients with similar clinical findings. This activation is reduced by enalapril therapy. The results suggest that the effect of enalapril on mortality is related to hormonal activation in general and the renin-angiotensin system in particular.

Effects of enalapril and neuroendocrine activation on prognosis in severe congestive heart failure (follow-up of the CONSENSUS trial). CONSENSUS Trial Study Group

This study enrolled 253 patients with severe heart failure (New York Heart Association functional class IV) from 35 centers in Scandinavia, randomly assigned to treatment with placebo or enalapril, in addition to their usual treatment for heart failure. After an initial titration period, the daily doses of enalapril ranged from 2.5 to 40 mg. At the end of the trial, 46% of the placebo-treated patients and 61% of the enalapril-treated patients were alive (p = 0.003); the survival figures at 8 months after completion of the trial were 32 and 48%, respectively (p = 0.001); and 21 and 30%, respectively (p = 0.006) at the 2-year follow-up. In the placebo group, there was a significant positive association between mortality and baseline levels of norepinephrine, epinephrine, angiotensin II, aldosterone and atrial natriuretic peptide; no such association was found in the enalapril-treated patients. The results suggest that the effects of enalapril on mortality are related to a counteraction of the neuroendocrine activation in general and to the renin-angiotensin system in particular.

Tolerance to intravenous nitroglycerin in patients with congestive heart failure: role of increased intravascular volume, neurohumoral activation and lack of prevention with N-acetylcysteine

To better understand the mechanism of nitrate tolerance in patients with congestive heart failure, 13 patients received a 24 h infusion of nitroglycerin (1.5 micrograms/kg body weight per min) with or without N-acetylcysteine (225 mg/kg per 24 h). The infusions were separated by a 24 h nitrate-free interval. By the end of the nitroglycerin infusion, mean arterial pressure had returned to baseline values and there was a significant increase in ventricular filling pressures and systemic vascular resistance compared with values after 1 h of treatment. The simultaneous infusion of N-acetylcysteine had no effect on these changes. Although a strict fluid restriction of 1.5 liters/day was maintained for 1 week before and throughout the study, after 24 h of nitroglycerin infusion there was a significant and similar degree of hemodilution whether nitroglycerin was infused alone (9.1 +/- 4.3%) or with N-acetylcysteine (8.7 +/- 4.1%). This hemodilution corresponded to an increase in intravascular volume of 745 +/- 382 ml, most of which occurred during the 1st h. Plasma renin activity increased and plasma atrial natriuretic peptide decreased during the infusion. The results of this study suggest that nitrate tolerance is multifactorial. In addition to the previously described pharmacologic tolerance to the effect of nitroglycerin on vascular smooth muscle, a capillary fluid shift from the extravascular to intravascular space appears to be involved, especially during the 1st h of the infusion. A third mechanism, reflex neurohumoral activation, also seems to contribute to the genesis of nitroglycerin tolerance.

Role of left ventricular dysfunction in selective neurohumoral activation in the recovery phase of anterior wall acute myocardial infarction

Neurohumoral activation is readily apparent in patients with symptomatic congestive heart failure (CHF) and in the acute phase after acute myocardial infarction. In this study, the neurohumoral profiles of 36 asymptomatic patients in the early convalescent phase after acute myocardial infarction were examined. All patients in the study had a radionuclide ejection fraction less than or equal to 45% and underwent cardiac catheterization 11 to 30 days after infarction. Venous blood samples were obtained in the supine state for the measurement of norepinephrine, angiotensin II, plasma renin activity and aldosterone in all patients. Despite the reduced ejection fraction and extensive wall motion abnormalities, plasma norepinephrine was not elevated and did not correlate with any measured hemodynamic, angiographic or clinical variables. The renin-angiotensin II aldosterone system was activated, as expected, in the 9 study patients receiving loop diuretics. However, even in the 27 patients not taking diuretics, plasma angiotensin II and renin activity levels were increased in relation to Killip classification, the presence of a left ventricular (LV) aneurysm and LV ejection fraction. Activation of the renin-angiotensin-aldosterone system can be identified in hemodynamically compensated postinfarction patients not taking diuretics and appears to be related to the extent of LV dysfunction.

Failure of captopril to prevent nitrate tolerance in congestive heart failure secondary to coronary artery disease

The possible role of angiotensin-converting enzyme inhibition in preventing or minimizing tolerance to intravenous nitroglycerin in severe congestive heart failure (CHF) was studied by quantitating the degree of tolerance in 12 patients receiving nitroglycerin (group 1) and in 9 patients (group 2) receiving nitroglycerin and concurrent treatment with captopril (60 +/- 29 mg/day). At peak effect, nitroglycerin produced almost identical hemodynamic changes in both groups, with significant decreases in right atrial and pulmonary arterial wedge pressure, systolic blood pressure and systemic and pulmonary vascular resistances. Cardiac index increased. The extent of nitrate tolerance was calculated for each hemodynamic parameter as the percentage loss of the peak effect achieved by the drug. At 24 hours, 98 +/- 80% of the benefit achieved with respect to right atrial pressure was lost in group 1 and 61 +/- 74% in group 2 (group 1 vs 2, difference not significant). For pulmonary arterial wedge pressure, 51 +/- 31% (group 1) and 85 +/- 53% (group 2) (difference not significant) of the effect was lost, and for cardiac index, 53 +/- 58% (group 1) and 54 +/- 44% (group 2) (difference not significant). Tolerance was also almost identical regarding systolic blood pressure and systemic and pulmonary vascular resistance. Thus, the extent of tolerance to high-dose intravenous nitroglycerin in CHF was unaltered by administration of captopril, indicating that in clinical dosage, counter-regulatory neurohumoral mechanisms involving the renin-angiotensin system appear to be unimportant in its development.

The correlation of cardiac power output to exercise capacity in chronic heart failure

Cardiac haemodynamics are deranged in chronic heart failure but fail to predict the exercise capacity of the patient. Cardiac power output is a descriptor of cardiac function derived from preload, blood pressure and cardiac output. Forty-one patients with moderately severe and severe chronic heart failure were exercised on a cycle ergometer to determine the relationship between traditional haemodynamics and cardiac power output and exercise capacity. Resting cardiac power output was no more predictive of exercise capacity than resting stroke-work index or resting cardiac index (r = 0.53, 0.61 and 0.51 respectively). Maximum cardiac power output and the ability to increase cardiac power output, however, were correlated with exercise capacity (r = 0.79 and 0.80). It is concluded that resting cardiac power output does not predict subsequent exercise capacity but that maximum cardiac power output and the ability to increase cardiac power output on stimulation are good descriptors of functional cardiac reserve.

Enalapril as initial and sole treatment in severe chronic heart failure with sodium retention

Five patients, who had never received any drug treatment but who had severe chronic congestive heart failure with salt and water retention, were studied before and after a single dose of enalapril (10 mg orally). Three patients continued on enalapril as monotherapy (10 mg b.d. orally) for one month. Central haemodynamics, body fluid volumes, renal function and plasma hormones were measured at rest. The initial mean right atrial pressure was 13 +/- 4 mm Hg, pulmonary wedge pressure 29 +/- 4 mm Hg and cardiac index 1.8 +/- 0.21/min/m2. Enalapril, given acutely, caused only small changes. Two patients were withdrawn after the single dose of enalapril and treated with diuretics for clinical reasons. The remaining three patients each lost more than 4 kg in weight after one month of treatment with enalapril alone. Total body exchangeable sodium and total body water were reduced but central haemodynamics were unchanged. Although enalapril was of some benefit when given alone to patients with severe congestive heart failure, all five patients were finally treated with diuretics for clinical reasons. Enalapril is not recommended as the initial and only therapy for patients with severe congestive heart failure.

Neuroendocrine changes post myocardial infarction: effects of xamoterol

This study reports the effects of the new beta 1 adrenoceptor partial agonist, xamoterol, on neuroendocrine activity after acute myocardial infarction (AMI). Fifty-one consecutive patients with AMI were randomized to treatment with xamoterol, 200 mg twice a day, or placebo; patients were also stratified as to whether or not diuretic therapy was given for left ventricular dysfunction. Noradrenaline, plasma renin activity (PRA), and atrial natriuretic factor (ANF) were measured over a 10-day period. Noradrenaline concentrations are higher (p less than 0.05) in patients treated with diuretics at the time of admission and fell over the subsequent 10 days (p less than 0.01). Treatment with xamoterol did not affect this noradrenaline response to myocardial infarction. PRA was also significantly higher in the patients treated with diuretics, and there was a nonsignificant trend for xamoterol to blunt the PRA response in these patients. There was no difference in ANF levels between those patients who were treated with diuretics and those who were not; xamoterol did not affect ANF. Thus xamoterol does not further elevate noradrenaline levels as do conventional beta blockers, and it does not activate the renin-angiotensin system as do potent nonselective beta agonists. Furthermore, xamoterol does not increase ANF levels, probably because it is not negatively inotropic. We conclude that xamoterol does not cause deleterious neuroendocrine changes in patients with AMI even in those treated for heart failure.

Intravenous captopril in congestive heart failure

Hemodynamic and neurohumoral effects of intravenous captopril were studied in ten patients with severe chronic congestive heart failure (NYHA Functional Class III and IV). Incremental bolus doses of captopril, titrated to a maximum cumulative dose of 15 mg, were given at 10-minute intervals. Systemic arterial pressure, mean pulmonary capillary wedge pressure, systemic vascular resistance, mean pulmonary artery pressure, and heart rate decreased (P less than .05). Cardiac index and stroke volume index increased (P less than .05). Maximum hemodynamic effects occurred after cumulative doses of 7 mg and were seen within 30 minutes after initiation of therapy; responses persisted for 30-90 minutes after the last dose. Plasma renin activity increased, and plasma atrial natriuretic factor concentration decreased. No adverse effects were observed with the use of intravenous captopril. Thus, intravenous captopril produces rapid and favorable hemodynamic improvement in advanced heart failure patients.

Acute and chronic effects of a diuretic monotherapy with piretanide in congestive heart failure--a placebo-controlled trial

To evaluate the acute and chronic effects of diuretic monotherapy with 3 mg piretanide bid, 46 patients (pts) with congestive heart failure (NYHA II-III) secondary to coronary artery disease were studied. Within 3 weeks of therapy, the patients lost 1.6 kg body weight. Forty-four patients reported a subjective feeling of improvement. Echocardiographically, a highly significant (p less than 0.001) reduction of diastolic and systolic diameters was found, as well as an increase of fraction shortening. Chest x-ray indicated a reduction of heart volume from 1012 +/- 263 ml to 936 +/- 233 ml (p less than 0.001). The serum potassium level remained unchanged. A subgroup of 26 pts underwent invasive hemodynamic examinations. IV injection of 6 mg piretanide resulted in an acute reduction of pulmonary wedge pressure (pc) from 20.2 +/- 5.3 mmHg to 11.9 +/- 5.0 mmHg (p less than 0.001); simultaneously a slight decrease of cardiac index from 3.2 +/- 0.6 l/min/m2 to 3.0 +/- 0.4 l/min/m2 was observed. Invasive control after 3 weeks of oral therapy showed no decline of the piretanide effect. The exercise tolerance increased clearly from 135 +/- 161 Wmin to 249 +/- 268 Wmin (p less than 0.05). A control group of further 14 pts was treated with placebo only and did not show any significant changes of pc (20.0 +/- 6.4 mmHg vs. 22.8 +/- 19.2 mmHg), exercise tolerance, or other clinical parameters. Thus, the diuretic monotherapy of congestive heart failure with piretanide is highly effective and shows a significant improvement in all clinical and hemodynamic parameters in the absence of any remarkable side effects.

Functional and morphological characteristics of compensated and decompensated cardiac hypertrophy in dogs with chronic infrarenal aorto-caval fistulas

The relation between cardiac hypertrophy, shunt size, myocardial contractility, capillary density, adrenergic responsiveness, and neurohumoral stimulation was evaluated in dogs with compensated and decompensated cardiac hypertrophy caused by an infrarenal aorto-caval shunt. Shunt size varied from 5 to 35 mm2 due to an inability to create a uniform size. Dogs that developed heart failure within 4 months had 25 +/- 2 mm2 shunts, whereas those that developed it after 4 months had 19 +/- 3 mm2 shunts; those that did not develop heart failure had 10 +/- 1 mm2 shunts. Hypertrophy developed at the same rate in all the dogs that developed heart failure, which occurred at a critical heart weight (hypertrophy) for a given load (shunt size). In the dogs with heart failure there was a decrease in myocardial contractility (tension = 5.7 +/- 0.6 vs. 7.3 +/- 0.3 g/mm2, p less than 0.05), a decrease in adrenergic responsiveness (maximal heart rate with isoproterenol = 203 +/- 7 vs. 249 +/- 5 beats/min, p less than 0.01), an increase in circulating neurohormones, and a decrease in urinary sodium excretion (0.4 +/- 0.1 vs. 5.0 +/- 1.3 meq/3 hr, p less than 0.01). None of these abnormalities occurred in dogs with compensated hypertrophy. There were no differences in cardiac capillary density between the control dogs and the dogs with compensated cardiac hypertrophy or heart failure. Thus, it would appear that if heart failure is to develop after an initial toleration of a sudden volume overload, it will develop at a given combination of cardiac hypertrophy and volume overload, with cardiac hypertrophy developing at the same rate in all cases. In this model, once heart failure develops, myocardial contractility and cardiac adrenergic responsiveness are decreased and there is pronounced neurohumoral activation. All these changes are absent in hearts with compensated hypertrophy.

Drug treatment of heart failure

The objectives of treatment for patients with chronic heart failure are the prevention of the initial occurrence, the alleviation of signs and symptoms, the delay of the progression of damage to heart muscle and the reduction of the mortality rate. Many drugs are used in severe heart failure. Current controversy is concerned with which drugs to use in patients with mild heart failure or with left ventricular dysfunction. There is a trend towards the earlier introduction of an angiotensin-converting enzyme inhibitor combined with a diuretic.

Mild heart failure: diagnosis and treatment

CHF afflicts 15 million persons worldwide despite advances made in its diagnosis and treatment. A thorough physical examination and basic, noninvasive evaluation are essential for establishing the diagnosis of heart failure and for designing an optimal, individualized treatment regimen. Although digitalis and diuretics continue to be used commonly for the treatment of CHF of all severities, the use of vasodilators and ACE inhibitors has increased dramatically, as they are used more widely and earlier in the course of the illness. Because the RAA system contributes significantly to the altered cardiovascular hemodynamics and symptomatology characteristic of heart failure, the ACE inhibitors provide a rational approach to therapy for many patients. Results of controlled clinical trials have shown that selected vasodilators and ACE inhibitors can improve survival in patients with CHF and that patients receiving ACE inhibitors show sustained improvement in clinical class, exercise tolerance, and hemodynamics. Thus the therapeutic spectrum available to the clinician dealing with patients with CHF has broadened substantively over the past decade.

Xamoterol, a beta 1-adrenoceptor partial agonist: review of the clinical efficacy in heart failure

1. Xamoterol (Corwin, Carwin, Corwil, Xamtol, ICI 118,587), a beta 1-adrenoceptor partial agonist, improves both systolic and diastolic function in heart failure patients. 2. Double-blind, randomised studies comparing xamoterol with placebo showed that the beneficial haemodynamic effects of xamoterol produced significant improvements in exercise capacity and symptoms in patients with mild to moderate heart failure. These studies formed the basis for a large European multicentre study programme which recruited over 1000 patients, randomised to xamoterol (200 mg twice daily, n = 617), digoxin (0.125 mg twice daily, n = 135) or placebo (n = 300) for 3 months. 3. Efficacy was assessed by measuring exercise capacity and symptoms. The xamoterol group improved exercise capacity by 37% compared with an 18% improvement in the placebo group. Differences in the symptom scores measured by visual analogue scales and Likert scores indicated significant improvements by xamoterol in the cardinal symptoms of heart failure, dyspnoea and fatigue. 4. Analyses of data from subsets of patients in the study showed that elderly patients, patients on no other heart failure therapy and patients with cardiomegaly all had similar improvements in exercise and symptoms to those seen in the whole study population. In the subset which included digoxin treatment, xamoterol produced significantly greater improvements in exercise capacity than digoxin (33% vs 17%, P less than 0.05) and was associated with fewer side-effects. 5. Xamoterol is therefore a promising addition to heart failure therapies currently available.

Current therapy of the failing heart

Myocardial dysfunction eventuating in systolic and diastolic pump function abnormalities is a consequence of a wide variety of cardiac diseases. The symptoms that develop in this syndrome appear to be related as much to peripheral and neurohormonal mechanisms as to the underlying pathological and cardiac functional abnormality. Relief of symptoms, slowing of the progression of the cardiac functional abnormality, and prolongation of life provide the major agenda for the physician faced with the management of these patients. Judicious use of vasodilators, diuretics, digoxin, dietary therapy, and exercise therapy can relieve symptoms and improve the quality of life in most patients suffering from this syndrome. Recent evidence that vasodilator drugs can prolong life now provides the physician with further justification for routine use of this class of compounds. The eventual solution to the high mortality in this common disease process may be prevention of the development of overt heart failure by more prompt recognition and early treatment of the signs of ventricular dysfunction. This possibility must await the completion of current and proposed clinical trials.

Contributions of neuroendocrine and local autocrine-paracrine mechanisms to the pathophysiology and pharmacology of congestive heart failure

The degree of activation of neurohormonal mechanisms appears to depend on the severity and acuteness of cardiac impairment as well as the status of the extracellular fluid volume. Vasoconstrictive antinatriuretic mechanisms are markedly activated in severe decompensated cardiac failure. These are accompanied by parallel increases in endogenous vasodilatory natriuretic activities that modulate the powerful vasoconstrictive mechanisms. During chronic compensation, many of these neuroendocrine mechanisms returned to the baseline normal level. In addition to endocrine and neurogenic mechanisms, local autocrine-paracrine systems in the blood vessel wall may also contribute to the regulation of vascular tone. The role of these systems in congestive heart failure has not been systematically studied. It is possible that they may contribute to the long-term regulation of vascular tone and therefore may play an increasing role in the pathogenesis of ventricular remodeling, dilatation and progressive congestive heart failure.

Regional blood flow in congestive heart failure: concept of compensatory mechanisms with short and long time constants

With physiologic stress to the cardiovascular system, some circulatory compensatory mechanisms are designed to restore homeostasis quickly (e.g., sympathetic nervous system activation and the Frank-Starling mechanism). These compensatory mechanisms are not nearly as effective when there is a chronic pathologic stress such as congestive heart failure (CHF). In this circumstance, other mechanisms that operate with longer time constants come into play (e.g., activation of the renin-angiotensin-aldosterone system, myocardial hypertrophy and deconditioning). The most successful chronic drug therapies of CHF are those that are designed to reverse the latter group of compensatory mechanisms, a process that is slow. It takes especially long to reverse those CHF-induced changes in blood vessels and skeletal muscle metabolism that are activated to cope with inadequate delivery of oxygenated blood to working muscles. The concept that compensatory mechanisms have either short or long time constants for activation, effectiveness and reversal may help explain why the improvement in exercise tolerance with effective heart failure therapy lags behind hemodynamic improvement.

Current therapeutic principles in the acute management of severe congestive heart failure

The phrase "heart failure" encompasses many clinical entities. The therapeutic principles determining the treatment of these entities vary according to the etiology of congestive heart failure (CHF), the existing hemodynamics, and the mode of action of different drugs. In acute CHF due to myocardial ischemia, intracellular acidosis and the accumulation of phosphate may be the initial underlying causes of contractile failure while, minutes later, lack of high-energy compounds may be an important contributory factor. The cause of contractile failure in chronic syndromes is less well understood. There is evidence for the desensitization of beta receptors on the cell surface but the precise location of the defect is unclear. The receptors may be down-regulated but, in addition, abnormalities have been reported in several other parts of the contractile pathway including the contractile proteins and the sarcoplasmic reticulum. Deficiency of cyclic adenosine monophosphate has also been suggested as a mechanism of contractile failure. In both acute and chronic CHF, there is a redistribution of blood flow to the body organs. Of particular significance is the reduction of blood flow to the kidneys, and a reversal of this defect is one of the major therapeutic objectives. Positive inotropic drugs, vasodilators and drugs altering relaxation of the heart, have been evaluated in the treatment of CHF. Pure inotropic drugs can cause tachycardia, ischemia and "metabolic exhaustion" of the myocardium. The most advantageous profile for an "inotropic" drug in many patients with CHF would be a drug combining systemic vasodilatation, renal vasodilatation, increased relaxation of the myocardium only a mild positive inotropic effect and no chronotropic effect.