ALDOSTERONE AND THE EDEMA OF CONGESTIVE HEART FAILURE

Mineralocorticoid receptor antagonists for heart failure with reduced ejection fraction: integrating evidence into clinical practice

Mineralocorticoid receptor antagonists (MRAs) improve survival and reduce morbidity in patients with heart failure, reduced ejection fraction (HF-REF), and mild-to-severe symptoms, and in patients with left ventricular systolic dysfunction and heart failure after acute myocardial infarction. These clinical benefits are observed in addition to those of angiotensin converting enzyme inhibitors or angiotensin receptor blockers and beta-blockers. The morbidity and mortality benefits of MRAs may be mediated by several proposed actions, including antifibrotic mechanisms that slow heart failure progression, prevent or reverse cardiac remodelling, or reduce arrhythmogenesis. Both eplerenone and spironolactone have demonstrated survival benefits in individual clinical trials. Pharmacologic differences exist between the drugs, which may be relevant for therapeutic decision making in individual patients. Although serious hyperkalaemia events were reported in the major MRA clinical trials, these risks can be mitigated through appropriate patient selection, dose selection, patient education, monitoring, and follow-up. When used appropriately, MRAs significantly improve outcomes across the spectrum of patients with HF-REF.

Traditional and novel approaches to management of heart failure: successes and failures

Although considerable progress has been made in the pharmacologic and device management of chronic heart failure in recent decades, heart failure patients continue to remain symptomatic, with high hospitalization and mortality rates. A number of novel agents, including endothelin antagonists and tumor-necrosis factor blockers, have recently failed to improve the clinical outcomes of patients with heart failure. Have we reached a ceiling in preventing the progression of the disease? This article reviews successes and late-stage clinical trial disappointments in the treatment of patients with heart failure. Furthermore, the article discusses how agents that have beneficial effects in heart failure also generally attenuate or reverse ventricular remodeling, whereas the newer agents that have failed to improve clinical outcomes either had no effect on remodeling or have been associated with adverse remodeling.

The discovery, isolation and identification of aldosterone: reflections on emerging regulation and function

This paper has a focus on the early history of aldosterone. The Taits take us on a chronological trawl through the history in which they had a first hand role and made a major contribution-their bioassay was in many ways the key. The gifted Swiss chemists made a critical contribution to the scale and isolation of larger amounts. This was international collaboration at its best. Developing technologies were utilised as crucial cutting edge applications in the advancing front, technology transfer before the word was invented. Measurement of aldosterone and angiotensin were crucial advances to the understanding of the regulation of the hormone. In the period 1960-2003, some 30,000 papers mentioned aldosterone as a keyword, even so advances on a larger scale were slow. I have indicated some of my own work with the Howard Florey team using the adrenal autotransplant in the conscious sheep. Recently, the understanding of the role of induced proteins, the flow on from the RALES trial and the development of eplerenone has revitalised the aldosterone field.

Sustained reduction of aldosterone in response to the angiotensin receptor blocker valsartan in patients with chronic heart failure: results from the Valsartan Heart Failure Trial

BACKGROUND

Aldosterone has been implicated in the progression of heart failure. The Valsartan Heart Failure Trial (Val-HeFT) provided the first opportunity to examine the long-term effects of an angiotensin receptor blocker on plasma aldosterone levels in patients with NYHA class II through IV heart failure.

METHODS AND RESULTS

Plasma aldosterone was measured by radioimmunoassay in core laboratories at baseline and during follow-up in patients assigned to valsartan at a target dose of 160 mg twice daily or placebo. In the placebo group, aldosterone (baseline, 150+/-160 pg/mL, mean+/-SD; n=2025) increased at 4, 12, and 24 months. In the valsartan group, aldosterone (baseline, 137+/-124 pg/mL, mean+/-SD; n=2023) decreased at 4 months and remained suppressed for up to 2 years. At end point (last measurement in each patient), mean aldosterone increased by 17.8+/-3.0 pg/mL (SEM) (11.9%) in the placebo group and decreased by 23.8+/-3.0 pg/mL (SEM) (-17.4%) in the valsartan group (P<0.00001). The effect of valsartan was similar in all subgroups, including those receiving neither ACE inhibitors (ACE-I) nor beta-blockers (BB) at baseline and those receiving concomitant ACE-I or BB. In contrast, outcome effects varied in the 4 subgroups, with a statistically significant reduction in the combined mortality/morbidity end point in those receiving neither neurohormonal inhibitor and an adverse trend in those treated with both drugs.

CONCLUSIONS

Valsartan added to background therapy for heart failure produces sustained reduction in plasma aldosterone, consistent with the observed significant reduction in the combined mortality/morbidity end point. A similar reduction in all subgroups based on ACE-I or BB therapy, despite differing clinical outcomes in these subgroups, suggests that aldosterone plasma levels may not be a critical marker of the progression of heart failure.

Pathogenesis of sodium and water retention in edematous disorders

Edema is a collection of fluid within the body's interstitial space which occurs when there is an alteration of the Starling forces which control transfer of fluid from the vascular compartment to surrounding tissue spaces. Generalized edema results when altered Starling forces affect all capillary beds, such as occurs in cardiac failure, cirrhosis, and nephrotic syndrome. Common to these conditions is the development of increased total body sodium and water content. The kidneys play an essential role in the retention of this sodium and water. In this article we shall discuss the signals the kidneys receive for sodium and water retention in these edematous disorders (afferent mechanisms). We shall also examine the means by which the kidney responds to these signals and retains sodium and water (efferent mechanisms). As shall become apparent these edematous states may share many of the same afferent and efferent mechanisms for sodium and water retention.

Long-term treatment of congestive heart failure with captopril

1 The efficacy of the converting-enzyme inhibitor captopril in the management of severe congestive heart failure was assessed in 14 patients over 360-885 days by clinical evaluation, M-mode echocardiography, systolic time intervals, plasma renin activity, and plasma aldosterone. 2 As compared with baseline values, a significant reduction was observed in heart rate, mean arterial pressure, left ventricular end-diastolic and end-systolic diameters, left ventricular pre-ejection period, tension time index, body weight, and plasma aldosterone. Significant increases in left ventricular ejection time and fractional circumferential shortening (p less than 0.01) were also observed. 3 The functional and haemodynamic benefit provided by captopril was therefore sustained during long-term therapy without severe untoward effects or attenuation.

Sustained effectiveness of converting-enzyme inhibition in patients with severe congestive heart failure

Eight patients with severe congestive heart failure refractory to conventional therapy, including vasodilators, were given captopril (seven patients) or teprotide (one patient). All had dyspnea, edema, elevated pulmonary wedge pressure (28.0 +/- 2.6 mm Hg), low cardiac index (1.6 +/- 0.1 liters per minute per square meter), and elevated levels of serum creatinine (2.3 +/- 0.2 mg per deciliter [203.3 +/- 17.7 mumol per liter]), blood urea nitrogen (48 +/- 5 mg per deciliter [17.1 +/- 1.8 mmol of urea per liter]), plasma renin activity (21 +/- 7 ng of angiotensin I per milliliter per hour), plasma angiotensin II (271 +/- 51 pg per milliliter), and plasma aldosterone (65 +/- 14 ng per deciliter). After one week of therapy, all indexes improved. Creatinine and p-aminohippurate clearances were also increased (P less than 0.01). Improvement was sustained (more than six months) and was associated with a statistically significant increase in the cardiac ejection fraction (12 +/- 3 to 26 +/- 7 per cent). With a mean follow-up of seven months, the New York Heart Association Functional Class has been reduced from IV to II, and the number of days of hospitalization to less than 10 per cent of that before captopril therapy. We conclude that captopril reduces afterload in advanced congestive heart failure and induces sustained improvements in clinical status and renal function.

The urinary sodium: potassium ratio and response to diuretics in resistant oedema

Nineteen patients with severe oedema due to either cirrhosis of the liver or to congestive cardiac failure, who had failed to respond to previous diuretic therapy, were treated with either increasing doses of frusemide (Group A), or with frusemide in a fixed dose of 80 mg daily and increasing doses of spironolactone (Group B). In Group A there was an inverse correlation between the baseline 24-hr urinary sodium: potassium (Na : K) ratio and the 24-hr urinary potassium excretion during diuresis, and a direct correlation between the urinary Na : K ratio before and after diuresis. Thus, in patients of this group during diuresis, there was a significantly higher urinary potassium excretion in those with a baseline urinary Na : K ratio of less than 1, as compared with those with a ratio of greater than 1. In Group B a satisfactory diuresis was achieved without marked urinary potassium loss in those patients with a baseline urinary Na : K ratio of less than 1, whereas no diuresis was obtained in the two patients with a baseline urinary Na : K ratio of greater than 1. These results suggest that the measurement of the baseline urinary Na : K ratio is of help in determining the potential value of spironolactone in patients with resistant oedema.

George C. Griffith lecture. The role of renin in normal and pathological cardiovascular homeostasis

Recently, the availability of a number of specific inhibitors of the renin-angiotensin system has made it possible to address certain critical questions concerning the role of angiotensin II in physiologic homeostasis and in a number of pathologic states. These studies indicate that angiotensin II does not have an obligatory role in blood pressure maintenance in the normal, sodium replete individual, but it is essential following sodium depletion. The role of angiotensin II in feedback control of renin secretion is confirmed as is its importance in aldosterone stimulation both in relation to posture and sodium depletion. Angiotensin II is responsible for the initial pressor response of experimental renovascular hypertension and appears to be important in the initiation of chronic renovascular hypertension. Converting enzyme blockers and competitive inhibitors of angiotensin II are helpful in the diagnosis of clinical renovascular hypertension and in the identification of renin dependent hypertensives. Homeostatic mechanisms leading to maintenance of blood pressure and accumulation of edema in experimental congestive heart failure appear to be dependent on angiotensin II.

Renal consequences of valvular heart disease

Three aspects of potential renal involvement in patients with valvular heart disease are discussed. These include (1) disturbances in renal salt and water handling and their implications with respect to diuretic management; (2) the hemodynamic effects of angiographic contrast agents with identification of potentially dangerous effects on the kidneys; and (3) the histologic patterns of bacterial endocarditis in the kidney and their similarity to those of immunologically mediated disease.

Intrarenal blood flow in congestive heart failure

Intrarenal blood flow distribution was measured by the 133 xenon washout technic in 10 patients with heart disease who were studied at time of left and right heart catheterization. Renal washout curves were analyzed by computer using a weighted least-squares nonlinear regression technic. In three patients with heart disease without edema the compartment I blood flow rates (outer cortex) were not significantly different from those found in nine normal kidney donors. In seven patients with hemodynamic evidence of heart failure and clinical edema the compartment I flow rates were significantly lower than those of the normal control group and of a group of sodium-depleted hypertensive patients. The rate constants of isotope removal from more central regions of the kidney (compartments II and III) were not depressed to a similar degree. Infusion of furosemide into the renal artery induced diuresis in eight studies which was accompained by preferential increases in compartment I flow rates in six. The data suggest that preferential vasoconstriction of renal cortical vessels may contribute to increased sodium retention by the kidneys and to edema formation in patients with congestive heart failure.

Plasma renin in chronic experimental heart failure and during renal sodium "escape" from mineralocorticoids

A striking increase in the plasma renin level occurred in dogs with low output right heart failure secondary to tricuspid insufficiency and pulmonic stenosis and in three of five animals with high output failure produced by a large arteriovenous fistula. When dogs with a small arteriovenous fistula were given daily injections of DOCA, the renal sodium "escape" phenomenon occurred. In these animals, the level of plasma renin was suppressed during DOCA administration both during the initial period of sodium retention and also later when sodium balance was normal or negative. In contrast, when dogs with a larger arteriovenous fistula but without evidence of cardiac failure were given DOCA, they retained sodium and developed signs of congestive heart failure. However, in these animals with congestion and ascites, in contrast to the dogs that developed spontaneous high output failure, the plasma renin was low. Renin-substrate was unaltered in all of the experimental situations studied except for the decrease observed in dogs with low output right heart failure. In these animals, it seems likely that decreased renin-substrate was secondary to hepatic congestion and liver damage. The renin-angiotensin system does not seem to be related to the "escape" phenomenon, and renin does not appear to be the factor that makes the kidney unusually responsive to mineralocorticoids. Thus, in experimental heart failure the renin-angiotensin system was activated, but in the congestive syndrome produced by DOCA the plasma renin level was suppressed.

Steroids Produced in Vitro by Adrenal Glands of Normal and Arteriosclerotic Rats During and After Drug-Induced Myocardial Necrosis

The subcutaneous injection of the potent catecholamine, isoproterenol, on two consecutive days causes active and massive myocardial necrosis in rats. Infarctoid myocardial necrosis was produced in male and female virgin rats free of arterial disease, in male breeder rats which have microscopic arteriosclerosis only, and in female breeder rats having early or advanced gross arteriosclerosis. During the active development of myocardial necrosis and heart failure, an apparent shift in distribution of body fluid produced systemic dehydration, pulmonary edema, and hydrothorax. Animals which survived the myocardial destruction showed gradual reduction of the congestive heart failure and beginning myocardial repair. Virgin animals with no pre-existing arterial disease developed more severe signs of shock and congestive heart failure than breeder rats with pre-existing arteriosclerosis.

In vitro estimation of the adrenal steroids produced by the animals with myocardial necrosis indicated intense in vivo stimulation of adrenocorticoid production coincident with the increasing severity of the myocardial necrosis. Steroid production returned to normal during progressive myocardial repair. Virgin rats showed a very prompt adrenal response to the stress of myocardial destruction but breeder rats, which also have pre-existing reduced adrenal function, showed a lag in the response of their adrenal glands. Chemical and histological analyses of the adrenal glands indicated a pronounced increase of aldoster-one production during the experiment, this increase being associated with loss of fluid and electrolytes from the vascular space. The production of aldosterone appears to be vital to the physiological adjustments needed by these animals during heart failure because the production of aldosterone seems to occur at the expense of the other adrenal steroids, e.g., corticosterone, 18-hydroxy-deoxycorticoster-one and total steroid. These comparative studies suggest that adrenal responsiveness during the stress of myocardial infarctoid necrosis is quantitatively different in animals free of previous arterial disease from that found in animals with pre-existing microscopic or grossly visible arteriosclerosis. The specific kind and the amount of adrenal steroid produced during myocardial destruction may be of vital importance for survival.