Combination of loop diuretics with thiazide-type diuretics in heart failure

Volume overload is an important clinical target in heart failure management, typically addressed using loop diuretics. An important and challenging subset of heart failure patients exhibit fluid overload despite significant doses of loop diuretics. One approach to overcome loop diuretic resistance is the addition of a thiazide-type diuretic to produce diuretic synergy via "sequential nephron blockade," first described more than 40 years ago. Although potentially able to induce diuresis in patients otherwise resistant to high doses of loop diuretics, this strategy has not been subjected to large-scale clinical trials to establish safety and clinical efficacy. We summarize the existing literature evaluating the combination of loop and thiazide diuretics in patients with heart failure in order to describe the possible benefits and hazards associated with this therapy. Combination diuretic therapy using any of several thiazide-type diuretics can more than double daily urine sodium excretion to induce weight loss and edema resolution, at the risk of inducing severe hypokalemia in addition to hyponatremia, hypotension, and worsening renal function. We provide considerations about prudent use of this therapy and review potential misconceptions about this long-used diuretic approach. Finally, we seek to highlight the need for pragmatic clinical trials for this commonly used therapy.     

Congestive heart failure in hypertensive patients with normal systolic function and dynamic left ventricular outflow obstruction

BACKGROUND: Hypertensive patients with left ventricular hypertrophy and normal systolic function can develop congestive heart failure refractory to conventional drug therapy with digoxin, diuretic, and vasodilators. METHODS: We studied 8 patients with a history of systemic hypertension (6 females and 2 males, mean age 69+/-6 years), affected by New York Heart Association (NYHA) class IV congestive heart failure notwithstanding conventional drug therapy with digoxin, diuretic, and vasodilators. After clinical history and physical examination, blood chemistry including cardiac enzymes, arterial blood gases, chest roentgenogram, standard 12-lead ECG, and complete echocardiographic study were performed in all patients. RESULTS: In all cases, a left ventricle with increased wall thickness, normal cavity size, and normal or supernormal systolic function was shown. All patients had left ventricular systolic dynamic obstruction, with peak gradient between 36 and 130 mmHg (mean 83+/-31). After having stopped treatment with nitrates, digoxin, and diuretics, drug therapy with calcium channel antagonists or beta-blockers was started, and rapid clinical improvement with disappearance of left ventricular outflow obstruction was observed. CONCLUSIONS: Sometimes, a distinction between several forms of heart failure is clinically impossible. However, when conventional therapy is not effective in patients with longstanding history of systemic hypertension and ECG signs of left ventricular hypertrophy, diastolic heart failure and/or dynamic left ventricular obstruction should be suspected. Thus, an early echocardiographic study should be performed.     

Diuretic therapy in congestive heart failure

The principal goals of treatment of the patient in heart failure are the relief of their symptoms and improvement in their prognosis. Of all antiheart failure drugs currently available, the diuretics are therapeutically superior in their efficacy in relieving clinical symptoms and signs. Whether administered intravenously or orally, all diuretics result in a substantial reduction in the raised pulmonary vascular pressures in combination with a small reduction in cardiac output. Diuretics stimulate release of renin with subsequent activation of the renin-angiotensin-aldosterone system, particularly if used in large doses, although their quantitative impact on the neuroendocrine profile at different stages of heart failure remains to be defined. In patients with mild heart failure, diuretics reduce plasma catecholamine concentrations, but their sympatholytic effects in more severe cases are unknown, as are their effects on the metabolically active tissues in these patients. Diuretic resistance can be circumvented by segmental nephron blockade with a combination of low-dose diuretics that simultaneously block sodium reabsorption in the proximal tubule, the loop of Henle, the distal tubule, and the collecting duct. Diuretics improve symptoms of breathlessness and signs of peripheral edema in patients with congestive heart failure in direct relationship to the induced diuresis. These benefits are frequently associated with a substantial improvement in patients' appreciation of quality of life and economic capacity. There are few adverse reactions to chronic diuretic therapy, but the serum electrolytes should be monitored for hypokalemia and hypomagnesemia. The impact of diuretics on prognosis of patients with congestive heart failure is unknown; however, diuretics have been a major ingredient of the therapies used in all the survival trials with vasodilators, angiotensin-converting enzyme inhibitors, and beta-blocking drugs. In addition to their clinical benefits, diuretics are the most cost-effective treatment of any single drug group currently available for the treatment of patients with congestive heart failure.     

Treatment of heart failure in older persons. Dilemmas with coexisting conditions: diabetes mellitus,chronic obstructive pulmonary disease,and arthritis

Diabetes mellitus is a risk factor for congestive heart failure. Diabetics with congestive heart failure should have good glycemic control, treatment of hypertension and dyslipidemia, and treatment with diuretics, angiotensin-converting enzyme inhibitors, and beta blockers as well as digoxin, if the left ventricular ejection fraction is abnormal. Patients with chronic obstructive pulmonary disease may have left ventricular failure because of a coexistent cardiac disorder or right ventricular failure from pulmonary hypertension. An acute respiratory tract infection may precipitate right ventricular failure and should be treated. Alveolar hypoxia should be corrected by improving alveolar ventilation through relieving airflow obstruction with bronchodilators and by increasing inspired oxygen concentration. Loop diuretics should be used cautiously. Beta blockers may be given to patients with chronic obstructive pulmonary disease and left ventricular failure if bronchospasm is not present. Angiotensin-converting enzyme inhibitors should be used to treat left ventricular failure. Digitalis should not be used in patients with right ventricular failure due to chronic obstructive pulmonary disease. Nonsteroidal anti-inflammatory drugs are contraindicated in patients with congestive heart failure. There are controversial data about the negative interaction between aspirin and angiotensin-converting enzyme inhibitors in patients with congestive heart failure. Patients with arthritis and congestive heart failure needing large doses of aspirin for pain relief may be treated instead with acetaminophen, tramadol, or Percocet if necessary for chronic severe pain.     

Effect of diuretics on cardiopulmonary performance in severe chronic airflow obstruction. A controlled clinical trial

In a randomized, controlled trial, ten patients with pulmonary heart disease due to severe chronic airflow obstruction were stratified into two groups: group 1 had clinical features of congestive heart failure during respiratory failure and were regularly receiving diuretics; group 2 had no such clinical features and were not receiving diuretics. In group 1, when placebo was substituted for diuretics, pulmonary edema developed in three patients; exercise performance and ventricular function of the remaining two patients deteriorated. In group 2, there was no difference in exercise tolerance or ventricular function between placebo and diuretic therapy. The clinical deterioration in group 1 was related to abnormal left ventricular function. Thus, diuretics benefit only patients who have clinical features of congestive heart failure. In patients with isolated abnormal right ventricular function, diuretics may be harmful.     

Diuretic therapy in congestive heart failure

Diuretics are a mainstay of therapy in patients with congestive heart failure. A small number of patients can achieve adequate diuresis with a thiazide diuretic alone, but most require a loop diuretic. Some patients with severe disease require combinations of diuretics. Most patients with congestive heart failure manifest resistance to diuretics by having a diminished natriuresis compared with healthy counterparts. This diminished response even to potent diuretics means that dietary sodium may exceed sodium excretion, resulting in patient decompensation. The pharmacokinetics and pharmacodynamics of loop diuretics have been characterized in patients with congestive heart failure, thereby allowing rational therapeutic strategies in terms of what type of doses should be administered, how often, and when to use diuretic combinations. The purpose of this review is to show how understanding pharmacokinetics and pharmacodynamics results in logical diuretic use. (c)2000 by CHF, Inc.     

The increase in serum uric acid concentration caused by diuretics might be beneficial in heart failure

Patients with mild-moderate chronic heart failure (CHF) often have raised levels of serum uric acid (UA). This is due, amongst other factors, to reduced UA excretion by the kidneys, which is partly explained by restriction of sodium intake and treatment with diuretics. The decline in renal function that parallels worsening cardiac function also contributes to elevated serum UA in patients with advanced CHF. However, UA production also appears to be augmented in CHF. Because UA scavenges various reactive oxygen species, diuretic-induced elevations in serum UA could be beneficial in patients with CHF. This concept is supported by the superior performance of antihypertensive therapy with diuretics in preventing heart failure. The present hypothesis may be tested by examining the effects of add-on treatment with a thiazide-type diuretic on morbidity and mortality, or surrogate variables, in asymptomatic patients with left ventricular dysfunction but without fluid retention.     

Pharmacotherapy in congestive heart failure: drug absorption in the management of congestive heart failure: loop diuretics

Congestive heart failure is a disease state distinguished by the regular presence of both renal and hepatic abnormalities in drug handling. One such abnormality involves flaws in the process of drug absorption. In most instances, congestive heart failure-related abnormalities in drug absorption are of inconsequential significance. However, this is not the case with loop diuretics. Loop diuretic action ordinarily tracks the rate and extent of absorption if a sufficient amount of diuretic has been given to exceed the threshold for diuretic effect. In congestive heart failure, both the rate and absolute amount of loop diuretic absorbed can be reduced as a function of the heart failure state itself. In this setting, drug dissolution characteristics can assume added significance. Furosemide is the loop diuretic with the widest intra- and interpatient variability of absorption. Alternatively, the loop diuretic torsemide is rapidly and fairly completely absorbed independent of the heart failure state. This pattern of absorption establishes it as the preferred loop diuretic in the otherwise diuretic-resistant heart failure patient. However, the exact role of torsemide in the outpatient management of congestive heart failure remains to be determined.     

Loop diuretics versus others in the treatment of congestive heart failure after myocardial infarction

Summary Most frequently, diuretic therapy in congestive heart failure has as its main objective ridding the lungs of water. The work of the muscles of external respiration is thus decreased, the fraction of cardiac output that is distributed to vascular beds other than that of the respiratory muscles is consequently increased, and the functional and clinical condition of the patient improves. Diuretic therapy does not change cardiac output significantly in most cases; in some circumstances diuretic therapy may increase cardiac output in a clinically relevant fashion, and in some other cases diuretic therapy may lower cardiac output to the extent of impairing the overall functional situation. The dose of diuretics should be the minimal compatible with the prosecution of the main clinical objective (class betterment), to minimize possible increases in the afterload to the left ventricle (intravenous administration), to minimize hemodynamically detrimental decreases in the preload, and to minimize the likelihood of development or the severity of undesired changes in plasma biochemistry (hyponatremia, hypokalemia, hypomagnesemia, hyperuricemia, etc.). Loop diuretics are preferred shortly after myocardial infarction, given the ample dose-effect range of these substances and their relatively benign effect on renal blood flow. During chronic therapy, loop diuretics at low doses may be tried first, and the dose may be increased if necessary, provided higher doses do not cause symptomatic falls in cardiac output through the striking renal excretory response that these drugs elicit shortly after dosing. Thiazide-type drugs should be used if the brisk diuresis induced by loop diuretics causes a symptomatic fall in cardiac output and/or when it is necessary that once-daily (oral) diuretic therapy exert a highly potent 24-hour natriuretic action.     

Pharmacotherapy in congestive heart failure: diuretic resistance and strategies to overcome resistance in patients with congestive heart failure

Congestive heart failure is a complex clinical hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Although the overall impact of diuretic therapy on congestive heart failure mortality remains unknown, diuretics remain a vital component of symptomatic congestive heart failure management. Over time, sodium and water excretion are equalized before adequate fluid elimination occurs. This phenomenon is thought to occur in one out of three patients with congestive heart failure on diuretic therapy and is termed diuretic resistance. In congestive heart failure, both pharmacokinetic and pharmacodynamic alterations are thought to be responsible for diuretic resistance. Due to disease chronicity, symptomatic management is vital to improved quality of life and enhancing diuretic response is therefore pivotal.     

Diuretics in therapy of "diuretic resistance" by patients with congestive heart failure

Loop diuretics are integral part of overall therapy of severe congestive heart failure. Approximately 10-20 % of patients with congestive heart failure (NYHA class III-IV) do not respond satisfactorily to diuretic treatment. Despite its frequency, the term "diuretic resistance" remains inadequately defined. In general, failure to decrease the extracellular fluid volume despite liberal use of diuretics is often termed "diuretic resistance". The combination of diuretics, particularly of loop diuretic with thiazide agents, is recommended for prevention as well as treatment of this complication. Effective management is also continuous infusion of loop diuretic. If it is impossible to achieve adequate response by combination of diuretics, increasing of its dosage or/and frequency or continuous infusion, then dialysis methods may be employed (however it is not intended to discuss this option in this article).     

Loop diuretics block calcium currents in cardiac cells.

Loop diuretics are widely used drugs; serving to alleviate congestive heart failure and hypertension. Their mechanism of action is considered to be an inhibition of sodium retention in the kidneys, by a block of the Na/K/Cl cotransporter. The ensuing natriuresis and diuresis reduces blood pressure and alleviates congestive heart failure. Several earlier reports suggested direct cardiovascular effects, partly preceding the onset of diuresis. In the present study, evidence is presented for a direct action of two loop diuretic agents, bumetanide and furosemide, on cardiac L-type calcium currents in rabbit ventricular and atrial myocytes. This current is reversibly reduced by micromolar concentrations of these drugs. The onset of this effect can be observed within 1-2s, which could indicate a direct action on the calcium channel, independent of secondary effects subsequent to inhibition of the cotransporter. Thus, part of the therapeutic effects of the loop diuretics may be achieved through a direct reduction of cardiac output.     

Preliminary report of tolvaptan treatment in Japanese patients with heart failure

While diuretic drugs are commonly used in patients with congestive heart failure, the efficacy of their long-term use still remains controversial. Recently, a new class of diuretics, vasopressin receptor 2 antagonists, has been launched, and tolvaptan is one such drug. We describe our initial experience with this novel agent. Tolvaptan is potentially useful for treatment of heart failure patients with fluid overload who are refractory to conventional diuretic therapies.     

Diuretic use in renal disease

Diuretics are agents commonly used in diseases characterized by excess extracellular fluid, including chronic kidney disease, the nephrotic syndrome, cirrhosis and heart failure. Multiple diuretic classes, including thiazide-type diuretics, loop diuretics and K(+)-sparing diuretics, are used to treat patients with these diseases, either individually or as combination therapies. An understanding of what determines a patient's response to a diuretic is a prerequisite to the correct use of these drugs. The response of patients with these diseases to diuretics, which is related to the dose, is best described by a sigmoid curve whose contour can become distorted by any of the several sodium-retaining states that are directly or indirectly associated with renal disease. Diuretic actions are of considerable importance to patients who have renal disease, as their effective use assists in extracellular fluid volume control, reducing excretion of protein in urine and lessening the risk of developing hyperkalemia. Diuretic-related adverse events that involve the uric acid, Na(+) and K(+) axes are not uncommon; therefore the clinician must be vigilant in looking for biochemical disturbances. As a result of diuretic-related adverse events, clinicians must be resourceful in the dose amount and frequency of dosing.     

The immediate effect of mercurial diuretics on the vital capacity of the lungs

In a group of nine patients with congestive heart failure in whom breathlessness was an outstanding symptom, the immediate effect of a mercury diuretic on the respiratory mechanism was studied. It was found that the average increase in the vital capacity of the lungs twenty-four hours after the injection was 290 c.c. This was accompanied by a prompt improvement in the subjective symptom of respiratory distress and a decrease in the signs of pulmonary congestion.It is emphasized that the mercury diuretics have a decidedly beneficial effect in cardiac patients with dyspnea, even in those cases in which there is no peripheral pitting edema.     

The aldosterone antagonist and facultative diuretic eplerenone: A critical review

Eplerenone is a new aldosterone-receptor blocker that differs from spironolactone by virtue of higher selectivity for the aldosterone receptor. Therefore, eplerenone treatment is associated with comparative and absolute low incidences of gynecomastia, mastodynia, and abnormal vaginal bleeding. Similarly, a lower incidence of sexual impotence than that associated with spironolactone administration may be anticipated. Eplerenone and spironolactone increase natriuresis and cause renal retention of potassium when plasma aldosterone is high, i.e., both agents are facultative diuretics. Eplerenone reduces high blood pressure effectively. The results of a recent large study and an ensuing meta-analysis on antihypertensive treatment suggest that a diuretic should be the first-choice agent in most circumstances. Low-dose eplerenone combinations with a low-dose thiazide-type diuretic appear to be options worth investigating, since the overall cardiovascular benefit brought about by reducing blood pressure with the thiazide would be increased, inter alia, by the antikaliuretic action and by the blockade of extrarenal aldosterone receptors provoked by eplerenone. Eplerenone should replace spironolactone as a natriuretic and antikaliuretic in heart failure and as add-on treatment in severe systolic cardiac insufficiency, and it is indicated after an acute myocardial infarction complicated by left ventricular dysfunction and heart failure. The finding that hypertension control with diuretic-based pharmacotherapy results in better prevention of heart failure than pressure reduction with other drugs makes it pertinent to investigate whether diuretics in general, and eplerenone in particular, should constitute part of the initial pharmacotherapy for heart failure when there is no overt fluid retention and independent of the etiology. Eplerenone may cause hyperkalemia, and it might favor the development of metabolic acidosis or hyponatraemia in some circumstances.     

The aldosterone antagonist and facultative diuretic eplerenone: a critical review

Eplerenone is a new aldosterone-receptor blocker that differs from spironolactone by virtue of higher selectivity for the aldosterone receptor. Therefore, eplerenone treatment is associated with comparative and absolute low incidences of gynecomastia, mastodynia, and abnormal vaginal bleeding. Similarly, a lower incidence of sexual impotence than that associated with spironolactone administration may be anticipated. Eplerenone and spironolactone increase natriuresis and cause renal retention of potassium when plasma aldosterone is high, i.e., both agents are facultative diuretics. Eplerenone reduces high blood pressure effectively. The results of a recent large study and an ensuing meta-analysis on antihypertensive treatment suggest that a diuretic should be the first-choice agent in most circumstances. Low-dose eplerenone combinations with a low-dose thiazide-type diuretic appear to be options worth investigating, since the overall cardiovascular benefit brought about by reducing blood pressure with the thiazide would be increased, inter alia, by the antikaliuretic action and by the blockade of extrarenal aldosterone receptors provoked by eplerenone. Eplerenone should replace spironolactone as a natriuretic and antikaliuretic in heart failure and as add-on treatment in severe systolic cardiac insufficiency, and it is indicated after an acute myocardial infarction complicated by left ventricular dysfunction and heart failure. The finding that hypertension control with diuretic-based pharmacotherapy results in better prevention of heart failure than pressure reduction with other drugs makes it pertinent to investigate whether diuretics in general, and eplerenone in particular, should constitute part of the initial pharmacotherapy for heart failure when there is no overt fluid retention and independent of the etiology. Eplerenone may cause hyperkalemia, and it might favor the development of metabolic acidosis or hyponatraemia in some circumstances.     

Therapy of dilated cardiomyopathy with digitalis, diuretics and vasodilators

The treatment of dilated cardiomyopathy is primarily concerned with that of congestive heart failure. Digitalis is widely use in dilated cardiomyopathy but an improvement in the prognosis has not yet been demonstrated. Furthermore, the effects of digitalis in patients with sinus rhythm are debatable. If dilated cardiomyopathy induces atrial fibrillation and tachyarrhythmia, digitalis should be used. Diuretics are helpful in the treatment of congestive heart failure associated with dilated cardiomyopathy. By reducing hypervolemia and by venous dilatation, diuretics lower preload and afterload. This leads to relief of congestion and termination of the vicious cycle of congestive heart failure. Accordingly, the prognosis of dilated cardiomyopathy might be improved by diuretics. There are numerous diuretics acting differently on the renal tubules, the choice of which depends on the renal function and serum electrolyte concentrations. Reduction of preload and afterload improves congestive heart failure as has been demonstrated repeatedly. Many substances have therefore been used for arterial and venous dilation with differing results. At least for short-term periods, congestion is reduced and cardiac output increases. Especially inhibitors of angiotensin II converting enzyme are very effective since they act both in the arterial and venous systems. Additionally, inhibition of the action of angiotensin may be regarded as causal therapy since the renin-angiotensin system is the trigger for vasoconstriction and fluid retention in congestive heart failure. Unlike other substances, ACE inhibitors have been demonstrated to improve prognosis of patients with congestive heart failure. At present, combined diuretic therapy and angiotensin conversion enzyme inhibition would seem the most reasonable treatment for patients with dilated cardiomyopathy and sinus rhythm. If atrial fibrillation and tachyarrhythmia develop, additional digitalis therapy is effective.     

Aldosterone and magnesium

Magnesium ion (Mg) directly inhibits aldosterone production in rat adrenal glomerulosa cells, while potassium ion directly stimulates aldosterone production. It is reported that Mg shows antihypertensive effect in patients with essential hypertension. Secondary hyperaldosteronism induced by diuretic treatment in patients with congestive heart failure accelerates potassium and magnesium ions' excretion in urine. Diuretic-induced falls in potassium and magnesium ions and aldosterone-induced cardiac fibrosis and remodelling are associated with fatal ventricular arrhythmia. Aldosterone antagonists, such as spironolactone and eplerenone, correct not only potassium deficiency but also magnesium deficiency induced by diuretics. Mg supplementation also may be useful procedure to correct potassium and magnesium deficiency, because Mg itself inhibits aldosterone release from the adrenal glands.     

The use of digitalis for the treatment of congestive heart failure: A tale of its decline and resurrection

Summary The decline of the use of digitalis for the treatment of congestive heart failure was due to the introduction of oral diuretic therapy, the recognition of the frequency of digitalis induced arrhythmias and the uncontrolled observations that digitalis could frequently be withdrawn from patients with a history of heart failure without recurrence of heart failure. Subsequently, it has been well documented that digitalis has chronic beneficial hemodynamic effects in patients with chronic congestive heart failure. Moreover, digitalis has been shown to improve hemodynamics when added to other drugs including diuretics, ACE inhibitors and vasodilators. It is concluded that digitalis is a mild inotropic agent that is still a primary drug for the treatment of mild to moderate acute or chronic left ventricular failure.