Attenuation of the pressor response to intravenous furosemide by angiotensin converting enzyme inhibition in congestive heart failure

Flexible diuretic titration in chronic heart failure: where is the evidence?

BACKGROUND

Several sets of heart failure (HF) consensus/guideline statements support the use of a flexible diuretic dosing regimen for HF outpatient management of fluid overload-related signs and symptoms. However, despite the widespread acceptance of such an approach, the evidence supporting the effectiveness of this approach in improving clinical outcomes is unknown. The primary objective of this manuscript was to summarize and review the evidence supporting the use of a flexible diuretic regimen in the management of outpatient heart failure patients.

METHODS AND RESULTS

A systematic review was performed, and 9 studies were identified relevant to the question of flexible diuretic titration in the setting of chronic heart failure. Among the 9 studies, 5 were randomized. Three of the randomized trials included flexible diuretic titration as part of a broader multifaceted disease management program, and only 2 were designed to specifically evaluate the sole contribution of flexible diuretic titration. Collectively, data from all of the studies reviewed supported the idea that flexible and individualized diuretic dosing is potentially associated with reduced emergency room visits, reduced rehospitalization, and improved quality of life in HF patients with reduced ejection fraction.

CONCLUSIONS

To date, only 2 randomized clinical studies were identified that were designed to determine the effects of a flexible diuretic dosing regimen in outpatient HF patients with reduced ejection fraction. Data are lacking in HF patients with preserved ejection fraction. There is a critical need to test this strategy in well designed prospective randomized clinical trials.

Renal effects of conivaptan, furosemide, and the combination in patients with chronic heart failure

BACKGROUND

Loop diuretics, though often effective for treating congestion, have significant limitations. Discovering ways to limit exposure to loop diuretics while achieving effective decongestion is an important goal of current clinical research in heart failure (HF). Vasopressin antagonists are effective in removing large amounts of water, but not salt, in HF. Few data exist about the detailed renal and hormonal effects of these agents compared with or in combination with loop diuretics. This study investigated the renal and neurohormonal effects of loop diuretics, the mixed vasopressin antagonist conivaptan, and the combination in patients with chronic stable HF.

METHODS AND RESULTS

In 8 patients with chronic stable HF on standard medical treatment, heart rate, arterial pressure, systemic vascular resistance, and cardiac output (the latter 2 by using impedance cardiography), as well as glomerular filtration rate (iothalamate clearance), renal blood flow (para-aminohippurate clearance), urinary volumes and urinary sodium, plasma catecholamines, renin activity, arginine vasopressin, and B-type natriuretic peptide were assessed before and at hourly intervals for 4 hours after receiving furosemide, conivaptan, or the combination on 3 different study days at a minimum of 1-week intervals. There were no significant effects of conivaptan, furosemide, or the combination on any hemodynamic variable, neurohormonal level, renal blood flow, or glomerular filtration rate. Conivaptan and furosemide similarly increased urine volumes; the effect of the combination was significantly greater. Furosemide, but not conivaptan, increased urinary sodium excretion, and the combination was significantly greater than after furosemide alone.

CONCLUSIONS

Without adversely affecting important hemodynamic variables, neurohormones, renal blood flow, or glomerular filtration rate, conivaptan significantly augmented both the diuretic and the natriuretic response to furosemide in patients with chronic HF. These results may have implications for the design of furosemide-sparing regimens in the treatment of acute HF.

The effects of adding torasemide to standard therapy on peak oxygen consumption, natriuretic peptides, and quality of life in patients with compensated left ventricular systolic dysfunction

AIMS

Diuretics, when used to treat congestion in patients with chronic heart failure, improve symptoms and, perhaps, prognosis but little information is available to guide their use in patients with left ventricular systolic dysfunction (LVSD) who are not congested. Chronic diuretic therapy causes persistent and potentially harmful neuroendocrine activation. Alternatively, in patients in whom neuroendocrine activation is blocked with angiotensin-converting enzyme (ACE)-inhibitors and beta-blockers, diuretics may be beneficial by decreasing preload and afterload and preventing congestion. We aimed to assess the effect of the loop diuretic, torasemide on quality of life, and surrogate markers of prognosis when given to patients with LVSD who were not clinically congested and who were optimally treated with ACE-inhibitors (or angiotensin receptor antagonists) and beta-blockers.

METHODS AND RESULTS

Thirty patients with stable LVSD who had no clinically detectable fluid overload were randomized to receive either torasemide 5 mg daily or placebo for 3 months (Phase A), and after a washout phase of 2 months, cross-over was performed for 3 months (Phase B). Diuretic therapy did not cause significant change in peak VO(2), mean N-terminal pro-hormone brain natriuretic peptide (NT-proBNP) levels, or measures of quality of life compared with placebo. Diuretic therapy did however lead to significant fall in systolic and diastolic blood pressures and increase in plasma renin levels compared with placebo.

CONCLUSION

Diuretic therapy with torasemide is not superior to placebo in improving peak VO(2) or reducing NT-proBNP levels in patients with left ventricular dysfunction who are not clinically congested.

Novel strategies: challenge loop diuretics and sodium management in heart failure--Part I

This is the first of a 2-part series. This article reviews the relationships among diuretics, neurohormonal activation, renal function, fluid and Na management, the cardiorenal syndrome, and heart failure. Part II will describe novel therapies based on these relationships, focusing particularly on vasopressin antagonists and treatment using hypertonic saline solution with high-dose loop diuretics. Heart failure (HF) is a complex hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Diuretics are a vital component of symptomatic management, and enhancing diuretic response in the setting of diuretic resistance is therefore pivotal. In HF patients treated with diuretics, compensatory pathophysiologic mechanisms to maintain vascular resistance, such as nonosmotic stimulation of vasopressin secretion and activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, promote renal Na and water reabsorption. Thus, there remains a need to develop novel therapies for HF patients who are refractory to conventional medical treatment. The conflicting results of diuretic treatments in HF and the importance of Na management in the context of the cardiorenal syndrome and neurohormonal activation have suggested novel and counterintuitive strategies, focusing primarily on the use of vasopressin antagonists and hypertonic saline solution with high doses of loop diuretics and neurohormonal interference. The authors review the current evidence for these therapies and suggest hypothetical bases for their efficacy.

Treating hyponatremia in heart failure

Hyponatremia is common and associated with adverse outcomes in patients with congestive heart failure (CHF). In many patients who have CHF with hyponatremia, plasma arginine vasopressin (AVP) is elevated inappropriately. AVP causes water retention by interacting with V2 receptors in the renal collecting duct, leading to dilutional hyponatremia and increased ventricular preload. AVP also may contribute to pathophysiologic process in CHF by interacting with V(IA) receptors on vascular smooth muscle cells and myocytes. The potential utility of AVP antagonists--V2 antagonists and dual V(IA)/V2 antagonists--in correcting hyponatremia and relieving the congestion and edema associated with CHF is being actively explored. Combined antagonists may offer additional benefit by interfering with excessive V(IA) signaling. Unlike diuretics, which increase urine volume and electrolyte excretion, AVP antagonists of these types produce an aquaresis characterized by an increase in free water clearance concomitant with sparing of electrolytes. Studies in experimental CHF as well as preliminary clinical trials with selective and nonselective V2 antagonists have been encouraging, suggesting that these agents may hold promise for treatment of hyponatremia in CHF.

Diuretic usage in heart failure: a continuing conundrum in 2005

Several large well-designed clinical trials have shown that the use of diuretics is beneficial in patients with hypertension. However, similarly robust data regarding their role in chronic heart failure are lacking. Historically, diuretics were developed for treatment of sodium and water retention in oedematous disorders and clinically, they remain the most potent drugs available to relieve symptoms and eliminate oedema in the congested patient with heart failure. In the non-congested patient, however, diuretics continue to be used on a purely clinical basis without sufficient characterization of benefits, adverse effects, and potential influence on mortality. There are also concerns that chronic diuretic usage can cause adverse vascular effects, unfavourable neuroendocrine activation, electrolyte imbalances, and life-threatening arrhythmias. In this article, we review the limited evidence available regarding the benefits and perils of using diuretics in heart failure.

Brain natriuretic peptide enhances renal actions of furosemide and suppresses furosemide-induced aldosterone activation in experimental heart failure

BACKGROUND

The renal actions of brain natriuretic peptide (BNP) in congestive heart failure (CHF) are associated with increased diuresis and natriuresis, preserved glomerular filtration rate (GFR), and lack of activation of the renin-angiotensin-aldosterone system (RAAS). In contrast, diuretic-induced natriuresis may be associated with reduced GFR and RAAS activation. The objective of this study was to test the hypothesis that exogenous BNP enhances the renal diuretic and natriuretic actions of furosemide (Fs) and retards the activation of aldosterone in a model of CHF.

METHODS AND RESULTS

CHF was produced in 2 groups of dogs by ventricular pacing. One group received continuous (90-minute) intravenous Fs (1 mg x kg(-1) x h(-1)). A second group (Fs+BNP) received 45-minute intravenous coinfusion of Fs (1 mg x kg(-1) x h(-1)) and low-dose (2 pmol x kg(-1) x min(-1)) BNP followed by 45-minute coinfusion of Fs (1 mg x kg(-1) x h(-1)) and high-dose (10 pmol x kg(-1) x min(-1)) BNP. Fs increased urinary flow, but the effect of Fs+BNP was greater. Similarly, urinary sodium excretion was higher in the Fs+BNP group. Although GFR tended to decrease in the Fs group, it increased in the Fs+BNP group (35+/-3 to 56+/-4*) (* indicates P<0.05 versus baseline) (P<0.0001 between groups). Plasma aldosterone increased with Fs (41+/-10 to 100+/-11* ng/dL) but was attenuated in the Fs+BNP group (44+/-11 to 54+/-9 ng/dL low-dose and to 47+/-7 ng/dL high-dose) (P=0.0007 between groups).

CONCLUSIONS

Fs+BNP has more profound diuretic and natriuretic responses than Fs alone and also increases GFR without activation of aldosterone. Coadministration of BNP and loop diuretic is effective in maximizing natriuresis and diuresis while preserving renal function and inhibiting activation of aldosterone.

Current and newer approaches in the drug treatment of congestive heart failure

Most patients with chronic congestive heart failure (CHF) are subjected to symptomatic treatment, predominantly with drugs. Over the years, it has become clear that treatment with unloading drugs is probably more beneficial than treatment with inotropic agents. In addition, it has been widely recognized that the neuroendocrine compensatory changes associated with CHF afford and important target for drug treatment. This may also hold for some of the changes in receptor density, such as the downregulation of cardiac beta-adrenoceptors. The present and clearly changing insights into the backgrounds of drugs for the treatment of CHF are critically discussed. Apart from the changing views and appreciation of the currently used drugs (diuretics, ACE inhibitors, digoxin, beta-adrenoceptor agonists), the following new approaches are discussed: beta-blockers, angiotensin II receptor antagonists, ibopamine, calcium antagonists, inhibitors of ANP degradation, vasopression antagonist, vesnarinone, and calcium sensitizers.

Furosemide elicits immediate sympathoexcitation via a renal mechanism independent of angiotensin II

This investigation aimed at examing the hypothesis that furosemide elicits renal sympathoexcitation through stimulation of renal renin release, which in turn produces increased plasma angiotensin II levels, causing centrally mediated sympathoexcitation. In addition, direct central nervous actions of furosemide on central control of mean arterial pressure, heart rate, and efferent renal sympathetic nerve activity were examined. Furosemide (300 mg/kg intravenously) was administered to four groups of rats: (1) control; (2) nephrectomized; (3) with intravenous losartan blockade (10 mumol/kg); and (4) with intracerebroventricular losartan blockade (10 nmol). In a fifth group of rats, furosemide was administered intracerebroventricularly (0, 2.5, 25 or 250 micrograms). To eliminate reflex control of mean arterial pressure, heart rate and efferent renal sympathetic nerve activity, all experiments were performed in rats with sinoaortic denervation and bilateral vagotomy. Experiments were performed during Saffan anaesthesia (0.9% alphaxalone/0.3% alphadolone), and rats were paralyzed with pancuronium and artifically ventilated. Furosemide produced an immediate 40% increase in efferent renal sympathetic nerve activity while the furosemide vehicle, 2 vol.% ethanolamine, did not affect efferent renal sympathetic nerve activity. The furosemide-induced increase in efferent renal sympathetic nerve activity was abolished in rats with bilateral nephrectomy but it was not affected by intravenous or intracerebroventricular losartan blockade. Intracerebroventricular angiotensin II produced an increase in mean arterial pressure and efferent renal sympathetic nerve activity whereas intravenous angiotensin II produced a pressor response in absence of increased efferent renal sympathetic nerve activity. Losartan effectively blocked responses to intravenous or intracerebroventricular angiotensin II. Intracerebroventricular administration of furosemide produced no changes in mean arterial pressure, heart rate or efferent renal sympathetic nerve activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacotherapy of congestive heart failure. Currently used and experimental drugs

A survey is given of the currently used therapeutics in the treatment of chronic congestive heart failure. Symptomatic treatment is usually performed along the following lines: rest, sodium and fluid restriction to unload the decompensating heart, loop diuretics, angiotensin-converting enzyme inhibitors or other vasodilators; inotropic agents to improve the heart's mechanical performance; attempts to counteract the neuro-endocrine compensatory mechanisms, that is the activated sympathetic nervous and renin-angiotensin-aldosterone systems, as well as the rise in vasopressine levels. New insights have been obtained in the effects of cardiac glycosides, which are probably rather based on counteracting the elevated sympathetic neuronal activity than on their weak and uncertain inotropic action. Angiotensin-converting enzyme inhibitors are probably more effective than classical vasodilators owing to their additional interaction with the neuro-endocrine compensatory mechanisms. Ibopamine, a prodrug of epinine, appears to be rather a vasodilator and antagonist of the neuro-endocrine compensatory mechanisms than an inotropic agent. The most important clinical trials addressing the efficacy and adverse reactions to the various aforementioned therapeutics are discussed. New, experimental approaches in the drug treatment of chronic congestive heart failure include beta-blockers, calcium antagonists, vasopressin antagonists and inhibitors of atrial natriuretic peptide degradation.

Interaction of intravenous atrial natriuretic factor with furosemide in patients with heart failure

Furosemide is frequently administered intravenously to patients with chronic heart failure. However, use of diuretics may cause neuroendocrine activation and by itself may not consistently afford diuresis. Atrial natriuretic factor (ANF) in pharmacologic doses is a vasodilator and has favorable neuroendocrinologic effects in patients with congestive heart failure. To examine whether exogenous ANF might enhance the effects of acute furosemide injection, we studied 14 patients with chronic stable heart failure and measured the effects of the combination of ANF and furosemide on hemodynamics, neuroendocrine activation, and urine output. Eight patients were randomly assigned to receive placebo plus furosemide (1.3 mg/kg intravenously). Six patients received ANF (2 micrograms/kg intravenously) plus furosemide at the same dose in a double-blind manner. The group receiving placebo plus furosemide exhibited a slight increase in mean arterial pressure (92 to 96 mm Hg; p < 0.03), systemic vascular resistance (1989 to 2271 dynes.sec.cm-5; p = 0.0007), and pulmonary capillary wedge pressure (22 to 24 mm Hg; p < 0.04) from baseline to 10 minutes. The group receiving ANF plus furosemide exhibited no change in mean arterial pressure and systemic vascular resistance from baseline to 10 minutes. Pulmonary capillary wedge pressure and mean pulmonary pressure were unchanged. In the group receiving placebo plus furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)