Intravenous nesiritide, a natriuretic peptide, in the treatment of decompensated congestive heart failure. Nesiritide Study Group

Secretion of A-type and B-type natriuretic peptides into the bloodstream and pericardial space in children with congenital heart disease

OBJECTIVE

To determine the secretion of A-type and B-type natriuretic peptides into the bloodstream and pericardial space in children with congenital heart disease.

METHODS

Plasma and pericardial fluid samples were obtained from 77 patients undergoing total correction for congenital heart disease. All patients underwent detailed right-sided and left-sided cardiac catheterization preoperatively.

RESULTS

A-type natriuretic peptide levels in pericardial fluid were lower than those in plasma (33.0 +/- 23.1 versus 39.8 +/- 33.6 pg/mL, P <.05), and B-type natriuretic peptide levels in pericardial fluid showed marked elevations compared with those in plasma (231.9 +/- 305.6 versus 19.8 +/- 29.3 pg/mL, P <.0001). The A-type and B-type natriuretic peptide levels in plasma correlated with those in pericardial fluid (R =.522, P <.0001; R =.595, P <.0001). For A-type and B-type natriuretic peptide levels in plasma, the relation with biventricular volume had the highest correlation (R =.669, P <.0001; R =.652, P <.0001). The patients with a pulmonary-to-systemic flow ratio greater than 2 (n = 19) had high levels of natriuretic peptides not only in plasma (58.3 +/- 43.2, 40.5 +/- 49.4 pg/mL, P <.05) but also in pericardial fluid (44.4 +/- 31.5, 287.2 +/- 198.5 pg/mL, P <.05), and higher correlation between A-type and B-type natriuretic peptide plasma levels and left ventricular volume (R =.913, P <.0001; R =.787, P <.0001).

CONCLUSIONS

B-type natriuretic peptide is secreted not only into the bloodstream but also into the pericardial space in children with congenital heart disease. Natriuretic peptide levels in plasma correlated well with biventricular volume. The left ventricle was considered to be the main source of secreted natriuretic peptides in the patients with a pulmonary-to-systemic flow ratio greater than 2.

Heart Failure in the Elderly

Incidence and prevalence of heart failure are particularly common with advancing age, with notoriously grim prognoses. The absolute number of heart failure patients will undoubtedly surge as the population of older adults continues to escalate. This review emphasizes the importance of factors inherent in aging itself and the resulting predisposition to disease. Physiologic changes associated with cardiovascular aging fundamentally increase susceptibility to heart failure and to complexity of heart failure management. Likewise, typical age-associated diet and lifestyle changes compound risks of heart failure through mechanisms connected to the substrate of disease. In this review, the authors first summarize the demographics of heart failure and the intrinsic aspects of aging and lifestyle that predispose to heart failure. They then expand on related intricacies of diagnosis and therapy. Orientation to heart failure, particularly as a disease of aging, can help critically refine management of acute and chronic disease, as well as foster preventive strategies to reduce incidence of this common malady.

Management of Decompensated Heart Failure

Much has been written about the management of chronic heart failure (HF) and there is strong evidence from many controlled, multicenter trials to support a specific strategy for management of compensated HF. There is little evidence and limited guidance for the management of patients during a period of decompensation. The use of diuretics, inodilators, and vasodilators is based primarily on anecdotal observation. This article reviews selected current literature in three areas (diuretics, vasodilators, and inotropes) to examine objective evidence and expert opinion that are available to guide the advanced practitioner who manages the care of patients with decompensated HF.

New and emerging drug therapies for the management of acute heart failure

In recent times, there have been many developments in therapies for acute heart failure, in contrast to the preceding 20 years. These have been mainly fueled by new and expanding knowledge about the pathophysiology of heart failure, which has allowed for insight into potential therapeutic strategies. This review will examine the key emerging therapies for acute heart failure, in light of available pathophysiological and clinical evidence.

Practical considerations for BNP use

The evolving paradigm of heart failure has now been expanded to include the favorable neurohormonal, structural and hemodynamic profile of B-type natriuretic peptide [BNP]. As a marker of left ventricular dysfunction, BNP is a practical tool that facilitates diagnosis, contributes to prognostic evaluations and tracks disease severity. BNP elevations vary according to gender, disease states and perhaps obesity but in general elevated levels are consistent not only with left ventricular stress but likely represent the best surrogate for ongoing left ventricular remodeling. The full utility of BNP surveys has not yet been realized but emerging areas of use include clinical assessment by physician extenders, post-MI assessment, and a target of tailored therapy for heart failure. New biomarkers for heart failure similar to BNP are on the horizon but their clinical niche has yet to be determined.

Structure, Regulation, and Function of Mammalian Membrane Guanylyl Cyclase Receptors, With a Focus on Guanylyl Cyclase-A

Besides soluble guanylyl cyclase (GC), the receptor for NO, there are at least seven plasma membrane enzymes that synthesize the second-messenger cGMP. All membrane GCs (GC-A through GC-G) share a basic topology, which consists of an extracellular ligand binding domain, a short transmembrane region, and an intracellular domain that contains the catalytic (GC) region. Although the presence of the extracellular domain suggests that all these enzymes function as receptors, specific ligands have been identified for only three of them (GC-A through GC-C). GC-A mediates the endocrine effects of atrial and B-type natriuretic peptides regulating arterial blood pressure and volume homeostasis and also local antihypertrophic actions in the heart. GC-B is a specific receptor for C-type natriuretic peptide, having more of a paracrine function in vascular regeneration and endochondral ossification. GC-C mediates the effects of guanylin and uroguanylin on intestinal electrolyte and water transport and on epithelial cell growth and differentiation. GC-E and GC-F are colocalized within the same photoreceptor cells of the retina and have an important role in phototransduction. Finally, the functions of GC-D (located in the olfactory neuroepithelium) and GC-G (expressed in highest amounts in lung, intestine, and skeletal muscle) are completely unknown. This review discusses the structure and functions of membrane GCs, with special emphasis on the physiological endocrine and cardiac functions of GC-A, the regulation of hormone-dependent GC-A activity, and the relevance of alterations of the atrial natriuretic peptide/GC-A system to cardiovascular diseases.

The Evolving Role of Nesiritide in Advanced or Decompensated Heart Failure

Nesiritide is a recombinant form of human brain natriuretic peptide (BNP) that is structurally and biochemically identical to endogenously produced BNP. In humans, BNP is important in hemodynamic and neurohormonal equilibrium, helping to maintain adequate vascular volume and pressure in response to volume overload. The pharmacodynamic effects of nesiritide mimic the biologic effects of BNP. The molecular biology and actions of nesiritide and BNP are reviewed, with the therapeutic rationale for nesiritide in patients with acute or advanced decompensated heart failure highlighted. In addition, recommendations for its administration are provided, and unresolved therapeutic considerations are discussed.

Intravenous vasodilator therapy in congestive heart failure

The prevalence of congestive heart failure (CHF) is increasing in the US and worldwide, partly because patients are living longer. Treatment of CHF is mostly on an outpatient basis, but inpatient care is required for decompensated CHF, acute CHF or poor response to outpatient treatment. Control of symptoms is usually achieved by diuresis. Intravenous (IV) vasodilators are an important adjunct to the inpatient treatment of CHF. They work mainly by reducing the afterload on the myocardium although preload reduction also occurs. After clinical stabilisation, the goal is to switch to a maintenance oral regimen to be continued as outpatient therapy. The range of IV vasodilators available for inpatient treatment of CHF includes nitrates, phosphodiesterase inhibitors, dobutamine, morphine, ACE inhibitors, B-type natriuretic peptides and endothelin receptor antagonists. As each agent may have a different mechanism or site of action, each agent may affect preload, contractility or afterload to a different extent and it may be desirable to choose one over the other in a particular clinical setting. Examples of standard therapy include dobutamine, milrinone and nitroglycerin. Nesiritide, a B-type natriuretic peptide, is a newer vasodilator and US FDA approved for use in acute CHF. However, most studies with this agent have been in small numbers of patients with anecdotal findings. Larger studies are warranted to pinpoint the efficacy and adverse effects of this agent. It is primarily used to reduce the acuity of decompensated CHF on admission to hospital.Endothelin receptor antagonists show promise in the management of acute CHF, but continue to be investigational. Long-term data on their efficacy and safety are limited. None of the endothelin receptor antagonists are FDA approved for use in patients with CHF.

Economic implications of nesiritide versus dobutamine in the treatment of patients with acutely decompensated congestive heart failure

Pooled data from trials comparing nesiritide with dobutamine for treatment of acute decompensated congestive heart failure were combined with national hospital cost data in an economic model. Results indicate that the acquisition cost of nesiritide is fully offset by decreased hospital costs.

B-type natriuretic peptide prevents acute hypertrophic responses in the diabetic rat heart: importance of cyclic GMP

Stimulation of cardiomyocyte guanosine 3',5'-cyclic monophosphate (cyclic GMP) via endothelial-derived nitric oxide (NO) is an important mechanism by which bradykinin and ACE inhibitors prevent hypertrophy. Endothelial NO dysfunction and cardiac hypertrophy are morbid features of diabetes not entirely prevented by ACE inhibitors. In cardiomyocyte/endothelial cell cocultures, bradykinin efficacy is abolished by high-glucose-induced endothelial NO dysfunction. We now demonstrate that antihypertrophic actions of natriuretic peptides, which stimulate cyclic GMP independently of NO, are preserved in cardiomyocytes despite high-glucose-induced endothelial dysfunction. Further, streptozotocin-induced diabetes significantly impairs the effectiveness of acute antihypertrophic strategies in isolated rat hearts. In hearts from citrate-treated control rats, angiotensin II-stimulated [(3)H]phenylalanine incorporation and atrial natriuretic peptide and beta-myosin heavy chain mRNA expression were prevented by B-type natriuretic peptide (BNP), bradykinin, the ACE inhibitor ramiprilat, and the neutral endopeptidase inhibitor candoxatrilat. These antihypertrophic effects were accompanied by increased left ventricular cyclic GMP. In age-matched diabetic hearts, the antihypertrophic and cyclic GMP stimulatory actions of bradykinin, ramiprilat, and candoxatrilat were absent. However, the blunting of hypertrophic markers and accompanying increases in cyclic GMP stimulated by BNP were preserved in diabetes. Thus BNP, which increases cyclic GMP independently of NO, is an important approach to prevent growth in the diabetic myocardium, where endothelium-dependent mechanisms are compromised.

Hemodynamic and renal effects of low-dose brain natriuretic peptide infusion in humans: a randomized, placebo-controlled crossover study

Brain natriuretic peptide (BNP) is a cardiac hormone with natriuretic activity. The aim of this study was to investigate the cardiovascular effects of pathophysiological levels of BNP on central hemodynamics, cardiac function, renal hemodynamics and function, and microvascular hemodynamics in healthy subjects. In this double-blind, placebo-controlled crossover study, we intravenously infused BNP (4 pmol. kg-1. min-1) or placebo for 1 h on two separate days in 12 healthy subjects (mean age, 60 +/- 5 yr). Nailfold and conjunctival capillary density, finger-skin (thermoregulatory) microvascular blood flow, and cardiac output were studied before and after infusion using intravital videomicroscopy, laser-Doppler fluxmetry, and echocardiography, respectively. Furthermore, during infusion, we measured the effective renal plasma flow and glomerular filtration rate using p-aminohippurate and inulin clearances. Blood pressure and heart rate were monitored for all measurements. Compared with placebo, BNP significantly decreased stroke volume with a tendency to decrease cardiac output. With subjects in the sitting position, mean arterial pressure decreased and heart rate increased after BNP infusion, whereas with subjects in the supine position, these variables remained unchanged. BNP increased natriuresis, diuresis, glomerular filtration rate, filtration fraction, and filtered load of Na+ compared with placebo, whereas effective renal plasma flow did not change. BNP did not affect the microvascular capillary density of conjunctiva and skin, microvascular blood flow, total skin oxygen capacity, and postocclusive recruitment. These results suggest that BNP has predominantly central and renal hemodynamic effects; however, it does not influence peripheral microcirculation in skin and conjunctiva.

Effect of beta blockade (carvedilol or metoprolol) on activation of the renin-angiotensin-aldosterone system and natriuretic peptides in chronic heart failure

Beta blockers are known to suppress renin release in hypertension and in patients taking angiotensin-converting enzyme (ACE) inhibitors. This study sought to explore the effect of additional beta blockade on neurohumoral modulation in patients with severe heart failure (HF) who received ACE inhibitors. Forty-nine patients with chronic HF who received ACE inhibitors were given metoprolol 50 mg or carvedilol 25 mg twice daily after a 4-week dose titration period in addition to standard therapy in a prospective trial. Samples of plasma renin activity (PRA), aldosterone, aminoterminal B-type natriuretic peptide (N-BNP), and atrial natriuretic peptide (ANP) were taken at baseline and at 4, 12, and 52 weeks after starting therapy. Treatment with either beta blocker significantly lowered PRA at 4 weeks compared with baseline (-2.0 +/- 0.6 nmol/L/hour, p = 0.006), but at 12 weeks, PRA had reduced to -1.1 +/- 0.6 nmol/L/hour (p = 0.08), but at 52 weeks, it was not significantly different from baseline (+1.05 +/- 0.6 nmol/L/hour, p = 0.13). Aldosterone levels did not change significantly from baseline at 4 or 12 weeks, although there was a nonsignificant trend for lower levels at 52 weeks (baseline 232 +/- 154 pmol/L, 52 weeks 192 +/- 100 pmol/L, p = 0.09). There was significant reduction in N-BNP and ANP together with an improvement in symptom and left ventricular systolic function at 1-year follow-up. These results indicate that the suppressive effect of beta blockers on PRA in patients with HF taking ACE inhibitors is temporary, and that there is no significant effect on serum aldosterone levels.

Acute decompensated heart failure: a contemporary approach to pharmacotherapeutic management

Hospital admissions for acute decompensated heart failure (ADHF) have increased precipitously during the past few decades and are projected to continue to increase in the future. To optimize patient outcomes and reduce the costs associated with this disorder, evidenced-based pharmacotherapy is essential. Continuous infusions of loop diuretic therapy rather than bolus dosing may enhance efficacy and reduce the extent of diuretic resistance. Nesiritide is a pharmacologically novel preload and afterload reducer but based on clinical trial evidence should be reserved for those unable to take or with resistance to intravenous nitrate therapy. Catecholamine- and phosphodiesterase-based inotropic therapies are efficacious, but the increased risk of arrhythmogenesis and the potential for negative survival effects limit their use. The experimental agent levosimendan is a positive inotropic agent but does not increase myocyte calcium concentrations as do catecholamines or phosphodiesterase inhibitors. Clinical trial evidence demonstrates a positive survival benefit for levosimendan versus dobutamine.

B-type natriuretic peptide in cardiovascular disease

Natriuretic peptide hormones, a family of vasoactive peptides with many favourable physiological properties, have emerged as important candidates for development of diagnostic tools and therapeutic agents in cardiovascular disease. The rapid incorporation into clinical practice of bioassays to measure natriuretic peptide concentrations, and drugs that augment the biological actions of this system, show the potential for translational research to improve patient care. Here, we focus on the physiology of the natriuretic peptide system, measurement of circulating concentrations of B-type natriuretic peptide (BNP) and the N-terminal fragment of its prohormone (N-terminal BNP) to diagnose heart failure and left ventricular dysfunction, measurement of BNP and N-terminal BNP to assess prognosis in patients with cardiac abnormalities, and use of recombinant human BNP (nesiritide) and vasopeptidase inhibitors to treat heart failure.

B-type natriuretic peptide in ischemic heart disease

B-type natriuretic peptide (BNP) and the N-terminal fragment of its prohormone (N-proBNP) are released from the heart in response to increased wall stress. Assays for these peptides are now commercially available, and measurement of BNP and N-proBNP is becoming commonplace in patients with suspected heart failure. BNP and N-proBNP facilitate diagnosis and risk stratification in patients with heart failure, and may help guide response to therapy. This review focuses on the emerging role of BNP and N-proBNP measurement in patients with acute coronary syndromes (ACS). Although experimental studies demonstrate rapid BNP release in response to cardiac ischemia, it is unlikely that BNP will be used to diagnose cardiac ischemia, because many other conditions are also associated with modest BNP elevation. In contrast, BNP holds tremendous promise as a prognostic marker in patients with ACS. Studies to date have shown consistently that higher BNP levels are associated with worse clinical outcomes, and that BNP provides unique information to clinical variables, other biomarkers, and left ventricular ejection fraction. Future studies are needed to identify the therapeutic implications of BNP elevation in patients with ACS.

Effects of intravenous nesiritide on human coronary vasomotor regulation and myocardial oxygen uptake

BACKGROUND

Nesiritide, recombinant human B-type natriuretic peptide, has been shown to be efficacious in the treatment of decompensated heart failure. The effects of intravenous nesiritide on the human coronary vasculature have not been studied.

METHODS AND RESULTS

Ten patients underwent right and left heart catheterization. Baseline coronary blood flow was determined using quantitative coronary angiography (QCA) and an intracoronary Doppler-tipped guidewire. Myocardial oxygen uptake was measured using a coronary sinus catheter. Patients then received an intravenous infusion of nesiritide (2 microg/kg bolus followed by 0.01 microg/kg per min infusion) for 30 minutes. Right atrial pressure decreased 52% (P=0.012), pulmonary artery mean pressure decreased 19% (P=0.03), pulmonary capillary wedge pressure decreased 46% (P=0.002), and mean arterial pressure decreased 11% (P=0.007). QCA demonstrated a 15% increase in coronary artery diameter from a baseline of 2.6+/-0.8 to 3.0+/-0.8 mm at 30 minutes (P=0.007). The coronary velocity measure of average peak velocity increased 14% from 20.8+/-6.4 at baseline to 23.8+/-7.2 cm/s at 5 minutes (P=0.015) and then returned to baseline for the remainder of the infusion. Coronary blood flow increased 35% (P=0.007), whereas coronary resistance decreased 23% at 15 and 30 minutes (P=0.036). Myocardial oxygen uptake decreased 8% during the nesiritide infusion (P=0.043).

CONCLUSIONS

Nesiritide exerts coronary vasodilator effects on both the coronary conductance and resistance arteries. Despite a decrease in coronary perfusion pressure, coronary artery blood flow is increased, coronary resistance is decreased, and myocardial oxygen uptake is decreased.

Natriuretic peptides: biochemistry, physiology, and therapeutic role in heart failure

Cardiac natriuretic peptides are a family of structurally related peptides that are important in sodium and volume homeostasis. They consist of atrial natriuretic peptide, brain natriuretic peptide, and C-type natriuretic peptide and are elevated in patients with left ventricular dysfunction. In contrast with vasoconstrictive hormones, such as norepinephrine, angiotensin II, and arginine vasopressin, which worsen the physiological milieu in patients with left ventricular dysfunction and heart failure, the natriuretic peptides ameliorate these effects by promoting natriuresis, diuresis, peripheral vasodilation, and by inhibiting the renin-angiotensin system. The serum levels of the natriuretic peptides correlate with the severity of heart failure and appear to have prognostic value. The present article reviews the biochemistry, molecular biology, and physiology of natriuretic peptides and their pathophysiological link to heart failure. The therapeutic uses of natriuretic peptides are also reviewed. This includes the use of intravenous nesiritide, a synthetic human brain natriuretic peptide, and the recently developed vasopeptidase inhibitors which are designed to inhibit the degradation of natriuretic peptides.

New therapies for the management of acute heart failure

The standard treatment for acute heart failure (synonymous with pulmonary edema) is an upright posture, oxygen, morphine (often accompanied by an antiemetic), and intravenous diuretics. This treatment has remained unchanged for many years, and the precise mechanism by which each of these methods alleviates symptoms in patients is unclear. Nitrates, oral or intravenous, are also used with benefit, and have some hemodynamic advantages over intravenous diuretics. Recently, three new forms of treatment have been investigated. The use of milrinone, a phosphodiesterase inhibitor, for exacerbation of heart failure in patients with a background of chronic heart failure was not advantageous. The trials of levosimendan, a calcium sensitizer, in patients with pulmonary edema hinted at benefit. Nesiritide, a formulation of brain natriuretic peptide, does bring about hemodynamic improvement in acute heart failure, and is at least as effective as nitroglycerin, easier to prescribe, but prone to cause hypotension. These are small but important advances that increase our knowledge of the pathophysiology of acute heart failure, and also provide an indication of which drugs are preferable for the treatment of this distressing condition.

Management of heart failure in the elderly

Chronic heart failure is an epidemic disorder in the elderly population. The frequent coexistence of comorbid illnesses and psychosocial issues in older persons often makes diagnosis and management difficult. Physicians must be aware of the current diagnostic modalities and proven therapies as they apply to elderly patients in order to achieve optimal outcomes. This article reviews new approaches to the diagnosis of heart failure, and discusses the latest evidence for both pharmacologic and nonpharmacologic treatment for this condition. Multidisciplinary strategies for the management of heart failure and end-of-life care are also briefly discussed.

Nesiritide: a review of its use in acute decompensated heart failure

Nesiritide (Natrecor) is a recombinant form of human B-type (brain) natriuretic peptide that has beneficial vasodilatory, natriuretic, diuretic and neurohormonal effects. The drug is administered intravenously for the management of patients with decompensated congestive heart failure (CHF). In the Vasodilation in the Management of Acute Congestive Heart Failure (VMAC) study, patients hospitalised with acute decompensated CHF who received nesiritide had significantly greater mean reductions from baseline in pulmonary capillary wedge pressure 3 hours after starting treatment than nitroglycerin or placebo recipients (-5.8 vs -3.8 and -2 mm Hg, respectively); all patients also received standard therapy (e.g. intravenous diuretics). Improvements in other haemodynamic parameters were also seen in nesiritide recipients. In addition, significantly more nesiritide than placebo recipients reported an improvement in dyspnoea after 3 hours' treatment in VMAC, whereas there was no significant difference between nitroglycerin and placebo recipients. Improvements in global clinical status, dyspnoea and fatigue were also seen with nesiritide in another active-comparator study and in a placebo-controlled study. In VMAC, there was no significant difference between nesiritide and nitroglycerin recipients in 6-month mortality. In the other active-comparator trial, 6-month mortality was significantly lower in recipients of nesiritide 0.015 micro g/kg/min than in dobutamine recipients (although mortality was not a prespecified endpoint and this result should be interpreted with caution). In this same study, the 21-day all-cause hospital readmission rate was significantly lower with nesiritide 0.015 micro g/kg/min than with dobutamine and the duration of active drug treatment was significantly shorter with nesiritide than with dobutamine. Nesiritide is generally well tolerated. In VMAC, significantly more adverse events occurred with nitroglycerin than with nesiritide. The most common adverse events reported during the first 24 hours of therapy in nesiritide and nitroglycerin recipients included general pain, abdominal pain, catheter-related pain, headache, nausea, asymptomatic and symptomatic hypotension, nonsustained ventricular tachycardia and angina pectoris. Most episodes of symptomatic hypotension resolved spontaneously or after an intravenous volume challenge of </=250 ml. In addition, nesiritide does not appear to be proarrhythmic.

CONCLUSION

Short-term intravenous infusion of nesiritide is associated with haemodynamic and symptomatic improvements in patients with acutely decompensated CHF. Nesiritide may offer tolerability and practical advantages over currently used vasodilators, inodilators and inotropes in this condition; in particular, nesiritide does not appear to have proarrhythmic effects. Nesiritide also appears to be effective and well tolerated in patients receiving concomitant beta-blocker therapy and in patients with renal insufficiency. Thus, nesiritide is a suitable first-line option for the treatment of patients with acutely decompensated CHF and is a welcome addition in an area where intravenous agents are few.

Treatment of congestive heart failure a neuroendocrine disorder

The understanding of heart failure is no longer based on a supply and demand model of pump failure. Rather, heart failure is seen as a complex pathophysiological process with activation of various neuroendocrine systems. The goals of treatment have changed towards modifying these counterproductive neuroendocrine systems and slowing myocardial maladaptation. Angiotensin converting enzyme inhibitors are the only licensed drugs in veterinary practice that have a direct effect on neurohormones in heart failure. The range of drug options in human medicine is greater and some of these drugs are also increasingly being used in veterinary cardiology practice. This review describes the neuroendocrine systems involved in heart failure and discusses the range of drugs available in human and veterinary medicine. In doing so, it concentrates on the evidence available from good quality randomised trials in both the veterinary field and, where relevant, the human medical field.

Nesiritide treatment of noncardiogenic pulmonary edema

OBJECTIVE

To report the efficacy of nesiritide in treating noncardiogenic pulmonary edema.

CASE SUMMARY

A 50-year-old African American woman with a complex medical history including morbid obesity, acute bronchitis, obstructive sleep apnea, hypertension, and numerous hospitalizations for volume overload presented to the emergency department with severe dyspnea. A portable chest X-ray displayed perihilar congestion and bilateral pulmonary edema. An echocardiogram demonstrated normal left-ventricular systolic and diastolic function. She was aggressively treated with nitrates, diuretics, bronchodilators, and oxygen. Despite these efforts, the patient's arterial blood gas (ABG) continued to show respiratory acidosis, the oxygen saturation was significantly depressed, and the dyspnea continued. Since standard therapies were failing after 12 hours, the patient was treated with intravenous nesiritide. The results were profound in terms of rapid symptomatic and prognostic improvement (i.e., ABG) beginning within 45 minutes of administration, and the patient was discharged after a 5-day hospital course.

DISCUSSION

Nesiritide is a human B-type natriuretic peptide that has been shown to improve hemodynamic function and symptoms associated with decompensated heart failure. This is primarily due to the actions of this medication, including diuresis, decreased mean arterial pressure, and improvement of pulmonary arterial occlusion pressure as determined by published clinical trial outcomes. This case describes the use of nesiritide as an effective adjunctive therapy in treating a patient with noncardiogenic pulmonary edema.

CONCLUSIONS

Nesiritide appears to be an efficacious treatment for acute pulmonary edema, resistant to standard-of-care therapies, in the presence of normal left-ventricular function.

Revisiting salt and water retention: new diuretics, aquaretics, and natriuretics

Diuretics continue to be a mainstay in patients with CHF. Conventional diuretic therapy is associated, however, with potentially deleterious neurohumoral activation and renal impairment. It is not known to what extent these neurohumoral effects are offset by concurrent therapy with ACE-I, beta-blockers, and other agents. In the past, there was no alternative to conventional diuretic therapy, so their potential for adverse outcome in the long term could not be assessed. Enhancement of the natriuretic peptide system could provide us with a better strategy to treat sodium and water retention. In a unique way, the natriuretic peptides combine several of the beneficial actions of the other diuretics, but without the associated cost. Natriuretic peptides, like conventional diuretics, are natriuretic and diuretic. There are important differences, however. First, unlike conventional diuretics, NPs do not activate RAAS. Activation of this system is associated with progression of CHF. Second, NPs inhibit the sympathetic nervous system, the activation of which is associated with heart failure progression, myocyte necrosis and apoptosis, and arrhythmias. Third, unlike conventional diuretics that lead to a decrease in GFR by reflex mechanisms. NPs maintain or even improve GFR. We now appreciate that some "old" drugs may be beneficial to CHF patients in a new way, as is the case with spironolactone. The survival benefit of this aldosterone antagonist is clear: its usefulness, however, may be more a result of both its antifibrotic actions in addition to its tradional role as a potassium-sparing and natriuretic agent. It is hoped that the SARAs will provide the same survival benefit, but with fewer of the sex-steroid side effects. In addition, AVP-receptor antagonists may become useful tools in the treatment of patients with hyponatremia. Likewise, the A1 AR antagonists may find a role in the CHF armamentarium by providing good diuresis and natriuresis while at the same time maintaining GFR through inhibition of TGF. Many questions remain unanswered, and studies are needed to demonstrate that the positive results seen in basic research translate into improved morbidity and mortality.

Vasopeptidase inhibition: a double-edged sword?

The enormous benefits of inhibition of ACE demonstrate that manipulation of the metabolism of peptide hormones is a valuable therapeutic strategy for cardiovascular disease. Recent attempts to expand these benefits have combined ACE inhibition with inhibition of other peptidases such as neutral endopeptidase (NEP) in a single molecule, a strategy known as vasopeptidase inhibition. NEP metabolizes natriuretic peptides, and NEP inhibition offers the prospect of combining the benefits of increased natriuretic peptide levels with those of ACE inhibition. However, peptidases such as ACE and NEP have many different substrates, and there are complex interactions between ACE inhibition and NEP inhibition. Both ACE and NEP metabolize the kinin peptides bradykinin and kallidin, and NEP also converts angiotensin (Ang) I to Ang-(1-7) and metabolizes Ang II and endothelin. Addition of NEP inhibition to ACE inhibition potentiates the ACE inhibitor-induced increase in kinin levels, increases Ang II levels, reduces Ang-(1-7) levels, and may increase endothelin levels. These additional consequences of combined ACE/NEP inhibition increase the risk of angioedema and may counteract any benefit of ACE inhibition that depends on reduced Ang II levels and increased Ang-(1-7) levels. Further considerations are that the ratio of ACE and NEP inhibition is fixed for vasopeptidase inhibitors, and there is uncertainty how these drugs should be compared with ACE inhibitors. Vasopeptidase inhibitors will therefore require careful evaluation before they are introduced to patient care.

Role of nonglycosidic inotropic agents: indications, ethics, and limitations

Nonglycosidic inotropic agents have been used for the short-term management of low output states and hypotension complicating acute myocardial infarction for several years. Without adequate reperfusion of the ischemic myocardium, inotropic agents are seldom effective in producing sustained hemodynamic responses. Furthermore, the potential exists for enhancement of ischemia and extension of myocardial necrosis. Thus, inotropic and vasopressors therapy should be regarded as temporary supportive treatment in patients with acute coronary syndrome and should be discontinued as soon as feasible. Parenteral sympathomimetic agents, usually dobutamine, and phosphodiesterase inhibitors, usually milrinone, are used for the management of exacerbations of chronic systolic heart failure. Although hemodynamics, and occasionally clinical status, improve, such therapy is associated with increased mortality and can potentially hasten a patient's demise. Nonparenteral sympathomimetics, such as ibopamine, phosphodiesterase-III inhibitors, such as milrinone and enoximone, calcium-sensitizing agents, such as pimobendan, and other novel inotropic agents, such as vesnarinone, all increase mortality of patients with chronic heart failure. Furthermore, newer noninotropic agents, such as B-natriuretic peptide, have been introduced for treatment of decompensated heart failure. New nonpharmacologic devices, such as biventricular pacing, are available for the treatment of advanced heart failure. Thus, indications for the use of presently available nonglycosidic inotropic agents are limited and should be considered only for short-term therapy or when no other treatment is available.

Nesiritide: a novel approach for acute heart failure

OBJECTIVE

To review preclinical and clinical information related to nesiritide, a recombinant form of B-type natriuretic peptide approved for treatment of acutely decompensated heart failure.

DATA SOURCES

Primary and review articles were identified by MEDLINE search (1966-May 2002) using the key words natriuretic peptide and heart failure, and through secondary sources. Natrecor's document submitted for the Food and Drug Administration (FDA) New Drug Application were obtained from the FDA Web site.

STUDY SELECTION/DATA EXTRACTION

Peer-reviewed articles and abstracts of randomized clinical trials in humans were included in this review.

DATA SYNTHESIS

Nesiritide has beneficial actions for treatment of heart failure, including arterial and venous dilatation, enhanced sodium and urinary excretion, and suppression of the renin-angiotensin-aldosterone and sympathetic nervous systems. It has been shown to improve hemodynamic parameters, primarily pulmonary capillary wedge pressure, as well as clinical symptoms in patients with acutely decompensated heart failure. Nesiritide produced more rapid hemodynamic improvement and caused significantly fewer adverse effects than intravenous nitroglycerin. The incidence of hypotension, the most common adverse effect, was comparable between nesiritide and nitroglycerin. Additionally, nesiritide is associated with a lower incidence of arrhythmias than dobutamine and has a neutral effect on mortality.

CONCLUSIONS

Nesiritide offers an alternative for management of acutely decompensated heart failure. It is considered an option for patients who do not respond to other vasodilators, inotropes, or diuretics and for those at high risk of arrhythmias. Further pharmacoeconomic investigations for nesiritide are warranted.

The therapeutic effect of natriuretic peptides in heart failure; differential regulation of endothelial and inducible nitric oxide synthases

The abnormal regulation of nitric oxide synthase activity represents an underlying feature of heart failure. Increased peripheral vascular resistance, and decreased renal function may be in part related to impaired endothelium-dependent nitric oxide (NO) synthesis. Paradoxically, the chronic production of NO by inducible nitric oxide synthase (iNOS) in heart failure exerts deleterious effects on ventricular contractility, and circulatory function. Consequently, pharmacologically improving endothelium-dependent NO synthesis and the concomitant inhibition of iNOS activity would be therapeutically advantageous. Interestingly, natriuretic peptides have been shown to differentially regulate endothelial NOS (eNOS) and iNOS activity. Moreover, in both patients and animal models of heart failure, pharmacologically increasing plasma natriuretic peptide levels ameliorated vascular tone, renal function, and ventricular contractility. Based on these observations, the following review will explore whether the therapeutic benefit of the natriuretic peptide system in heart failure may occur in part via the amelioration of endothelium-dependent NO synthesis, and the concomitant inhibition of cytokine-mediated iNOS expression.

Pharmacotherapeutic approaches for decompensated heart failure: a role for the calcium sensitiser, levosimendan?

Although no universal definition exists, decompensated heart failure may be regarded as either a worsening of chronic heart failure or new-onset heart failure precipitated by an acute incident. Haemodynamic management of patients hospitalised with decompensated heart failure may include the administration of diuretics, vasodilators and positive inotropic agents. Until recently, these latter agents constituted the only drug class to produce a direct increase in stroke volume via enhanced myocardial contractility. However, despite their short-term benefits, the clinical utility of inotropic agents is compromised by their potentially deleterious effects on calcium handling and oxygen consumption, resulting in an increased risk of serious ventricular arrhythmias and death. In contrast, calcium sensitisers enhance cardiac performance without affecting calcium movement and, therefore, are potentially associated with a reduced risk of rhythmic disturbances. These agents constitute a heterogeneous group of compounds with different affinities for calcium sensitisation. Levosimendan is a potent calcium sensitiser with vasodilating properties that has been shown to provide symptomatic and haemodynamic improvement with no increase in oxygen consumption. Calcium sensitisation is therefore emerging as a promising treatment approach in this challenging therapeutic area.

Effect of nesiritide (B-type natriuretic peptide) and dobutamine on ventricular arrhythmias in the treatment of patients with acutely decompensated congestive heart failure: the PRECEDENT study

BACKGROUND

Dobutamine is commonly used as a means of treating decompensated congestive heart failure (CHF). Although typically effective at improving short-term hemodynamics and symptomatology, the frequent occurrence of arrhythmias and tachycardia is undesirable. In this randomized, multicenter trial, we compared the safety and clinical effectiveness of the cardiac hormone nesiritide (human B-type natriuretic peptide) with dobutamine in hospitalized patients with decompensated CHF.

METHODS

The study population consisted of 255 patients who were randomized to 1 of 2 doses of intravenous nesiritide (0.015 or 0.03 microg/kg/min) or dobutamine (> or =5 microg/kg/min) and stratified by means of an earlier history of ventricular tachycardia. Patients were also assessed with 24 hour Holter recordings immediately before and during study drug therapy and by means of signs and symptoms of CHF.

RESULTS

Dobutamine significantly increased the mean (1) number of ventricular tachycardia events per 24 hours by 48 +/- 205 (P =.001), (2) repetitive ventricular beats per hour by 15 +/- 53 (P =.001), (3) premature ventricular beats per hour by 69 +/- 214 (P =.006), and (4) heart rate by 5.1 +/- 7.7 beats per minute (P <.001). These end points were significantly decreased or unchanged in the nesiritide groups. Nesiritide did not increase heart rate, despite a greater reduction of blood pressure. Both drugs were similarly effective means of improving signs and symptoms of CHF.

CONCLUSIONS

Dobutamine is associated with substantial proarrhythmic and chronotropic effects in patients with decompensated CHF, whereas nesiritide actually reduces ventricular ectopy or has a neutral effect. Compared with dobutamine, nesiritide may be a safer, short-term treatment for patients with decompensated CHF.

Nesiritide for Acute Decompensated Heart Failure

Objective:

To evaluate nesiritide for the treatment of acute decompensated heart failure (HF) with respect to its pharmacology, pharmacokinetics, clinical efficacy, adverse effect profile, and outcomes.

Data Source:

Primary and review articles were identified by MEDLINE search (1966–March 2001). Data from the PRECEDENT trial and additional dosing/administration and safety information were obtained from Scios, Inc.

Study Selection:

All of the articles identified from the data sources were evaluated and all information deemed relevant was included in this review.

Data Synthesis:

Research into the cardiac natriuretic peptides has revealed that brain natriuretic peptide (BNP) is elevated in patients with HF and may counterregulate the pathophysiologic mechanisms involved in progression of the disease. Nesiritide (Natrecor), recombinant human BNP, is the first natriuretic peptide to be approved by the FDA for treatment of acute decompensated HF. Nesiritide is a potent venous and arterial vasodilator that reduces pulmonary capillary wedge pressure and systemic vascular resistance in a dose-dependent manner with minimal effect on heart rate. It improves signs and symptoms of HF; however, its effect on patient outcomes is unclear because of limited data. The most commonly reported adverse effects in clinical trials were dose-related hypotension and nausea.

Conclusions:

Nesiritide is an intravenous arterial and venous vasodilator that may be particularly useful in patients who may not tolerate the arrhythmogenic effects of dobutamine and milrinone or who cannot tolerate nitroglycerin and nitroprusside. Further well-designed comparative studies are needed to define nesiritide's place in management of acute decompensated HF.

Beta-blocker therapy influences the hemodynamic response to inotropic agents in patients with heart failure: a randomized comparison of dobutamine and enoximone before and after chronic treatment with metoprolol or carvedilol

OBJECTIVE

We compared the hemodynamic effects of dobutamine and enoximone administration before and after long-term beta-blocker therapy with metoprolol or carvedilol in patients with chronic heart failure (HF).

BACKGROUND

Patients with HF on beta-blocker therapy may need hemodynamic support with inotropic agents, and the hemodynamic response may be influenced by both the inotropic agent and the beta-blocker used.

METHODS

The hemodynamic effects of dobutamine (5 to 20 microg/kg/min intravenously) and enoximone (0.5 to 2 mg/kg intravenously) were assessed by pulmonary artery catheterization in 29 patients with chronic HF before and after 9 to 12 months of treatment with metoprolol or carvedilol at standard target maintenance oral doses. Hemodynamic studies were performed after >/=12 h of wash-out from all cardiovascular medications, except the beta-blockers that were administered 3 h before the second study.

RESULTS

Compared with before beta-blocker therapy, metoprolol treatment decreased the magnitude of mean pulmonary artery pressure (PAP) and pulmonary wedge pressure (PWP) decline during dobutamine infusion and increased the cardiac index (CI) and stroke volume index (SVI) response to enoximone administration, without any effect on other hemodynamic parameters. Carvedilol treatment abolished the increase in heart rate, SVI, and CI and caused a rise, rather than a decline, in PAP, PWP, systemic vascular resistance, and pulmonary vascular resistance during dobutamine infusion. The hemodynamic response to enoximone, however, was maintained or enhanced in the presence of carvedilol.

CONCLUSIONS

In contrast with its effects on enoximone, carvedilol and, to a lesser extent, metoprolol treatment may significantly inhibit the favorable hemodynamic response to dobutamine. No such beta-blocker-related attenuation of hemodynamic effects occurs with enoximone.

Exercise capacity and brain natruiretic peptide in hypertension

Brain natriuretic peptide (BNP) is increased and it is also released during exercise in hypertension, but its biologic role is unclear. However, since BNP is released from the left ventricule and it is known to reduce left ventricular filling pressure, it is possible that it exerts a favorable effect on exercise performance. We studied the relationship between endogenous BNP release and exercise capacity in hypertension with reference to left ventricular hypertrophy (LVH). Cardiopulmonary exercise study was carried out in 2 groups of hypertensives, 24 [16 men, aged 50 (SD 11) years] of whom had echocardiographic LVH and 25 [16 men, aged 41 ( 12)] who did not have LVH. In multiple regression analyses, the major determinants of peak oxygen uptake (VO max) were age (-), sex (male), peak exercise systolic BP (+) and post-exercise BNP (-). For the predicted adjusted %VO max as a measure of individualised exercise capacity, the significant predictors were the exercise-induced BNP rise (-) (p = 0.0003) and peak exercise systolic BP (+) (p = 0.001). In other words, subjects with greater myocardial dysfunction had a greater rise in BNP during exercise. LVH did not however relate to exercise capacity. The baseline, post-exercise and the % rise in BNP (pmol/L) with exercise were not statistically different in those with LVH compared with those without (median values of 11.2, 14.6 and 133% versus 10.6, 11.5 and 120% respectively). Similarly, there were no significant differences in exercise capacity between the groups: exercise time, oxygen uptakes at ventilatory threshold and at peak exercise (VO max) were 10.8 (2.5) min, 15.8 (4.6) and 33.6 (7.6) ml/min/kg in the LVH group against 11.4 (2.9) min, 18.6 (5.2) and 36 (11.1) ml/min/kg in the non-LVH group respectively. The estimated VO max was not different from that predicted from age, sex, weight and height in either group suggesting preserved exercise capacity in these subjects as a whole. In Conclusion, BNP may potentially act as a homeostatic mechanism that helps to limit exercise incapacity in hypertension irrespective of LVH.

Examination of the in vivo cardiac electrophysiological effects of nesiritide (human brain natriuretic peptide) in conscious dogs

BACKGROUND

Human brain natriuretic peptide (hBNP) is a new therapeutic agent, nesiritide, indicated in patients with decompensated congestive heart failure, a group at significant risk of developing cardiac arrhythmias. Whether hBNP has cardiac electrophysiologic effects has not been reported.

METHODS AND RESULTS

In 9 healthy, chronically instrumented, conscious dogs, hemodynamic and electrophysiologic parameters were assessed at baseline and during recombinant hBNP (nesiritide) infusion at 0.03 and 0.09 microg/kg/min after 1 hour at each dose. Infusion of hBNP produced dose-related increases (P <.001) in hBNP and cyclic GMP plasma levels and reductions (P <.05) in mean arterial pressure. Mean central venous pressure and sinus cycle length did not change significantly. Infusion of hBNP produced no significant changes in any of the electrophysiologic parameters including no change in surface ECG variables (P wave duration, PR interval, QRS duration, and QTc interval), corrected sinus node recovery time, atrioventricular nodal Wenckebach cycle length, and atrial and ventricular effective refractory periods measured at a 400 ms cycle length. Spontaneous or induced arrhythmias were not observed during hBNP infusion.

CONCLUSIONS

In conscious, healthy dogs, short-term infusion of recombinant hBNP has no significant effects on atrial or ventricular electrophysiologic parameters.

"BNP" for heart failure: role of nesiritide in cardiovascular therapeutics

B-type natriuretic peptide, or nesiritide, recently gained US Food and Drug Administration approval as the first new parenteral agent approved for heart failure therapy in more than a decade. Nesiritide refers to a peptide identical to endogenous B-type natriuretic peptide, currently manufactured by recombinant DNA technology. Nesiritide has been evaluated in clinical trials involving more than 700 subjects. The drug produces a prompt fall in systemic vascular resistance and pulmonary capillary wedge pressure, associated with rapid clinical improvement in decompensated heart failure. Nesiritide represents an attractive choice for first-line therapy of acutely decompensated heart failure patients. In this review, the authors summarize the currently available data regarding the use of nesiritide, and offer recommendations for its use based on our experience with the compound in clinical trials.

Acute renal failure in hospitalized patients: part II

BACKGROUND

Acute renal failure (ARF) is a common condition in hospitalized patients. Research has been unable to identify the optimal target for therapeutic intervention; hence, effective prevention of and/or treatment for ARF remain elusive.

OBJECTIVE

To examine the usefulness of current and potential pharmacologic treatments in seriously ill, hospitalized patients.

DATA SOURCES

A MEDLINE search (1996-June 2002) was conducted using the search terms kidney (drug effects) and acute kidney failure (drug therapy). Bibliographies of selected articles were also examined to include all relevant investigations.

STUDY SELECTION AND DATA EXTRACTION

Review articles, meta-analyses, and clinical trials describing prevention of and treatment for hospital-acquired ARF were identified. Results from prospective, controlled trials were given priority when available.

CONCLUSIONS

Appropriate management of ARF includes prospective identification of at-risk patients, fluid administration, and optimal hemodynamic support. Drug treatments, including low-dose dopamine and diuretics, have demonstrated extremely limited benefits and have not been shown to improve patient outcome. Experimental agents influence cellular processes of renal dysfunction and recovery; unfortunately, relatively few drugs show promise for the future.

Role of Nesiritide in Decompensated Heart Failure

Nesiritide is a human brain type natriuretic peptide. The addition of nesiritide, a balanced venous and arterial dilator for the treatment of decompensated heart failure, is the first intravenous (IV) therapy developed in the past decade. Nesiritide binds to receptors in the kidneys, vasculature, and other organs to produce vasodilation and natriuresis. These effects act to reduce ventricular filling pressures and rapidly improve symptoms of heart failure. Nesiritide reduces pulmonary capillary wedge pressure and pulmonary artery pressure, improves the cardiac index, and has minimal effects on heart rate. The limiting side effect of nesiritide is dose-related hypotension. It should not be used in patients with suspected or measured low filling pressures or patients with baseline hypotension. Current literature supports the efficacy of nesiritide; however, there are very few outcome data demonstrating the superiority of nesiritide over conventional therapy. Because this vasodilator does not require hemodynamic monitoring for utilization, it may be an attractive agent for a defined group of patients with decompensated heart failure.

Brain natriuretic peptide (nesiritide) in the treatment of heart failure

Over the last decade brain natriuretic peptide (BNP) emerged as a cardiac hormone of clinical interest in diagnosis, prognosis and treatment of patients with Heart Failure (HF). The diagnostic potential of BNP is now well established both in patients with suspected HF as well as in patients with asymptomatic left ventricular systolic dysfunction. The prognostic information obtained from BNP levels in HF and acute myocardial infarction patients seems even more promising. Nesiritide is a synthetic peptide, homologous to endogenous BNP. It is a balanced vasodilator with diuretic and natriuretic properties. It decreases the elevated levels of neurohormones resulting from activation of the sympathetic and renin-aldosterone systems in HF. The results of clinical trials involving more than 2000 patients with decompensated HF are now available. In these trials nesiritide was administered by single or repeated bolus injections, as well as by sustained infusions. Nesiritide has been shown to produce a potent, dose-related vasodilator effect that is rapid in onset and sustained during infusion. Balanced vasodilation is reflected by decreases in systemic vascular resistance, pulmonary artery wedge pressure and right atrial pressure. No tachyphylaxis has been observed in these trials. Efficacy of nesiritide in the treatment of decompensated HF has been demonstrated. Trials comparing nesiritide with conventional treatment of decompensated HF showed that nesiritide compares favorably to standard agents. The safety profile has been excellent with a dose-dependent hypotension as the major side effect. Ventricular arrhythmia was not more frequent in patients treated with nesiritide than with placebo. Thus, nesiritide appears to be useful as a first-line agent in the treatment of patients with decompensated HF.