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

B-type natriuretic peptide as a biomarker beyond heart failure: speculations and opportunities

Cardiac secretion of B-type natriuretic peptide (BNP) Increases with the progression of heart failure (HF), and plasma measurement of BNP has emerged recently as a useful, cost-effective biomarker for the diagnosis and prognosis of HF. The diagnostic utility of BNP is complemented by its therapeutic use in decompensated HF. Although clinical use of BNP as a biomarker in HF is Increasing, the specificity of BNP for HF is not robust, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Several studies have shown that BNP levels Increase in other cardiovascular disease states including ischemia, arrhythmias, fibrosis, cardiac hypertrophy, and coronary endothelial dysfunction. Furthermore, 2 important studies revealed recently that moderate elevations In BNP level, well below the HF range, have prognostic value for future cardiovascular events. Specifically, BNP levels greater than 20 pg/mL were associated with significantly Increased risk of HF and atrial fibrillation. These observations increase speculation that elevated BNP levels represent a final common pathway for many cardiovascular pathologic states and that BNP can be used as a biomarker for non-HF mechanisms, preclinical disease, and other pathologic states of myocardial disease.

Oral human brain natriuretic peptide activates cyclic guanosine 3',5'-monophosphate and decreases mean arterial pressure

BACKGROUND

The objective of this study was to address the feasibility and the biological activity of orally administered human brain natriuretic peptide (hBNP). Proprietary technology has been developed in which short, amphiphilic oligomers are covalently attached to peptides. The conjugated peptides are intended to have an improved pharmacokinetic profile and to enable oral administration. We hypothesized that novel oral conjugated hBNP (CONJ-hBNP) increases plasma hBNP, activates cGMP, and reduces mean arterial pressure (MAP).

METHODS AND RESULTS

This randomized crossover-designed study tested the biological activity of oral CONJ-hBNP compared with oral native hBNP in normal conscious dogs. Measurements of MAP, plasma hBNP, and cGMP were made at baseline (BL) and repeated at 10, 30, 60, 120, 180, and 240 minutes after oral administration. Plasma hBNP was not detectable in dogs at BL. Plasma hBNP was detected after native hBNP and CONJ-HBNP administration. However, plasma hBNP concentration was significantly higher after CONJ-hBNP than after native hBNP administration (P=0.0374 between groups). Plasma cGMP increased after CONJ-hBNP for 60 minutes (from 10.8+/-3 to 36.8+/-26 pmol/mL; P<0.05), whereas it did not change after native hBNP (P=0.001 between groups). MAP decreased at 10 minutes and remained decreased for 60 minutes after CONJ-hBNP (from 113+/-8 to 101+/-12 mm Hg after 10 minutes to 97.5+/-10 mm Hg after 30 minutes to 99+/-13 mm Hg after 60 minutes) while remaining unchanged after native hBNP (P=0.0387 between groups).

CONCLUSIONS

This study reports for the first time that novel conjugated oral BNP activates cGMP and significantly reduces MAP, thus implying an efficacious coupling of CONJ-hBNP to the natriuretic receptor-A. These data advance a new concept of orally administered chronic BNP therapy for cardiovascular diseases.

In-hospital mortality in patients with acute decompensated heart failure requiring intravenous vasoactive medications: an analysis from the Acute Decompensated Heart Failure National Registry (ADHERE)

OBJECTIVES

We sought to compare the in-hospital mortality of patients with acute decompensated heart failure (ADHF) who were receiving parenteral treatment with one of four intravenous vasoactive medications.

BACKGROUND

There are limited data regarding the effects of the choice of intravenous vasoactive medication on in-hospital mortality in patients hospitalized with ADHF.

METHODS

This was a retrospective analysis of observational patient data from the Acute Decompensated Heart Failure National Registry (ADHERE), a multicenter registry designed to prospectively collect data on each episode of hospitalization for ADHF and its clinical outcomes. Data from the first 65,180 patient episodes (October 2001 to July 2003) were included in this analysis. Cases in which patients received nitroglycerin, nesiritide, milrinone, or dobutamine were identified and reviewed (n = 15,230). Risk factor and propensity score-adjusted odds ratios (ORs) for in-hospital mortality were calculated.

RESULTS

Patients who received intravenous nitroglycerin or nesiritide had lower in-hospital mortality than those treated with dobutamine or milrinone. The risk factor and propensity score-adjusted ORs for nitroglycerin were 0.69 (95% confidence interval [CI] 0.53 to 0.89, p < or = 0.005) and 0.46 (94% CI 0.37 to 0.57, p < or = 0.005) compared with milrinone and dobutamine, respectively. The corresponding values for nesiritide compared with milrinone and dobutamine were 0.59 (95% CI 0.48 to 0.73, p < or = 0.005) and 0.47 (95% CI 0.39 to 0.56, p < or = 0.005), respectively. The adjusted OR for nesiritide compared with nitroglycerin was 0.94 (95% CI 0.77 to 1.16, p = 0.58).

CONCLUSIONS

Therapy with either a natriuretic peptide or vasodilator was associated with significantly lower in-hospital mortality than positive inotropic therapy in patients hospitalized with ADHF. The risk of in-hospital mortality was similar for nesiritide and nitroglycerin.

The Role of Brain Natriuretic Peptide in Systolic Heart Failure

Heart failure (HF) is a progressive multisystem disease that involves neurohormonal activation, dysfunction of cardiac and skeletal musculature, and a host of other pathological changes. The neurohormonal activation in HF triggers the release of the natriuretic peptides. One peptide of particular interest is brain natriuretic peptide (BNP). It is primarily released by the ventricles of the heart and has adaptive function in counteracting the effects of neurohormonal activation in patients with HF. The focus of this article is the discussion of the physiology of BNP as well as its role in systolic HF, although it also plays a role in diastolic HF.

Natriuretic Peptides in ESRD

Natriuretic peptides are involved in the regulation of volume homeostasis. Their levels generally are increased in the setting of volume expansion and act on multiple effector systems to cause vasodilation and natriuresis in an effort to return volume status back to normal. In patients with end-stage renal disease, the natriuretic capabilities of these peptides are limited. However, there has been much interest in the potential applicability of measurement of these peptides as a surrogate marker of volume status and in the determination of dry weight. Furthermore, atrial natriuretic peptide and brain natriuretic peptide can serve as markers of left ventricular dysfunction and may have utility in determining cardiac prognosis in patients on long-term dialysis therapy.

Natriuretic Peptides in the Perioperative Management of Cardiac Surgery Patients

Both heart failure (HF) and cardiac surgery with cardiopulmonary bypass result in a release of neurohormones, with a variety of physiologic effects. Administration of exogenous B-type natriuretic peptide (BNP) has beneficial hemodynamic effects and reduces the level of several neurohormones in HF patients. BNP is currently being investigated in the perioperative management of cardiac surgery patients and may be especially beneficial for patients with ventricular dysfunction, pulmonary hypertension, or renal dysfunction. Using a neurohormonal approach to supportive therapy may enhance future strategies for patients undergoing cardiac surgery, especially those at greatest risk for complications.

A review of the renal and neurohormonal effects of B-type natriuretic peptide

Adverse neurohormonal activation is an essential component in the pathogenesis of acute decompensated congestive heart failure (CHF). Consequently, blunting this activation is an important therapeutic goal. B-type natriuretic peptide (BNP) is a counterregulatory hormone produced by the ventricles in response to pressure and volume load. Endogenous BNP levels are significantly elevated in patients with acute CHF, but these levels are frequently inadequate to overcome the excess neurohormonal activation present in this condition. Infusion of nesiritide, a recombinant form of endogenous human BNP, increases circulating BNP levels by several-fold, augmenting the counterregulatory effects of this hormone. Clinical trials demonstrate that in patients with acute decompensated CHF, nesiritide produces arterial and venous vasodilation, reducing both preload and afterload; blunts adverse neurohormones, including renin, aldosterone, norepinephrine, and endothelin-1; and improves renal hemodynamics and tubular function. As a result, nesiritide quickly reduces clinical symptoms and improves mortality in patients with acute CHF.

AlbuBNP, a recombinant B-type natriuretic peptide and human serum albumin fusion hormone, as a long-term therapy of congestive heart failure

PURPOSE

B-type natriuretic peptide (BNP) has been in clinical use for the treatment of decompensated congestive heart failure. However, BNP has a very short half-life in circulation, which limits its application to acute CHF and requires continuous i.v. infusion. To provide superior pharmacological benefits of BNP to other stages of chronic congestive heart failure and to eliminate problems associated with drug delivery via continuous i.v. infusion, we have designed and evaluated AlbuBNP, a long-acting form of BNP by recombinant fusion to human serum albumin for use in chronic congestive heart failure, post-acute follow-up, and postmyocardial infarction.

METHODS

Human BNP (1-32) was seamlessly fused to mature human serum albumin at N-terminus to create AlbuBNP. The bioactivities of AlbuBNP were evaluated by natriuretic peptide receptor-A mediated cGMP activation assay, hemodynamic responses, and plasma cGMP elevation. The pharmacokinetic properties were determined after single i.v. or s.c. bolus injection in C57/BL6 mice.

RESULTS

AlbuBNP had approxiamtely the same maximal bioactivity as BNP to activate cGMP in the in vitro NPRA/cGMP assay. The EC50s were 28.4+/-1.2 and 0.46+/-1.1 nM for AlbuBNP and BNP, respectively. In spontaneously hypertensive rats, AlbuBNP lowered both systolic and diastolic blood pressure, having sustainable mean arterial pressure reduction for more than 2 days. Six nmol/kg AlbuBNP i.v. bolus in mice increased plasma cGMP level 5.6-fold over the baseline. The elimination half-life in mice was dramatically increased from 3 min for BNP to 12-19 h for AlbuBNP.

CONCLUSIONS

AlbuBNP is bioactive and has desired pharmacokinetic properties for long-term use. It has the potential to be further developed as a new therapeutic option for chronic, acute, and post-acute CHF to alleviate symptoms, improve clinical status, and slow the disease progression by sustained drug exposure via infrequent simple subcutaneous injections.

Nesiritide added to standard care favorably reduces systolic blood pressure compared with standard care alone in patients with acute decompensated heart failure

The Prospective Randomized Outcomes study of Acutely decompensated Congestive heart failure Treated Initially as Outpatients with Nesiritide (PROACTION) trial evaluated the safety of nesiritide administration in the emergency department in patients with decompensated heart failure. Patients (N=237) were treated for at least 12 hours with standard care plus either intravenous nesiritide or placebo. Compared to placebo, nesiritide favorably decreased systolic blood pressure (SBP) in patients with elevated baseline SBP, without negatively impacting patients with lower baseline SBP (SBP, >140 mm Hg: nesiritide, -28.7 mm Hg, vs placebo, -8.4 mm Hg [P<.001]; SBP, 101-140 mm Hg: nesiritide, -12.3 mm Hg, vs placebo, -5 mm Hg [P<.017]; SBP, <101 mm Hg: nesiritide, -1.2 mm Hg vs placebo, +16.7 mm Hg [P<.03]). Both treatment groups had similar incidences of symptomatic and asymptomatic hypotension. These data demonstrate that early administration of nesiritide in the emergency department is a safe and effective treatment of heart failure.

Novel markers for heart failure diagnosis and prognosis

PURPOSE OF REVIEW

This paper reviews recent advances in heart failure biomarkers for identification of disease precursors, subclinical disease, and onset or progression of overt disease.

RECENT FINDINGS

Heart failure biomarkers can be categorized empirically as neurohormonal mediators, markers of myocyte injury and remodeling, and indicators of systemic inflammation. Brain natriuretic peptide is the most widely studied, with a potentially important but evolving role for determining prognosis and as a surrogate endpoint in clinical trials. Strong evidence exists for use of brain natriuretic peptide in the diagnosis of acute heart failure and for improved clinical outcomes with a brain natriuretic peptide-guided approach to heart failure care. The use of brain natriuretic peptide as a screening tool for asymptomatic left ventricular systolic dysfunction, or to distinguish systolic from diastolic heart failure, is not supported by current data. Markers of myocyte injury, including troponins, heart-type fatty acid binding protein, and myosin light chain-1, may further improve heart failure prognostication in conjunction with plasma brain natriuretic peptide. Biomarkers of matrix remodeling and inflammation have emerged as potential preclinical indicators to identify individuals at risk of developing clinical heart failure. A role for cellular adhesion molecules may also emerge in identifying those at risk for cardiovascular thrombotic complications, such as stroke.

SUMMARY

The spectrum of heart failure biomarkers and their potential clinical applications continues to grow. Ongoing research on multimarker strategies will likely identify biomarker combinations that are optimal at various stages during the evolution of heart failure, ranging from their use for screening, diagnosis, determining prognosis, and guiding management.

Assessment of myocardial viability

The prevalence of left ventricular (LV) dysfunction and resultant congestive heart failure is increasing. Patients with this condition are at high risk for cardiac death and usually have significant limitations in their lifestyles. Although there have been advances in medical therapy resulting in improved survival and well being, the best and most definitive therapy, when appropriate, is revascularization. In the setting of coronary artery disease, accounting for approximately two thirds of cases of congestive heart failure, LV dysfunction often is not the result of irreversible scar but rather caused by impairment in function and energy use of still viable-myocytes, with the opportunity for improved function if coronary blood flow is restored. Patients with LV dysfunction who have viable myocardium are the patients at highest risk because of the potential for ischemia but at the same time benefit most from revascularization. It is important to identify viable myocardium in these patients, and radionuclide myocardial scintigraphy is an excellent tool for this. Single-photon emission computed tomography perfusion scintigraphy, whether using thallium-201, Tc-99m sestamibi, or Tc-99m tetrofosmin, in stress and/or rest protocols, has consistently been shown to be an effective modality for identifying myocardial viability and guiding appropriate management. Metabolic imaging with positron emission tomography radiotracers frequently adds additional information and is a powerful tool for predicting which patients will have an improved outcome from revascularization, including some patients referred instead for cardiac transplantation. Other noninvasive modalities, such as stress echocardiography, also facilitate the assessment of myocardial viability, but there are advantages and disadvantages compared with the nuclear techniques. Nuclear imaging appears to require fewer viable cells for detection, resulting in a higher sensitivity but a lower specificity than stress echocardiography for predicting post-revascularization improvement of ventricular function. Nevertheless, it appears that LV functional improvement may not always be necessary for clinical improvement. Future directions include use of magnetic resonance imaging, as well as larger, multicenter trials of radionuclide techniques. The increasing population of patients with LV dysfunction, and the increased benefit afforded by newer therapies, will make assessment of myocardial viability even more essential for proper patient management.

Practical application of human B-type natriuretic peptide as a therapeutic intervention in the perioperative setting

The use of human B-type natriuretic peptide (BNP, nesiritide) as a therapeutic intervention is now well established for patients with acute decompensated heart failure. Nesiritide mimics the actions of endogenous BNP by binding to and stimulating receptors in the heart, kidney, and vasculature. Postsurgical patients are typically managed with various combinations of vasodilators, diuretics, and inotropes. Many of these therapeutic interventions lack significant proof of efficacy and are potentially deleterious to these patients, despite the acute hemodynamic improvement that results from their use. Use of nesiritide may supplant some of these therapies as an equally efficacious and possibly safer alternative in patients with decompensated heart failure. Nesiritide is a unique, balanced vasodilator that markedly decreases the signs and symptoms of heart failure in perioperative patients, and also may decrease the need for inotropic agents. This review summarizes nesiritide's mechanism of action and addresses special concerns and practical considerations for cardiothoracic surgeons and anesthesiologists. Overall, nesiritide appears to be an effective and safe therapeutic option in perioperative patients with decompensated heart failure.

Risk of Worsening Renal Function With Nesiritide in Patients With Acutely Decompensated Heart Failure

Background— Renal function is an important prognostic factor for patients with acutely decompensated heart failure (ADHF). We investigated the renal effects of nesiritide as treatment for ADHF.

Methods and Results— Randomized clinical trials comparing nesiritide with either placebo or active control for ADHF were identified by electronic and manual searches and thorough review of US Food and Drug Administration files available via the website. Worsening renal function was defined as an increase in serum creatinine >0.5 mg/dL. Relative risk across all studies was determined by meta-analysis with Mantel-Haenszel fixed-effects models (RR MH ). Risk of dialysis and medical intervention for worsening renal function were compared between therapies. Frequency of worsening renal function was determined from 5 randomized studies that included 1269 patients. Use of Food and Drug Administration–approved doses of nesiritide (≤0.03 μg · kg −1 · min −1 ) significantly increased the risk of worsening renal function compared with non–inotrope-based control (RR MH , 1.52; 95% CI, 1.16 to 2.00; P =0.003) or any control therapy, including non–inotrope- and inotrope-based therapies (RR MH , 1.54; 95% CI, 1.19 to 1.98; P =0.001). Even low-dose nesiritide (≤0.015 μg · kg −1 · min −1 ) significantly increased risk ( P =0.012 and P =0.006 compared with non–inotrope- and inotrope-based controls, respectively), as did nesiritide administered at any dose up to 0.06 μg · kg −1 · min −1 ( P =0.002 and P =0.001, respectively). There was no difference in the need for dialysis between therapies.

Conclusions— Nesiritide significantly increases the risk of worsening renal function in patients with ADHF. Whether worsening renal function reflects hemodynamic effect or renal injury is unknown, but the prognostic importance of worsening renal function suggests the need for further investigation in appropriately powered clinical trials.

Genetic expression profiles during physiological and pathological cardiac hypertrophy and heart failure in rats

Cardiac hypertrophy is a complex and nonhomogenous response to various stimuli. In this study, we used high-density oligonucleotide microarray to examine gene expression profiles during physiological hypertrophy, pathological hypertrophy, and heart failure in Dahl salt-sensitive rats. There were changes in 404/3,160 and 874/3,160 genes between physiological and pathological hypertrophy and the transition from hypertrophy to heart failure, respectively. There were increases in stress response genes (e.g., heat shock proteins) and inflammation-related genes (e.g., pancreatitis-associated protein and arachidonate 12-lipoxygenase) in pathological processes but not in physiological hypertrophy. Furthermore, atrial natriuretic factor and brain natriuretic protein showed distinctive changes that are very specific to different conditions. In addition, we used a resampling-based gene score-calculating method to define significantly altered gene clusters, based on Gene Ontology classification. It revealed significant alterations in genes involved in the apoptosis pathway during pathological hypertrophy, suggesting that the apoptosis pathway may play a role during the transition to heart failure. In addition, there were significant changes in glucose/insulin signaling, protein biosynthesis, and epidermal growth factor signaling during physiological hypertrophy but not during pathological hypertrophy.

Nesiritide for secondary pulmonary hypertension in patients with end-stage heart failure

PURPOSE

The impact of adding nesiritide to standard therapy and positive inotropic agents in patients with end-stage heart failure and secondary pulmonary hypertension (PH) was studied.

METHODS

Patients included in this retrospective study were 18 years of age or older, admitted to the hospital with PH secondary to end-stage heart failure (New York Heart Association functional class IV), had received a pulmonary artery catheter, had been treated with nesiritide because of inadequate hemodynamic response to previous therapy (pulmonary capillary wedge pressure [PCWP], >18 mm Hg), and had shown minimal symptomatic benefit from standard heart-failure therapy, continuous infusions of loop diuretics, and positive inotropic agents (milrinone or dobutamine or both). The primary endpoint was change in PCWP. Secondary endpoints included change in mean pulmonary artery pressure (MPAP), change in cardiac index (CI), change in mean arterial pressure (MAP), change in serum creatinine (SCr) concentration, and occurrence of symptomatic hypotension.

RESULTS

The study included 33 patients. Mean PCWP was reduced by 31.1% with the addition of nesiritide to previous therapy (p < 0.0001). Significant improvements in other hemodynamic variables, including MPAP (15.6% reduction) and CI (13.0% increase), were also observed. MAP was reduced significantly (by 15.2%), but SCr concentration did not change. There were five episodes of symptomatic hypotension. All patients exhibited relief of dyspnea symptoms.

CONCLUSION

The addition of nesiritide to standard therapy and positive inotropic agents improved hemodynamic measures and clinical symptoms in patients with end-stage heart failure and secondary pulmonary hypertension.

Atrial BNP endocrine function during chronic unloading of the normal canine heart

The goal of the study was to define the effect of chronic unloading of the normal heart on atrial endocrine function with a focus on brain natriuretic peptide (BNP), specifically addressing the role of load and neurohumoral stimulation. Although produced primarily by atrial myocardium in the normal heart, controversy persists with regard to load-dependent vs. neurohumoral mechanisms controlling atrial BNP synthesis and storage. We used a unique canine model of chronic unloading of the heart produced by thoracic inferior vena caval constriction (TIVCC), which also resulted in activation of plasma endothelin (ET-1), ANG II, and norepinephrine (NE), known activators of BNP synthesis, compared with sham. TIVCC was produced by banding of the inferior vena cava for 10 days (n = 6), whereas in control (n = 5) the band was not constricted (sham). In a third group (n = 7), the band was released on day 11, thus acutely reloading the heart. Chronic TIVCC decreased cardiac output and right atrial pressure with a decrease in atrial mass index consistent with atrial atrophy. Atrial BNP mRNA decreased compared with sham. Immunoelectron microscopy revealed an increase in BNP in atrial granules consistent with increased storage. Acute reloading increased cardiac filling pressures and resulted in an increase in plasma BNP. We conclude that chronic unloading of the normal heart results in atrial atrophic remodeling and in suppression of atrial BNP mRNA despite intense stimulation by ET, ANG II, and NE, underscoring the primacy of load in the control of atrial endocrine function and structure.

Biomarker Responses during and after Treatment with Nesiritide Infusion in Patients with Decompensated Chronic Heart Failure

Background: Objective methods to assess the adequacy of medication therapy for patients with advanced heart failure are lacking. Serial measurements of biomarkers might be beneficial. Therapy guided by N-terminal pro-B-type natriuretic peptide (NT-proBNP) might be helpful because NT-proBNP should be lowered by therapies that decrease endogenous BNP secretion.

Methods: NT-proBNP and BNP were measured in a nonconsecutive patient cohort receiving clinically indicated intravenous nesiritide. Blood samples were drawn before, at 6 and 24 h during, and at 6 h after infusion. A reduction in NT-proBNP was defined as a decrease from baseline during infusion (“infusion responders”) of &gt;3 SD of the variability of the assay measurement (∼20%). Patients with decreases &gt;20% in both NT-pro BNP and BNP at 6 h post infusion were designated “biochemical responders”.

Results: Forty patients [27 males; mean (SE) age, 68 (2) years; mean (SE) left ventricular ejection fraction, 25 (1.4)%] were studied. All patients improved clinically. Overall, the changes in NT-proBNP were a 18 (4.6)% [mean (SE)] and 19.8% (median) decrease from baseline at 24 h of infusion and a 22 (6.0)% and 17.8% decrease at 6 h post infusion (P &lt;0.001 compared with baseline). In a large number of patients, decreases in NT-proBNP were, however, within the variability of the assay. Subgroup analysis showed that 22 of 40 patients were infusion responders with a &gt;20% decrease from baseline in NT-proBNP during nesiritide infusion, whereas only 12 patients were biochemical responders with &gt;20% decreases from baseline postinfusion for both NT-proBNP and BNP.

Conclusions: In this study, many patients had decreased NT-proBNP and BNP values after therapy with nesiritide, but the majority of patients did not demonstrate biochemically significant decreases in analytes despite a clinical response. Until we know more about the responses of natriuretic peptides to therapies such as nesiritide, a strategy of monitoring NT-proBNP and BNP to guide therapy cannot be universally advocated.

The Role of Hospitalists in the Management of Acute Decompensated Heart Failure

Heart failure and episodes of acute decompensated heart failure have an important effect on the US health care system, especially the elderly Medicare population. Efforts to improve the quality of care for patients hospitalized with acute decompensated heart failure have focused on creating standardized treatment guidelines based on substantial clinical evidence, but inadequate implementation of these guidelines continues to result in excess morbidity and mortality from heart failure. Hospitalists specializing in inpatient treatment strategies may play an important role in implementing clinical guidelines because their main commitment is to overall clinical treatment of inpatients. This review focuses on current recommended guidelines for diagnosis, treatment, and long-term management of patients with acute decompensated heart failure and the hospitalist's role in providing the oversight needed to adhere to these guidelines and manage this complex disease state.

Current and future uses of nesiritide

Nesiritide, recombinant human B-type natriuretic peptide, is an intravenous vasodilator that is used to treat acutely decompensated heart failure. In addition to its modest diuretic and natriuretic properties, nesiritide reduces intracardiac filling pressures, increases cardiac index and improves symptoms. Long-term safety data are accruing, and a number of ongoing clinical trials will explore the potential benefit of nesiritide in a variety of clinical situations: peri-operative cardiac surgery, serial out-patient infusions, continuous out-patient or pretransplant infusions, and infusions in patients with pulmonary hypertension, bronchospasm, renal insufficiency, and acute coronary syndromes. Alternative delivery methods also are under development.

Clinical and Hemodynamic Effects of Nesiritide (B-Type Natriuretic Peptide) in Patients With Decompensated Heart Failure Receiving ? Blockers

The use of beta blockers in congestive heart failure presents a therapeutic challenge for patients with acute episodes of decompensation. Such patients may be less responsive to positive inotropic agents, whereas the beneficial effects of nesiritide, which are not dependent on the beta-adrenergic receptor signal-transduction pathway, may be preserved. This analysis of the Vasodilation in the Management of Acute CHF trial evaluated the safety and efficacy of nesiritide in decompensated congestive heart failure patients receiving beta blockers. The Vasodilation in the Management of Acute CHF trial was a multicenter, randomized, controlled evaluation of nesiritide in 489 hospitalized patients with decompensated congestive heart failure. One hundred twenty-three patients were on chronic beta-blocker therapy at enrollment (31 randomized to placebo, 50 to nesiritide, and 42 to nitroglycerin). Primary end points included pulmonary capillary wedge pressure and dyspnea evaluation at 3 hours. Patients receiving nesiritide, but not IV nitroglycerin, had significantly reduced pulmonary capillary wedge pressure vs. placebo at 3 hours regardless of beta-blocker use. The use of beta blockers did not alter the beneficial effects of nesiritide on systemic blood pressure, heart rate, or dyspnea evaluation. In nesiritide-treated subjects, safety profiles were similar regardless of beta-blocker use. Thus, the clinical and hemodynamic benefits and safety of nesiritide are preserved in decompensated congestive heart failure patients receiving chronic beta blockade.

B-type natriuretic peptide in heart failure: diagnostic, prognostic, and therapeutic use

Chronic heart failure affects nearly 5 million people living in the United States, and the majority of economic burden is the result of hospitalizations for acute decompensated congestive heart failure. Patient history and symptom assessment, physical examination, and chest radiography remain the cornerstones of diagnosis and prognostic assessment. Evaluation of endogenous B-type natriuretic peptide (BNP) has emerged as a useful addition to standard methods for diagnosis and risk stratification of suspected congestive heart failure, and final diagnosis requires integration of BNP assays with traditional methods. BNP levels >500 pg/mL are more likely to be comfirmative of a primary diagnosis of heart failure and are also important predictors for long-term adverse prognosis; >100 pg/mL but <500 pg/mL suggests a reasonable likelihood for the diagnosis of heart failure but does require thoughtful exclusion of other potential confounders such as pulmonary disease resulting in right heart failure; and <100 indicates that heart failure is very unlikely. Positive physiological effects of BNP, including improvements in hemodynamics, suppression of neurohormonal activity, preservation of renal function, diuresis and natriuresis, and balanced arterial and venous dilatation have suggested that this peptide also may have therapeutic use in congestive heart failure. In clinical trials, treatment of patients with acute decompensated congestive heart failure with nesiritide, a recombinant form of human BNP, was shown to significantly reduce pulmonary capillary wedge pressure versus placebo plus standard care, as well as provide a significant improvement in dyspnea versus placebo. Diagnostic, prognostic, and therapeutic applications of BNP can be integrated easily with standard methods to provide physicians with a useful evaluation and treatment algorithm that may result in faster identification of patients likely to benefit from early therapy, including nesiritide, thereby leading to the potential for more favorable patient outcomes.

Recent advances in natriuretic peptides in congestive heart failure

Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are secreted by the heart and play important roles in the compensation of congestive heart failure with their vasodilating, natriuretic, antiproliferative, lusitropic and neurohumoral-modulating properties. Based on these beneficial properties, exogenous BNP was developed as a new treatment for congestive heart failure and approved in the US for acute decompensated heart failure. New therapeutic strategies for heart failure that are currently being investigated include chronic subcutaneous BNP administration and intermittent BNP infusions. Furthermore, strategies combining exogenous BNP with an inhibitor of the BNP-degrading enzyme neutral endopeptidase could contribute to maximising the actions of BNP and reduce the amount of exogenous BNP needed.

Determinants of B-type natriuretic peptide plasma levels in the chronic phase after heart transplantation*

Determinants of B-type natriuretic peptide (BNP) plasma levels in the chronic phase after heart transplantation remain unclear. BNP was measured in 105 stable long-term heart transplant recipients with normal left ventricular function by echocardiography and correlated with clinical, demographic and hemodynamic parameters. Multivariate analysis revealed a significant correlation of BNP with female recipient gender (P = 0.006), time post-transplant (P =0.006), donor age (P = 0.007), angiographic signs of transplant vasculopathy (TVP) (P = 0.03), serum creatinine level (P = 0.04), and a strong trend for diastolic dysfunction (P = 0.09). Donor gender, recipient age, cyclosporin A blood levels, rejection history, and pulmonary artery pressure had no independent effect on BNP. BNP after heart transplantation appears to be influenced both by established general determinants (female gender, renal function) and transplant-specific determinants such as time post-transplant, donor age and potentially also TVP. In order to determine the value of BNP as a potential surrogate marker of TVP serial intraindividual measurements appear appropriate.

Nesiritide during extracorporeal membrane oxygenation

Nesiritide is a recombinant formulation of B-type natriuretic peptide (BNP). Preliminary experience in the adult population has shown nesiritide to be an effective agent in the treatment of decompensated congestive heart failure (CHF) in adults. Given its physiological effects, it may be an effective agent in other clinical scenarios. We report the use of nesiritide in two infants during extracorporeal membrane oxygenation (ECMO). In one patient, nesiritide in doses up to 0.09 microg.kg(-1).min(-1) were used to control mean arterial pressure while in the other patient, doses of 0.01-0.03 microg.kg(-1).min(-1) were used to augment urine output. The potential applications of nesiritide and dosing regimens for this agent in the ECMO population are discussed.

Cardiac natriuretic peptides for cardiac health

The cardiac natriuretic peptides, ANP (atrial natriuretic peptide) and BNP (brain natriuretic peptide), are secreted by the heart in proportion to cardiac transmural pressures. They possess a wide range of effects in multiple tissues facilitating overall pressure/volume homoeostasis. The close relationship between plasma concentrations of these peptides and 'cardiac load' has led to their use as biomarkers of cardiac health with diagnostic and prognostic applications in a variety of disorders affecting the cardiovascular system. BNP and its N-terminal fragment (NT-BNP) are especially sensitive indicators of cardiac dysfunction and remodelling, and correlate strongly with severity. Given that cardiac ischaemia is also an important trigger for the release of these ventricular peptides, they may likewise play a role in the detection of coronary artery disease. Measurement of BNP/NT-BNP shows particular promise as a 'rule out' test for suspected cases of HF (heart failure) in both emergency care and outpatient settings, and may assist in identifying individuals with asymptomatic ventricular impairment who will benefit from therapy preventing progression to overt HF. The BNP peptides also predict subsequent haemodynamic deterioration and adverse events in cardiovascular disease, and can therefore be used to monitor those at high risk and act as a guide to optimization of treatment. The favourable biological properties of the natriuretic peptides have also led to their use as therapeutic agents.

Nesiritide for the treatment of decompensated heart failure

Heart failure is the leading cause of hospitalizations in the USA, and is associated with significant morbidity, mortality and resource utilization. Established therapies for chronic heart failure have been shown to improve outcomes, but treatment for decompensated heart failure remains largely empiric. Nesiritide (Natrecor) is a synthetic analog of human B-type natriuretic peptide, a peptide released by the ventricular myocardium in response to increased wall tension. The physiologic effects of human B-type natriuretic peptide include natriuresis, vasodilation and neurohormonal modulation. In clinical trials, nesiritide has been shown to decrease cardiac filling pressures, increase cardiac index, and improve the clinical status of patients with acute decompensated heart failure. Compared with other available intravenous agents for heart failure, nesiritide is effective, generally well-tolerated with few adverse effects, and does not require invasive monitoring during administration. Nesiritide has proven to be an effective new treatment for patients with decompensated heart failure.

Treatment with B-Type Natriuretic Peptide for Chronic Decompensated Heart Failure: Insights Learned from the Follow-Up Serial Infusion of Nesiritide (FUSION) Trial

Several evidence-based treatment regimens are modestly effective in patients with moderately severe to severe heart failure, but truly effective therapies that improve symptoms, reduce hospitalizations, and extend meaningful survival do not exist for these patients. Only ventricular replacement therapy, with either heart transplantation or left ventricular assist devices, has been shown to significantly improve outcomes. Nesiritide, a recombinant B-type natriuretic peptide, is associated with significant reductions in filling pressure, with corresponding relief of symptoms, and diminished neurohormonal levels and has no inotropic effects and no evidence of proarrhythmia when given to patients with decompensated acute heart failure. Results of the Follow-Up Serial Infusion of Nesiritide (FUSION) trial suggest that a regimen incorporating nesiritide can be accomplished with a reasonable assurance of safety and tolerability; pre-study concerns regarding hypotension were not realized. A qualified look at outcomes data within FUSION I suggests that further study of this paradigm is reasonable, especially if the studied patient population includes patients with a low left ventricular ejection fraction and New York Heart Association (NYHA) class III disease with renal insufficiency, or patients with low left ventricular ejection fraction and NYHA class IV heart failure. Therefore, FUSION II, a double-blind, placebo-controlled trial, will randomly assign approximately 900 such patients to treatment with usual care plus nesiritide or usual care plus placebo and will use mortality/cardiorenal hospitalization as a composite end point. If positive data emerge from FUSION II that either confirm or strengthen the data in FUSION I, a new therapeutic option may be available for patients with chronic decompensated heart failure.

Brain natriuretic peptide in the contemporary management of congestive heart failure

Brain natriuretic peptide is a cardiac neurohormone that is secreted by the left ventricle in response to an increase in wall stress. Brain natriuretic peptide has emerged as a neurohormone with multiple roles in heart failure management. This review will discuss the role of brain natriuretic peptide in heart failure diagnosis, prognostic assessment, screening for asymptomatic left-ventricular dysfunction, and in the treatment of heart failure.

Equimolar doses of atrial and brain natriuretic peptides and urodilatin have differential renal actions in overt experimental heart failure

A hallmark of overt congestive heart failure (CHF) is attenuated cGMP production by endogenous atrial natriuretic peptide (ANP) with renal resistance to ANP. ANP and brain natriuretic peptides (BNP) are of myocardial origin, whereas urodilatin (Uro) is thought to be derived from kidney. All three peptides are agonists to the natriuretic peptide-A receptor. Our objective was to compare the cardiorenal and humoral actions of ANP, BNP, and Uro in experimental overt CHF. We determined cardiorenal and humoral actions of 90 min of intravenous equimolar infusion of ANP, BNP, and Uro (2 and 10 pmol.kg-1.min-1) in three separate groups of anesthetized dogs with rapid ventricular pacing-induced overt CHF (240 beats/min for 10 days). BNP resulted in increases in urinary sodium excretion (U(Na)V) (2.2+/-0.7 to 164+/-76 microeq/min, P<0.05) and glomerular filtration rate (GFR) (27+/-4 to 52+/-11 ml/min, P<0.05) that were greater than those with Uro (P<0.05), whereas ANP did not result in increases in U(Na)V or GFR. Increases in plasma cGMP (25+/-2 to 38+/-2 pmol/ml, P<0.05) and urinary cGMP excretion with BNP (1,618+/-151 to 6,124+/-995 pmol/min, P<0.05) were similar to those with Uro; however, there was no change with ANP. Cardiac filling pressures were reduced in all three groups. These studies also support the conclusion that in experimental overt CHF, renal resistance to natriuretic peptides in increasing rank order is BNP<Uro<ANP.

Nesiritide use in pediatric patients with congestive heart failure

Nesiritide (B-type natriuretic peptide) is one of the newest therapies available in the treatment of adults with decompensated congestive heart failure (CHF). It rapidly improves hemodynamics and induces diuresis in adult patients with moderate to severe CHF. This report details our experience with nesiritide in 4 pediatric cases in 3 subjects with chronic CHF of various causes. As described in adults, our patients generally diuresed and had symptomatic improvement in response to the infusion with only dose-related hypotension and asymptomatic hyponatremia as recognized side effects. Given the number of pediatric patients who progress to CHF as a result of myocarditis, cardiomyopathy, or failed palliation for complex congenital heart disease, we believe nesiritide has a role in managing acutely decompensated CHF in the pediatric population.

Overexpression of Brain Natriuretic Peptide Facilitates Neutrophil Infiltration and Cardiac Matrix Metalloproteinase-9 Expression After Acute Myocardial Infarction

Background— Recent clinical trials have shown that systemic infusion of nesiritide, a recombinant human brain natriuretic peptide (BNP), improves hemodynamic parameters in acutely decompensated hearts. This suggests that BNP exerts a direct cardioprotective effect and might thus be a useful therapeutic agent with which to treat acute myocardial infarction (MI). In the present study, we used BNP-transgenic (BNP-Tg) mice with elevated plasma BNP to determine whether and how BNP contributes to left ventricular remodeling and healing after MI.

Methods and Results— We examined the accumulation of neutrophils and the expression and activation of matrix metalloproteinase (MMP)-9 in the ventricles of male BNP-Tg mice and their nontransgenic (non-Tg) littermates during the early phase after acute MI. The numbers of neutrophils infiltrating the infarcted area were significantly increased in BNP-Tg mice 3 days after MI. In addition, both the gene expression and zymographic activity of MMP-9, but not MMP-2, were significantly higher in BNP-Tg than non-Tg mice. Double immunostaining revealed that neutrophils are the main source of the MMP-9, although doxycycline, an MMP inhibitor, had no effect on neutrophil infiltration of the infarcted area in BNP-Tg mice.

Conclusions— These results demonstrate that elevated plasma BNP facilitates neutrophil infiltration of the infarcted area after MI and increases the activity of the MMP-9 they produce. This suggests that BNP plays a key role in the processes of extracellular matrix remodeling and wound-healing during the early phase after acute MI.

Effect of nesiritide (human b-type natriuretic peptide) and dobutamine on heart rate variability in decompensated heart failure

BACKGROUND

Previous studies have suggested that natriuretic peptides may have direct sympathoinhibitory effects. Nesiritide (recombinant human B-type natriuretic peptide) has been recently approved for treatment of decompensated congestive heart failure (CHF). We sought to assess the effects of nesiritide compared with dobutamine on time-domain indices of heart rate variability (HRV) in patients with decompensated CHF.

METHODS

The study population consisted of 185 patients, who were randomized to intravenous nesiritide at a low (0.015 microg/kg/min, n = 56) or high (0.03 microg/kg/min, n = 58) dose, or to dobutamine (> or = 5 microg/kg/min, n = 58). Time-domain HRV indices were obtained from 24-hour Holter recordings immediately before and during study drug therapy.

RESULTS

Dobutamine therapy resulted in a decrease in standard deviation of the R-R intervals over a 24-hour period (SDNN), standard deviation of all 5-minute mean R-R intervals (SDANN), and the percentage of R-R intervals with >50 ms variation (pNN50) (all P < .05). Low-dose nesiritide induced an increase in SDNN (P < .05), and high-dose nesiritide resulted in a nonsignificant decrease in all measures of HRV. A significant interaction was noted between baseline HRV and the effect of vasoactive therapy on HRV (P = .028). Therefore, the effect of nesiritide and dobutamine was analyzed in relation to baseline HRV. In the dobutamine group, patients with moderately depressed HRV at baseline displayed a reduction in SDNN (P = .01), SDANN (P = .01), pNN50 (P = .04), and the square root of mean squared differences of successive R-R intervals (RMSSD) (P = .05), whereas no significant changes occurred in patients with severely depressed HRV. In the low-dose nesiritide group, patients with severely depressed HRV displayed an increase in SDNN (P = .001), SDANN (P = .02), and RMSSD (P = .01), with no significant changes in patients with moderately depressed HRV. HRV response to high-dose nesiritide was similar to that of dobutamine.

CONCLUSIONS

Low-dose nesiritide therapy in patients with decompensated CHF improves indices of overall HRV and parasympathetic modulation, particularly if HRV is severely depressed at baseline. Dobutamine and possibly high-dose nesiritide can potentially lead to further deterioration of autonomic dysregulation.

Neurohormonal therapy for congestive heart failure

Guidelines for heart failure management have been published by the American College of Cardiology and the American Heart Association in 2001. These guidelines recommend the use of angiotensin-converting enzyme inhibitors and beta blockers to improve the symptoms and prognosis of heart failure. Despite being advocated as the cornerstone of medical management, these agents remain underutilized. Not only are these drugs underutilized, but titration to dosages with proven beneficial effects is lacking. Simply achieving widespread usage of these agents would have a significant impact on heart failure outcomes.

The use of recombinant human B-type natriuretic peptide (nesiritide) in the management of acute decompensated heart failure

Nesiritide is a synthetic human B-type natriuretic factor that has a balanced arterial and venous dilator effect, with natriuretic, diuretic, anti-aldosterone and antisympathetic action. It was launched in the US for the treatment of acute decompensated heart failure (ADHF) in August 2001 and, recently, in Switzerland and Israel. It has been demonstrated to provide more rapid and sustained haemodynamic stabilisation than glyceryl trinitrate and significant symptomatic improvement vs. placebo at 3 h, and to be safer than dobutamine. The main side effects associated with nesiritide therapy are asymptomatic and symptomatic hypotension, which are treated with dose reduction. When compared to dobutamine, the increased acquisition costs of nesiritide are completely offset by reduced intensity of hospital admissions and reduced readmission rate at 3 weeks.