Effect of BNP on renal hemodynamics, tubular function and vasoactive hormones in humans

Use of Animal Models for Investigating Cardioprotective Roles of SGLT2 Inhibitors

Sodium-glucose co-transporter 2 (SGLT2) inhibitors represent one type of new-generation type 2 diabetes (T2DM) drug treatment. The mechanism of action of an SGLT2 inhibitor (SGLT2i) in treating T2DM depends on lowering blood glucose levels effectively via increasing the glomerular excretion of glucose. A good number of randomized clinical trials revealed that SGLT2is significantly prevented heart failure (HF) and cardiovascular death in T2DM patients. Despite ongoing clinical trials in HF patients without T2DM, there have been a limited number of translational studies on the cardioprotective properties of SGLT2is. As the cellular mechanism behind the cardiac benefits of SGLT2is is still to be elucidated, animal models are used to better understand the pathways behind the cardioprotective mechanism of SGLT2i. In this review, we summarize the animal models constructed to study the cardioprotective mechanisms of SGLT2is to help deliver a more comprehensive understanding of the in vivo work that has been done in this field and to help select the most optimal animal model to use when studying the different cardioprotective effects of SGLT2is.

Congestion and Use of Diuretics in Heart Failure and Cardiomyopathies: a Practical Guide

PURPOSE OF REVIEW

Heart failure is a highly prevalent condition caused by many different aetiologies and characterised by cardiac dysfunction and congestion. Once developed, congestion leads to signs (peripheral oedema) and symptoms (breathlessness on exertion), adverse cardiac remodelling, and an increased risk of hospitalisation and premature death. This review summarises strategies that could enable early identification and a more objective management of congestion in patients with heart failure.

RECENT FINDINGS

For patients with suspected or diagnosed heart failure, combining an echocardiogram with assessment of great veins, lungs, and kidneys by ultrasound might facilitate recognition and quantification of congestion, the management of which is still difficult and highly subjective. Congestion is a one of the key drivers of morbidity and mortality in patients with heart failure and is often under-recognised. The use of ultrasound allows for a timely, simultaneous identification of cardiac dysfunction and multiorgan congestion; ongoing and future studies will clarify how to tailor diuretic treatments in those with or at risk of heart failure.

Effect of sacubitril/valsartan on renal function: a systematic review and meta-analysis of randomized controlled trials

A worsening renal function is prevalent among patients with cardiovascular disease, especially heart failure (HF). Sacubitril/valsartan appears to prevent worsening of renal function and progression of chronic kidney disease (CKD) as compared with renin-angiotensin system (RAS) inhibitors alone in HF patients. It is unclear whether these advantages are present in HF patients only, or can be extended to other categories of patients, in which this drug was studied. We performed a systematic review and meta-analysis to assess the consistency of effect size regarding renal outcome across randomized controlled trials (RCTs) that compared sacubitril/valsartan with RAS inhibitors in patients with or without HF. We searched Medline (PubMed), Scopus, and Thomson Reuters Web of Science databases until June 2020. We took into account RCTs that compared sacubitril/valsartan with a RAS inhibitor and reported data regarding renal function. We used random-effects models to obtain summary odds ratio (OR) with 95% confidence interval (CI). We extracted hazard ratios for renal outcomes, glomerular filtration rate slopes or rates of renal adverse events. Sensitivity analyses were performed by moderator analysis and random-effects meta-regression. The search revealed 10 RCTs (published between 2012 and 2019) on 16 456 subjects. Sacubitril/valsartan resulted in a lower risk of renal dysfunction as compared with RAS inhibitors alone [k = 10; pooled OR = 0.70 (95% CI 0.57-0.85); P < 0.001], with a moderate inconsistency between studies [Q(9) = 15.18; P = 0.086; I²  = 40.73%]. A stronger association was found in studies including older patients (k = 10; β = -0.047730; P = 0.020) or HF patients with preserved ejection fraction [pooled OR = 0.53 (0.41-0.68) vs. 0.76 (0.57-1.01) for studies on HF patients with reduced ejection fraction; P for comparison = 0.065]. The effect size did not change with different comparators (angiotensin-converting enzyme inhibitors vs. angiotensin II type 1 receptor blockers, P = 0.279). No significant association was found when the analysis was restricted to studies on non-HF patients [k = 3; pooled OR = 0.86 (0.61-1.22); P = 0.403] and studies with high risk of bias [k = 3; pooled OR = 0.34 (0.08-1.44); P = 0.143]. Our findings support the role of sacubitril/valsartan on preservation of renal function, especially in older patients and HF patients with preserved ejection fraction. However, evidence is currently limited to HF patients, while the renal outcome of sacubitril/valsartan therapy outside the HF setting needs to be further investigated.

BNP as a Major Player in the Heart-Kidney Connection

Brain natriuretic peptide (BNP) is an important biomarker for patients with heart failure, hypertension and cardiac hypertrophy. Although it is known that BNP levels are relatively higher in patients with chronic kidney disease and no heart disease, the mechanism remains unknown. Here, we review the functions and the roles of BNP in the heart-kidney interaction. In addition, we discuss the relevant molecular mechanisms that suggest BNP is protective against chronic kidney diseases and heart failure, especially in terms of the counterparts of the renin-angiotensin-aldosterone system (RAAS). The renal medulla has been reported to express depressor substances. The extract of the papillary tips from kidneys may induce the expression and secretion of BNP from cardiomyocytes. A better understanding of these processes will help accelerate pharmacological treatments for heart-kidney disease.

Impact of Nesiritide Infusion on Early Postoperative Recovery After Total Cavopulmonary Connection Surgery

OBJECTIVE

The purpose of the study is to compare the effects of nesiritide on the discharge time and pleural effusion in children with total cavopulmonary connection (TCPC), and to provide a more reasonable clinical method for these children.

METHODS

Forty-four who children underwent cavopulmonary connection between January 2016 and 2017 were retrospectively collected, and 5 children were excluded from analysis due to postoperative thrombosis or second Fontan surgery due to high pulmonary hypertension. Thirteen children received nesiritide (3-11 days) plus conventional treatment as the nesiritide group, continuous infusion of nesiritide with the dose of 0.01 ug kg^-1 min^-1. Twenty-six children with the conventional treatment as the conventional treatment group. The length of stay in hospital and the retention time of chest drainage tube were compared between two groups.

RESULTS

There were no significant differences in the time of cardiopulmonary bypass, postoperative ventilation time, ICU time, and vasoactive inotropic drug scores in the two groups. There were no hospital deaths in two groups. The median hospital stay was 20 days in the nesiritide group (11-56 days, means 25 days), and the median length of hospital stay was 28 days in the routine treatment group (9-95 days, means 34 days). There is no statistically significant difference between two groups with regard to the length of stay in hospital (P = 0.281). Regarding the thoracic drainage duration, the median was 17 days (9-55 days, means 22 days) in the nesiritide group and 23 days in the conventional treatment group (7-91 days, means 31 days) (P = 0.294). All the patients had no severe complications such as excessive fluid load, intractable hypotension, and liver or kidney injury.

CONCLUSION

Nesiritide is safe in children who underwent cavopulmonary connection surgery. Compared with the conventional treatment group, postoperative nesiritide is not associated with improved early clinical outcomes after TCPC surgery.

Genome-Wide Association Study Implicates Atrial Natriuretic Peptide Rather Than B-Type Natriuretic Peptide in the Regulation of Blood Pressure in the General Population

BACKGROUND

Cardiomyocytes secrete atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in response to mechanical stretching, making them useful clinical biomarkers of cardiac stress. Both human and animal studies indicate a role for ANP as a regulator of blood pressure with conflicting results for BNP.

METHODS AND RESULTS

We used genome-wide association analysis (n=6296) to study the effects of genetic variants on circulating natriuretic peptide concentrations and compared the impact of natriuretic peptide-associated genetic variants on blood pressure (n=27 059). Eight independent genetic variants in 2 known (NPPA-NPPB and POC1B-GALNT4) and 1 novel locus (PPP3CC) associated with midregional proANP (MR-proANP), BNP, aminoterminal proBNP (NT-proBNP), or BNP:NT-proBNP ratio. The NPPA-NPPB locus containing the adjacent genes encoding ANP and BNP harbored 4 independent cis variants with effects specific to either midregional proANP or BNP and a rare missense single nucleotide polymorphism in NT-proBNP seriously altering its measurement. Variants near the calcineurin catalytic subunit gamma gene PPP3CC and the polypeptide N-acetylgalactosaminyltransferase 4 gene GALNT4 associated with BNP:NT-proBNP ratio but not with BNP or midregional proANP, suggesting effects on the post-translational regulation of proBNP. Out of the 8 individual variants, only those correlated with midregional proANP had a statistically significant albeit weak impact on blood pressure. The combined effect of these 3 single nucleotide polymorphisms also associated with hypertension risk (P=8.2×10-4).

CONCLUSIONS

Common genetic differences affecting the circulating concentration of ANP associated with blood pressure, whereas those affecting BNP did not, highlighting the blood pressure-lowering effect of ANP in the general population.

Potential Expanded Indications for Neprilysin Inhibitors

PURPOSE OF REVIEW

The goal of this article is to review potential expanded indications for neprilysin inhibitors. This article reviews the rationale and design for ongoing and future trials of sacubitril/valsartan in cardiovascular and non-cardiovascular disease.

RECENT FINDINGS

Randomized trial data are lacking for use of sacubitril/valsartan in acute heart failure and advanced heart failure. Mechanistic data from animal studies suggest a role for neprilysin inhibition in the treatment of post-myocardial infarction systolic dysfunction and heart failure with preserved ejection fraction. Beyond the cardiovascular system, renal and neurological function may be impacted by neprilysin inhibition. Forthcoming randomized trials will address the clinical impact of sacubitril/valsartan on these conditions. Neprilysin inhibition with sacubitril/valsartan offers a new therapeutic strategy with a broad range of potential therapeutic actions. In PARADIGM-HF, the combination of neprilysin and RAAS inhibition was proven to be superior to enalapril for patients with stable NYHA class II-III heart failure and reduced left ventricular ejection fraction. Preliminary data suggests it may also have a role in other cardiovascular and non-cardiovascular disease. Several ongoing and planned studies will determine the extent of its benefit for these other indications.

Novel Therapies for Heart Failure - Where Do They Stand?

Despite advances in therapy, patients with heart failure (HF) continue to experience unacceptably high rates of hospitalization and death, as well as poor quality of life. As a consequence, there is an urgent need for new treatments that can improve the clinical course of the growing worldwide population of HF patients. Serelaxin and ularatide, both based on naturally occurring peptides, have potent vasodilatory as well as other effects on the heart and kidneys. For both agents, phase 3 studies that are designed to determine whether they improve outcomes in patients with acute HF have completed enrollment. TRV027, a biased ligand for the type 1 angiotensin receptor with effects that extend beyond traditional angiotensin-receptor blockers is also being studied in the acute HF population. Omecamtiv mecarbil, an inotropic agent that improves myocardial contractility by a novel mechanism, and vericiguat, a drug that stimulates soluble guanylate cyclase, are both being developed to treat patients with chronic HF. Finally, despite the negative results of the CUPID study, gene transfer therapy continues to be explored as a means of improving the function of the failing heart. The basis for the use of these drugs and their current status in clinical trials are discussed. (Circ J 2016; 80: 1882-1891).

Renal Insufficiency After Cardiac Surgery

The new millennium ushered in a number of changes in cardiac surgery. Off-pump coronary artery bypass surgery became technically easier so that multivessel surgery became less of a challenge and cardiologists were supplied with new catheters that accessed lesions that were previously thought of as being unapproachable. New drugs were introduced that made the management of heart failure patients feasible on an outpatient basis, and new devices extend the bridging period to transplantation. However, these advances have not necessarily been attended by significant improvements in outcome, possibly because the less challengng a procedure becomes, the sicker the patients that can be managed. This observation is particularly true with the incidence and outcome of renal failure after cardiac surgery. Bypass factors have been manipulated without much effect, and the traditional drugs that were found to increase renal blood flow in animal experiments did not translate into clinical improvement in renal outcome. Recent research has given us insight into the pathophysiology of ischemic acute renal failure, and it has been found that the paradigm was not as simple as previously thought, possibly accounting for the failure of the more traditional renal drugs (dopamine, mannitol and diuretics). However, these new insights open up the possibility of novel targets for renal protection and repair.

Utilizing cardiac biomarkers to detect and prevent chemotherapy-induced cardiomyopathy

The success achieved in advances in cancer therapy has been marred by development of cardiotoxicity, which causes significant morbidity and mortality. This has led to the development of surveillance protocols for cardiotoxicity utilizing multimodality imaging techniques and investigation of various drugs to treat and prevent cardiotoxicity in this subset of patients. Cardiac biomarkers hold important diagnostic and prognostic value in various cardiac diseases. In this review, we discuss the use of biomarkers in patients receiving chemotherapy, highlighting data behind the use of troponin, B-type natriuretic peptide, and myeloperoxidase. We also discuss the use of dexrazoxane, angiotensin-converting enzyme inhibitors, and beta blockers in the treatment and prevention of chemotherapy-induced cardiotoxicity. Cardiac biomarkers may serve an important role in selecting patients that are at high risk of cardiotoxicity and can potentially be used to guide the administration of drugs to treat and prevent cardiotoxicity.

Serum biomarkers for the detection of cardiac toxicity after chemotherapy and radiation therapy in breast cancer patients

Multi-modality cancer treatments that include chemotherapy, radiation therapy, and targeted agents are highly effective therapies. Their use, especially in combination, is limited by the risk of significant cardiac toxicity. The current paradigm for minimizing cardiac morbidity, based on serial cardiac function monitoring, is suboptimal. An alternative approach based on biomarker testing, has emerged as a promising adjunct and a potential substitute to routine echocardiography. Biomarkers, most prominently cardiac troponins and natriuretic peptides, have been evaluated for their ability to describe the risk of potential cardiac dysfunction in clinically asymptomatic patients. Early rises in cardiac troponin concentrations have consistently predicted the risk and severity of significant cardiac events in patients treated with anthracycline-based chemotherapy. Biomarkers represent a novel, efficient, and robust clinical decision tool for the management of cancer therapy-induced cardiotoxicity. This article aims to review the clinical evidence that supports the use of established biomarkers such as cardiac troponins and natriuretic peptides, as well as emerging data on proposed biomarkers.

Natriuretic peptides buffer renin-dependent hypertension

The renin-angiotensin-aldosterone system and cardiac natriuretic peptides [atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP)] are opposing control mechanisms for arterial blood pressure. Accordingly, an inverse relationship between plasma renin concentration (PRC) and ANP exists in most circumstances. However, PRC and ANP levels are both elevated in renovascular hypertension. Because ANP can directly suppress renin release, we used ANP knockout (ANP−/−) mice to investigate whether high ANP levels attenuate the increase in PRC in response to renal hypoperfusion, thus buffering renovascular hypertension. ANP−/− mice were hypertensive and had reduced PRC compared with that in wild-type ANP+/+ mice under control conditions. Unilateral renal artery stenosis (2-kidney, 1-clip) for 1 wk induced similar increases in blood pressure and PRC in both genotypes. Unexpectedly, plasma BNP concentrations in ANP−/− mice significantly increased in response to two-kidney, one-clip treatment, potentially compensating for the lack of ANP. In fact, in mice lacking guanylyl cyclase A (GC-A−/− mice), which is the common receptor for both ANP and BNP, renovascular hypertension was markedly augmented compared with that in wild-type GC-A+/+ mice. However, the higher blood pressure in GC-A−/− mice was not caused by disinhibition of the renin system because PRC and renal renin synthesis were significantly lower in GC-A−/− mice than in GC-A+/+ mice. Thus, natriuretic peptides buffer renal vascular hypertension via renin-independent effects, such as vasorelaxation. The latter possibility is supported by experiments in isolated perfused mouse kidneys, in which physiological concentrations of ANP and BNP elicited renal vasodilatation and attenuated renal vasoconstriction in response to angiotensin II.

Effects of nesiritide and predictors of urine output in acute decompensated heart failure: results from ASCEND-HF (acute study of clinical effectiveness of nesiritide and decompensated heart failure)

OBJECTIVES

This study sought to determine if nesiritide increases diuresis in congestive heart failure patients.

BACKGROUND

In the ASCEND-HF (Acute Study of Clinical Effectiveness of Nesiritide and Decompensated Heart Failure), 7,141 patients hospitalized with acute decompensated heart failure (ADHF) were randomized to receive nesiritide or placebo for 24 to 168 h, in addition to standard care. There were minimal effects of nesiritide on survival, future hospitalizations, and symptoms. However, whether or not nesiritide increases diuresis in ADHF patients is unknown.

METHODS

Urine output was measured in 5,864 subjects; of these, 5,320 received loop diuretics and had dose data recorded. Loop diuretics other than furosemide were converted to furosemide equivalent doses. A total of 4,881 patients had complete data. We used logistic regression models to identify the impact of nesiritide on urine output and the factors associated with high urine output.

RESULTS

Median (25th, 75th percentiles) 24-h urine output was 2,280 (1,550, 3,280) ml with nesiritide and 2,200 (1,550, 3,200) ml with placebo (p = NS). Loop diuretic dose (furosemide equivalent) was 80 (40, 140) mg with both nesiritide and placebo. Diuretic dose was a strong predictor of urine output. Other independent predictors included: male sex, greater body mass index, higher diastolic blood pressure, elevated jugular venous pressure, recent weight gain, and lower blood urea nitrogen. The addition of nesiritide did not change urine output. None of the interaction terms between nesiritide and predictors affected the urine output prediction.

CONCLUSIONS

Nesiritide did not increase urine output in patients with ADHF. Higher diuretic dose was a strong predictor of higher urine output, but neurohormonal activation (as evidenced by blood urea nitrogen concentration) and lower blood pressure limited diuresis.

Demonstration of natriuretic activity in urine of neurosurgical patients with renal salt wasting

We have utilized the persistent elevation of fractional excretion (FE) of urate, > 10%, to differentiate cerebral/renal salt wasting (RSW) from the syndrome of inappropriate antidiuretic hormone secretion (SIADH), in which a normalization of FEurate occurs after correction of hyponatremia.  Previous studies suggest as well  that an elevated FEurate with normonatremia, without pre-existing hyponatremia, is also consistent with RSW, including studies demonstrating induction of RSW in rats infused with plasma from normonatremic neurosurgical and Alzheimer’s disease patients.  The present studies were designed to test whether precipitates from the urine of normonatremic neurosurgical patients, with either normal or elevated FEurate, and patients with SIADH, display natriuretic activity.  

Methods: Ammonium sulfate precipitates from the urine of 6 RSW and 5 non-RSW Control patients were dialyzed (10 kDa cutoff) to remove the ammonium sulfate, lyophilized, and the reconstituted precipitate was tested for its effect on transcellular transport of ²²Na across LLC-PK1 cells grown to confluency in transwells.

Results: Precipitates from 5 of the 6 patients with elevated FEurate and normonatremia significantly inhibited the in vitro transcellular transport of ²²Na above a concentration of 3 μg protein/ml, by 10-25%, versus to vehicle alone, and by 15-40% at concentrations of 5-20 μg/ml as compared to precipitates from 4 of the 5 non-RSW patients with either normal FEurate and normonatremia (2 patients) or with SIADH (2 patients).

Conclusion: These studies provide further evidence that an elevated FEurate with normonatremia is highly consistent with RSW.  Evidence in the urine of natriuretic activity suggests significant renal excretion of the natriuretic factor. The potentially large source of the natriuretic factor that this could afford, coupled with small analytical sample sizes required by the in-vitro bioassay used here, should facilitate future experimental analysis and allow the natriuretic factor to be investigated as a potential biomarker for RSW.

Natriuretic and neurohormonal responses to nesiritide, furosemide, and combined nesiritide and furosemide in patients with stable systolic dysfunction

BACKGROUND

In patients with heart failure, few data describe the neurohormonal response to nesiritide and furosemide either alone or in combination. This study systematically compared the effects of nesiritide, furosemide, and their combination on natriuresis/diuresis and plasma aldosterone in patients with chronic stable heart failure who were relatively diuretic resistant.

HYPOTHESIS

Natriuretic, diuretic, and neurohormonal responses to furosemide and nesiritide will differ when these agents are administered alone vs. in combination.

METHODS

Twenty-eight subjects completed a multicenter, open-label, three-arm crossover study. Each subject received the following treatments in random order on alternate days: (1) furosemide, 40 mg intravenous bolus; (2) nesiritide, 2 microg/kg intravenous bolus followed by a 0.01 microg/kg/min infusion for 6 hours; (3) both furosemide and nesiritide, with furosemide given at least 15 minutes after initiation of nesiritide.

RESULTS

Plasma aldosterone increased by 2.2 +/- 1.6 ng/dL after furosemide alone, decreased by 3.9 +/- 1.6 ng/dL after nesiritide alone (P = 0.005 vs furosemide alone and P = 0.56 vs furosemide plus nesiritide), and decreased by 2.8 +/- 1.6 ng/dL after furosemide plus nesiritide (P = 0.02 vs furosemide alone).

CONCLUSIONS

Furosemide alone produced natriuresis/diuresis and a prompt rise in plasma aldosterone values. Nesiritide alone produced no significant natriuresis/diuresis, but decreased plasma aldosterone values. When furosemide was administered on a background of nesiritide infusion, the observed natriuresis/diuresis was similar to that seen with furosemide alone, without the anticipated increase in plasma aldosterone observed with furosemide alone.

Brain natriuretic peptide in pulmonary arterial hypertension: biomarker and potential therapeutic agent

B-type natriuretic peptide (BNP) is a member of the natriuretic peptide family, a group of widely distributed, but evolutionarily conserved, polypeptide mediators that exert myriad cardiovascular effects. BNP is a potent vasodilator with mitogenic, hypertrophic and pro-inflammatory properties that is upregulated in pulmonary hypertensive diseases. Circulating levels of BNP correlate with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in patients with pulmonary arterial hypertension (PAH). Elevated plasma BNP levels are associated with increased mortality in patients with PAH and a fall in BNP levels after therapy is associated with improved survival. These findings have important clinical implications in that a noninvasive blood test may be used to identify PAH patients at high-risk of decompensation and to guide pulmonary vasodilator therapy. BNP also has several biologic effects that could be beneficial to patients with PAH. However, lack of a convenient method for achieving sustained increases in circulating BNP levels has impeded the development of BNP as a therapy for treating pulmonary hypertension. New technologies that allow transdermal or oral administration of the natriuretic peptides have the potential to greatly accelerate research into therapeutic use of BNP for cor pulmonale and pulmonary vascular diseases. This review will examine the basic science and clinical research that has led to our understanding of the role of BNP in cardiovascular physiology, its use as a biomarker of right ventricular function and its therapeutic potential for managing patients with pulmonary vascular disease.

Differential associations between renal function and "modifiable" risk factors in patients with chronic heart failure

BACKGROUND

Reduced glomerular filtration rate (GFR) is strongly associated with reduced survival in patients with chronic heart failure (CHF). Our aim was to determine different pathophysiologic markers that are associated with reduced renal function in CHF.

METHODS AND RESULTS

We studied 86 patients with CHF (58+/-12 years, 78% male). GFR and renal blood flow (RBF) were determined by (125)I-Iothalamate and (131)I-Hippuran clearances. Filtration fraction (FF) was calculated. We determined haemoglobin levels, endothelial function, inflammatory status, plasma renin activity (PRA) and N-terminal pro brain natriuretic peptide (NT-proBNP). Urinary albumin excretion (UAE) was measured in 24 h urine. Mean GFR was 74+/-28 ml/min/1.73 m(2). GFR was strongly related to RBF (r=0.915, P<0.001), FF (r=0.546, P<0.001), but only weakly to endothelial function and PRA. In multivariate analysis, RBF (r=0.938, P < 0.001), FF (r=0.786, P < 0.001) and haemoglobin levels (r= -0.520, P<0.001) were independently associated with GFR. UAE was mainly dependent on RBF (r= -0.401, P < 0.001) and increased exponentially with decreasing RBF. RBF was mainly associated with NT-proBNP (r= -0.561, P<0.001) and PRA (r= -0.422, P<0.001).

CONCLUSION

Reduced GFR is mainly dependent of decreased RBF in patients with CHF. Endothelial function and neurohormonal activation showed only mild associations with GFR. NT-proBNP showed a strong relationship with RBF, and may be used as a marker of reduced renal perfusion.

B-type natriuretic peptide: beyond a diagnostic

The concept of the heart as an endocrine organ has been attractive since the discovery of atrial natriuretic peptide. This review focuses on the second discovered natriuretic peptide from the heart - B-type natriuretic peptide (BNP), widely used as a tool in the diagnosis of heart failure (HF). Controversy remains regarding its use as a therapeutic agent in HF. This article places into perspective some of the debate and provides insights into the therapeutics of BNP and the importance of its second messenger 3'5' cyclic guanosine monophosphate, which also is the second messenger for nitric oxide and is modulated by renal phosphodiesterases.

Management strategies for stage-D patients with acute heart failure

Heart Failure (HF) accounted for 3.4 million ambulatory visits in 2000. Current guidelines from the American Heart Association/American College of Cardiology, the Heart Failure Society of America, and the International Society for Heart & Lung Transplantation recommend aggressive pharmacologic interventions for patients with HF. This may include a combination of diuretics, Angiotensin Converting Enzyme inhibitors, beta-blockers, angiotensin receptor blockers, aldosterone antagonists, and digoxin. Nitrates and hydralazine are also indicated as part of standard therapy in addition to beta-blockers and Angiotensin Converting Enzyme inhibitors, especially but not exclusively, for African Americans with left ventricular (LV) systolic dysfunction. For those with acute decompensated HF, additional treatment options include recombinant human B-type natriuretic peptide, and in the future possible newer agents not yet approved for use in the U.S., such as Levosimendan. Medical devices for use in patients with advanced HF include LV assist devices, cardiac resynchronization therapy, and implantable cardioverter defibrillators. For refractory patients, heart transplantation, the gold-standard surgical intervention for the treatment of refractory HF, may be considered. Newer surgical options such as surgical ventricular restoration may be considered in select patients.

Distinct roles for renal particulate and soluble guanylyl cyclases in preserving renal function in experimental acute heart failure

Worsening renal function in the setting of human acute heart failure (AHF) predicts poor outcomes, such as rehospitalization and increased mortality. Understanding potential renoprotective mechanisms is warranted. The guanylate cyclase (GC) enzymes and their second messenger cGMP are the target of two important circulating neurohumoral systems with renoprotective properties. Specifically, natriuretic peptides (NP) released from the heart with AHF target particulate GC in the kidney, while the nitric oxide (NO) system is an activator of renal soluble GC. We hypothesized that both systems are essential to preserve renal excretory and hemodynamic function in AHF but with distinct roles. We investigated these roles in three groups of anesthetized dogs (6 each) with AHF induced by rapid ventricular pacing. After a baseline AHF clearance, each group received intrarenal vehicle (control), N(G)-monomethyl-l-arginine (l-NMMA), a competitive NO inhibitor (50 microg.kg(-1).min(-1)) or a specific NP receptor antagonist, HS-142-1 (0.5 mg/kg). We observed that intrarenal l-NMMA decreased renal blood flow (RBF) without significant decreases in glomerular filtration rate (GFR), urinary sodium excretion (UNaV), or urinary cGMP. In contrast, HS-142-1 resulted in a decrease in UNaV and cGMP excretion together with a reduction in GFR and an increase in distal fractional tubular sodium reabsorption. We conclude that in AHF, the NP system plays a role in maintaining sodium excretion and GFR, while the function of NO is in the maintenance of RBF. These studies have both physiological and therapeutic implications warranting further research into cardiorenal interactions in this syndrome of AHF.

Brain natriuretic peptide and optimal management of heart failure

Aside from the important role of brain natriuretic peptide (BNP) in diagnosis, and differential diagnosis of heart failure, this biological peptide has proved to be an independent surrogate marker of rehospitalization and death of the fatal disease. Several randomized clinical trials demonstrated that drugs such as beta blocker, angiotensin converting enzyme inhibitor, spironolactone and amiodarone have beneficial effects in decreasing circulating BNP level during the management of chronic heart failure. The optimization of clinical decision-making appeals for a representative surrogate marker for heart failure prognosis. The serial point-of-care assessments of BNP concentration provide a therapeutic goal of clinical multi-therapy and an objective guidance for optimal treatment of heart failure. Nevertheless new questions and problems in this area remain to be clarified. On the basis of current research advances, this article gives an overview of BNP peptide and its property and role in the management of heart failure.

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.