Effects of BG9719 (CVT-124), an A1-adenosine receptor antagonist, and furosemide on glomerular filtration rate and natriuresis in patients with congestive heart failure

Purinoceptor: a novel target for hypertension

Hypertension is the leading cause of morbidity and mortality globally among all cardiovascular diseases. Purinergic signalling plays a crucial role in hypertension through the sympathetic nerve system, neurons in the brain stem, carotid body, endothelium, immune system, renin-angiotensin system, sodium excretion, epithelial sodium channel activity (ENaC), and renal autoregulation. Under hypertension, adenosine triphosphate (ATP) is released as a cotransmitter from the sympathetic nerve. It mediates vascular tone mainly through P2X1R activation on smooth muscle cells and activation of P2X4R and P2YR on endothelial cells and also via interaction with other purinoceptors, showing dual effects. P2Y1R is linked to neurogenic hypertension. P2X7R and P2Y11R are potential targets for immune-related hypertension. P2X3R located on the carotid body is the most promising novel therapeutic target for hypertension. A₁R, A_2AR, A_2BR, and P2X7R are all related to renal autoregulation, which contribute to both renal damage and hypertension. The main focus is on the evidence addressing the involvement of purinoceptors in hypertension and therapeutic interventions.

Efficacy and Safety of Ultrafiltration in Patients with Heart Failure: A Single-Center Experience

INTRODUCTION

There is a paucity of literature on the efficacy and safety of ultrafiltration in Chinese patients with heart failure (HF). Therefore, we aimed to compare the efficacy and safety of ultrafiltration with diuretics and provide information and evidence as to the best approach for patients with HF.

METHODS

In this single-center, non-randomized interventional study patients with HF either received diuretics or ultrafiltration. The efficacy outcomes included changes in the weight, dyspnea score, and 6-min walk distance from baseline to 48 h after treatment. Safety outcomes were evaluated in both the groups with respect to changes in systolic blood pressure, heart rate, serum creatinine, blood urea nitrogen, blood potassium ion concentration, and blood sodium ion concentration.

RESULTS

A total of 149 patients with HF (diuretics, 73; ultrafiltration, 76) were included. At 48 h, patients in the ultrafiltration group showed significantly greater weight loss and better improvement in dyspnea score and 6-min walk distance compared to patients in the control group (P < 0.05). However, the two groups showed no statistically significant difference in terms of safety outcomes such as systolic blood pressure, heart rate, serum creatinine, blood urea nitrogen, blood potassium ion concentration, and blood sodium ion concentration, suggesting similar safety profiles of both the groups.

CONCLUSION

Ultrafiltration was associated with greater weight loss and better dyspnea score and 6-min walk distance with similar safety profiles as compared with diuretics. Ultrafiltration can be considered as an optimal option for Chinese patients with HF.

Determining risk factors for triple whammy acute kidney injury

Concurrent use of a diuretic, a renin-angiotensin system (RAS) inhibitor, and a non-steroidal anti-inflammatory drug (NSAID) significantly increases the risk of acute kidney injury (AKI). This phenomenon is known as "triple whammy". Diuretics and RAS inhibitors, such as an angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker, are often prescribed in tandem for the treatment of hypertension, whereas some NSAIDs, such as ibuprofen, are available over the counter. As such, concurrent treatment with all three drugs is common. The goals of this study are to better understand the mechanisms underlying the development of triple whammy AKI and to identify physiological factors that may increase an individual's susceptibility. To accomplish these goals, we utilize sex-specific computational models of long-term blood pressure regulation. These models include variables describing the heart and circulation, kidney function, sodium and water reabsorption in the nephron and the RAS and are parameterized separately for men and women. Hypertension is modeled as overactive renal sympathetic nervous activity. Model simulations suggest that low water intake, the myogenic response, and drug sensitivity may predispose patients with hypertension to develop triple whammy-induced AKI. Triple treatment involving an ACE inhibitor, furosemide, and NSAID results in blood pressure levels similar to double treatment with ACEI and furosemide. Additionally, the male and female hypertensive models act similarly in most situations, except for the ACE inhibitor and NSAID double treatment.

Renal negative pressure treatment as a novel therapy for heart failure-induced renal dysfunction

Congestion is the primary pathophysiological lesion in most heart failure (HF) hospitalizations. Renal congestion increases renal tubular pressure, reducing glomerular filtration rate (GFR) and diuresis. Because each nephron is a fluid-filled column, renal negative pressure therapy (rNPT) applied to the urinary collecting system should reduce tubular pressure, potentially improving kidney function. We evaluated the renal response to rNPT in congestive HF. Ten anesthetized ∼80-kg pigs underwent instrumentation with bilateral renal pelvic JuxtaFlow catheters. GFR was determined by iothalamate clearance (mGFR) and renal plasma flow (RPF) by para-aminohippurate clearance. Each animal served as its own control with randomization of left versus right kidney to -30 mmHg rNPT or no rNPT. mGFR and RPF were measured simultaneously from the rNPT and no rNPT kidney. Congestive HF was induced via cardiac tamponade maintaining central venous pressure at 20-22.5 mmHg throughout the experiment. Before HF induction, rNPT increased natriuresis, diuresis, and mGFR compared with the control kidney (P < 0.001 for all). Natriuresis, diuresis, and mGFR decreased following HF (P < 0.001 for all) but were higher in rNPT kidney versus control (P < 0.001 for all). RPF decreased during HF (P < 0.001) without significant differences between rNPT treatments. During HF, the rNPT kidney had similar diuresis and natriuresis (P > 0.5 for both) and higher fractional excretion of sodium (P = 0.001) compared with the non-rNPT kidney in the no HF period. In conclusion, rNPT resulted in significantly increased diuresis, natriuresis, and mGFR, with or without experimental HF. rNPT improved key renal parameters of the congested cardiorenal phenotype.

Efficacy and Renal Tolerability of Ultrafiltration in Acute Decompensated Heart Failure: A Meta-analysis and Systematic Review of 19 Randomized Controlled Trials

Background: Acute decompensated heart failure (ADHF) is a life-threatening and costly disease. Controversy remains regarding the efficacy and renal tolerability of ultrafiltration for treating ADHF. We therefore performed this meta-analysis to evaluate this clinical issue.Methods: A search of PubMed, EMBASE, and the Cochrane database of controlled trials was performed from inception to March 2021 for relevant randomized controlled trials. The quality of the included trials and outcomes was evaluated with the use of the risk of bias assessment tool and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, respectively. The risk ratio and the standardized mean difference (SMD) or weighted mean difference (WMD) were computed and pooled with fixed-effects or random-effects models.Results: This meta-analysis included 19 studies involving 1281 patients. Ultrafiltration was superior to the control treatments for weight loss (WMD 1.24 kg, 95% confidence interval [CI] 0.38‐2.09 kg, P=0.004) and fluid removal (WMD 1.55 L, 95% CI 0.51‐2.59 l, P=0.003) and was associated with a significant increase in serum creatinine level compared with the control treatments (SMD 0.15 mg/dL, 95% CI 0.00‐0.30 mg/dL, P=0.04). However, no significant effects were found for serum N-terminal prohormone of brain natriuretic peptide level, length of hospital stay, all-cause mortality, or all-cause rehospitalization in the ultrafiltration group.Conclusions: The use of ultrafiltration in patients with ADHF is superior to the use of the control treatments for weight loss and fluid removal, but has adverse renal effects and lacks significant effects on long-term prognosis, indicating that this approach to decongestion in ADHF patients is efficient for fluid management but less safe renally.

Adenosine Receptor Ligands: Coumarin-Chalcone Hybrids as Modulating Agents on the Activity of hARs

Adenosine receptors (ARs) play an important role in neurological and psychiatric disorders such as Alzheimer’s disease, Parkinson’s disease, epilepsy and schizophrenia. The different subtypes of ARs and the knowledge on their densities and status are important for understanding the mechanisms underlying the pathogenesis of diseases and for developing new therapeutics. Looking for new scaffolds for selective AR ligands, coumarin–chalcone hybrids were synthesized (compounds 1–8) and screened in radioligand binding (hA₁, hA_2A and hA₃) and adenylyl cyclase (hA_2B) assays in order to evaluate their affinity for the four human AR subtypes (hARs). Coumarin–chalcone hybrid has been established as a new scaffold suitable for the development of potent and selective ligands for hA₁ or hA₃ subtypes. In general, hydroxy-substituted hybrids showed some affinity for the hA₁, while the methoxy counterparts were selective for the hA₃. The most potent hA₁ ligand was compound 7 (K_i = 17.7 µM), whereas compound 4 was the most potent ligand for hA₃ (K_i = 2.49 µM). In addition, docking studies with hA₁ and hA₃ homology models were established to analyze the structure–function relationships. Results showed that the different residues located on the protein binding pocket could play an important role in ligand selectivity.

New potent and selective A1 adenosine receptor antagonists as potential tools for the treatment of gastrointestinal diseases

The synthesis of 9-alkyl substituted adenine derivatives presenting aromatic groups and cycloalkyl rings in 8- and N⁶-position, respectively, is reported. The compounds were tested with radioligand binding studies showing, in some cases, a low nanomolar A₁ adenosine receptor affinity and a very good selectivity versus the other adenosine receptor subtypes. Functional assays at human adenosine receptors and at a mouse ileum tissue preparation clearly demonstrate the antagonist profile of these molecules, with inhibitory potency at nanomolar level. A molecular modeling study, consisting in docking analysis at the recently reported A₁ adenosine receptor crystal structure, was performed for the interpretation of the obtained pharmacological results. The N⁶-cyclopentyl-9-methyl-8-phenyladenine (17), resulting the most active derivative of the series (K_i = 2.8 nM and IC₅₀ = 14 nM), was also very efficacious in counteracting the effect of the agonist CCPA on mouse ileum contractility. This new compound represents a tool for the development of new agents for the treatment of intestinal diseases as constipation and postoperative ileus.

An exploratory analysis of the competing effects of aggressive decongestion and high-dose loop diuretic therapy in the DOSE trial

BACKGROUND

Effective decongestion of heart failure patients predicts improved outcomes, but high dose loop diuretics (HDLD) used to achieve diuresis predict adverse outcomes. In the DOSE trial, randomization to a HDLD intensification strategy (HDLD-strategy) improved diuresis but not outcomes. Our objective was to determine if potential beneficial effects of more aggressive decongestion may have been offset by adverse effects of the HDLD used to achieve diuresis.

METHODS AND RESULTS

A post hoc analysis of the DOSE trial (n=308) was conducted to determine the influence of post-randomization diuretic dose and fluid output on the rate of death, rehospitalization or emergency department visitation associated with the HDLD-strategy. Net fluid output was used as a surrogate for beneficial decongestive effects and cumulative loop diuretic dose for the dose-related adverse effects of the HDLD-strategy. Randomization to the HDLD-strategy resulted in increased fluid output, even after adjusting for cumulative diuretic dose (p=0.006). Unadjusted, the HDLD-strategy did not improve outcomes (p=0.28). However, following adjustment for cumulative diuretic dose, significant benefit emerged (HR=0.64, 95% CI 0.43-0.95, p=0.028). Adjusting for net fluid balance eliminated the benefit (HR=0.95, 95% CI 0.67-1.4, p=0.79).

CONCLUSIONS

A clinically meaningful benefit from a randomized aggressive decongestion strategy became apparent after accounting for the quantity of loop diuretic administered. Adjusting for the diuresis resulting from this strategy eliminated the benefit. These hypothesis-generating observations may suggest a role for aggressive decongestion in improved outcomes.

Combination of drugs acting on the natriuretic system and the renin-angiotensin system in heart failure

Conventional diuretic agents are very effective agents in relieving volume overload and congestive symptoms in chronic heart failure (CHF). However, they are associated with activation of the renin-angiotensin system (RAS) and the sympathetic nervous system and a reduction in glomerular filtration rate, all of which have been associated with adverse outcomes in CHF. Therefore, there is an increasing interest in drugs that target the natriuretic system without neurohormonal activation and deterioration of renal function. In this review, we will discuss the underlying rationale and evidence behind currently pursued strategies that target the natriuretic system. This includes the administration of natriuretic peptides (NPs) and strategies that potentiate the NP system, such as neutral endopeptidase inhibition. We will also highlight some potentially important interactions of these strategies with drugs that target the RAS.

A pharmacokinetic/pharmacodynamic model capturing the time course of torasemide-induced diuresis in the dog

A pharmacokinetic/pharmacodynamic modelling approach was used to determine a dosage regimen which maximizes diuretic efficiency of torasemide in dogs. Kinetic profiles of plasma concentration, torasemide excretion rate in urine (TERU) and diuresis were investigated in 10 dogs after single oral administrations at 3 dose levels, 0.2, 0.8 and 1.6 mg/kg, and an intravenous injection of 0.2 mg/kg. Endogenous regulation was evidenced by a proteresis loop between TERU and diuresis. To describe the diuresis-time profile, TERU served as input into a turnover model with inhibition of loss of response, extended by a moderator acting on both loss and production of response. Estimated maximum inhibition of loss of response, I_max , was 0.984 showing that torasemide is an efficacious diuretic able to suppress almost total water reabsorption. A TERU_50, value producing half of I_max , of 1.45 μg/kg/h was estimated from the model. Pharmacokinetic and pharmacodynamic parameters were used to simulate the torasemide dose-effect relationship after oral administration. Model predictions were in good agreement with diuresis measured in a validation study conducted in 10 dogs, which were administered oral doses of 0.15, 0.4, 0.75, 1.5 and 4.5 mg/kg for 5 days. Finally, oral dose associated with the highest daily diuretic efficiency was predicted to be 0.1 mg/kg.

Adenosine, type 1 receptors: role in proximal tubule Na+ reabsorption

Adenosine type 1 receptor (A1 -AR) antagonists induce diuresis and natriuresis in experimental animals and humans. Much of this effect is due to inhibition of A1 -ARs in the proximal tubule, which is responsible for 60-70% of the reabsorption of filtered Na(+) and fluid. Intratubular application of receptor antagonists indicates that A1 -AR mediates a portion of Na(+) uptake in PT and PT cells, via multiple transport systems, including Na(+) /H(+) exchanger-3 (NHE3), Na(+) /PO4(-) co-transporter and Na(+) -dependent glucose transporter, SGLT. Renal microperfusion and recollection studies have shown that fluid reabsorption is reduced by A1 -AR antagonists and is lower in A1 -AR KO mice, compared to WT mice. Absolute proximal reabsorption (APR) measured by free-flow micropuncture is equivocal, with studies that show either lower APR or similar APR in A1 -AR KO mice, compared to WT mice. Inhibition of A1 -ARs lowers elevated blood pressure in models of salt-sensitive hypertension, partially due to their effects in the proximal tubule.

Echolucent Carotid Plaque is Associated with Future Renal Dysfunction in Patients with Stable Coronary Artery Disease

AIM

Functional and structural abnormalities of the peripheral arteries are associated with renal dysfunction, independent of the presence of renal artery stenosis. This study investigated whether echolucent carotid plaque is associated with a future decline in the renal function in patients with coronary artery disease (CAD).

METHODS

Ultrasound assessments of carotid plaque echolucency with integrated backscatter (IBS) analyses were performed in 327 patients with stable CAD and carotid plaque who exhibited a normal renal function (estimated glomerular filtration rate [eGFR] ≥60 mL/min/1.73 m(2)) at baseline. A lower IBS value reflects the presence of echolucent and lipid-rich unstable plaque. All patients were followed up for 36 months or until the occurrence of renal dysfunction, defined as an eGFR of ＜45 mL/min/1.73 m(2).

RESULTS

During the follow-up period, 39 patients developed renal dysfunction. A multivariate logistic regression analysis showed that the presence of carotid plaque with a low IBS value was significantly associated with progression to renal dysfunction (odds ratios 0.48; 95% CI 0.30-0.78, p= 0.003). In addition, carotid plaque with a low IBS value had a significant incremental effect on the predictive value of known risk factors for renal dysfunction in analyses using c-statistics (AUC of the baseline risk model with and without IBS: 0.83 vs. 0.79, respectively, p=0.04), net reclassification improvement (index=0.549, p=0.001) and integrated discrimination improvement (index=0.068, p=0.002).

CONCLUSIONS

Echolucency of the carotid arteries is associated with future renal dysfunction in patients with stable CAD, indicating that the mechanisms related to plaque instability may be involved in the onset of renal dysfunction.

Renal neurohormonal regulation in heart failure decompensation

Decompensation in heart failure occurs when the heart fails to balance venous return with cardiac output, leading to fluid congestion and contributing to mortality. Decompensated heart failure can cause acute kidney injury (AKI), which further increases mortality. Heart failure activates signaling systems that are deleterious to kidneys such as renal sympathetic nerve activity (RSNA), renin-angiotensin-aldosterone system, and vasopressin secretion. All three reduce renal blood flow (RBF) and increase tubular sodium reabsorption, which may increase renal oxygen consumption causing AKI through renal tissue hypoxia. Vasopressin contributes to venous congestion through aquaporin-mediated water retention. Additional water retention may be mediated through vasopressin-induced medullary urea transport and hyaluronan but needs further study. In addition, there are several systems that could protect the kidneys and reduce fluid retention such as natriuretic peptides, prostaglandins, and nitric oxide. However, the effect of natriuretic peptides and nitric oxide are blunted in decompensation, partly due to oxidative stress. This review considers how neurohormonal signaling in heart failure drives fluid retention by the kidneys and thus exacerbates decompensation. It further identifies areas where there is limited data, such as signaling systems 20-HETE, purines, endothelin, the role of renal water retention mechanisms for congestion, and renal hypoxia in AKI during heart failure.

Advances in pathogenesis and current therapeutic strategies for cardiorenal syndrome

Cardiorenal syndrome (CRS) is characterized as a syndrome involving both the cardiovascular system and kidneys. Due to its complexity and high mortality, it has becoming a significant burden and a universal clinical challenge to society worldwide. The mechanisms underlying CRS are potentially multifactorial, including hemodynamic alterations, neurohormonal activation, inflammation, oxidative stress, iron disorders, anemia, and mineral metabolic derangements. Despite the understanding and awareness of CRS gaining attention, appropriate approaches to manage CRS remain deficient. Loop diuretic and thiazides, inhibition of the renin-angiotensin system, vitamin D receptor activation and dopamine and natriuretic peptides could potentially be helpful to improve the prognosis of CRS. Ultrafiltration might be an alternative therapeutic strategy for the loss of liquid. However, adenosine receptor antagonists do not appear to be superior to furosemide in CRS treatment. novel therapeutic approaches should be explored.

Recognizing hospitalized heart failure as an entity and developing new therapies to improve outcomes: academics', clinicians', industry's, regulators', and payers' perspectives

Hospitalized heart failure (HHF) is associated with unacceptably high postdischarge mortality and rehospitalization rates. This heterogeneous group of patients, however, is still treated with standard, homogenous therapies that are not preventing their rapid deterioration. The costs associated with HHF have added demands from society, government, and payers to improve outcomes. With coordinated and committed efforts in the development of new therapies, improvements may be seen in outcomes for patients with HHF. This article summarizes concepts in developing therapies for HHF discussed during a multidisciplinary panel at the Heart Failure Society of America's Annual Scientific Meeting, September 2012.

Vasopressin antagonists in the management of heart failure

Vasopressin antagonists have been studied in a variety of clinical settings, including patients with acute and chronic heart failure. The clinical trials published to date have sought to describe the clinical and physiologic effects of these agents in an effort to prove clinical efficacy and safety. A variety of agents with varying effects on V2 and V1a vasopressin receptor subtype have been studied. They have been shown to reduce bodyweight and improve serum sodium without worsening renal function. They may also decrease the need for loop diuretic use and may be particularly useful in patients with hyponatremia in the setting of volume overload. Further studies are underway that are powered to assess for morbidity and mortality benefits. The beneficial effects have been well documented but, until outcomes are understood more fully, the use of these agents should be limited to currently approved indications. In the USA, this includes only the treatment of euvolemic hyponatremia.

Renal participation in cardiovascular risk inessential hypertension

The kidney plays a relevant role in the origin of essential hypertension in humans, and it suffers the consequences of sustained elevated blood pressure in the absence of therapy. Recently, a relevant prevalence of mild renal insufficiency both in general population than in hypertensive patients has been described. A direct relationship seems to exist between the level of cardiovascular risk and the prevalence of the renal disorder, whether this is detected as an elevation in serum creatinine or as a diminution of estimated creatinine clearance. This renal function impairment is a strong predictor of cardiovascular risk in patients with chronic heart failure and following myocardial infarction. Prevention of renal and cardiovascular damage in these patients will be one of the most relevant tasks in the future. The aim of this short review is to discuss the evidence in favor of a relevant prevalence of mild renal insufficiency in hypertensive patients, as well as the association of this disorder with a very significant increment in global cardiovascular risk.

M-atrial natriuretic peptide and nitroglycerin in a canine model of experimental acute hypertensive heart failure: differential actions of 2 cGMP activating therapeutics

Background

Systemic hypertension is a common characteristic in acute heart failure (HF). This increasingly recognized phenotype is commonly associated with renal dysfunction and there is an unmet need for renal enhancing therapies. In a canine model of HF and acute vasoconstrictive hypertension we characterized and compared the cardiorenal actions of M‐atrial natriuretic peptide (M‐ANP), a novel particulate guanylyl cyclase (pGC) activator, and nitroglycerin, a soluble guanylyl cyclase (sGC) activator.

Methods and Results

HF was induced by rapid RV pacing (180 beats per minute) for 10 days. On day 11, hypertension was induced by continuous angiotensin II infusion. We characterized the cardiorenal and humoral actions prior to, during, and following intravenous M‐ANP (n=7), nitroglycerin (n=7), and vehicle (n=7) infusion. Mean arterial pressure (MAP) was reduced by M‐ANP (139±4 to 118±3 mm Hg, P<0.05) and nitroglycerin (137±3 to 116±4 mm Hg, P<0.05); similar findings were recorded for pulmonary wedge pressure (PCWP) with M‐ANP (12±2 to 6±2 mm Hg, P<0.05) and nitroglycerin (12±1 to 6±1 mm Hg, P<0.05). M‐ANP enhanced renal function with significant increases (P<0.05) in glomerular filtration rate (38±4 to 53±5 mL/min), renal blood flow (132±18 to 236±23 mL/min), and natriuresis (11±4 to 689±37 mEq/min) and also inhibited aldosterone activation (32±3 to 23±2 ng/dL, P<0.05), whereas nitroglycerin had no significant (P>0.05) effects on these renal parameters or aldosterone activation.

Conclusions

Our results advance the differential cardiorenal actions of pGC (M‐ANP) and sGC (nitroglycerin) mediated cGMP activation. These distinct renal and aldosterone modulating actions make M‐ANP an attractive therapeutic for HF with concomitant hypertension, where renal protection is a key therapeutic goal.

Determinants of the creatinine clearance to glomerular filtration rate ratio in patients with chronic kidney disease: a cross-sectional study

BACKGROUND

Creatinine secretion, as quantified by the ratio of creatinine clearance (CrCl) to glomerular filtration rate (GFR), may introduce another source of error when using serum creatinine concentration to estimate GFR. Few studies have examined determinants of the CrCl/GFR ratio. We sought to study whether higher levels of albuminuria would be associated with higher, and being non-Hispanic black with lower, CrCl/GFR ratio.

METHODS

We did a cross-sectional analysis of 1342 patients with chronic kidney disease from the Chronic Renal Insufficiency Cohort (CRIC) who had baseline measure of iothalamate GFR (iGFR) and 24-hour urine collections. Our predictors included urine albumin as determined from 24-hour urine collections (categorized as: <30, 30-299, 300-2999 and ≥3000 mg), and race/ethnicity (non-Hispanic white, non-Hispanic black, Hispanic). Our outcome was CrCl/iGFR ratio, a measure of creatinine secretion.

RESULTS

Mean iGFR was 48.0 ± 19.9 mL/min/1.73 m², median albuminuria was 84 mg per day, and 36.8% of the study participants were non-Hispanic black. Mean CrCl/iGFR ratio was 1.19 ± 0.48. There was no association between the CrCl/iGFR ratio and urine albumin (coefficient 0.11 [95% CI-0.01-0.22] for higest verus lowest levels of albuminuria, p = 0.07). Also, there was no association between race/ethnicity and CrCl/iGFR ratio (coefficient for non-Hispanic blacks was-0.03 [95% CI-0.09-0.03] compared with whites, p = 0.38).

CONCLUSIONS

Contrary to what had been suggested by prior smaller studies, CrCl/GFR ratio does not vary with degree of proteinuria or race/ethnicity. The ratio is also closer to 1.0 than reported by several frequently cited reports in the literature.

Can we prevent or treat renal dysfunction in acute heart failure?

Most patients with heart failure (HF) already have or develop renal dysfunction; this might contribute to their poor outcome. Current treatment for HF can also contribute to worsen renal function. High furosemide doses are traditionally associated with worsening renal function (WRF), but patients with fluid overload may benefit of aggressive fluid removal. Unfortunately, promising therapies like vasopressin antagonists and adenosine antagonists have not been demonstrated to improve outcomes. Likewise, correction of low renal blood flow through dopamine, inotropic agents, or vasodilators does not seem to be associated with a clear benefit. However, transient WRF associated with acute HF treatment may not necessarily portend a poor prognosis. In this review, we focus on the strategies to detect renal dysfunction in acute HF, the underlying pathophysiological mechanisms, and the potential treatments.

The kidney in heart failure: friend or foe?

Heart failure constitutes a significant source of morbidity and mortality in the United States and its incidence and prevalence continue to grow, increasing its burden on the health care system. Renal dysfunction in patients with heart failure is common and has been associated with adverse clinical outcomes. This complex interaction is characterized by a pathophysiological disequilibrium between the heart and the kidney, in which cardiac malfunction promotes renal impairment, which in turn feeds back for further deterioration of cardiovascular function. Multiple neurohumoral and hemodynamic mechanisms are involved in this cardiorenal dyshomeostasis, including the deficiency of and/or resistance to compensatory natriuretic peptides, leading to sodium retention, volume overload and organ remodeling. Management of patients with cardiorenal dysfunction can be challenging and should be individualized. Emerging therapies must address the impairment of both organs to secure better clinical outcomes. To this end, a multidisciplinary approach is warranted to achieve optimal results.

Diuretics and ultrafiltration in acute decompensated heart failure

Congestion and volume overload are the hallmarks of acute decompensated heart failure (ADHF), and loop diuretics have historically been the cornerstone of treatment. The demonstrated efficacy of loop diuretics in managing congestion is balanced by the recognized limitations of diuretic resistance, neurohormonal activation, and worsening renal function. However, the recently published DOSE (Diuretic Optimization Strategies Evaluation) trial suggests that previous concerns about the safety of high-dose diuretics may not be valid. There has been a growing interest in alternative strategies to manage volume retention in ADHF with improved efficacy and safety profiles. Peripheral venovenous ultrafiltration (UF) represents a potentially promising approach to volume management in ADHF. Small studies suggest that UF may allow for more effective fluid removal compared with diuretics, with improved quality of life and reduced rehospitalization rates. However, further investigation is needed to completely define the role of UF in patients with ADHF. This review summarizes available data on the use of both diuretics and UF in ADHF patients and identifies challenges and unresolved questions for each approach.

Emerging therapies for heart failure: renal mechanisms and effects

Improved understanding of the pathophysiology of salt and water homeostasis has provided a foundation for explaining the renal mechanisms of emerging therapies for heart failure, as well as why renal function might potentially be improved or harmed. These aspects are reviewed in this article for a number of newer therapies including adenosine, endothelin, and vasopressin receptor antagonists, as well as extracorporeal ultrafiltration. An appreciation of the complexity and sometimes opposing pathways of these approaches may explain their limited efficacy in early trials, in which there has not been a substantial improvement in patient or renal outcomes. In that there is often a balance between beneficial and maladaptive receptor actions and neurohumoral responses, this physiologic approach also provides insight into the rationale for combining therapies. Multi-agent strategies may thus maximize their effectiveness while minimizing adverse effects and tolerance. In this paper, the theoretical impact of the emerging agents based on their mechanism of action and pathophysiology of the disease is initially addressed. Then, the available clinical evidence for each class of drugs is reviewed with special emphasis on their effect on kidney-related parameters. Finally, a general overview of the complexity of the interpretation of trials is offered along with a number of potential explanations for the observed results.

Adenosine A(2A) Receptor Antagonists and Parkinson's Disease

This Review summarizes and updates the work on adenosine A(2A) receptor antagonists for Parkinson's disease from 2006 to the present. There have been numerous publications, patent applications, and press releases within this time frame that highlight new medicinal chemistry approaches to this attractive and promising target to treat Parkinson's disease. The Review is broken down by scaffold type and will discuss the efforts to optimize particular scaffolds for activity, pharmacokinetics, and other drug discovery parameters. The majority of approaches focus on preparing selective A(2A) antagonists, but a few approaches to dual A(2A)/A(1) antagonists will also be highlighted. The in vivo profiles of compounds will be highlighted and discussed to compare activities across different chemical series. A clinical report and update will be given on compounds that have entered clinical trials.

Decongestive treatment of acute decompensated heart failure: cardiorenal implications of ultrafiltration and diuretics

In patients with acute decompensated heart failure (ADHF), treatment aimed at adequate decongestion of the volume overloaded state is essential. Despite diuretic therapy, many patients remain volume overloaded and symptomatic. In addition, adverse effects related to diuretic treatment are common, including worsening kidney function and electrolyte disturbances. The development of decreased kidney function during treatment affects the response to diuretic therapy and is associated with important clinical outcomes, including mortality. The occurrence of diuretic resistance and the morbidity and mortality associated with diuretic therapy has stimulated interest to develop effective and safe treatment strategies that maximize decongestion and minimize decreased kidney function. During the last few decades, extracorporeal ultrafiltration has been used to remove fluid from diuretic-refractory hypervolemic patients. Recent clinical studies using user-friendly machines have suggested that ultrafiltration may be highly effective for decongesting patients with ADHF. Many questions remain regarding the comparative impact of diuretics and ultrafiltration on important clinical outcomes and adverse effects, including decreased kidney function. This article serves as a summary of key clinical studies addressing these points. The overall goal is to assist practicing clinicians who are contemplating the use of ultrafiltration for a patient with ADHF.

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Renal replacement therapy in special situations: heart failure and neurological injury

The cardiorenal syndrome is a complicated and increasingly prevalent entity requiring a multidisciplinary approach. Renal replacement therapy (RRT) in the form of slow ultrafiltration (UF) demonstrates promise for the treatment of acutely decompensated heart failure. Despite the lack of evidence for decreased mortality, there is considerable short-term benefit in decreased rehospitalizations and a restoration of diuretic responsiveness. Given the potential for improvement in quality of life and cost if hospitalizations are minimized, slow UF should be considered in patients with repeated hospitalization for decompensated heart failure. Acute neurologic injury is a highly unstable state requiring strict adherence to evidence-based guidelines to achieve the best possible functional outcomes. With improved short-term survival, a greater burden of non-neurologic injury may hinder long-term functional recovery. Acute kidney injury is among such important considerations that can lead to worsened neurological injury. Careful application of continuous modalities of therapy, probably early in the course of illness to avoid intradialytic osmolar shifts and provide hemodynamic stability, will allow for unimpeded neurologic recovery. Newer evidence on dose and RRT modality on patients with acute and chronic brain injury will certainly add important knowledge to this field.

Rationale, design, and results from RENO-DEFEND 1: a randomized, dose-finding study of the selective A1 adenosine antagonist SLV320 in patients hospitalized with acute heart failure

BACKGROUND

Baseline renal impairment as well as worsening renal function during hospitalization is associated with worse short- and long-term outcomes in patients hospitalized for acute heart failure (AHF). We hypothesized that selective A1 adenosine receptor blockade would induce natriuresis while preserving renal function in AHF patients with renal dysfunction.

METHODS

A phase II, randomized, double-blind, placebo-controlled, parallel group, multicenter study to evaluate the efficacy and safety of 2.5, 7.5, 15, and 30 mg/d SLV320 (1 hour intravenous infusions of 1.25, 3.75, 7.5, and 15 mg SLV320, every 12 hours for 3 days [a total of 6 doses] in addition to standard therapy) in subjects hospitalized with AHF and renal impairment who meet all inclusion/exclusion criteria. The study planned to enroll 450 subjects, with 90 subjects allocated equally to each treatment arm.

RESULTS

The study was terminated early. The decision, which was unrelated to the study conduct or results, with a total of 46 subjects randomized. Of those randomized, 6:8:8:8 and 6 patients, respectively, completed the study in each of the dosing subgroups, with placebo as the fifth group. For the 1.25-mg study group, the mean age was 73 years; mean (SD) systolic blood pressure (SBP), 128.5 (16.2); heart rate, 80.8 (25.0); brain natriuretic peptide, 969.7 (571.28); creatinine (μmol/L), 149.7 (41.0); cystatin C, 1.468 (0.2777); estimated glomerular filtration rate, 33.8 (7.913); and blood urea nitrogen, 12.1 (2.9), with roughly similar values in each treatment arm. No seizures were reported during the study. Eight patients died during the study, none of whom were associated with the study drug per an independent, blinded, data safety monitoring board.

CONCLUSION

Because of the limited number of subjects and variability observed in the results, no definite conclusions can be made regarding the efficacy and safety of SLV320.

Ultrafiltration in the management of acute decompensated heart failure

PURPOSE OF REVIEW

Admissions to hospital for acute decompensated heart failure continue to increase and represent a significant burden on both patients' and healthcare resources. The majority of these admissions are for the control of volume overload; however, standard treatment with intravenous diuretics is not always effective and can lead to increased renal morbidity. One alternative to standard therapy is mechanical fluid removal with ultrafiltration, this review will highlight the current evidence and efficacy regarding ultrafiltration use in acute heart failure.

RECENT FINDINGS

Multiple recent clinical trials have demonstrated the safety and feasibility of ultrafiltration in the management of acute heart failure. Ultrafiltration may be more effective at removing fluid than standard diuretic therapy and has been associated with beneficial long-term results. However, it remains to be determined whether ultrafiltration is truly nephroprotective and when and how this therapy is best utilized.

SUMMARY

Ultrafiltration is an attractive alternative to standard diuretic therapy in the management of volume overload from acute heart failure. Further research is needed to confirm the cost-effectiveness and to determine long-term impacts on morbidity and mortality.

[Renoprotective effect of small volumes of hypertonic saline solution in chronic heart failure patients with marked fluid retention: results of a case-control study]

During intensive therapy of chronic heart failure (CHF) patients with marked fluid retention using high doses of i.v. furosemide the additional effect of agents which might exert osmotic attraction of interstitial fluids has been proposed. They are thought to impede the impairment of renal blood supply and glomerular filtration rate, which may be caused by a combined action of cardiac preload acute reduction, hypotension and neurohormonal activation.We therefore assessed in CHF patients with NYHA class III and BNP values from 900 to 1500 pg/ml, who were treated with i.v. furosemide, the predictors of iatrogenic short term creatinine impairment by means of a case-control observational study from two centers. Patients with CHF had been treated for 6-8 days with intravenous loop diuretics alone or with an additional i.v. administration of other agents (plasma expanders, albumin, mannitol, inotropic support etc.). A rise in serum creatinine ≥ 25% of the basal value was considered as renal impairment.A total of 15 cases and 38 controls were enrolled. At univariate analysis, serum creatinine basal value ≥ 2.2 mg/dl, absence of hypertonic saline solution (HSS) in the therapeutic protocol, hyposodic diet and refractory oligoanuria were associated with an increased risk of worsening renal function precipitated by i.v. diuretic therapy. At multivariate analysis as a predictor of loop diuretic-related renal function impairment, we found a serum creatinine ≥ 2.2 mg/dl at baseline (OR: 63.33, 95% CI: 3.68-1088.73, p=0.0043) and the absence of HSS in the therapeutic regimen (OR: 25.0461, 95% CI: 2.07-302.53, p=0.0113). Moreover, in multivariate analysis ascites had some predictive value of renal deterioration (OR: 13.28, 95% CI: 1.0055-175.41, p=0,0495).

Haemodynamic effects of rolofylline in the treatment of patients with heart failure and impaired renal function

AIMS

The direct effects of adenosine A1 receptor antagonists on haemodynamic parameters in patients with acute heart failure (HF) remain largely unknown.

METHODS AND RESULTS

We evaluated the haemodynamic effects of the AA(1)RA rolofylline in 59 HF patients with concomitant renal impairment (estimated creatinine clearance 20-80 mL/min). Placebo or rolofylline 30 mg was administered as a 4 h infusion followed by intravenous (i.v.) loop diuretic administration. Haemodynamic measurements were carried out hourly up to 8 h post-dosing by pulmonary artery catheterization. Urine output, fractional excretion of sodium, potassium, urea, and uric acid, and blood urea nitrogen (BUN) and creatinine levels were also measured. In both groups, the changes from baseline in all haemodynamic indices except mean pulmonary artery pressure (PAP) were not clinically significant. Mean [95% confidence interval (CI)] PAP showed a placebo-adjusted decrease with rolofylline of -1.5 (-4.1, 1.1)mmHg at Hour 4 and -3.5 mmHg (95% CI: -6.2, -0.2) at Hour 8. There was a significant increase with rolofylline in diuresis [placebo-corrected mean (95% CI) change of 68 (20, 116)mL/h at Hour 2-4 and 103 (21, 185)mL/h at Hour 4-8] and in fractional excretion of sodium, potassium, and uric acid. Placebo-corrected changes in plasma levels of creatinine and BUN with rolofylline were non-significant.

CONCLUSION

Single administration of rolofylline in patients with HF and impaired renal function produced a slight decrease in mean PAP and consistently increased diuresis and natriuresis without compromising renal function, both before and after administration of i.v. loop diuretics.

Glomerular tubular balance is suppressed in adenosine type 1 receptor-deficient mice

Glomerular tubular balance maintains a stable fractional solute and fluid reabsorption in the proximal tubule over a range of glomerular filtration rates. The mediators of this process are unknown. We tested the hypothesis that adenosine, produced in proximal tubule cells acting on adenosine type 1 receptors (A(1)-AR) promotes Na(+) and fluid uptake and mediates glomerular tubular balance. Absolute proximal fluid reabsorption (J(v)) was measured by in vivo microperfusion in A(1)-AR knockout and wild-type mice during perfusion of the closed proximal tubule at 2-10 nl/min. J(v) increased with perfusate flow from 2-4 nl/min in both strains, but the fractional increase was lower in A(1)-AR(-/-) mice (A(1)-AR(+/+): 114% vs. A(1)-AR(-/-): 38%; P < 0.001), suggesting reduced glomerular tubular balance (GTB). At higher perfusion rates, J(v) increased modestly in both strains, indicating less GTB at higher flow. The physiological effects of reduced GTB in A(1)-AR(-/-) mice were assessed from the response to an acute volume load (1 ml/2 min). Na(+) excretion and urine flow increased 76 and 73% more in A(1)-AR(-/-) mice than A(1)-AR(+/+) over the following 30 min, accompanied by a higher proximal tubule flow (A(1)-AR(-/-): 6.9 ± 0.9 vs. A(1)-AR(+/+): 5.2 ± 0.6 nl/min; P < 0.05). The expression of the sodium-hydrogen exchanger 3 and sodium phosphate cotransporter-2 were similar between strains. In conclusion, GTB is dependent on adenosine acting on type 1 receptors in the proximal tubule. This may contribute to acute changes in Na(+) and fluid reabsorption.

The cardiorenal syndrome in heart failure: an evolving paradigm

Heart failure constitutes a significant source of morbidity and mortality in the United States, and its incidence and prevalence continue to grow, increasing its burden on the healthcare system. Renal dysfunction in patients with heart failure is common and has been associated with adverse clinical outcomes. This interaction, termed the cardiorenal syndrome, is a complex phenomenon characterized by a pathophysiologic disequilibrium between the heart and the kidney, in which malfunction of 1 organ consequently promotes the impairment of the other. Multiple neurohumoral mechanisms are involved in this cardiorenal interaction, including the deficiency of and/or resistance to compensatory natriuretic peptides, leading to sodium retention, volume overload and organ remodeling. Management of patients with the cardiorenal syndrome can be challenging and should be individualized. Emerging therapies must address the function of both organs to secure better clinical outcomes. To this end, a multidisciplinary approach is recommended to achieve optimal results.

The effects of adenosine A(1) receptor antagonism in patients with acute decompensated heart failure and worsening renal function: the REACH UP study

BACKGROUND

Worsening renal function (WRF) portends a poor prognosis, and recent deterioration in creatinine might identify patients with elevated intrarenal adenosine in whom adenosine A(1) antagonism may improve renal hemodynamics and function. The purpose of this pilot study was to assess whether rolofylline, an adenosine A(1) antagonist (A(1)RA), would facilitate diuresis while maintaining renal function in patients with acutely decompensated heart failure (ADHF) and recent WRF.

METHODS AND RESULTS

Seventy-six patients with ADHF, volume overload, and recent renal deterioration received rolofylline (30 mg, n = 36) or placebo (n = 40) for 3 days. Rolofylline did not demonstrate a beneficial effect on the primary end points of worsening heart failure or renal function after admission or death or readmission within 30 days. Similar proportions of patients receiving rolofylline (33%) and placebo (30%) were treatment failures within 30 days. However, persistent renal impairment (through Day 14) tended to be less common with rolofylline (6%) than placebo (18%). At Day 14, 11 patients receiving placebo and 13 patients receiving rolofylline had a decrease in creatinine > or = 0.3 mg/dL. There were fewer heart failure readmissions with rolofylline (n = 2) than with placebo (n = 7) through Day 60.

CONCLUSIONS

The Placebo-Controlled Study of the Effects of KW-3902 Injectable Emulsion on Heart Failure Signs and Symptoms, Diuresis, Renal Function, and Clinical Outcomes in Subjects Hospitalized with Worsening Renal Function and Heart Failure Requiring Intravenous Therapy (ie, REACH UP) study did not demonstrate any clear benefit of rolofylline in patients with ADHF and worsening renal function. However, beneficial trends raise the possibility that A(1)RAs might prevent renal dysfunction in these high risk patients. To test this hypothesis, further larger studies need to evaluate the effects of adenosine A(1) antagonists in patients with progressive renal dysfunction in the face of active heart failure therapy.

Design and rationale of the PROTECT study: a placebo-controlled randomized study of the selective A1 adenosine receptor antagonist rolofylline for patients hospitalized with acute decompensated heart failure and volume overload to assess treatment effect on congestion and renal function

BACKGROUND

Current treatment for acute decompensated heart failure (ADHF) is associated with incomplete resolution of symptoms and signs, recurrent symptoms of heart failure in-hospital and after discharge and high mortality. Studies have consistently demonstrated an association between worsening renal function in ADHF and adverse outcomes. Adenosine A(1) receptor antagonists, such as rolofylline, appear in preliminary studies to produce potentially beneficial effects on natriuresis, diuresis, renal blood flow, and glomerular filtration rate. In a previous dose-finding study, rolofylline 30 mg intravenously daily for 3 days was associated with symptom improvement, less worsening of renal function, and trends toward lower 60-day rates of death or readmission for cardiovascular or renal causes.

METHODS AND RESULTS

This manuscript describes the rationale underlying the design of the phase 3 PROTECT (Placebo-controlled Randomized study of the selective A(1) adenosine receptor antagonist rolofylline for patients hospitalized with acute heart failure and volume Overload to assess Treatment Effect on Congestion and renal funcTion) trial.

CONCLUSION

Rolofylline 30 mg or matching placebo was given intravenously as a 4-hour continuous infusion on 3 consecutive days and the hospital course was assessed by measurements dyspnea, clinical status, renal function, and subsequent morbidity and mortality in a large population of patients with ADHF with renal impairment.

Cardiorenal syndrome in acute decompensated heart failure

Renal dysfunction is highly prevalent in patients with heart failure. Furthermore, worsening renal function in patients with acute decompensated heart failure (ADHF), the so-called cardiorenal syndrome, impacts short and long-term morbidity and mortality. In recent years, more evidence has surfaced from clinical trials and heart failure registries that a complex cross-talk between the kidney and heart in patients with ADHF exists. Meanwhile, management of patients presenting with ADHF and concomitant renal dysfunction continues to be challenging. Therefore, understanding the interaction of the heart and kidneys is pivotal in tailoring therapy of these patients. We have extensively reviewed the pathophysiology of ADHF, the role of neurohoromones as well as other biomarkers and predictors of mortality in these patients based on the current evidence. Moreover, we have discussed the current and future pharmacologic and non-pharmacologic therapies for treatment of this deadly disease. The strength of the evidence is limited, however, due to a paucity of randomized controlled trials in this patient population. What is evident from current national statistics; however, are the poor results in treating the congestion of ADHF. In this regard, the role of secondary hyperaldosteronism is discussed in the diuretic section as well as diuretic resistance in ADHF. In conclusion, since renal function is the single most important prognostic factor in the outcome of patients with ADHF, a better understanding of the pathophysiology of the cardiorenal syndrome is needed to target therapy and ultimately improve the mortality of patients with ADHF.

Cardiorenal syndrome

Kidney dysfunction in patients with heart failure and cardiovascular disorders in patients with chronic kidney disease are common. A recently proposed consensus definition of cardiorenal syndrome stresses the bidirectional nature of these heart-kidney interactions. The treatment of cardiorenal syndrome is challenging, however, promising new therapeutic options are currently being investigated in recent and ongoing clinical trials.

Cardio-renal effects of the A1 adenosine receptor antagonist SLV320 in patients with heart failure

BACKGROUND

Blocking the tubuloglomerular feedback mechanism with adenosine A1 receptor antagonists seems to improve diuresis and sodium excretion without compromising the glomerular filtration rate in patients with heart failure. However, the direct cardiac effects of this compound class have not been investigated to date.

METHODS AND RESULTS

In total, 111 patients (109 men and 2 women) received a 1-hour infusion of 5, 10, and 15 mg SLV320, an adenosine A1 receptor antagonist, placebo, or 40 mg furosemide. Mean age was 57.9 years, mean ejection fraction was 28.1%, 82 patients were of New York Heart Association class II, and 29 patients were of New York Heart Association class III. Hemodynamic parameters (heart rate, blood pressure, pulmonary capillary wedge pressure, mean pulmonary arterial pressure, systemic vascular resistance, right atrial pressure, and cardiac output) were determined. Kidney function was assessed by cystatin C measurements and by analysis of urine output and urine electrolytes. In addition, pharmacokinetics of SLV320 and ex vivo inhibition of adenosine A1 receptor activity were performed. SLV320 was well tolerated, and no serious adverse events were observed. Heart rate, blood pressure, pulmonary capillary wedge pressure, mean pulmonary arterial pressure, right atrial pressure, and cardiac output were not altered by any dose of SLV320. Pulmonary capillary wedge pressure was significantly (P=0.04) decreased by furosemide (-6.2+/-5.9 mm Hg). Systemic vascular resistance was significantly (P=0.04) increased in the furosemide group (+166.70+/-261.87 dynes . s(-1) . cm(-5)), whereas all SLV320 groups showed no significant alterations of systemic vascular resistance. Changes from baseline cystatin C plasma concentrations decreased after 10 mg SLV320 (-0.093+/-0.137 mg/L, P=0.046), whereas furosemide resulted in a significant (P=0.03) increase of cystatin C (+0.052+/-0.065 mg/L) versus baseline. All values represent mean changes+/-SD from baseline at 3 hours postdosing: SLV320 (10 and 15 mg) increased significantly sodium excretion and diuresis compared with placebo during the 0- to 6-hour collection period postdosing.

CONCLUSIONS

SLV320 infusion shows no immediate effects on cardiac hemodynamics. SLV320 might improve glomerular filtration rate while simultaneously promoting natriuresis and diuresis. Clinical Trial Registration- clinicaltrials.gov Indentifier: NCT00160134.

Pharmacologic management of the cardiorenal syndrome in heart failure

Cardiorenal syndrome describes the impairment of renal function and associated diuretic resistance in patients with heart failure and clinically manifest volume overload. The pathophysiology of this syndrome is poorly understood, but appears to be caused by impairment of tubuloglomerular feedback, neurohormonal activation, and other factors and therapies used in the management of heart failure. Early diagnosis of the cardiorenal syndrome by way of markers of renal injury and function is critical for timely interventions that may attenuate progression. Many novel therapies have been evaluated in the cardiorenal syndrome setting, including agents that block key local factors (eg, adenosine A(I) receptor antagonists), improve diuresis, aquaresis, and natriuresis, and augment natural vasodilator mechanisms to improve renal perfusion. Furthermore, device-based approaches such as ultrafiltration may also play an important therapeutic role.