Regulation of glomerular filtration rate in chronic congestive heart failure patients

Brain natriuretic peptide in acute heart failure and its association with glomerular filtration rate: A systematic review and meta-analysis

BACKGROUND

Acute heart failure (AHF) is one of the most common cardiovascular diseases. Early diagnosis and prognosis are essential, as they can eventually lead to a fatal condition. Recently, brain natriuretic peptide (BNP) has been recognized as one of the most popular biomarkers for AHF. Changes in glomerular filtration rate (GFR) are often observed in AHF.

METHODS

We searched PubMed, Google Scholar, and ScienceDirect between March and June 2023. Original case control studies written in English that assessed levels oh BNP in AHF were included. Systematic reviews, letters to editor, correspondence, comprehensive reviews, and duplicated studies were excluded. Funnel plots were constructed to assess publication bias.

RESULTS

A total of 9 studies were selected and we obtained the mean difference (MD) of BNP level to be 2.57 (95% CI: 1.35, 3.78), and GFR to be -15.52, (95% CI: -23.35, -7.70) in AHF patients. Sensitivity analyses supported the robustness of the outcome.

CONCLUSION

Results indicated that BNP was a promising prognostic biomarker of AHF, whereas GFR was found to be negatively correlated with AHF.

Renal Biomarkers in Heart Failure: Systematic Review and Meta-Analysis

Background

Cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule (KIM)-1 are renal biomarkers increasingly appreciated for their role in the risk stratification and prognostication of heart failure (HF) patients. However, very few have been adopted clinically, owing to the lack of consistency.

Objectives

The authors aimed to study the association between cystatin C, NGAL, and KIM-1 and outcomes, mortality, hospitalizations, and worsening renal function (WRF) in patients with acute and chronic HF.

Methods

We included peer-reviewed English-language articles from PubMed and EMBASE published up to December 2021. We analyzed the above associations using random-effects meta-analysis. Publication bias was assessed using funnel plots.

Results

Among 2,631 articles, 100 articles, including 45,428 patients, met the inclusion criteria. Top-tertile of serum cystatin C, when compared to the bottom-tertile, carried a higher pooled hazard ratio (pHR) for mortality (pHR: 1.59, 95% CI: 1.42-1.77) and for the composite outcome of mortality and HF hospitalizations (pHR: 1.49, 95% CI: 1.23-1.75). Top-tertile of serum NGAL had a higher hazard for mortality (pHR: 2.91, 95% CI: 1.49-5.67) and composite outcome (HR: 4.11, 95% CI: 2.69-6.30). Serum and urine NGAL were significantly associated with WRF, with pHRs of 2.40 (95% CI: 1.48-3.90) and 2.01 (95% CI: 1.21-3.35). Urine KIM-1 was significantly associated with WRF (pHR: 1.60, 95% CI: 1.24-2.07) but not with other outcomes. High heterogeneity was noted between studies without an obvious explanation based on meta-regression.

Conclusions

Serum cystatin C and serum NGAL are independent predictors of adverse outcomes in HF. Serum and urine NGAL are important predictors of WRF in HF.

Renal effects of SGLT2 inhibitors in cardiovascular patients with and without chronic kidney disease: focus on heart failure and renal outcomes

The kidney has a prominent role in maintaining glucose homeostasis by using glucose as a metabolic substrate. This occurs by generating glucose through gluconeogenesis, and by reuptaking filtered glucose through the sodium-glucose cotransporters SGLT1 and SGLT2 located in the proximal tubule. In recent studies, the administration of sodium-glucose cotransporters inhibitors demonstrated that inhibition of renal glucose reabsorption significantly reduces adverse renal events and heart failure exacerbations, in type 2 diabetic patients with and without cardiovascular damage as well as in advanced chronic kidney disease and heart failure patients with reduced ejection fraction with and without diabetes. The benefit was consistent throughout the different investigated clinical conditions, ameliorating overall patient outcome. The efficacy of sodium glucose cotransporters inhibitors was prominently linked to the limitation of renal damage as highlighted by the significant reduction on global mortality achieved in the studies investigating diabetic and not diabetic populations with advanced chronic kidney disease. Both studies were halted at the interim analysis because of unquestionable evidence of treatment benefit. In current review, we examine the role of SGLT2 and SGLT1 in the regulation of renal glucose reabsorption in health and disease and the effect of SGLT2 inhibition on clinical outcomes of populations with different cardiovascular conditions investigated with large-scale outcome trials.

Distinctive kidney function trajectories following left ventricular assist device implantation

BACKGROUND

The aim of this study was to assess for distinct kidney function trajectories following left ventricular assist device (LVAD) placement. Cohort studies of LVAD recipients demonstrate that kidney function tends to increase early after LVAD placement, followed by decline and limited sustained improvement. Inter-individual differences in kidney function response may be obscured.

METHODS

We identified continuous flow LVAD implantations in US adults (2016-2017) from INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support). Primary outcomes were estimated glomerular filtration rate (eGFR) trajectories pre-implantation to ∼12 months. Latent class mixed models were applied to primary and validation samples. Clinical differences among trajectory groups were investigated.

RESULTS

Among 4,615 LVAD implantations, 5 eGFR trajectory groups were identified. The 2 largest groups (Groups 1 and 2) made up >80% of the cohort, and were similar to group average trajectories previously reported, with early eGFR rise followed by decline and stabilization. Three novel trajectory groups were found: worsening followed by sustained low kidney function (Group 3, 10.1%), sustained improvement (Group 4, 3.3%), and worsening followed by variation (Group 5, 1.7%). These groups differed in baseline characteristics and outcomes. Group 4 was younger and had more cardiogenic shock and pre-implantation dialysis; Group 3 had higher rates of pre-existing chronic kidney disease, along with older age.

CONCLUSIONS

Novel eGFR trajectories were identified in a national cohort, possibly representing distinct cardiorenal processes. Type 1 cardiorenal syndrome may have been predominant in Group 4, and parenchymal kidney disease may have been predominant in Group 3.

Comprehensive and Safe Decongestion in Acutely Decompensated Heart Failure

PURPOSE OF THE REVIEW

Progressive intravascular, interstitial, and alveolar fluid overload underlies the transition from compensated to acutely decompensated heart failure and loop diuretics are the mainstay of treatment. Adverse effects and resistance to loop diuretics received much attention while the contribution of a depressed cardiac output to diuretic resistance was downplayed.

RECENT FINDINGS

Analysis of experience with positive inotropic agents, especially dobutamine, indicates that enhancement of cardiac output is not consistently associated with increased renal blood flow. However, urinary output and renal sodium excretion increase likely due to dobutamine-mediated decrease in renal and systemic reduced activation of sympathetic nervous- and renin-angiotensin-aldosterone system. Mechanical circulatory support with left ventricular assist devices ascertained the contribution of low cardiac output to diuretic resistance and the pathogenesis and progression of kidney disease in acutely decompensated heart failure. Diuretic resistance commonly occurs in acutely decompensated heart failure. However, failure to resolve fluid overload despite high doses of loop diuretics should alert to the presence of a low cardiac output state.

Peripheral chemoreflex modulation of renal hemodynamics and renal tissue PO2 in chronic heart failure with reduced ejection fraction

Aberrant carotid body chemoreceptor (CBC) function contributes to increased sympathetic nerve activity (SNA) and reduced renal blood flow (RBF) in chronic heart failure (CHF). Intermittent asphyxia (IA) mimicking sleep apnea is associated with additional increases in SNA and may worsen reductions in RBF and renal PO2 (RPO2) in CHF. The combined effects of decreased RBF and RPO2 may contribute to biochemical changes precipitating renal injury. This study sought to determine the role of CBC activity on glomerular filtration rate (GFR), RBF and RPO2 in CHF, and to assess the additive effects of IA. Furthermore, we sought to identify changes in gene expression that might contribute to renal injury. We hypothesized that GFR, RBF, and RPO2 would be reduced in CHF, that decreases in RBF and RPO2 would be worsened by IA, and that these changes would be ameliorated by CBC ablation (CBD). Finally, we hypothesized that CHF would be associated with pro-oxidative pro-fibrotic changes in renal gene expression that would be ameliorated by CBD. CHF was induced in adult male Sprague Dawley rats using coronary artery ligation (CAL). Carotid body denervation was performed by cryogenic ablation. GFR was assessed in conscious animals at the beginning and end of the experimental period. At 8-weeks post-CAL, cardiac function was assessed via echocardiography, and GFR, baseline and IA RBF and RPO2 were measured. Renal gene expression was measured using qRT-PCR. GFR was lower in CHF compared to sham (p < 0.05) but CBD had no salutary effect. RBF and RPO2 were decreased in CHF compared to sham (p < 0.05), and this effect was attenuated by CBD (p < 0.05). RBF and RPO2 were reduced to a greater extent in CHF vs. sham during exposure to IA (p < 0.05), and this effect was attenuated by CBD for RBF (p < 0.05). Downregulation of antioxidant defense and fibrosis-suppressing genes was observed in CHF vs. sham however CBD had no salutary effect. These results suggest that aberrant CBC function in CHF has a clear modulatory effect on RBF during normoxia and during IA simulating central sleep apnea.

Renal Hemodynamics and Renin-Angiotensin-Aldosterone System Profiles in Patients With Heart Failure

OBJECTIVE

Understanding cardiorenal pathophysiology in heart failure (HF) is of clinical importance. We sought to characterize the renal hemodynamic function and the transrenal gradient of the renin-angiotensin-aldosterone system (RAAS) markers in patients with HF and in controls without HF.

METHODS

In this post hoc analysis, the glomerular filtration rate (GFR_inulin), effective renal plasma flow (ERPF_PAH) and transrenal gradients (arterial-renal vein) of angiotensin converting enzyme (ACE), aldosterone, and plasma renin activity (PRA) were measured in 47 patients with HF and in 24 controls. Gomez equations were used to derive afferent (R_A) and efferent (R_E) arteriolar resistances. Transrenal RAAS gradients were also collected in patients treated with intravenous dobutamine (HF, n = 11; non-HF, n = 11) or nitroprusside (HF, n = 18; non-HF, n = 5).

RESULTS

The concentrations of PRA, aldosterone and ACE were higher in the renal vein vs the artery in patients with HF vs patients without HF (P < 0.01). In patients with HF, a greater ACE gradient was associated with greater renal vascular resistance (r = 0.42; P 0.007) and greater arteriolar resistances (R_A: r = 0.39; P = 0.012; R_E: r = 0.48; P = 0.002). Similarly, a greater aldosterone gradient was associated with lower GFR (r = -0.51; P = 0.0007) and renal blood flow (RBF), r = -0.32; P = 0.042) whereas greater PRA gradient with lower ERPF (r = -0.33; P = 0.040), GFR (r = -0.36; P = 0.024), and RBF (r = -0.33; P = 0.036). Dobutamine and nitroprusside treatment decreased the transrenal gradient of ACE (P = 0.012, P < 0.0001, respectively), aldosterone (P = 0.005, P = 0.030) and PRA (P = 0.014, P = 0.002) in patients with HF only.

CONCLUSIONS

A larger transrenal RAAS marker gradient in patients with HF suggests a renal origin for neurohormonal activation associated with a vasoconstrictive renal profile.

Effects of neprilysin-renin inhibition in comparison with neprilysin-angiotensin inhibition on the neurohumoral changes in rats with heart failure

Background

The activation of neurohumoral compensatory mechanisms is a common physiological phenomenon in heart failure in order to make up for a failing heart, which will usually have a deteriorating effect on overall health condition. Many medications, such as neprilysin and angiotensin inhibitors, have recently been introduced to remediate neurohumoral changes. This study was conducted to evaluate the efficacy of the sacubitril-aliskiren combination versus the sacubitril-ramipril combination in the treatment of neurohumoral changes in rats with experimentally induced heart failure.

Method

Thirty Wister rats were randomly assigned into five groups each of six rats, the first group was the control group. Intraperitoneal isoprenaline injections of 5 mg/kg/day for 1 week were used to induce experimental models of heart failure in rats of the rest of experimental groups. The second group served as a positive control. Rats in the third, fourth, and fifth groups received oral daily dose of sacubitril 30 mg/kg/day, sacubitril-aliskiren 30,10 mg/kg/day, and sacubitril-ramipril 30/10 mg/kg/day respectively, for 2 weeks.

Results

Induction of heart failure in rats has significantly increased circulating NT-proBNP (980 ± 116.71 pg/ml), MMP9 (15.85 ± 0.57 ng/ml), troponin-I (3.09 ± 0.147 ng/ml), CK-MB (31.55 ± 1.69 ng/ml), renin (736 ± 45.8 pg/ml), urea (52.1 ± 1.57 mg/dl), and creatinine (0.92 ± 0.04 mg/dl). Significant decreases in glomerular filtration rate (7.031 ± 1.6 ml/hr./kg), urine flow (0.2761 ± 0.06 ml/h/kg), total solute excretion (0.11 ± 0.03 meq/m), and mean blood pressure (83.5 ± 2.6 mm hg) were seen in rats with heart failure.

Rats treated with sacubitril combined with aliskiren or ramipril showed a statistically significant reduction of NT-proBNP, MMP9, troponin serum urea, and serum creatinine.

Sacubitril-aliskiren or sacubitril-ramipril administration produced a significant increase in renin plasma level, total solute excretion, urine flow, and glomerular filtration rate.

Conclusion

Sacubitril in combination with aliskiren or with ramipril effectively reduced plasma cardiac biomarkers, such as CK-MB, MMP9, and NT-proBNP, in rats with heart failure. Both combinations showed significant remediation of renal function through increasing GFR, urine flow, and total solute excretion, as well as reducing plasma level of renin. Net results revealed that the sacubitril-aliskiren combination has similar remediating effects on neurohumoral changes compared to the sacubitril-ramipril combination.

Increased Intra-abdominal Pressure Induces Acute Kidney Injury in an Experimental Model of Congestive Heart Failure

BACKGROUND

Congestive heart failure (CHF) entails a complex interaction between the heart and the kidney that represents a clinical entity called cardiorenal syndrome (CRS). One of the mechanisms underlying CRS includes increased intra-abdominal pressure (IAP). We examined the effect of elevated IAP on kidney function in rats with low- and high-output CHF.

METHODS AND RESULTS

Rats with compensated and decompensated CHF induced by means of aortocaval fistula, rats with myocardial infraction (MI) induced by means of left anterior descending artery ligation, and sham control rats were subjected to either 10 or 14 mm Hg IAP. Urine flow (V), Na⁺ excretion (U_NaV), glomerular filtration rate (GFR), and renal plasma flow (RPF) were determined. The effects of pretreatment with tadalafil (10 mg/kg orally for 4 days) on the adverse renal effects of IAP were examined in decompensated CHF and MI. Basal V and GFR were significantly lower in rats with decompensated CHF compared with sham control rats. Decompensated CHF rats and MI rats subjected to 10 and 14 mm Hg IAP exhibited more significant declines in V, U_NaV, GFR and RPF than compensated and sham controls. Elevated IAP also induced tubular injury, as evidenced by significantly increased absolute urinary excretion of neutrophil gelatinase-associated lipocalin. In addition, in a nonquantitative histologic analysis, elevated IAP was associated with increase in necrosis and cell shedding to the tubule lumens, especially in the decompensated CHF subgroup. Pretreatment of decompensated CHF rats and MI rats with tadalafil ameliorated the adverse renal effects of high IAP.

CONCLUSIONS

Elevated IAP contributes to kidney dysfunction in high- and low-cardiac output CHF. IAP induces both hemodynamic alterations and renal tubular dysfunction. These deleterious effects are potentially reversible and can be ameliorated with the use of phosphodiesterase-5 inhibition.

Plasma levels of endothelin-1 and renal function among young and healthy adults

Background:

Endothelin-1 (ET-1), a vasoconstrictive and pro-inflammatory peptide, is associated with several cardiovascular risk factors and outcomes. We aimed to investigate the association of plasma ET-1 levels and renal function among young and healthy adults.

Methods:

Individuals aged 25–41 years were enrolled in a population-based cohort study. Main exclusion criteria were established kidney disease, cardiovascular diseases, diabetes mellitus and a body mass index>35 kg/m2. Fasting venous plasma samples were used to measure creatinine, cystatin C and ET-1. The estimated glomerular filtration rate (eGFR) was calculated using the creatinine based chronic kidney disease epidemiology collaboration (CKD-EPI) formula. Multivariable regression models were constructed to assess interrelationships of plasma ET-1 with parameters of renal function.

Results:

Median age of the 2139 participants was 37 years, 47% males. Median creatinine and eGFR were 67 μmol/L and 112 mL/min/1.73 m2, respectively. Using quartile one as the reference group, the β-coefficients (95% confidence intervals [CIs]) for eGFR were 0.06 (− 1.22 to 1.35),−0.66 (− 1.95 to 0.62) and−1.70 (− 3.01 to−0.39) for quartiles 2–4 (p-for-trend=0.0056), respectively and β-coefficients (95% CIs) for cystatin C were 0.002 (− 0.01 to 0.02), 0.02 (0.003–0.03) and 0.03 (0.01–0.04) for quartiles 2–4 (p-for-trend<0.0001), respectively. Using ET-1 as a continuous variable, the β-coefficient (95% CI) for eGFR per 1-unit increase was−1.82 (− 3.19 to−0.44, p=0.0095) and 0.02 (0.01–0.04, p=0.0003) for cystatin C. Similar results were found between creatinine and ET-1 levels.

Conclusions:

ET-1 levels are strongly associated with parameters of renal function among young and healthy adults, suggesting an important role of ET-1 and endothelial function in the regulation of kidney function.

Hemodynamic and neurochemical determinates of renal function in chronic heart failure

Abnormal renal function is common in acute and chronic congestive heart failure (CHF) and is related to the severity of congestion. However, treatment of congestion often leads to worsening renal function. Our objective was to explore basal determinants of renal function and their response to hemodynamic interventions. Thirty-seven patients without CHF and 59 patients with chronic CHF (ejection fraction; 23 ± 8%) underwent right heart catheterization, measurements of glomerular filtration rate (GFR; inulin) and renal plasma flow (RPF; para-aminohippurate), and radiotracer estimates of renal sympathetic activity. A subset (26 without, 36 with CHF) underwent acute pharmacological intervention with dobutamine or nitroprusside. We explored the relationship between baseline and drug-induced hemodynamic changes and changes in renal function. In CHF, there was an inverse relationship among right atrial mean pressure (RAM) pressure, RPF, and GFR. By contrast, mean arterial pressure (MAP), cardiac index (CI), and measures of renal sympathetic activity were not significant predictors. In those with CHF there was also an inverse relationship among the drug-induced changes in RAM as well as pulmonary artery mean pressure and the change in GFR. Changes in MAP and CI did not predict the change in GFR in those with CHF. Baseline values and changes in RAM pressure did not correlate with GFR in those without CHF. In the CHF group there was a positive correlation between RAM pressure and renal sympathetic activity. There was also an inverse relationship among RAM pressure, GFR, and RPF in patients with chronic CHF. The observation that acute reductions in RAM pressure is associated with an increase in GFR in patients with CHF has important clinical implications.

Prevalence, predictors, and outcomes of cardiorenal syndrome in children with dilated cardiomyopathy: a report from the Pediatric Cardiomyopathy Registry

BACKGROUND

The association of cardiorenal syndrome (CRS) with mortality in children with dilated cardiomyopathy (DCM) is unknown.

METHODS

With a modified Schwartz formula, we estimated glomerular filtration rates (eGFR) for children ≥1 year of age with DCM enrolled in the Pediatric Cardiomyopathy Registry at the time of DCM diagnosis and annually thereafter. CRS was defined as an eGFR of <90 mL/min/1.73 m(2). Children with and without CRS were compared on survival and serum creatinine concentrations (SCr). The association between eGFR and echocardiographic measures was assessed with linear mixed-effects regression models.

RESULTS

Of 285 eligible children with DCM diagnosed at ≥1 year of age, 93 were evaluable. CRS was identified in 57 of these 93 children (61.3%). Mean (standard deviation) eGFR was 62.0 (22.6) mL/min/1.73 m(2) for children with CRS and 108.0 (14.0) for those without (P < 0.001); median SCr concentrations were 0.9 and 0.5 mg/dL, respectively (P < 0.001). The mortality hazard ratio of children with CRS versus those with no CRS was 2.4 (95% confidence interval 0.8-7.4). eGFR was positively correlated with measures of left ventricular function and negatively correlated with age.

CONCLUSIONS

CRS in children newly diagnosed with DCM may be associated with higher 5-year mortality. Children with DCM, especially those with impaired left ventricular function, should be monitored for renal disease.

Biomarkers of renal injury and function: diagnostic, prognostic and therapeutic implications in heart failure

Heart failure guidelines suggest evaluating renal function as a routine work-up in every patient with heart failure. Specifically, it is advised to calculate glomerular filtration rate and determine blood urea nitrogen. The reason for this is that renal impairment and worsening renal function (WRF) are common in heart failure, and strongly associate with poor outcome. Renal function, however, consists of more than glomerular filtration alone, and includes tubulointerstitial damage and albuminuria. For each of these renal entities, different biomarkers exist that have been investigated in heart failure. Hypothetically, and in parallel to data in nephrology, these markers may aid in the diagnosis of renal dysfunction, or for risk stratification, or could help in therapeutic decision-making. However, as reviewed in the present manuscript, while these markers may carry prognostic information (although not always additive to established markers of renal function), their role in predicting WRF is limited at best. More importantly, none of these markers have been evaluated as a therapeutic target nor have their serial values been used to guide therapy. The evidence is most compelling for the oldest-serum creatinine (in combination with glomerular filtration rate)-but even for this biomarker, evidence to guide therapy to improve outcome is circumstantial at best. Although many new renal biomarkers have emerged at the horizon, they have only limited usefulness in clinical practice until thoroughly and prospectively studied. For now, routine measurement of (novel) renal biomarkers can help to determine cardiovascular risk, but there is no role for these biomarkers to change therapy to improve clinical outcome in heart failure.

Evaluation of Renal Blood Flow and Oxygenation in CKD Using Magnetic Resonance Imaging

BACKGROUND

Animal studies suggest that progression of chronic kidney disease (CKD) is related to renal hypoxia. With renal blood supply determining oxygen delivery and sodium absorption being the main contributor to oxygen consumption, we describe the relationship between renal oxygenation, renal artery blood flow, and sodium absorption in patients with CKD and healthy controls.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

62 stable patients with CKD stages 3 to 4 (mean age, 61±13 [SD] years) and 24 age- and sex-matched controls.

PREDICTORS

CKD versus control status.

OUTCOMES

Renal artery blood flow, tissue oxygenation (relative changes in deoxyhemoglobin concentration of the renal medulla [MR2*] and cortex [CR2*]), and sodium absorption.

MEASUREMENTS

Renal artery blood flow was determined by phase-contrast magnetic resonance imaging (MRI); MR2* and CR2* were determined by blood oxygen level-dependent MRI. Ultrafiltered and reabsorbed sodium were determined from measured glomerular filtration rate (mGFR) and 24-hour urine collections.

RESULTS

mGFR in patients was 37% that of controls (36±15 vs 97±23 mL/min/1.73 m(2); P < 0.001), and reabsorbed sodium was 37% that of controls (6.9 vs 19.1 mol/24 h; P < 0.001). Single-kidney patient renal artery blood flow was 72% that of controls (319 vs 443 mL/min; P < 0.001). Glomerular filtration fraction was 9% in patients and 18% in controls (P < 0.001). Patients and controls had similar CR2* (13.4 vs 13.3 s(-1)) and medullary MR2* (26.4 vs 26.5 s(-1)) values. Linear regression analysis demonstrated no associations between R2* and renal artery blood flow or sodium absorption. Increasing arterial blood oxygen tension by breathing 100% oxygen had very small effects on CR2*, but reduced MR2* in both groups.

LIMITATIONS

Only renal artery blood flow was determined and thus regional perfusion could not be related to CR2* or MR2*.

CONCLUSIONS

In CKD, reductions of mGFR and reabsorbed sodium are more than double that of renal artery blood flow, whereas cortical and medullary oxygenation are within the range of healthy persons. Reduction in glomerular filtration fraction may prevent renal hypoxia in CKD.

A prospective, randomized study to evaluate the efficacy of various diuretic strategies in acute decompensated heart failure

AIM

To evaluate the safety and efficacy of various initial strategies of loop diuretic administration in patients with acute decompensated heart failure (ADHF) on diuresis, renal function, electrolyte balance and clinical outcomes.

METHODS

Consecutive patients admitted with ADHF were randomized into three groups - intravenous furosemide infusion + intravenous dopamine, intravenous furosemide bolus in two divided doses and intravenous furosemide continuous infusion alone. At 48 h, the treating physician could adjust the diuretic strategy. Primary endpoint was negative fluid balance at 24 h after admission. Secondary end points were duration of hospital stay, negative fluid balance at 48, 72, 96 h, the trend of serum electrolytes, and renal function and 30 day clinical outcome (death and emergency department visits).

RESULTS

Overall ninety patients (thirty in each group) were included in the study. There was a greater diuresis in first 24 h (p = 0.002) and a shorter hospital stay (p = 0.023) with the bolus group. There was no significant difference in renal function and serum sodium and serum potassium levels. There was no difference in the number of emergency department visits among the three groups.

CONCLUSION

All three modes of diuretic therapies can be practiced with no difference in worsening of renal function and electrolyte levels. Bolus dose administration with its rapid volume loss and shorter hospital stay might be a more effective diuretic strategy.

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.

Renal dysfunction, restrictive left ventricular filling pattern and mortality risk in patients admitted with heart failure: a 7-year follow-up study

Background

Renal dysfunction is associated with a variety of cardiac alterations including left ventricular (LV) hypertrophy, LV dilation, and reduction in systolic and diastolic function. It is common and associated with an increased mortality risk in heart failure (HF) patients. This study was designed to evaluate whether severe diastolic dysfunction contribute to the increased mortality risk observed in HF patients with renal dysfunction.

Methods

Using Cox Proportional Hazard Models on data (N = 669) from the EchoCardiography and Heart Outcome Study (ECHOS) study we evaluated whether estimated glomerular filtration rate (eGFR) was associated with mortality risk before and after adjustment for severe diastolic dysfunction. Severe diastolic dysfunction was defined by a restrictive left ventricular filling pattern (RF) (=deceleration time < 140 ms) by Doppler echocardiography.

Results

Median eGFR was 58 ml/min/1.73 m², left ventricular ejection fraction was 33% and RF was observed in 48%. During the 7 year follow up period 432 patients died. Multivariable adjusted eGFR was associated with similar mortality risk before (Hazard Ratio(HR)_{eGFR 10 ml increase}: 0.94 (95% CI: 0.89-0.99, P = 0.024) and after (HR_{eGFR 10 ml increase}: 0.93 (0.89-0.99), P = 0.012) adjustment for RF (HR: 1.57 (1.28-1.93), P < 0.001).

Conclusions

In patients admitted with HF RF does not contribute to the increased mortality risk observed in patients with a decreased eGFR. Factors other than severe diastolic dysfunction may explain the association between renal function and mortality risk in HF patients.

Systemic arterial and venous determinants of renal hemodynamics in congestive heart failure

Heart and kidney interactions are fascinating, in the sense that failure of the one organ strongly affects the function of the other. In this review paper, we analyze how principal driving forces for glomerular filtration and renal blood flow are changed in heart failure. Moreover, renal autoregulation and modulation of neurohumoral factors, which can both have repercussions on renal function, are analyzed. Two paradigms seem to apply. One is that the renin-angiotensin system (RAS), the sympathetic nervous system (SNS), and extracellular volume control are the three main determinants of renal function in heart failure. The other is that the classical paradigm to analyze renal dysfunction that is widely applied in nephrology also applies to the pathophysiology of heart failure: pre-renal, intra-renal, and post-renal alterations together determine glomerular filtration. At variance with the classical paradigm is that the most important post-renal factor in heart failure seems renal venous hypertension that, by increasing renal tubular pressure, decreases GFR. When different pharmacological strategies to inhibit the RAS and SNS and to assist renal volume control are considered, there is a painful lack in knowledge about how widely applied drugs affect primary driving forces for ultrafiltration, renal autoregulation, and neurohumoral control. We call for more clinical physiological studies.

The role of the kidney in heart failure

Renal dysfunction is common in patients with heart failure and is associated with high morbidity and mortality. Cardiac and renal dysfunction may worsen each other through multiple mechanisms such as fluid overload and increased venous pressure, hypo-perfusion, neurohormonal and inflammatory activation, and concomitant treatment. The interaction between cardiac and renal dysfunction may be critical for disease progression and prognosis. Renal dysfunction is conventionally defined by a reduced glomerular filtration rate, calculated from serum creatinine levels. This definition has limitations as serum creatinine is dependent on age, gender, muscle mass, volume status, and renal haemodynamics. Changes in serum creatinine related to treatment with diuretics or angiotensin-converting enzyme inhibitors are not necessarily associated with worse outcomes. New biomarkers might be of additional value to detect an early deterioration in renal function and to improve the prognostic assessment, but they need further validation. Thus, the evaluation of renal function in patients with heart failure is important as it may reflect their haemodynamic status and provide a better prognostic assessment. The prevention of renal dysfunction with new therapies might also improve outcomes although strong evidence is still lacking.

Right ventricular dysfunction is associated with chronic kidney disease and predicts survival in patients with chronic systolic heart failure

AIMS

Chronic kidney disease (CKD) and right ventricular (RV) dysfunction are important predictors of prognosis in heart failure (HF). We investigated the relationship between RV dysfunction and CKD in outpatients with chronic systolic HF, an association which remains poorly defined.

METHODS AND RESULTS

Outpatients (n = 373) with chronic HF and left ventricular ejection fraction (LVEF) ≤45% underwent clinical and echo-Doppler evaluations and were followed up for 31 ± 24 months. Tricuspid annular plane systolic excursion (TAPSE) assessed RV dysfunction. The estimated glomerular filtration rate (GFR) was measured by the simplified Modification of Diet in Renal Disease (MDRD) formula. Correlation analysis was used to characterize the association between TAPSE and estimated GFR. Odds ratios (ORs) for CKD and hazard ratios (HRs) for all-cause mortality were assessed using multivariable logistic or proportional hazards regression models. TAPSE and estimated GFR were significantly correlated (r = 0.38, P < 0.0001). TAPSE ≤14 mm was associated with elevated estimated right atrial pressure and N-terminal pro brain natriuretic peptide levels. TAPSE ≤14 mm increased the odds of estimated GFR <60 mL/min/1.73 m(2), OR [95% confidence interval (CI)] = 2.51(1.44-4.39), P < 0.0001 and predicted all-cause mortality, HR (95% CI) = 1.80 (1.20-2.71) after multivariable adjustment.

CONCLUSIONS

Right ventricular dysfunction is cross-sectionally associated with CKD and prospectively predicts survival in outpatients with chronic systolic HF. These data suggest RV dysfunction to be one of the possible mechanistic links between HF and CKD.

Cardiorenal syndrome in acute decompensated heart failure

Cardiorenal syndrome (CRS) commonly occurs during treatment of acute decompensated heart failure (ADHF) and is associated with poor clinical outcome. The pathophysiology of CRS entails a complex interaction between hemodynamic alterations, including reduced renal perfusion, increased venous pressure and activation of multiple neurohormonal systems. Attempts to effectively treat congestion while preserving renal function in ADHF are often met with limited clinical success and often require therapeutic decisions that reflect a compromise between potential benefits and harm. At present, there is no evidence-based intervention specifically targeted at renal function. Recent Phase III randomized trials, using novel agents in patients with ADHF, have largely failed to demonstrate any benefits of therapy on renal and clinical outcomes. Early diagnosis of CRS using novel markers of tubular injury may allow for timely interventions and attenuate progression. Future studies are needed to further elucidate the pathophysiology of this complex syndrome and identify new potential targets for effective evidence-based treatments.

Organ-specific responses to circulatory disturbances in heart failure: new insights

Recent studies have provided new insights into the pathophysiology of congestive heart failure. Organ-specific responses to circulatory disturbances may differ via a hypoperfusion state and a venous congestion state. The liver and the kidneys serve as a good example of a differential injury pattern based on the predominant circulatory insult. Cardiorenal syndrome appears to be a kidney-specific response to predominantly right-sided backward heart failure ("congestive state"), rather than forward heart failure. Despite significant progress in our understanding of cardiorenal interactions, there is no specific therapy for the cardiorenal syndrome, which is a marker of the severity of the heart failure state.

Intravenous high-dose furosemide and hypertonic saline solutions for refractory heart failure and ascites

Several studies have shown the efficacy of hypertonic saline solution infusion in conditions in which regional organ blood flow is impaired. Our group has shown that treatment of patients with diuretic-resistant heart failure with high-dose furosemide plus hypertonic saline is effective and well tolerated, improving symptoms of congestion, reducing plasma levels of markers of neurohormonal and inflammatory activation, decreasing hospital readmission rates, and reducing long-term mortality. The same regimen was shown to be better than repeated paracentesis in patients with cirrhosis and refractory ascites, yielding better control of ascites, pleural effusions, and/or leg edema without an increase of common adverse effects linked to high-dose furosemide such as hepatic encephalopathy.

Prognostic importance of early worsening renal function after initiation of angiotensin-converting enzyme inhibitor therapy in patients with cardiac dysfunction

BACKGROUND

Worsening renal function (WRF) in the setting of heart failure has been associated with increased mortality. However, it is unclear if this decreased survival is a direct result of the reduction in glomerular filtration rate (GFR) or if the mechanism underlying the deterioration in GFR is driving prognosis. Given that WRF in the setting of angiotensin-converting enzyme inhibitor (ACE-I) initiation is likely mechanistically distinct from spontaneously occurring WRF, we investigated the relative early WRF-associated mortality rates in subjects randomized to ACE-I or placebo.

METHODS AND RESULTS

Subjects in the Studies Of Left Ventricular Dysfunction (SOLVD) limited data set (n=6337) were studied. The interaction between early WRF (decrease in estimated GFR ≥20% at 14 days), randomization to enalapril, and mortality was the primary end point. In the overall population, early WRF was associated with increased mortality (adjusted hazard ratio [HR], 1.2; 95% CI, 1.0-1.4; P=0.037). When analysis was restricted to the placebo group, this association strengthened (adjusted HR, 1.4; 95% CI, 1.1-1.8; P=0.004). However, in the enalapril group, early WRF had no adverse prognostic significance (adjusted HR, 1.0; 95% CI, 0.8-1.3; P=1.0; P=0.09 for the interaction). In patients who continued to receive study drug despite early WRF, a survival advantage remained with enalapril therapy (adjusted HR, 0.66; 95% CI, 0.5-0.9; P=0.018).

CONCLUSIONS

These data support the notion that the mechanism underlying WRF is important in determining its prognostic significance. Specifically, early WRF in the setting of ACE-I initiation appears to represent a benign event that is not associated with a loss of benefit from continued ACE-I therapy.

The complexity of the cardio-renal link: taxonomy, syndromes, and diseases

Bidirectional mechanisms exist that link diseases affecting the heart and kidney. This link is complex and remains poorly understood; therefore, charting the shared territory of cardiovascular (CV) and renal medicine poses major problems. Until now, no convincing rationale for delineating new syndromes existed. The multiple connections of the arterial system and the heart and kidney with other systems, from energy and protein balance to the musculoskeletal, clearly require special focus and rigorous framing. Nephrologists have yet to fully understand why the application of dialysis has had only limited success in halting the parallel burdens of CV and non-CV death in patients with end-stage renal disease. Cardiologists, intensivists, and nephrologists alike should settle whether and when extracorporeal ultrafiltration benefits patients with decompensated heart failure. These sparse but interconnected themes spanning from the basic science-clinical transition phase to clinical science, epidemiology, and medical technology already form the basis for the young discipline of 'CV and renal medicine'.

Importance of venous congestion for worsening of renal function in advanced decompensated heart failure

OBJECTIVES

To determine whether venous congestion, rather than impairment of cardiac output, is primarily associated with the development of worsening renal function (WRF) in patients with advanced decompensated heart failure (ADHF).

BACKGROUND

Reduced cardiac output is traditionally believed to be the main determinant of WRF in patients with ADHF.

METHODS

A total of 145 consecutive patients admitted with ADHF treated with intensive medical therapy guided by pulmonary artery catheter were studied. We defined WRF as an increase of serum creatinine >/=0.3 mg/dl during hospitalization.

RESULTS

In the study cohort (age 57 +/- 14 years, cardiac index 1.9 +/- 0.6 l/min/m(2), left ventricular ejection fraction 20 +/- 8%, serum creatinine 1.7 +/- 0.9 mg/dl), 58 patients (40%) developed WRF. Patients who developed WRF had a greater central venous pressure (CVP) on admission (18 +/- 7 mm Hg vs. 12 +/- 6 mm Hg, p < 0.001) and after intensive medical therapy (11 +/- 8 mm Hg vs. 8 +/- 5 mm Hg, p = 0.04). The development of WRF occurred less frequently in patients who achieved a CVP <8 mm Hg (p = 0.01). Furthermore, the ability of CVP to stratify risk for development of WRF was apparent across the spectrum of systemic blood pressure, pulmonary capillary wedge pressure, cardiac index, and estimated glomerular filtration rates.

CONCLUSIONS

Venous congestion is the most important hemodynamic factor driving WRF in decompensated patients with advanced heart failure.

Misapplications of commonly used kidney equations: renal physiology in practice

Equations for estimating GFR, quantifying urinary protein excretion, and assessing renal sodium handling are widely used in routine nephrology and general medical and surgical practice. If these equations are applied in circumstances inconsistent with the clinical situations for or extrapolated beyond the limits in which they were validated, clinicians can come to erroneous conclusions, which could be detrimental for patient care. This review uses clinical vignettes to demonstrate some of the common pitfalls that clinicians may encounter in the use of these equations and considers the physiologic principles underlying their use. Equations for assessing aspects of renal function should only be used in specific clinical situations, if the underlying assumptions regarding their calculations and values are satisfied.

Database for physiologically based pharmacokinetic (PBPK) modeling: physiological data for healthy and health-impaired elderly

Physiologically based pharmacokinetic (PBPK) models have increasingly been employed in chemical health risk assessments. By incorporating individual variability conferred by genetic polymorphisms, health conditions, and physiological changes during development and aging, PBPK models are ideal for predicting chemical disposition in various subpopulations of interest. In order to improve the parameterization of PBPK models for healthy and health-impaired elderly (herein defined as those aged 65 yr and older), physiological parameter values were obtained from the peer-reviewed literature, evaluated, and entered into a Microsoft ACCESS database. Database records include values for key age-specific model inputs such as ventilation rates, organ volumes and blood flows, glomerular filtration rates, and other clearance-related processes. In total, 528 publications were screened for relevant data, resulting in the inclusion of 155 publications comprising 1051 data records for healthy elderly adults and 115 data records for elderly with conditions such as diabetes, chronic obstructive pulmonary disease (COPD), obesity, heart disease, and renal disease. There are no consistent trends across parameters or their associated variance with age; the gross variance in body weight decreased with advancing age, whereas there was no change in variance for brain weight. The database contains some information to inform ethnic and gender differences in parameters; however, the majority of the published data pertain to Asian (mostly Japanese) and Caucasian males. As expected, the number of records tends to decrease with advancing age. In addition to a general lack of data for parameters in the elderly with various health conditions, there is also a dearth of information on blood and tissue composition in all elderly groups. Importantly, there are relatively few records for alveolar ventilation rate; therefore, the relationship between this parameter and cardiac output (usually assumed to be 1:1) in the elderly is not well informed by the database. Despite these limitations, the database represents a potentially useful resource for parameterizing PBPK models for the elderly to facilitate the prediction of dose metrics in older populations for application in risk assessment.

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.

Hyperkalemia risk and treatment of heart failure

This article briefly reviews the participation of the kidney in heart failure and the renal consequences of the treatment, with special emphasis on the risk for hyperkalemia and its management in daily clinical practice.

Effects of Body Mass Index and Age on N-Terminal Pro–Brain Natriuretic Peptide Are Associated with Glomerular Filtration Rate in Chronic Heart Failure Patients

Background: Obesity is a state characterized by glomerular hyperfiltration and age-related decreases in glomerular filtration rate (GFR). Body mass index (BMI), age, and GFR are associated with plasma concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP) in chronic heart failure (CHF) patients. We hypothesized that the effects of BMI and age on plasma concentrations of NT-proBNP are associated with GFR.

Methods: We obtained clinical data and laboratory test results from 345 CHF patients at the baseline visit in our heart failure clinic and examined the hypothesis using multiple linear regression models.

Results: Age (P = 0.0184), BMI (P = 0.0098), hemoglobin (P = 0.0043), heart rhythm (P &lt;0.0001), and left ventricular ejection fraction (P &lt;0.0001) were associated with log(NT-proBNP). After adjustment for GFR estimated by the Cockcroft and Gault equation, the parameter estimates for BMI (P = 0.3807) and age (P = 0.7238) changed markedly and became insignificant. In another model, after adjustment for GFR estimated by the 4-component Modification of Diet in Renal Disease formula (eGFRMDRD), the parameter estimates for age (P = 0.0674) changed markedly and became insignificant, but BMI (P = 0.0067) remained significant and unchanged. The eGFRMDRD is adjusted for body surface area, which may explain the difference.

Conclusions: In CHF patients, the effect of age on NT-proBNP is associated with estimates for GFR derived from serum creatinine, and the significance of the effects of BMI on NT-proBNP depends on the method by which GFR is estimated.

Anemia, chronic renal disease and congestive heart failure--the cardio renal anemia syndrome: the need for cooperation between cardiologists and nephrologists

Many patients with congestive heart failure (CHF) fail to respond to maximal CHF therapy and progress to end stage CHF with many hospitalizations, poor quality of life (QoL), progressive chronic kidney disease (CKD) which can lead to end stage kidney disease (ESKD), or die of cardiovascular complications within a short time. One factor that has generally been ignored in many of these people is the fact that they are often anemic. The anemia in CHF is due mainly to the frequently-associated CKD but also to the inhibitory effects of cytokines on erythropoietin production and on bone marrow activity, as well as to their interference with iron absorption from the gut and their inhibiting effect on the release of iron from iron stores. Anemia itself may further worsen cardiac and renal function and make the patients resistant to standard CHF therapy. Indeed anemia in CHF has been associated with increased severity of CHF, increased hospitalization, worse cardiac function and functional class, the need for higher doses of diuretics, progressive worsening of renal function and reduced QoL. In both controlled and uncontrolled studies of CHF, the correction of the anemia with erythropoietin (EPO) and oral or intravenous (IV) iron has been associated with improvement in many cardiac and renal parameters and an increased QoL. EPO itself may also play a direct role in improving the heart unrelated to the improvement of the anemia--by reducing apoptosis of cardiac and endothelial cells, increasing the number of endothelial progenitor cells, and improving endothelial cell function and neovascularization of the heart. Anemia may also play a role in the worsening of acute myocardial infarction and chronic coronary heart disease (CHD) and in the cardiovascular complications of renal transplantation. Anemia, CHF and CKD interact as a vicious circle so as to cause or worsen each other- the so-called cardio renal anemia syndrome. Only adequate treatment of all three conditions can prevent the CHF and CKD from progressing.

Left Ventricular Geometry and Renal Function in Hypertensive Patients With Diastolic Heart Failure

BACKGROUND

The objective is to define the relationship between cardiac geometry and renal function in hypertensive subjects with and without diastolic heart failure (DHF).

METHODS

This is a prospective observational study in a tertiary-care teaching institute in a 15-month period of consecutive hospitalized hypertensive patients. Patients on dialysis therapy or with atrial fibrillation, systolic heart failure, gross proteinuria, and glomerular diseases were excluded. Two-dimensional echocardiography was performed and stable glomerular filtration rate (GFR) was calculated by using the Modification of Diet in Renal Disease formula. Patients were classified into stage 1 to 5 chronic kidney disease (CKD).

RESULTS

Five hundred forty hypertensive patients were separated into 2 groups: 286 patients with DHF and 254 patients without DHF. Mean age was 69.1 +/- 13.7 (SD) years in general. In patients with DHF, from stages 1 to 5 CKD, there was a significant graded increase in left ventricular mass index (from 117.3 to 162.4 g/m(2)) and relative wall thickness (from 0.42 to 0.52) and a significant graded decrease in aortic cusp separation (from 1.85 to 1.55 cm). Among echocardiographic variables, left ventricular mass index and relative wall thickness were associated inversely and aortic cusp separation was associated directly with GFR. In the absence of DHF, only left ventricular mass index was associated inversely with GFR, suggesting a prominent role of aortic cusp separation and relative wall thickness in the variability in GFR in patients with DHF through a hemodynamic disturbance.

CONCLUSION

Hemodynamic alterations have a prominent role in the variability of GFR in patients with CKD with DHF. Adverse cardiac geometry is linked to the severity of CKD in hypertensive patients, raising the possibility of preserving both cardiac and renal function by means of hypertension control.

Risk Factors for Acute Renal Insufficiency Induced by Diuretics in Patients With Congestive Heart Failure

BACKGROUND

In patients with congestive heart failure (CHF), continuous diuretic therapy may result in acute renal insufficiency (ARI). This study examines factors contributing to this complication.

METHODS

We analyzed clinical data from 318 consecutive patients who were hospitalized for CHF. All were treated with diuretics and had echocardiography performed within 4 days of hospitalization. Systolic left ventricular (LV) dysfunction is defined as an ejection fraction less than 50%, and diastolic LV dysfunction, as an ejection fraction of 50% or greater in the presence of LV hypertrophy and a reversed E/A ratio.

RESULTS

ARI, defined as a 25% increase in serum creatinine level, occurred in 110 patients (35%) after diuretic therapy. Risk factors for ARI on univariate analyses were older age, higher baseline serum creatinine level, lower baseline serum sodium level, lower mean arterial pressure (MAP) during diuretic therapy, and greater doses and longer duration of diuretic therapy. In multivariate analyses, ARI occurred more frequently in patients with systolic (40%) than diastolic dysfunction (28%). The use of digoxin in patients with systolic LV dysfunction was observed to decrease the risk for ARI by 61%, independent of other agents used for the treatment of patients with CHF.

CONCLUSION

Age, baseline renal function and serum sodium concentration, MAP, and intensity of diuretic therapy can identify individuals at risk for ARI while receiving diuretic therapy for CHF. This complication is observed more often in individuals with systolic dysfunction, and its risk may be decreased with the use of digoxin.

Management of the cardiorenal syndrome in heart failure

Heart failure treatment has seen great improvements in the past few decades. In many cases of heart failure, coexisting renal dysfunction, known as the cardiorenal syndrome, complicates treatment. Renal dysfunction is known to be a predictor of increased mortality. Renal dysfunction can be caused by various hemodynamic forces, medications, and intrinsic renal disease. With an understanding of the underlying etiology and physiology of the renal dysfunction, the appropriate treatment strategy can be planned. This understanding can also indicate when it is necessary to resort to therapies such as left ventricular assist device or dialysis. Such targeting of therapy can improve the prognosis of patients with heart failure and renal dysfunction.

Changes in brain natriuretic peptide levels and bioelectrical impedance measurements after treatment with high-dose furosemide and hypertonic saline solution versus high-dose furosemide alone in refractory congestive heart failure: a double-blind study

OBJECTIVES

The aim of this study was to evaluate the effect of a new treatment for refractory congestive heart failure (CHF) on brain natriuretic peptide (BNP) plasma levels and hydration station.

BACKGROUND

The study was aimed at evaluating the effects of the combination of high-dose furosemide and small-volume hypertonic saline solution (HSS) in refractory CHF patients.

METHODS

A total of 94 patients (34 women/60 men) with refractory CHF (age 55 to 80 years) were enrolled. They had to have an ejection fraction <35%, serum creatinine <2 mg/dl, blood urea nitrogen <60 mg/dl, a reduced urinary volume, and a low natriuresis (<500 ml/24 h and <60 mEq/24 h, respectively). Patients were divided (double-blind) into two groups: group 1 (18 women/30 men) received an intravenous furosemide (500 to 1,000 mg) plus HSS twice a day in 30 min. Group 2 (16 women/30 men) received an intravenous bolus of furosemide (500 to 1,000 mg/twice a day) alone, for four to six days. At entry, body weight, blood pressure, heart rate, and laboratory parameters were checked during hospitalization; BNP levels were measured on admission, 6 and 30 days after discharge, while on admission and 6 days after, impedance plethysmography was performed. The HSS group received 120 mmol of Na intake versus 80 mmol in non-HSS group. Fluid intake of 1,000 was given to both groups.

RESULTS

The groups were similar for clinical characteristics. A significant increase in daily diuresis and natriuresis was observed in HSS group, p < 0.05. The BNP values showed significant intragroup and intergroup differences, 6 and 30 days after treatment. The patients from the HSS group reached a better hydration state than the non-HSS group after six days. In addition, the HSS group showed a significant reduction in hospitalization time and readmission rate.

CONCLUSIONS

Our data show that the HSS group reached dry weight more rapidly, a significantly faster reduction in BNP levels, shorter hospitalization stay, and lower incidence in readmissions in the 30-day study period.

Pharmacotherapy in congestive heart failure: aldosterone receptor antagonism: interface with hyperkalemia in heart failure

Aldosterone receptor antagonism (ARA) is an increasingly well-accepted element of heart failure therapy. The experimental underpinnings for the use of ARA in heart failure are strong being linked to a variety of tissue-based cardiac effects characteristic of drugs in this class. However, the benefits of ARA therapy do not come without some risk since drugs in this class are potent inhibitors of renal potassium (K+) elimination. Thus, some increment in serum K+, up to and including the development of overt hyperkalemia (typically defined as a serum K+ value in excess of 6.0 mEq/L), is to be expected whenever they are used. Hyperkalemia attributable to ARA relates to several factors including ARA dose, patient predisposition to hyperkalemia, as in the case of renal failure, and dietary intake of K+. The risk of some change in serum K+ with ARA should not be a deterrent to use of drugs in this class but, rather should prompt careful surveillance for the onset of this potentially life-threatening electrolyte disturbance. The frequency of such scrutiny should be patient-specific and based on the constellation of risk factors for hyperkalemia.

High-Dose Torasemide is Equivalent to High-Dose Furosemide with Hypertonic Saline in the Treatment of Refractory Congestive Heart Failure

OBJECTIVE

A randomised, double-blind study was performed to evaluate the effects of the combination of high-dose torasemide and hypertonic saline solution (HSS) infusion versus high-dose furosemide (frusemide) and HSS in the treatment of refractory New York Heart Association class IV congestive heart failure (CHF).

MATERIALS AND METHODS

Eighty-four patients (55 males, 29 females) with refractory CHF, aged 55-84 years, with an ejection fraction <35%, serum creatinine <2 mg/dL, blood urea nitrogen </=60 mg/dL, a reduced urinary volume and a low natriuresis, were randomised to two groups. Group 1 (27 males, 15 females) received an intravenous infusion of furosemide 500mg plus HSS (150mL of 1.4-4.6% sodium chloride) twice daily in 30 minutes. Group 2 (28 males, 14 females) received torasemide 200mg twice daily plus HSS during a period lasting 4-8 days. Physical examination, measurement of bodyweight, blood pressure, heart rate, evaluation of signs of CHF, and serum and urinary parameters were controlled daily during hospitalisation. Chest x-ray, ECG and echocardiogram were obtained at entry, during hospitalisation and at discharge. During the treatment and after discharge the daily dietary sodium intake was 120 mmol, with a fluid intake of 1.0-1.5L in both groups. Bodyweight and 24-hour urinary volume, serum and urinary laboratory parameters, until reaching a compensated state, were controlled daily, when intravenous furosemide and torasemide were replaced with oral furosemide administration only (250-500mg twice daily). After discharge the double-blind design was discontinued and the subsequent period was an open-label study with furosemide only; the patients were followed up as outpatients weekly for the first 3 months and subsequently once a month.

RESULTS

Baseline clinical characteristics of patients were similar in both groups. A significant increase in daily diuresis and natriuresis was observed in both groups. No difference was observed in serum sodium or potassium. Bodyweight was reduced in both groups. Blood pressure values decreased, and heart rate was corrected to normal values in both groups. In the follow-up period (12 +/- 3.9 months), 17 patients were re-admitted to the hospital for heart failure. Thirteen patients died during follow-up.

CONCLUSION

We conclude that high-dose torasemide is equivalent to high-dose furosemide in the treatment of refractory CHF.

Renal Insufficiency and Heart Failure

Background— The prevalence, prognostic import, and impact of renal insufficiency on the benefits of ACE inhibitors and β-blockers in community-dwelling patients with heart failure are uncertain.

Methods and Results— We analyzed data from a prospective cohort of 754 patients with heart failure who had ejection fraction, serum creatinine, and weight measured at baseline. Median age was 69 years, and 43% had an ejection fraction ≥35%. By the Cockcroft-Gault equation, 118 patients (16%) had creatinine clearances ≤30 mL/min and 301 (40%) had creatinine clearances between 30 and 59 mL/min. During follow-up (median 926 days), 385 patients (37%) died. Even after adjustment for all other prognostic factors, survival was significantly associated with renal function ( P =0.002) in patients with either systolic or diastolic dysfunction; patients exhibited a 1% increase in mortality for each 1-mL/min decrease in creatinine clearance. The associations with 1-year mortality reductions were similar for ACE inhibitors (OR 0.46 [95% CI 0.26 to 0.82] versus OR 0.28 [95% CI 0.11 to 0.70]) and β-blockers (OR 0.40 [95% CI 0.23 to 0.70] versus OR 0.41 [95% CI 0.19 to 0.85]) in patients with creatinine clearances <60 mL/min versus ≥60 mL/min, although these drugs were used less frequently in patients with renal insufficiency.

Conclusions— Renal insufficiency is more prevalent in patients with heart failure than previously reported and is an independent prognostic factor in diastolic and systolic dysfunction. ACE inhibitors and β-blockers were associated with similar reductions in mortality in patients with and without renal insufficiency.

Thromboxane inhibition improves renal perfusion and excretory function in severe congestive heart failure

OBJECTIVES

The aim of this study was to evaluate whether thromboxane inhibition can favorably affect renal perfusion and clinical conditions in patients affected by severe heart failure.

BACKGROUND

The renal formation of the vasoconstrictor thromboxane A(2) (TxA(2)) is increased during cardiac failure.

METHODS

By oral administration of picotamide (a renal TxA(2) synthase and TxA(2)/prostaglandin H(2) receptor inhibitor), we blocked renal TxA(2). Fourteen patients in New York Heart Association functional class IV were studied according to a randomized, double-blinded, cross-over design. Each of the two eight-day periods of testing was preceded by a three-day period during which certain vasoactive medications were stopped.

RESULTS

Daily 24-h total urinary thromboxane B(2) (TxB(2)), the stable metabolite of TxA(2), dropped at the end of picotamide treatment (p < 0.01 vs. baseline). Compared with placebo, effective renal plasma flow and the glomerular filtration rate increased (p < 0.01 and p < 0.05, respectively), thus leading to a significant decrease in the filtration fraction (p < 0.01). Renal vascular resistance decreased consistently (p < 0.01). In all patients, picotamide treatment was associated with an increase in diuresis and natriuresis (p < 0.001 vs. baseline). Plasma creatinine decreased (p < 0.05 vs. baseline). Patients also showed improvement in several clinical parameters, including a significant decrease in both pulmonary and venous pressure (p < 0.01 vs. baseline).

CONCLUSIONS

These results indicate that renal thromboxane formation plays an important role in renal vascular resistance in patients with severe heart failure, such as those described in the present study. Inhibition of TxA(2) improves renal hemodynamics and kidney function and favorably affects indexes of cardiac performance.

Hyperkalemia, congestive heart failure, and aldosterone receptor antagonism

Hyperkalemia is a common occurrence in patients with congestive heart failure, particularly when renal failure coexists. The level of renal function in congestive heart failure is often difficult to ascertain because good measurement tools for estimation of renal function are not available. Serum creatinine values have often been offered as a good gauge of renal function, although in most cases true renal function is appreciably lower than the estimate derived from a specific serum creatinine value. Thus, patients with congestive heart failure very commonly, particularly in the advanced stages of the disease, have moderate renal insufficiency, either due to specific heart failure-related renal perfusion changes or as the result of renal involvement from the same processes having caused the heart failure, as is the case with diabetes. It is in this setting of mild-to-moderate levels of renal failure that therapies, such as angiotensin-converting inhibitors, angiotensin-receptor blockers, and aldosterone-receptor antagonists, are administered either individually or collectively. Each of these drug classes reduces the homeostatic ability to eliminate ingested potassium loads by the renal route and increase the tendency to evolve into a hyperkalemic state. This is noteworthy because aldosterone-receptor antagonists are increasingly considered as important therapies in the long-term management of heart failure. Spironolactone has been employed in this capacity and a new aldosterone-receptor antagonist, eplerenone, will become available in the near future, which further increases the importance of evaluating and treating the hyperkalemia risk in a timely manner.

The prognostic significance of renal dysfunction in patients with chronic systolic heart failure

Renal insufficiency is an independent powerful predictor of morbidity and mortality in a number of cardiovascular disorders. A number of retrospective analyses of large heart failure trials have shown that even mild renal insufficiency has powerful negative predictive power in patients with both mild and severe heart failure. We discuss the available data on the prognostic value of mild renal insufficiency in heart failure, as well as possible mechanisms of this phenomenon. Future research should focus on its possible pathophysiology.

Why the kidney glomerulus does not clog: a gel permeation/diffusion hypothesis of renal function

Current interpretations of kidney function in terms of a coarse filter followed by a fine filter have difficulty explaining why the glomerulus does not clog. I propose, as an alternative, a semiquantitative hypothesis that assumes that the size-selective property of the glomerulus is a consequence of the limited fraction of space in the glomerular basement membrane (a concentrated gel) into which macromolecules can permeate. The glomerular epithelial cell slits and slit diaphragms are assumed to impose substantial resistance to liquid flow across the glomerulus without acting as a molecular sieve. Calculations based on gel behavior show that proteins cross the glomerular basement membrane mainly by diffusion rather than by liquid flow, whereas water crosses entirely by flow. Thus, diffusion provides most of the protein, whereas flow provides the diluent. As a result, the single-nephron glomerular filtration rate (GFR) becomes a prime factor in (inversely) determining the concentration of proteins in early proximal tubular fluid. Because the reabsorption of proteins from the tubules is a saturable process, the gel permeationdiffusion hypothesis readily accounts for the albuminuria observed when single-nephron GFR is substantially reduced by severe pathological decreases in slit diaphragm length, such as occur in minimal-change nephrotic syndrome in humans, in animals treated with puromycin aminonucleoside, or in humans or animals with mutations in the gene coding for nephrin. My hypothesis predicts that albuminuria will ensue, even with a normal kidney, if the single-nephron GFR falls below approximately 50% of normal.