Enhanced urinary excretion of albumin in congestive heart failure: effect of ACE-inhibition

Renal denervation modulates angiotensin receptor expression in the renal cortex of rabbits with chronic heart failure

Excessive sympathetic drive is a hallmark of chronic heart failure (HF). Disease progression can be correlated with plasma norepinephrine concentration. Renal function is also correlated with disease progression and prognosis. Because both the renal nerves and renin-angiotensin II system are activated in chronic HF we hypothesized that excessive renal sympathetic nerve activity decreases renal blood flow in HF and is associated with changes in angiotensin II type 1 receptor (AT1R) and angiotensin II type 2 receptor (AT2R) expression. The present study was carried out in conscious, chronically instrumented rabbits with pacing-induced HF. We found that rabbits with HF showed a decrease in mean renal blood flow (19.8±1.6 in HF vs. 32.0±2.5 ml/min from prepace levels; P<0.05) and an increase in renal vascular resistance (3.26±0.29 in HF vs. 2.21±0.13 mmHg·ml(-1)·min in prepace normal rabbits; P<0.05) while the blood flow and resistance was not changed in HF rabbits with the surgical renal denervation. Renal AT1R expression was increased by ∼67% and AT2R expression was decreased by ∼87% in rabbits with HF; however, kidneys from denervated rabbits with HF showed a near normalization in the expression of these receptors. These results suggest renal sympathetic nerve activity elicits a detrimental effect on renal blood flow and may be associated with alterations in the expression of angiotensin II receptors.

Causes and consequences of systemic venous hypertension

The causes of systemic venous hypertension (SVHT) include cardiac- and circulatory-related factors, whereas its consequences include the congestion of hepatic, splanchnic, and peripheral circulations, which contribute significantly to the clinical congestive heart failure syndrome. Based on a disequilibrium in hydrostatic and oncotic pressures, the increased filtration and formation of interstitial fluid at these sites with an accompanying increase in lymph flow mandates an increment in lymphatic drainage to protect against such congestion and the appearance of edema and ascites. However, lymph flow via the thoracic duct into systemic veins is opposed by elevations in central venous pressure. Various management strategies have the potential to prevent and/or correct SVHT. The case of a 54-year-old man with a dilated cardiomyopathy who presented with decompensated biventricular failure, expressed as anasarca and ascites, is used to illustrate the importance of SVHT.

Microalbuminuria in nondiabetic and nonhypertensive systolic heart failure patients

The American Diabetes Association and the National Kidney Foundation define microalbuminuria as an albumin (microg)/creatinine (mg) ratio (ACR) between 30 and 300 microg/mg regardless of sex. Microalbuminuria is associated with increased cardiovascular risk. The authors evaluated the prevalence of microalbuminuria in nondiabetic and nonhypertensive systolic heart failure (SHF) patients. Twenty-seven SHF patients, 18 years and older, with New York Heart Association functional classes II through IV and left ventricular ejection fraction < or =40%, who were nondiabetic and nonhypertensive and not receiving angiotensin-converting enzyme inhibitors, were selected. Twenty-seven healthy individuals, paired according to sex, ethnicity, and age, were used as controls. Early-morning midstream urine was used. Data are expressed as medians. Excretion of albumin in SHF patients (39 microg/mL urine) was significantly higher than in controls (26 microg/mL urine). Creatinine excretion was not significantly different between patients and controls. ACR was significantly higher in patients (54 microg/mg) than in controls (24 microg/mg). The results indicate that microalbuminuria was significantly present in nondiabetic and nonhypertensive SHF patients.

Urinary excretion of alpha1-microglobulin and albumin in acute myocardial infarction. Correlation with plasma concentrations of troponin I and C-reactive protein

OBJECTIVES

Microalbuminuria associated with myocardial infarction (MI) is normally ascribed to glomerular factors, but could just as well involve pathophysiological processes located in other parts of the nephron, e.g. proximal tubules where plasma albumin normally filtered through the glomerulus is almost completely reabsorbed. The aims of this study were to establish whether impaired tubular reabsorption of filtered albumin contributes to microalbuminuria during MI, and whether the urinary excretion of protein relates to plasma levels of C-reactive protein (CRP) and troponin I.

MATERIAL AND METHODS

We monitored plasma CRP and troponin I as well as the urinary excretion of albumin and alpha1-microglobulin, a low-molecular-weight plasma protein and marker of tubular proteinuria, in 18 patients with MI.

RESULTS AND CONCLUSIONS

The urinary excretion of alpha1-microglobulin and albumin was significantly elevated in nine patients, and the urinary excretion of the two proteins correlated significantly. A decrease in tubular reabsorption of albumin may thus be at least one of the causative factors underlying microalbuminuria during MI. The plasma levels of CRP and troponin I were also significantly higher in this group of nine patients, and correlated with urinary protein excretion, suggesting an interrelationship between inflammatory response and tubular dysfunction. Extrarenal inflammatory processes seem to affect renal tubular function, thereby contributing to microalbuminuria during MI.

High prevalence of microalbuminuria in chronic heart failure patients

BACKGROUND

Microalbuminuria is associated with increased risk for cardiovascular morbidity and mortality. However, the relation between microalbuminuria and chronic heart failure has not been well described yet. In this cross-sectional study, we aim to evaluate the prevalence of microalbuminuria and the association with neurohormonal parameters in severe chronic heart failure patients.

METHODS AND RESULTS

We studied 94 stable chronic heart failure patients (New York Heart Association class III/IV) receiving therapy with angiotensin-converting enzyme (ACE) inhibitors for over three months. In all patients, renal function and neurohormonal status were evaluated and correlated with urinary albumin/creatinine ratio. The studied population consisted of 70 men and 21 women (mean age 69 +/- 12 years). Ischemia was the underlying cause of heart failure in 61 patients. Overall, 100% of the patients were treated with an ACE inhibitor, 72% with a beta-blocker, and 47% with spironolactone. In 32% (95% confidence interval 22-42) of the patients, microalbuminuria was present, which is significantly higher than in the general population. However, we found no significant association between the presence of microalbuminuria and renal function. Plasma NT-proBNP, active renin protein, angiotensin I, angiotensin II, and aldosterone did not differ significantly between groups with and without microalbuminuria.

CONCLUSION

In 32% of the patients, microalbuminuria was present. No association was found with either renal or neurohormonal parameters.

Prognostic significance of microalbuminuria in non-diabetic patients with acute myocardial infarction

BACKGROUND

The aim of this study was to examine whether the presence of microalbuminuria (20-200 microg/min) can predict in-hospital morbidity and mortality in non-diabetic patients with acute myocardial infarction.

METHODS

Two hundred twenty-three (172 men and 51 women) non-diabetic patients with acute myocardial infarction were studied prospectively. The main outcome measures of the study were based on a comparison of in-hospital mortality and major non-fatal in-hospital events (pulmonary edema, post-infarction angina, infarct extension, mechanical complications, conduction disturbances and ventricular arrhythmias) between microalbuminuric and normoalbuminuric patients.

RESULTS

A significant proportion of patients (33.6%) had microalbuminuria. Seventy-six patients (34%) developed an in-hospital event (fatal or non-fatal). Six patients (2.7%) with acute myocardial infarction died in the hospital. Patients with microalbuminuria had a higher mortality rate in comparison with normoalbuminuric patients (6.6% vs. 0.68%, p = 0.01). For non-fatal events, the incidence of pulmonary edema and ventricular arrhythmias was significantly higher in patients with microalbuminuria (14.6% vs. 3.4%, p < 0.001 and 12% vs. 3.4%, p = 0.01, respectively). The combined end-point of the total number of fatal and non-fatal events was significantly higher in patients with microalbuminuria (57.3% vs. 22.3%, p < 0.001). In multiple logistic regression analysis, microalbuminuria (p < 0.001) and ejection fraction (p = 0.01) were independently related to the occurrence of major in-hospital events.

CONCLUSIONS

Microalbuminuria is a significant predictor of in-hospital morbidity and mortality in non-diabetic patients with acute myocardial infarction.

Blood pressure independent association of microalbuminuria and left ventricular hypertrophy in hypertensive men

BACKGROUND

Rather unique amongst the prognostic predictors, microalbuminuria (MA, albuminuria: 15-200 microg min-1) is associated with several cardiovascular risk factors including left ventricular hypertrophy (LVH). The relationship, usually assumed to reflect an increased blood pressure (BP) load on the heart and the kidney, may, however, represent more than a haemodynamic correlate.

METHODS

To evaluate this possibility, we related MA to left ventricular mass index (LVMI) and other functional and structural echocardiographic parameters, office and 24-h BP, weight, lipids and smoking status in 330 never treated nondiabetic hypertensive men.

RESULTS

The risk of MA increased linearly by ascending quartiles of LVMI and was 2.3-fold higher in the presence of LVH after adjustment for age, left atrial size, mean fractional shortening. Systolic BP, either office or 24 h, and smoking status were the only additional independent predictors in multivariate logistic regression models. The BP-adjusted risk of MA was about twofold higher in patients with LVH, either concentric or eccentric, and neutral in those with concentric remodelling compared with normal geometry.

CONCLUSIONS

The association between elevated LVMI and MA independent of several other potential confounders, systolic BP in particular, is consistent with the existence of cardiac albuminuric factors, possibly of hormonal nature, which are to be identified more precisely. The extent to which LVH explains the predictive power of MA for morbid events independent of the BP load remains unknown.

Long-acting natriuretic peptide, vessel dilator, and kaliuretic peptide enhance urinary excretion rate of albumin, total protein, and beta(2)-microglobulin in patients with congestive heart failure

BACKGROUND

Albumin excretion is increased in persons with congestive heart failure (CHF), but the mechanism of this increase is unknown. Atrial natriuretic peptide (ANP) does not correlate with this albumin excretion, but the other 3 cardiac hormones derived from the ANP prohormone have never been investigated as to whether they can enhance albumin and/or protein excretion in persons with CHF.

METHODS AND RESULTS

Long-acting natriuretic peptide (LANP), vessel dilator, and kaliuretic peptide (100 ng/kg body weight/min) given intravenously for 60 minutes to NYHA Class III CHF patients (n = 24) increased the albumin excretion rate 2- to 7-fold (P <.001) and total protein excretion rate 2- to 5-fold (P <.001). These peptide hormones similarly enhanced beta(2)-microglobulin, a specific marker of proximal tubular reabsorption, excretion rate 25- to 40-fold (P <.0005) at the end of their respective infusions. Three hours after stopping their respective infusions, the beta(2)-microglobulin excretion rate was still 11- to 33-fold (P <.0005) increased.

CONCLUSIONS

LANP, vessel dilator, and kaliuretic peptide each enhance albumin and total protein excretion in persons with CHF. Part of the mechanism of this enhanced protein excretion is the inhibition of proximal tubular reabsorption of protein as shown by the beta(2)-microglobulin data.

Prognostic significance of hypertension and albuminuria for early mortality after acute myocardial infarction

OBJECTIVE

To assess the risk of mortality associated with hypertension and microalbuminuria in patients with acute myocardial infarction.

DESIGN

A prospective study.

SETTING

Intensive care units in three Italian general hospitals.

PATIENTS

In total 309 consecutive patients (including 97 women) aged 66.6 +/- 12.5 years, admitted to hospital for acute myocardial infarction.

MAIN OUTCOME MEASURES

Albumin excretion rate measured by radioimmunoassay of 24 h urine samples, on the first and third days after admission to hospital. In-hospital mortality rate among the patients stratified according to their history of hypertension and albumin excretion rate.

RESULTS

Of the patients, 147 had histories of hypertension. Forty-four per cent of the normotensive and 43% of the hypertensive subjects had microalbuminuria on the first day. On the third day the percentages were 25 and 29%, respectively. Twenty-two patients died before discharge from hospital. Patients were divided into four groups according to whether they had microalbuminuria or not and likewise for hypertension. Mortality rate among the subjects with hypertension and microalbuminuria combined was greater than those among the other three groups (P < 0.0001 on the first and third days). The relative hazard ratio was 11.7 on the first day, and 15.6 on the third day. In a multivariate Cox's model hypertension and microalbuminuria combined had a greater predictive power for mortality than either variable alone. Killip class, age, and creatinine kinases MB level were other significant predictors of death.

CONCLUSIONS

These results show that the combination of hypertension and microalbuminuria is associated with a greater risk of in-hospital mortality among subjects with acute myocardial infarction, independently of degree of heart failure and other possible confounders.

Albumin excretion rate increases during acute myocardial infarction and strongly predicts early mortality

BACKGROUND

This study was undertaken to assess whether albumin excretion rate (AER) increases during acute myocardial infarction (AMI) and whether it predicts in-hospital mortality.

METHODS AND RESULTS

The study was carried out in 496 subjects admitted to hospital for suspected AMI. Of these, 360 had evidence of AMI. The other 136 were studied as control subjects. AER was assessed by radioimmunoassay in three 24-hour urine collections performed on the first, third, and seventh days after admission. Left ventricular ejection fraction was measured by two-dimensional echocardiography in 254 subjects. AER adjusted for several confounders was higher in the AMI than the non-AMI group on the first (69.2+/-5.2 versus 27.3+/-8.5 mg/24 h, P<.0001) and third (30.3+/-2.7 versus 12.5+/-4.4 mg/24 h, P=.001) days, whereas no difference was present on the seventh day. When the subjects with heart failure were excluded, the difference between the two groups remained significant (first day, P<.0001; third day, P=.001). On the basis of classification of the 26 AMI patients who died in hospital according to whether they had normal AER, microalbuminuria, or overt albuminuria, mortality rate progressively increased with increasing levels of AER (P<.0001). In a Cox's proportional hazards model, AER was a better predictor of in-hospital mortality than Killip class or echocardiographic left ventricular ejection fraction. A cutoff value of 50 mg/24 h for first-day AER and 30 mg/24 h for third-day AER yielded a sensitivity of 92.3% and of 88.5% and a specificity of 72.4% and of 79.3%, respectively, for mortality. Adjusted relative risks for the two cutoff values were 17.3 (confidence limits, 4.6 to 112.7) and 8.4 (confidence limits, 2.4 to 39.3), respectively.

CONCLUSIONS

These data show that AER increases during AMI and that it yields prognostic information additional to that provided by clinical or echocardiographic evaluation of left ventricular performance.

Chronic administration of aldosterone depresses baroreceptor reflex function in the dog

In a previous study it was shown that acute perfusion of aldosterone into the isolated carotid sinus decreased baroreceptor activity. The aim of the present study was to determine whether chronic, systemic administration of aldosterone also depresses baroreflex function. In six conscious dogs, the baroreflex was determined before and 10 days after an osmotic minipump containing aldosterone (100 micrograms/kg in 2 mL) was implanted. The slope of the relation between systolic arterial pressure and heart rate was significantly blunted after aldosterone administration (9.1 +/- 0.7 versus 13.3 +/- 1.2 for nitroglycerin, P < .01; 23.4 +/- 5.0 versus 40.1 +/- 5.0 for phenylephrine, P < .01). Baroreflex slopes did not change in a sham group (minipump with saline) and an aldosterone plus spironolactone (600 mg/d) group. Plasma aldosterone levels were significantly elevated after the aldosterone minipump was implanted (443 +/- 72 versus 37 +/- 11 pg/mL, P < .001). Mean arterial pressure was not significantly increased after aldosterone (106.5 +/- 3.8 versus 100.4 +/- 2.6 mm Hg, P = .2). On the 10th day after aldosterone or saline infusion, an acute experiment was carried out. Single baroreceptor fibers were recorded from the carotid sinus nerve. Compared with the sham group, the threshold was significantly elevated in the aldosterone group (111.3 +/- 2.1 versus 85.8 +/- 2.8 mm Hg), and the peak discharge rate was markedly decreased (32.5 +/- 1.5 versus 54.7 +/- 2.5 spikes per second, P < .01). The depressed baroreceptor function could be partially restored after a bolus injection of the Na+,K(+)-ATPase inhibitor ouabain (5 micrograms/kg i.v.).(ABSTRACT TRUNCATED AT 250 WORDS)