Frans Boomsma

Renal Function, Neurohormonal Activation, and Survival in Patients With Chronic Heart Failure

BACKGROUND Because renal function is affected by chronic heart failure (CHF) and it relates to both cardiovascular and hemodynamic properties, it should have additional prognostic value. We studied whether renal function is a predictor for mortality in advanced CHF, and we assessed its relative contribution compared with other established risk factors. In addition, we studied the relation between renal function and neurohormonal activation. METHODS AND RESULTS The study population consisted of 1906 patients with CHF who were enrolled in a recent survival trial (Second Prospective Randomized study of Ibopamine on Mortality and Efficacy). In a subgroup of 372 patients, plasma neurohormones were determined. The baseline glomerular filtration rate (GFR(c)) was calculated using the Cockroft Gault equation. GFR(c) was the most powerful predictor of mortality; it was followed by New York Heart Association functional class and the use of angiotensin-converting enzyme inhibitors. Patients in the lowest quartile of GFR(c) values (<44 mL/min) had almost 3 times the risk of mortality (relative risk, 2. 85; P<0.001) of patients in the highest quartile (>76 mL/min). Impaired left ventricular ejection fraction (LVEF) was only modestly predictive (P=0.053). GFR(c) was inversely related with N-terminal atrial natriuretic peptide (ANP; r=-0.53) and, to a lesser extent, with ANP itself (r=-0.35; both P<0.001). CONCLUSIONS Impaired renal function (GFR(c)) is a stronger predictor of mortality than impaired cardiac function (LVEF and New York Heart Association class) in advanced CHF, and it is associated with increased levels of N-terminal ANP. Moreover, impaired renal function was not related to LVEF, which suggests that factors other than reduced cardiac output are causally involved.

Reduction of Sympathetic Hyperactivity by Enalapril in Patients with Chronic Renal Failure

BACKGROUND Inhibition of angiotensin-converting enzyme (ACE) reduces the risk of cardiovascular problems in patients with chronic renal failure. This effect may be due in part to a decrease in sympathetic nervous activity, but no direct evidence of such an action is available. METHODS We studied muscle sympathetic-nerve activity in 14 patients with hypertension, chronic renal failure, and increased plasma renin activity before, during, and after administration of the ACE inhibitor enalapril. Ten other patients with similar clinical characteristics were studied before and during treatment with the calcium-channel blocker amlodipine. Normal subjects matched for age and weight were included in both studies. RESULTS At base line, mean (+/-SD) muscle sympathetic-nerve activity was higher in the group of patients who received enalapril than in the control subjects (35+/-17 vs. 19+/-9 bursts per minute, P=0.004). The baroreflex curve, which reflects changes in muscle sympathetic-nerve activity caused by manipulations of blood pressure with sodium nitroprusside and phenylephrine, was shifted to the right in the patients, but baroreflex sensitivity was similar to that in the control subjects (-2.1+/-1.9 and -2.7+/-1.3 bursts per minute per mm Hg, respectively; P=0.36). A single dose of the sympatholytic drug clonidine caused a greater fall in blood pressure in the patients than in the control subjects. Treatment with enalapril normalized blood pressure and muscle sympathetic-nerve activity (at 23+/-10 bursts per minute) in the patients and shifted the baroreflex curve to the left, reflecting normal blood-pressure levels, without significantly changing sensitivity (-2.3+/-1.8 bursts per minute per mm Hg, P=0.96). In the patients who received amlodipine, treatment also lowered blood pressure but increased muscle sympathetic-nerve activity, from 41+/-19 to 56+/-14 bursts per minute (P=0.02). CONCLUSIONS Increased sympathetic activity contributes to hypertension in patients with chronic renal disease. ACE inhibition controls hypertension and decreases sympathetic hyperactivity.

Angiotensin-(1–7) Attenuates the Development of Heart Failure After Myocardial Infarction in Rats

Background—The renin-angiotensin system (RAS) is a key player in the progression of heart failure. Angiotensin-(1–7) is thought to modulate the activity of the RAS. Furthermore, this peptide may play a part in the beneficial effects of angiotensin-converting enzyme inhibitors in cardiovascular disease. We assessed the effects of angiotensin-(1–7) on the progression of heart failure. Methods and Results—Male Sprague-Dawley rats underwent either coronary ligation or sham surgery. Two weeks after induction of myocardial infarction, intravenous infusion of angiotensin-(1–7) (24 &mgr;g/kg per hour) or saline was started by minipump. After 8 weeks of treatment, hemodynamic parameters were measured, endothelial function was assessed in isolated aortic rings, and plasma angiotensin-(1–7) levels were determined. Myocardial infarction resulted in a significant deterioration of left ventricular systolic and diastolic pressure, dP/dt, and coronary flow. Raising plasma levels 40-fold, angiotensin-(1–7) infusion attenuated this impairment to a nonsignificant level, markedly illustrated by a 40% reduction in left ventricular end-diastolic pressure. Furthermore, angiotensin-(1–7) completely preserved aortic endothelial function, whereas endothelium-dependent relaxation in aortas of saline-treated infarcted rats was significantly decreased. Conclusions—Angiotensin-(1–7) preserved cardiac function, coronary perfusion, and aortic endothelial function in a rat model for heart failure.

Effects of Dietary Sodium and Hydrochlorothiazide on the Antiproteinuric Efficacy of Losartan

There is large interindividual variability in the antiproteinuric response to blockade of the renin-angiotensin-aldosterone system (RAAS). A low-sodium diet or addition of diuretics enhances the effects of RAAS blockade on proteinuria and BP, but the efficacy of the combination of these interventions is unknown. Therefore, this randomized, double-blind, placebo-controlled trial to determine the separate and combined effects of a low-sodium diet and hydrochlorothiazide (HCT) on proteinuria and BP was performed. In 34 proteinuric patients without diabetes, mean baseline proteinuria was 3.8 g/d, and this was reduced by 22% by a low-sodium diet alone. Losartan monotherapy reduced proteinuria by 30%, and the addition of a low-sodium diet led to a total reduction by 55% and the addition of HCT to 56%. The combined addition of HCT and a low-sodium diet reduced proteinuria by 70% from baseline (all P < 0.05). Reductions in mean arterial pressure showed a similar pattern (all P < 0.05). In addition, individuals who did not demonstrate an antiproteinuric response to losartan monotherapy did respond when a low-sodium diet or a diuretic was added. In conclusion, a low-sodium diet and HCT are equally efficacious in reducing proteinuria and BP when added to a regimen containing losartan and especially seem to benefit individuals who are resistant to RAAS blockade. Combining these interventions in sodium status is an effective method to maximize the antiproteinuric efficacy of RAAS blockade.

Determination of catecholamines in human plasma by high-performance liquid chromatography: comparison between a new method with fluorescence detection and an established method with electrochemical detection.

We report a sensitive fluorimetric method, in which catecholamines are concentrated from plasma by liquid-liquid extraction and derivatized with the selective fluorescent agent 1,2-diphenylethyl-enediamine prior to chromatography. Optimal conditions for extraction, derivatization and chromatography were investigated. With alpha-methylnorepinephrine as internal standard, the chromatographic separations are complete within 6 min. Limits of detection are 0.3 pg for norepinephrine and epinephrine and 0.5 pg for dopamine. Coefficients of variation are low (3-7%). Comparison of plasma catecholamine values determined with this method and with an established method with electrochemical detection (n = 135) shows good correlation (r = 0.94-1.00), and regression lines are close to lines of identity.

Prognostic value of heart rate variability during long-term follow-up in patients with mild to moderate heart failure

OBJECTIVES We sought to assess the prognostic value of heart rate variability measures, including Poincaré plots, in patients with mild to moderate chronic heart failure. BACKGROUND Mortality is high in patients with heart failure, and many of them die suddenly. However, identification of high risk patients, particularly those with an increased risk for sudden death, has remained difficult. METHODS We studied 95 patients with heart failure (mean [+/- SD] age 60 +/- 8 years, left ventricular ejection fraction 0.29 +/- 0.09, New York Heart Association functional class II [81%] and III [19%]) during up to 4 years of follow-up. Heart rate variability measures and Poincaré plots were obtained from 24-h Holter recordings. RESULTS During follow-up, 17 (18%) of the 95 patients died. In 15 patients, death was cardiac related (11 patients experienced sudden death). None of the conventional time and frequency domain measures of heart rate variability were related to survival. In contrast, abnormal Poincaré plots identified a significantly higher risk for all-cause cardiac death (Cox proportional hazards ratio 5.7, 95% confidence interval [CI] 1.6 to 20.6, univariate analysis) and for sudden cardiac death (hazards ratio 6.8, 95% CI 1.5 to 31.4) compared with those with normal Poincaré plots. Patients with abnormal Poincaré plots were shown to have a lower left ventricular ejection fraction (0.26 +/- 0.10 vs. 0.31 +/- 0.08, p < 0.05) and higher plasma norepinephrine concentrations (506 +/- 207 pg/ml vs. 411 +/- 175 pg/ml, p < 0.05). In multivariate analysis, abnormal Poincaré plots still had independent prognostic value, both for all-cause cardiac mortality and for sudden cardiac death (hazards ratio 5.3, 95% CI 1.2 to 17.1, hazards ratio 4.5, 95% CI 1.0 to 27.5, respectively. CONCLUSIONS Heart rate variability analysis, as assessed by Poincaré plots, has independent prognostic value in patients with mild to moderate chronic heart failure and identifies an increased risk for all-cause and sudden cardiac death in these patients.

Renal Effects of Aliskiren Compared With and in Combination With Irbesartan in Patients With Type 2 Diabetes, Hypertension, and Albuminuria

OBJECTIVE We investigated whether the antiproteinuric effect of the direct renin inhibitor aliskiren is comparable to that of irbesartan and the effect of the combination. RESEARCH DESIGN AND METHODS This was a double-blind, randomized, crossover trial. After a 1-month washout period, 26 patients with type 2 diabetes, hypertension, and albuminuria (>100 mg/day) were randomly assigned to four 2-month treatment periods in random order with placebo, 300 mg aliskiren once daily, 300 mg irbesartan once daily, or the combination using identical doses. Patients received furosemide in a stable dose throughout the study. The primary end point was a change in albuminuria. Secondary measures included change in 24-h blood pressure and glomerular filtration rate (GFR). RESULTS Placebo geometric mean albuminuria was 258 mg/day (range 84–2,361), mean ± SD 24-h blood pressure was 140/73 ± 15/8 mmHg, and GFR was 89 ± 27 ml/min per 1.73 m2. Aliskiren treatment reduced albuminuria by 48% (95% CI 27–62) compared with placebo (P < 0.001), not significantly different from the 58% (42–79) reduction with irbesartan treatment (P < 0.001 vs. placebo). Combination treatment reduced albuminuria by 71% (59–79), more than either monotherapy (P < 0.001 and P = 0.028). Fractional clearances of albumin were significantly reduced (46, 56, and 67% reduction vs. placebo). Twenty-four-hour blood pressure was reduced 3/4 mmHg by aliskiren (NS/P = 0.009), 12/5 mmHg by irbesartan (P < 0.001/P = 0.002), and 10/6 mmHg by the combination (P = 0.001/P < 0.001). GFR was significantly reduced 4.6 (95% CI 0.3–8.8) ml/min per 1.73 m2 by aliskiren, 8.0 (3.6–12.3) ml/min per 1.73 m2 by irbesartan, and 11.7 (7.4–15.9) ml/min per 1.73 m2 by the combination. CONCLUSIONS The combination of aliskiren and irbesartan is more antiproteinuric in type 2 diabetic patients with albuminuria than monotherapy.

CONGENITAL DOPAMINE-BETA-HYDROXYLASE DEFICIENCY: A Novel Orthostatic Syndrome

A woman was referred with severe orthostatic hypotension at the age of 21. Ptosis, skeletal muscle hypotonia, and recurrent hypoglycaemia had been noticed in early childhood. There was noradrenergic denervation and adrenomedullary failure but baroreflex afferents, cholinergic innervation, and adrenocortical function were intact. Noradrenaline and adrenaline were undetectable in plasma, urine, and cerebrospinal fluid (CSF), but dopamine was 7-fold to 12-fold normal in plasma, 4-fold normal in urine, and 20-fold normal in CSF. Measurements of catecholamine metabolites showed further evidence for impairment of noradrenaline and adrenaline biosynthesis due to deficient dopamine-beta-hydroxylation. Dopamine-beta-hydroxylase was undetectable in plasma and CSF. Physiological and pharmacological stimuli of sympathetic neurotransmitter release caused increases in plasma dopamine rather than plasma noradrenaline.

Plasma semicarbazide-sensitive amine oxidase is elevated in patients with congestive heart failure

OBJECTIVE Semicarbazide-sensitive amine oxidase (SSAO) is present in various mammalian tissues, especially in vascular smooth muscle cells, but also in plasma. The enzyme has been suggested to play a role in vascular endothelial damage through conversion of amines into cytotoxic aldehydes, ammonia and hydrogen peroxide. Endothelial dysfunction is present in diabetes mellitus (DM) and congestive heart failure (CHF). Elevated plasma SSAO activities have been reported in patients with DM, but no data on patients with CHF are as yet available. METHODS AND RESULTS Plasma SSAO was measured in 271 patients with CHF and compared to values in 77 controls. SSAO was found to be elevated in patients with CHF compared to controls (589 +/- 252 vs. 455 +/- 114 mU/l; P < 0.0001). Plasma SSAO was higher in NYHA class III/IV than in class III (662 +/- 288 vs. 555 +/- 226 mU/l; P = 0.004) and also higher in patients with concomitant DM than in those without (706 +/- 248 vs. 557 +/- 245 mU/l; P < 0.0001). Plasma SSAO correlated with plasma atrial natriuretic peptide (r = 0.42; P < 0.0001), with plasma norepinephrine (r = 0.27; P < 0.0001) and with left ventricular ejection fraction (r = -0.13; P = 0.0162). Multiple regression analysis showed atrial natriuretic peptide, norepinephrine, DM and cardiothoracic ratio to be the main determinants of plasma SSAO. CONCLUSION The finding of elevated plasma SSAO in CHF, increasing with severity of the disease and with the concomitant presence of DM, supports the suggestion that SSAO may be involved in the pathogenesis of vascular endothelial damage. Plasma SSAO may be a useful parameter in assessing severity of CHF and in prognostic evaluation. Pharmacologic manipulation of SSAO activity might be an interesting new concept for prevention of vascular endothelial damage in various vascular disease entities.

Angiotensin-Converting Enzyme Inhibition and Angiotensin II Type 1 Receptor Blockade Prevent Cardiac Remodeling in Pigs After Myocardial Infarction: Role of Tissue Angiotensin II

BackgroundThe mechanisms behind the beneficial effects of renin-angiotensin system blockade after myocardial infarction (MI) are not fully elucidated but may include interference with tissue angiotensin II (Ang II). Methods and ResultsForty-nine pigs underwent coronary artery ligation or sham operation and were studied up to 6 weeks. To determine coronary angiotensin I (Ang I) to Ang II conversion and to distinguish plasma-derived Ang II from locally synthesized Ang II, 125I-labeled and endogenous Ang I and II were measured in plasma and in infarcted and noninfarcted left ventricle (LV) during 125I-Ang I infusion. Ang II type 1 (AT1) receptor–mediated uptake of circulating 125I-Ang II was increased at 1 and 3 weeks in noninfarcted LV, and this uptake was the main cause of the transient elevation in Ang II levels in the noninfarcted LV at 1 week. Ang II levels and AT1 receptor–mediated uptake of circulating Ang II were reduced in the infarct area at all time points. Coronary Ang I to Ang II conversion was unaffected by MI. Captopril and the AT1 receptor antagonist eprosartan attenuated postinfarct remodeling, although both drugs increased cardiac Ang II production. Captopril blocked coronary conversion by >80% and normalized Ang II uptake in the noninfarcted LV. Eprosartan did not affect coronary conversion and blocked cardiac Ang II uptake by >90%. ConclusionsBoth circulating and locally generated Ang II contribute to remodeling after MI. The rise in tissue Ang II production during angiotensin-converting enzyme inhibition and AT1 receptor blockade suggests that the antihypertrophic effects of these drugs result not only from diminished AT1 receptor stimulation but also from increased stimulation of growth-inhibitory Ang II type 2 receptors.