Basal and exercise-induced neuroendocrine activation in patients with heart failure and in normal subjects

Warming Yang Promoting Blood Circulation and Diuresis Alleviates Myocardial Damage by Inhibiting Collagen Fiber and Myocardial Fibrosis and Attenuating Mitochondria Signaling Pathway Mediated Apoptosis in Chronic Heart Failure Rats

Warming Yang promoting blood circulation and diuresis (WYPBD) has been proven effective in treating some diseases. This study aimed to evaluate therapeutic effect of WYPBD in treating chronic heart failure (CHF). CHF rats were established by intraperitoneally injecting doxorubicin (DOX). Therapeutic effects of WYPBD on cardiac function and hemodynamic parameters of myocardial tissues were analyzed. Collagen fiber production and myocardial fibrosis were evaluated. Transcriptions of COL1A1 gene, COL3A1 gene, and TGFB1 gene were evaluated with RT-PCR. Expression of BNP, AVP, PARP, caspase-3, and Bcl-2 in myocardial tissues were evaluated. TUNEL assay was used to identify apoptosis of cardiomyocytes. WYPBD alleviated degree of myocardial hypertrophy in CHF rats compared to the rats in CHF model group (P < 0.05). WYPBD significantly improved cardiac hemodynamics (increased LVEF and LVSF) of CHF rats compared to rats in the CHF model group (P < 0.05). WYPBD protected myocardial structure and inhibited collagen fiber production in myocardial tissues of CHF rats. WYPBD markedly decreased myocardial fibrosis mediators (Col1α, Col3α, TGF-β1) transcription in myocardial tissues of CHF rats compared to rats in CHF model group (P < 0.05). WYPBD significantly reduced BNP and AVP expression in myocardial tissues of CHF rats compared to rats in the CHF model group (P < 0.05). WYPBD markedly reduced the expression of PRAP and caspase-3, and increased Bcl-2 expression in myocardial tissues of CHF rats compared to rats in the CHF model group (P < 0.05). In conclusion, WYPBD alleviated CHF myocardial damage by inhibiting collagen fiber and myocardial fibrosis, attenuating apoptosis associated with the mitochondria signaling pathway of cardiomyocytes.

The Importance of Natriuretic Peptides in Cardiometabolic Diseases

The natriuretic peptide (NP) system is composed of 3 distinct peptides (atrial natriuretic peptide or ANP, B-type natriuretic peptide or BNP, and C-type natriuretic peptide or CNP) and 3 receptors (natriuretic peptide receptor-A or NPR-A or particulate guanynyl cyclase-A natriuretic peptide receptor-B or NPR-B or particulate guanynyl cyclase-B, and natriuretic peptide receptor-C or NPR-C or clearance receptor). ANP and BNP function as defense mechanisms against ventricular stress and the deleterious effects of volume and pressure overload on the heart. Although the role of NPs in cardiovascular homeostasis has been extensively studied and well established, much remains uncertain about the signaling pathways in pathological states like heart failure, a state of impaired natriuretic peptide function. Elevated levels of ANP and BNP in heart failure correlate with disease severity and have a prognostic value. Synthetic ANP and BNP have been studied for their therapeutic role in hypertension and heart failure, and promising trials are under way. In recent years, the expression of ANP and BNP in human adipocytes has come to light. Through their role in promotion of adipocyte browning, lipolysis, lipid oxidation, and modulation of adipokine secretion, they have emerged as key regulators of energy consumption and metabolism. NPR-A signaling in skeletal muscles and adipocytes is emerging as pivotal to the maintenance of long-term insulin sensitivity, which is disrupted in obesity and reduced glucose-tolerance states. Genetic variants in the genes encoding for ANP and BNP have been associated with a favorable cardiometabolic profile. In this review, we discuss several pathways that have been proposed to explain the role of NPs as endocrine networkers. There is much to be explored about the therapeutic role of NPs in improving metabolic milieu.

cGMP manipulation in cardiometabolic disease: chances and challenges

PURPOSE OF REVIEW

Cardiovascular and metabolic diseases are closely linked and commonly occur in the same patients. This review focuses on the cyclic guanosine monophosphate (cGMP) system and its crosstalk between metabolism and the cardiovascular system.

RECENT FINDINGS

Recent studies suggest that cGMP, which serves as second messenger for nitric oxide and for natriuretic peptides, improves oxidative metabolism and insulin signaling. The clinical evidence is particularly strong for the natriuretic peptide branch of the cGMP system. Clinical trials suggested improvements in insulin sensitivity and reductions in the risk of progressing to type 2 diabetes mellitus. However, further studies are needed.

SUMMARY

Enhancing cGMP signaling through nonpharmacological or pharmacological means may improve glucose metabolism in addition to affecting the cardiovascular system. However, excessive cGMP production could have significant unwanted cardiovascular and metabolic effects.

Natriuretic peptides in the control of lipid metabolism and insulin sensitivity

Natriuretic peptides have long been known for their cardiovascular function. However, a growing body of evidence emphasizes the role of natriuretic peptides in human substrate and energy metabolism, thereby connecting the heart with several insulin-sensitive organs like adipose tissue, skeletal muscle and liver. Obesity may be associated with an impaired regulation of the natriuretic peptide system, also indicated as a natriuretic handicap. Evidence points towards a contribution of this natriuretic handicap to the development of obesity, type 2 diabetes mellitus and cardiometabolic complications, although the causal relationship is not fully understood. Nevertheless, targeting the natriuretic peptide pathway may improve metabolic health in obesity and type 2 diabetes mellitus. This review will focus on current literature regarding the metabolic roles of natriuretic peptides with emphasis on lipid metabolism and insulin sensitivity. Furthermore, it will be discussed how exercise and lifestyle intervention may modulate the natriuretic peptide-related metabolic effects.

High intensity interval and endurance training have opposing effects on markers of heart failure and cardiac remodeling in hypertensive rats

There has been re-emerging interest and significant work dedicated to investigating the metabolic effects of high intensity interval training (HIIT) in recent years. HIIT is considered to be a time efficient alternative to classic endurance training (ET) that elicits similar metabolic responses in skeletal muscle. However, there is a lack of information on the impact of HIIT on cardiac muscle in disease. Therefore, we determined the efficacy of ET and HIIT to alter cardiac muscle characteristics involved in the development of diastolic dysfunction, such as ventricular hypertrophy, fibrosis and angiogenesis, in a well-established rodent model of hypertension-induced heart failure before the development of overt heart failure. ET decreased left ventricle fibrosis by ~40% (P < 0.05), and promoted a 20% (P<0.05) increase in the left ventricular capillary/fibre ratio, an increase in endothelial nitric oxide synthase protein (P<0.05), and a decrease in hypoxia inducible factor 1 alpha protein content (P<0.05). In contrast, HIIT did not decrease existing fibrosis, and HIIT animals displayed a 20% increase in left ventricular mass (P<0.05) and a 20% decrease in cross sectional area (P<0.05). HIIT also increased brain natriuretic peptide by 50% (P<0.05), in the absence of concomitant angiogenesis, strongly suggesting pathological cardiac remodeling. The current data support the longstanding belief in the effectiveness of ET in hypertension. However, HIIT promoted a pathological adaptation in the left ventricle in the presence of hypertension, highlighting the need for further research on the widespread effects of HIIT in the presence of disease.

Physical activity - an important preanalytical variable

The concentration of several biochemical and hematological biomarkers is strongly influenced by a number of preanalytical variables. Several lines of evidence attest that short, middle, and long-term exercise, as well as the relative intensity of physical effort (from mild to strenuous), may influence a broad array of laboratory variables. The amount of extracellular release and clearance from blood of most of these biomarkers is markedly influenced by the biological characteristics of the molecule(s), level of training, type, intensity and duration of exercise, and time of recovery after training. It is hence noteworthy that test results that fall outside the conventional reference ranges in athletes not only may reflect the presence of a given disease, but may frequently mirror an adaptation to regular training or changes that have occurred during and/or following strenuous exercise, and which should be clearly acknowledged to prevent misinterpretation of laboratory data. The aim of this narrative review is to provide an update about the most significant changes of some biochemical and hematological biomarkers in response to physical exercise, for appropriate interpretation of these changes in the context of physically active subjects.

Exercise testing in hypertensive patients for assessing the cardiovascular protective potential of antihypertensive drugs

Exercise testing is an established noninvasive tool in cardiology used to diagnose and guide treatment in individuals with suspected or confirmed coronary artery disease. Owing to the wealth of information it provides, exercise testing is also being utilized to evaluate prehypertensive stages, characterize hypertension, assess tolerance to exercise and the efficacy of antihypertensive therapies, and predict target organ damage and cardiovascular risk. The literature on exercise tolerance tests is relatively limited since these studies are difficult to conduct although they represent a valuable test for evaluating the benefits of antihypertensive therapies beyond their blood-pressure-lowering efficacy at rest or during exercise. Such a setting can be immensely useful for the evaluation and for the differentiation of treatments, especially in patients with evident rises in systolic blood pressure and with concomitant diseases, who are at higher risk of stroke. Exercise-induced increase in systolic blood pressure from rest to peak exercise should therefore be used as the primary efficacy variable. There is growing evidence that central pressure is a better predictor for cardiovascular risk than peripheral blood pressure, since this variable takes into account the overall effect of vascular aging and increased arterial stiffness that age and other concomitant diseases may induce. It is also important to include central aortic blood pressure and biomarkers of hypertension and cardiac disease in the overall assessment.

Biological variation of brain natriuretic peptide and cardiac events in stable outpatients with nonischemic chronic heart failure

BACKGROUND

To evaluate the biological variation and prognostic value of brain natriuretic peptide (BNP) for stable outpatients with nonischemic chronic heart failure (NICHF).

METHODS AND RESULTS

Biological variation in BNP was evaluated using an automated assay system in 140 outpatients with NICHF. The stable clinical condition during the 2-month study period was defined as unchanged NYHA and unchanged left ventricular ejection fraction; therefore, 7 patients were excluded during the 2 months. Thereafter, 133 patients were prospectively followed and the relationship between cardiac events and the plasma BNP concentrations (at baseline and after 2 months) were evaluated as well as the changes in BNP. The biological variation in BNP (2-month interval) was calculated as 22.3%. During a mean follow-up period of 42 months, 26 patients had cardiac events. According to stepwise multivariate analyses, plasma BNP after 2 months (P=0.0002) and % change in BNP (P=0.0067) were significant independent predictors of cardiac events.

CONCLUSIONS

These findings indicated that a combination of the absolute value of BNP after 2 months and % increase in BNP (2-month interval) is useful for predicting cardiac events in stable outpatients with NICHF.

Usefulness of NT-proBNP in the assessment of patients with aortic or mitral regurgitation

BACKGROUND

Recent application of brain natriuretic peptide and N-terminal prohormone brain natriuretic peptide (NT-proBNP) in cardiac valvular disease is very promising.

AIMS

To test the usefulness of NT-proBNP in the assessment of patients with aortic or mitral regurgitation.

PATIENTS AND METHODS

Sixty-seven patients - 23 with aortic and 12 with mitral regurgitation vs. 32 controls - were examined by color Doppler echocardiography, cardiopulmonary exercise testing, Minnesota Living with Heart Failure Questionnaire (MLWHFQ) and plasma NT-proBNP assay at rest (T0) and after maximal physical exercise (T1).

RESULTS

NT-proBNP was significantly higher in patients than in controls, both at T0 (298 +/- 85 vs. 46 +/- 11 pg/ml; P < 0.01) and at T1 (366 +/- 106 vs. 50 +/- 12 pg/ml; P < 0.01). MLWHFQ score was significantly higher in patients (19 +/- 3 vs. 1 +/- 0.6; P < 0.001) with a significant inverse correlation with VO2max (r = -0.538, P < 0.001) and a direct correlation with NT-proBNP (T0: r = 0.415, P < 0.01; T1: r = 0.458, P < 0.01). NT-proBNP was inversely correlated with VO2max (T0: r = -0.444, P < 0.001; T1:r = -0.428, P < 0.001) and directly correlated with left atrial diameter (T0: r = 0.370, P < 0.01; T1: r = 0.409, P = 0.001), and left ventricular mass index (r = 0.279, P < 0.01, and r = 0.272, P < 0.01). No correlations were found between echocardiographic parameters of valvular disease severity and VO2max, NT-proBNP and MLWHFQ.

CONCLUSIONS

NT-proBNP is useful in the assessment of the cardiac functional damage secondary to mitral and aortic regurgitation.

Differential effects of carvedilol and metoprolol succinate on plasma norepinephrine release and peak exercise heart rate in subjects with chronic heart failure

Dosing equivalency of carvedilol and metoprolol remains a debate. Degree of beta 1-blockade is best assessed by blunting of the exercise-induced heart rate. Accordingly, the authors have investigated dosing equivalency by examining baseline and peak exercise heart rates and norepinephrine levels in subjects with chronic heart failure treated with carvedilol or metoprolol. Thirty-seven subjects treated with carvedilol (32.9 +/- 3.5 mg; n = 23) or metoprolol succinate (XL) (96.4 +/- 15.9 mg; n = 14) referred for cardiopulmonary exercise testing were studied prospectively. Carvedilol versus metoprolol XL subjects did not differ with respect to baseline heart rate (73 +/- 2 vs 70 +/- 3 bpm), or baseline plasma norepinephrine levels (597.5 +/- 78.3 vs 602.1 +/- 69.6 pg/mL), P = NS. However, despite similar peak exercise norepinephrine levels (2735.8 +/- 320.1 vs 2403.1 +/- 371.6 pg/mL), heart rate at peak exercise was higher in subjects receiving carvedilol (135 +/- 4 bpm) than those receiving metoprolol XL (117 +/- 6 bpm), P = 0.02. Similar norepinephrine release and more complete beta 1-blockade is observed in well-matched subjects with chronic heart failure treated with a mean daily dose of metoprolol XL 96.4 mg compared with carvedilol 32.9 mg.

Exercise training in advanced heart failure patients: Discordance between improved exercise tolerance and unchanged NT-proBNP levels

BACKGROUND

Exercise training can improve aerobic capacity and symptoms in congestive heart failure (CHF) patients.

AIMS

To test the feasibility of exercise training in advanced CHF patients, and examine the potential benefit from peripheral vascular and muscular conditioning as well as improved central hemodynamic and neurohumoral status.

METHODS AND RESULTS

Thirty NYHA functional class III, CHF patients (mean age 61+/-13 yr, ejection fraction 27+/-4%, VO2max 11.3+/-3.9 ml/kg/min) were enrolled. Exercise capacity, cardiovascular parameters and serum levels of brain natriuretic peptide (NT-proBNP) were determined at baseline and after 18 weeks of moderate intensity exercise training. Twenty eight (93%) patients, who completed the exercise program, experienced marked improvements in the 6 min walk (+39%) and exercise duration on the modified Bruce protocol (+66%). Smaller improvements were recorded in the cardiac index (a 15% increase), in the maximal oxygen consumption (a 13% increase in VO2max), in the left ventricular ejection fraction (an 11% increase) and in the systemic vascular resistance and pulmonary artery pressure (an 11% decrease). NT-proBNP levels were not significantly affected. They correlated with exercise capacity and VO2max on baseline measurement, but these correlations were not found after training.

CONCLUSION

Rehabilitation is feasible, even in advanced CHF, and leads to markedly improved exercise performance, but does not affect the level of the principal neurohumoral marker of prognosis - NT-proBNP. Resting cardiovascular performance and maximal oxygen consumption improve less than functional capacity, suggesting that an important benefit is derived from muscle conditioning and improved peripheral vascular response to exercise.

Usefulness of N-terminal pro-B-type natriuretic peptide increase with exercise for predicting cardiovascular mortality in patients with heart failure

N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) level at rest is related to left ventricular (LV) function and cardiovascular mortality in patients with heart failure (HF). There are limited and controversial data regarding changes in NT-pro-BNP level during exercise in patients with HF. The aim of this study was to investigate the effects of exercise on NT-pro-BNP levels and the relation between increases in NT-pro-BNP and the LV ejection fraction and cardiovascular mortality in patients with HF. Seventy-five patients with HF (New York Heart Association classes I to III) and 20 healthy subjects were enrolled in the study. Echocardiographic examination was performed. The modified Bruce protocol was used for symptom-limited exercise testing. Levels of NT-pro-BNP were measured at rest and after peak exercise. The patients were followed up for 690 to 840 days for cardiovascular mortality. Exercise induced significant increases in NT-pro-BNP in patients and controls. Except for a relative increase in NT-pro-BNP during exercise (relative DeltaNT-pro-BNP), NT-pro-BNP concentrations at rest and during peak exercise and absolute increases in NT-pro-BNP during exercise (absolute DeltaNT-pro-BNP) were significantly higher in patients with HF (p <0.001). Absolute DeltaNT-pro-BNP was positively correlated with NT-pro-BNP at rest (p <0.001). The level of absolute DeltaNT-pro-BNP was the most important parameter in predicting a LV ejection fraction <30% (p <0.001). Absolute DeltaNT-pro-BNP and LV end-systolic volume were found to be independent predictors of mortality (p = 0.012 and p = 0.015, respectively). In conclusion, exercise induced increases in NT-pro-BNP in patients and healthy subjects. Absolute increase in NT-pro-BNP is a reliable parameter in predicting a low LV ejection fraction and may help in the identification of patients at high risk for mortality.

Amino-terminal pro-B-type natriuretic peptide: analytic considerations

Amino-terminal pro-B-type natriuretic peptide (NT-proBNP) is a convenient molecule to work with in clinical laboratories, with preanalytic and analytic advantages, such as excellent stability at different temperatures, flexibility in sample type, and strong harmony across all commercially available NT-proBNP assays (including recently released point-of-care methods). Another major advantage of NT-proBNP assays is that they show excellent analytic precision. Reference values for NT-proBNP testing are strongly affected by the population tested. Among nondiseased populations, lower values are expected, whereas in diseased populations, such as in patients with acute dyspnea, higher reference values are more useful. Also, the biologic variability of NT-proBNP should be taken into account to evaluate the significance of any change in its values. When analyzed in patients with stable heart failure, biologic variability was 25%-40%. This article reviews the laboratory aspects of NT-proBNP testing from the perspective of the clinical laboratorian.

Altered sodium intake affects plasma concentrations of BNP but not proBNP in healthy individuals and patients with compensated heart failure

AIMS

Plasma B-type natriuretic peptide (BNP) and proBNP are promising markers for treatment of heart failure (HF), but the intra-individual biological variation is high. We investigated whether changes in sodium intake and posture contribute to this variation.

METHODS AND RESULTS

A total of 12 healthy individuals and 12 patients with medically treated compensated HF were examined after 1 week of low (70 mmol [1.61 g] per day) and 1 week of high (250 mmol [5.75 g] per day) sodium intake. Plasma volume and plasma concentrations of BNP and proBNP were determined after 1 h in seated and 1 h in supine position. In healthy individuals, the plasma BNP concentration increased significantly on high sodium intake with a ratio (high sodium/low sodium) of 2.00 (1.32-3.03, P = 0.004). The corresponding values for HF patients were 1.69 (1.25-2.29, P = 0.003). The plasma BNP concentration changed modestly by a posture change, with a plasma BNP ratio (supine/seated) of 1.15 (1.07-1.14, P = 0.001) and 1.06 (0.99-1.24, P = 0.088) in healthy subjects and HF patients, respectively. Plasma proBNP concentrations were neither significantly affected by posture nor by sodium intake.

CONCLUSION

Sodium intake has a considerable effect on plasma BNP and therefore contributes to the intra-individual variability. We suggest dietary sodium intake to be standardized at least 3 days prior to blood sampling for the determination of plasma BNP.

Relation of B-type natriuretic peptide levels before and after exercise and functional capacity in patients with idiopathic dilated cardiomyopathy

Although much is known about the value of B-type natriuretic peptide (BNP) at rest, the significance of the responsiveness of BNP during exercise in patients with chronic heart failure (HF) without coronary artery disease remains to be established. A role of BNP release during exercise in the functional disability of patients with chronic HF and idiopathic dilated cardiomyopathy (IDC) was hypothesized. One hundred five consecutive patients with an established diagnosis of HF and IDC who underwent symptom-limited cardiopulmonary exercise testing were studied. BNP was measured immediately before exercise and within 1 minute of the end of exercise. BNP at rest increased significantly at peak exercise (median from 66.5 (first, third quartiles 18, 168) to 72.0 pg/ml (26, 208), p <0.001), but BNP response was not uniform. BNP response increased in 63% of patients, did not change in 22%, and decreased in 15%. BNP at rest and BNP response showed an inverse correlation (p <0.001, r = -0.523). Aging and low left ventricular ejection fraction were independent predictors of higher BNP levels at rest, but lower BNP response. Beta-blocker therapy did not influence BNP response. BNP at rest correlated negatively with functional capacity (p <0.001, r = -0.516), whereas BNP response correlated positively (p = 0.002, r = 0.326). Patients with BNP release (vs patients without) had higher maximum oxygen consumption (19.2 +/- 5.1 vs 15.9 +/- 3.6, p <0.001), better functional capacity (59 +/- 13% vs 50 +/- 15%, p = 0.002), and lower minute ventilation/carbon dioxide production slope (33.6 +/- 4.8 vs 36.5 +/- 7.7, p = 0.026) independent of other clinical parameters. In conclusion, BNP release during exercise could be a determinant of functional capacity in patients with chronic HF and IDC.

Unexplained week-to-week variation in BNP and NT-proBNP is low in chronic heart failure patients during steady state

BACKGROUND

The usefulness of brain-natriuretic-peptide (BNP) and N-terminal-pro-brain-natriuretic-peptide (NT-proBNP) for monitoring of chronic heart failure (CHF) patients has been questioned because of high levels of unexplained variation.

AIMS

Week-to-week total variance (CV(T)), unexplained variation (CV(I)), reference change values (RCV), index of individualities (IOI) and number of samples (N) with week-to-week intervals needed to estimate the underlying homeostatic set point (+/-15%) for BNP and NT-proBNP were calculated in pre-specified stable CHF patients.

METHODS AND RESULTS

We measured plasma concentrations of BNP and NT-proBNP, clinical and laboratory variables in 20 CHF patients with a 7-days interval. Only patients considered to be in steady state were included. The CV(I) was 15% (BNP) and 8% (NT-proBNP). CV(T) was 16% (BNP) and 8% (NT-proBNP) and RCV was 43% (BNP) and 23% (NT-proBNP). IOI was 0.14 for BNP and 0.03 for NT-proBNP and N was 1 for BNP and 1 for NT-proBNP.

CONCLUSIONS

Our data demonstrate that unexplained variation of BNP and NT-proBNP is low in CHF patients during steady state, which is a prerequisite for the use of these peptides for monitoring of the disease.

B-type natriuretic peptide concentrations and myocardial dysfunction in critical illness

B-type natriuretic peptide (BNP) is the first biomarker of proven value in screening for left ventricular dysfunction. The availability of point-of-care testing has escalated clinical interest and the resultant research is defining a role for BNP in the investigation and treatment of critically ill patients. This review was undertaken with the aim of collecting and assimilating current evidence regarding the use of BNP assay in the evaluation of myocardial dysfunction in critically ill humans. The information is presented in a format based upon organ system and disease category. BNP assay has been studied in a spectrum of clinical conditions ranging from acute dyspnoea to subarachnoid haemorrhage. Its role in diagnosis, assessment of disease severity, risk stratification and prognostic evaluation of cardiac dysfunction appears promising, but requires further elaboration. The heterogeneity of the critically ill population appears to warrant a range of cut-off values. Research addressing progressive changes in BNP concentration is hindered by infrequent assay and appears unlikely to reflect the critically ill patient's rapidly changing haemodynamics. Multi-marker strategies may prove valuable in prognostication and evaluation of therapy in a greater variety of illnesses. Scant data exist regarding the use of BNP assay to alter therapy or outcome. It appears that BNP assay offers complementary information to conventional approaches for the evaluation of cardiac dysfunction. Continued research should augment the validity of BNP assay in the evaluation of myocardial function in patients with life-threatening illness.

Neurohormonal activation and diagnostic value of cardiac peptides in patients with suspected mild heart failure

BACKGROUND

Data describing activation of brain natriuretic peptide (BNP) system relative to the renin-angiotensin-aldosterone system (RAAS) are sparse in the early phase of heart failure (HF).

AIMS

To compare activation of BNP system relative to RAAS hyperactivity and to assess diagnostic accuracy of cardiac peptides to detect any left ventricular dysfunction (LVD) in patients referred from primary care with suspected HF before institution of medical therapy.

METHODS

Of 166 referred patients 150 were consecutively included (14 were excluded and two refused consent). Echocardiography and measurements of neurohormonal activity were performed. Systolic dysfunction (LVSD) was defined as an ejection fraction<or=0.45. Abnormal left ventricular filling was determined by a combination of Doppler techniques.

RESULTS

LVSD with concomitant abnormal left ventricular filling was present in 22 patients, and abnormalities in left ventricular filling alone were present in 58. Median BNP were 307 and 37 pg/ml while median N-terminal proBNP (NT-proBNP) were 2285 and 199 pg/ml in the two groups respectively, and were significantly lower in patients without LVD (BNP: 8 pg/ml and NT-proBNP: 55 pg/ml, P<0.0001). NT-proBNP demonstrated a weak negative correlation with renin (r=-0.18, P=0.03) and aldosterone (r=-0.18, P=0.03), but no significant correlation with Ang II (r=-0.14, P=0.10) or noradrenaline (r=0.11, P=0.19). Renin correlated well with Ang II (r=0.85, P<0.0001), and aldosterone (r=0.41, P<0.0001). RAAS and noradrenaline demonstrated no diagnostic potential for the diagnosis of any LVD with areas under ROC curves close to 0.50. The area was 0.93 (95% CI 0.90-0.98) for BNP and 0.95 (0.91-0.99) for NT-proBNP. In 5-10% of patients with LVD, BNP and NT-proBNP were under the selected thresholds.

CONCLUSION

Patients with LVD demonstrated considerable activation of the BNP system, whereas RAAS hyperactivity could not be demonstrated. Thus, BNP and NT-proBNP had a considerable diagnostic potential even in patients with mild HF.

Influence of physical exercise and relationship with biochemical variables of NT-pro-brain natriuretic peptide and ischemia modified albumin

BACKGROUND

The diagnostic approach and the clinical management of patients presenting with suspected acute coronary syndrome or cardiac dysfunction are as yet challenging. Although ischemia modified albumin (IMA) and natriuretic peptides were recently proposed for detection of myocardial ischemia and cardiac dysfunction, little information is available on preanalytical and metabolic sources of variability of these markers.

METHODS

To establish the influence of a regular endurance training and the relationship with conventional biochemical variables, NT-pro-brain natriuretic peptide (NT-proBNP) and IMA were assayed, along with cardiac troponin T (cTnT), lactate dehydrogenase (LDH), creatine kinase (CK), creatinine and albumin, in 35 sedentary healthy individuals and 50 male professional road cyclists, 12-24 h following the last demanding training session.

RESULTS

Athletes displayed higher values of both LDH (299+/-61 vs. 257+/-36 U/l, P=0.002) and CK (184+/-123 vs. 115+/-74 U/l, P=0.011), and slightly lower concentrations of creatinine (82+/-12 vs. 87+/-9 micromol/l, P=0.044). No athlete or sedentary control displayed cTnT concentrations exceeding the lower sensitivity limit of the assay. As compared to the sedentary controls, main IMA concentration was increased in athletes (100+/-13 vs. 94+/-6 KU/l, P=0.035), whereas that of NT-proBNP appeared significantly decreased (2.8+/-1.6 vs. 4.3+/-34, P=0.005). The percentage of subjects displaying values exceeding the upper reference limit for the IMA assay was significantly different between athletes and sedentary controls (50% vs. 7%; P<0.001). Pearson correlation analysis revealed an inverse association between IMA and albumin in both athletes (r=-0.640; P<0.001) and sedentary controls (r=-0.583; P=0.001).

CONCLUSIONS

Results of our investigation indicate that a demanding and regular aerobic training regimen, though able to trigger skeletal muscle sufferance, is not associated with any biochemical sign of severe and irreversible chronic cardiac involvement. Moreover, we suggest the adoption of specific IMA diagnostic thresholds following patients' stratification according to serum albumin concentration and physical activity.

Kidneys extract BNP and NT-proBNP in healthy young men

Renal metabolism of the cardiac marker NH2-terminal-pro-brain natriuretic peptide (NT-proBNP) has been suggested. Therefore, we determined the renal extraction ratios of NT-proBNP and its bioactive coproduct brain natriuretic peptide (BNP) at rest and during exercise. In addition, the cerebral ratios were evaluated. Ten young healthy men were investigated at baseline, during moderate cycle exercise (heart rate: 140, Borg scale: 14–15), and in the recovery with BNP and NT-proBNP measured from the brachial artery and the jugular and renal veins, and the renal and cerebral extraction ratios (Ext-Ren and Ext-Cer, respectively) were calculated. Cardiac output, stroke volume, heart rate, mean arterial pressures, and estimated glomerular filtration were determined. BNP and NT-proBNP were extracted by the kidneys but not by the brain. We observed no effect of exercise. The mean values (± SE) of Ext-Ren of NT-proBNP were similar (0.19 ± 0.05, 0.21 ± 0.06, and 0.12 ± 0.03, respectively) during the three sessions ( P > 0.05). Also the Ext-Ren of BNP were similar (0.18 ± 0.07, 0.15 ± 0.11, and 0.14 ± 0.06, respectively; P > 0.05). There were no significant differences between Ext-Ren of BNP and NT-proBNP during the three sessions ( P > 0.05). The Ext-Cer of both peptides varied insignificantly between −0.21 ± 0.15 and 0.11 ± 0.08. The renal extraction ratio of both BNP and NT-proBNP is ∼0.15–0.20. There is no cerebral extraction, and short-term moderate exercise does not affect these values. Our findings suggest that the kidneys extract BNP and NT-proBNP to a similar extent in healthy young men.

High Intraindividual Variation of B-Type Natriuretic Peptide (BNP) and Amino-Terminal proBNP in Patients with Stable Chronic Heart Failure

Background: Plasma B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are promising markers for heart failure diagnosis, prognosis, and treatment. Insufficient data on the intraindividual biological variation (CVi) of BNP and NT-proBNP hamper interpretation of changes in concentration on disease progression or treatment optimization. We therefore investigated CVi values in stable heart failure patients.

Methods: We recruited 43 patients with stable chronic heart failure living in Curaçao (22 males, 21 females; median age, 63 years; range, 20–86 years; New York Heart Association classes I–III). Samples were collected for within-day CVi (n = 6; every 2 h starting at 0800), day-to-day CVi (n = 5; samples collected between 0800 and 1000 on 5 consecutive days), and week-to-week CVi (n = 6; samples collected between 0800 and 1000 on the same day of the week for 6 consecutive weeks). NT-proBNP (Roche) and BNP (Abbott) were measured by immunoassay.

Results: Median (range) concentrations were 134 (0–1630) ng/L (BNP) and 570 (17–5048) ng/L (NT-proBNP). Analytical variation, week-to-week CVi, and reference change values were 8.4%, 40%, and 113% (BNP), and 3.0%, 35%, and 98% (NT-proBNP). Week-to week CVis were inversely related to median BNP concentrations. Week-to week CVis for BNP were 44% (BNP ≤350 ng/L) and 30% (BNP &gt;350 ng/L). Both BNP and NT-proBNP increased between 0800 and 1000. Median NT-proBNP/BNP ratios were inversely related to median BNP concentrations.

Conclusions: The high CVis hamper interpretation of changes in BNP and NT-proBNP concentrations and may partly explain their poor diagnostic values in chronic heart failure. Easily modifiable determinants to lower CVi have not been identified. The value of BNP and NT-proBNP for chronic heart failure diagnosis, and especially for follow-up and treatment optimization of individuals, remains largely to be established.

Vasomotor responses to decreased venous return: effects of cardiac deafferentation in humans

We compared haemodynamic and peripheral vasomotor responses to lower body negative pressure (LBNP) in cardiac transplant recipients who had undergone bicaval anastomoses, involving right atrial deafferentation (-RA), and the conventional procedure in which some atrial baroreceptor afferents remain intact (+RA). We measured mean forearm blood flow (FBF) responses using Doppler/ultrasound during three randomised trials involving 0 (baseline), -20 and -40 mmHg LBNP in 15 transplant recipients (9 -RA, 6 +RA) and in eight healthy matched controls. A significant effect of LBNP on FBF existed between control and transplant groups (P < 0.05; two-way ANOVA). Mild LBNP (-20 mmHg), significantly decreased FBF by 29.7 +/- 10.0% relative to baseline in +RA subjects (P < 0.05), whereas the 17.7 +/- 10.3% decrease in -RA subjects was not significant. In response to -40 mmHg LBNP, FBF significantly decreased in control (42.4 +/- 4.6%, P < 0.05) and +RA subjects (33.3 +/- 11.4%, P < 0.05) with no significant change in the -RA group. The response of systolic blood pressure (SBP) to -40 mmHg significantly differed between groups (P < 0.05): -RA subjects decreased significantly (P < 0.05) whilst the decrease in SBP in +RA subjects did not achieve significance and control subjects exhibited an increase. The heart rate increase from baseline to -40 mmHg was significantly attenuated in -RA relative to controls and the +RA group (P < 0.05). The present study demonstrates that atrial deafferentation impairs reflex vasomotor control of the circulation in response to low- and high-level LBNP, indicating that atrial deafferentation may contribute to abnormal arterial pressure regulation.

Right and left ventricular cardiac function in a developed world population with human immunodeficiency virus studied with radionuclide ventriculography

BACKGROUND

Cardiac dysfunction has been reported in a substantial part of patients infected with the human immunodeficiency virus (HIV). However, most studies are from a time before the introduction of highly active antiretroviral treatment (HAART), which has significantly reduced HIV-associated morbidity and mortality rates. Accordingly, the prevalence of HIV-associated cardiac dysfunction may also have changed. The aim of the study was to establish the prevalence of right- and left-sided cardiac dysfunction in a Danish HIV population, most of whom were undergoing HAART, with radionuclide ventriculography.

METHODS

Ninety-five consecutive patients with HIV infection were included. Mean HIV duration was 104 months, and 84% of the patients received HAART. All patients underwent radionuclide ventriculography, and plasma levels of atrial natriuetic peptide (ANP), brain natriuetic peptide (BNP), and endothelin-1 (ET-1) were measured. Thirty age- and sex-matched healthy volunteer subjects were included to establish reference values of radionuclide measurements of left and right ventricular ejection fraction and of left ventricular volume.

RESULTS

Of 95 patients with HIV, 1 (1%) had a reduced left ventricular ejection fraction and 6 (7%) had a reduced right ventricle ejection fraction (0.35-0.42) compared with reference values from the age- and sex-matched reference population. Patients with HIV and reduced cardiac function did not differ in the duration of HIV, CD4 count, CD4 nadir, or HIV RNA load. No correlations were found between reduced cardiac function and levels of the 3 peptides measured.

CONCLUSIONS

No major dysfunction of the left ventricle is present in a developed world HIV population. However, a small but significant part of this population has modestly reduced right-sided systolic function.