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Heart transplantation (HT) should normalize cardiac endocrine function, but brain natriuretic peptide (BNP) levels remain elevated after HT, even in the absence of left ventricular hemodynamic disturbance or allograft rejection. Right ventricle (RV) abnormalities are common in HT recipients (HTx), as a result of engraftment process, tricuspid insufficiency, and/or repeated inflammation due to iterative endomyocardial biopsies. RV function follow-up is vital for patient management as RV dysfunction is a recognized cause of in-hospital death and is responsible for a worse prognosis. Interestingly, few and controversial data are available concerning the relationship between plasma BNP levels and RV functional impairment in HTx. This suggests that infra-clinical modifications, such as subtle immune system disorders or hypoxic conditions, might influence BNP expression. Nevertheless, due to other altered circulating molecular forms of BNP, a lack of specificity of BNP assays is described in heart failure patients. This phenomenon could exist in HT population and could explain elevated BNP plasmatic levels despite a normal RV function. In clinical practice, intra-individual change in BNP over time, rather than absolute BNP values, might be more helpful in detecting right cardiac dysfunction in HTx., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Increased brain natriuretic peptide (BNP), reflecting increased ventricular wall stress and pressure, is a well-known diagnostic and prognostic marker in patients with chronic heart failure. Heart transplantation (HT), the process of replacing the failing heart and restoring haemodynamics, should normalize cardiac endocrine function. Nevertheless, BNP levels remain raised after HT, likely because of increased secretion and/or decreased clearance of the cardiac hormone. Thus, BNP increases in proportion to the extent of left and right ventricular dysfunction after HT. Clinically complicated cardiac transplantation (cardiac systolic dysfunction, renal failure) is associated with the higher level of circulating BNP, and clinically successful cardiac transplantation (mild cardiac diastolic dysfunction) is associated with moderately increased BNP values. Surprisingly, however, increased BNP has also been found after HT in the absence of haemodynamic perturbations or allograft rejection, raising the hypothesis that even subtle modification in the immune system might influence BNP expression. In view of the potential interest in the cardiac hormone for subjects' risk stratification and therapy, a better knowledge of the mechanisms involved in the BNP increase after HT might be helpful for HT recipients' follow-up.

Brain natriuretic peptide (BNP) increases in proportion to the extent of right ventricular dysfunction in pulmonary hypertension and after heart transplantation. No data are available after lung transplantation. Clinical, biological, respiratory, echocardiographic characteristics and circulating BNP and its second messenger cyclic guanosine monophosphate (cGMP) were determined in thirty matched subjects (10 lung-, 10 heart-transplant recipients (Ltx, Htx) and 10 healthy controls). Eventual correlations between these parameters were investigated. Heart rate and pulmonary arterial blood pressure were slightly increased after transplantation. Creatinine clearance was decreased. Mean of forced expiratory volume in 1 s was 76.6 +/- 5.3% and vital capacity was 85.3 +/- 6.4% of the predicted values in Ltx. BNP was similarly increased in Ltx and Htx, as compared with control values (54.1 +/- 14.2 and 45.6 +/- 9.2 vs. 6.2 +/- 1.8 pg/ml, respectively). Significant relationships were observed between plasma BNP and cGMP values (r = 0.62; P < 0.05 and r = 0.75; P < 0.01, in Ltx and Htx) and between BNP and right ventricular fractional shortening and tricuspid E/Ea ratio in Ltx (r = -0.75 and r = 0.93; P < 0.01, respectively). BNP is increased after lung transplantation, like after heart transplantation. The relationships observed suggest that the cardiac hormone might counterbalance possible deleterious effects of lung-transplantation on right functioning of patient's heart.

Objective: To determine whether the six-minute walk test (6MWT) might predict peak oxygen consumption (VO2peak) after heart transplantation., Design: Case-control prospective study., Setting: Public hospital., Participants: Patients with heart transplant (n=22) and age-matched sedentary male subjects (n=13)., Interventions: Not applicable., Main Outcome Measures: Exercise performance using a maximal exercise test, distance walked using the 6MWT, heart rate, and VO2peak., Results: Compared with controls, exercise performance was decreased in patients with heart transplant with less distance ambulated (516+/-13m vs 592+/-13m; P<.001) and a decrease in mean VO2peak (23.3+/-1.3 vs 29.6+/-1mL x min(-1) x kg(-1); P<.001). Patients with heart transplant showed an increased resting heart rate, a response delayed both at the onset of exercise and during recovery. However, the patient's heart rate at the end of the 6MWT was similar to that obtained at the ventilatory threshold. The formula did not predict measured VO2, with a weak correlation observed between the six-minute walk distance and both VO2peak (r=.53; P<.01) and ventilatory threshold (r=.53; P<.01) after heart transplantation. Interestingly, when body weight was considered, correlations coefficient increased to .74 and .77, respectively (P<.001)., Conclusions: In heart transplant recipients, the 6MWT is a safe, practical, and submaximal functional test. The distance-weight product can be used as an alternative method for assessing the functional capacity after heart transplantation but cannot totally replace maximal VO2 determination.

Background: Increased brain natriuretic peptide (BNP) in cardiovascular disease is thought to be a compensatory protective mechanism allowing to delay the occurrence of terminal heart failure. Heart transplantation should normalize the neuroendocrine balance but BNP remains elevated in stable heart-transplant recipients (Htx). Such increase has been related to persistent endothelial and cardiac dysfunctions. The purpose of this study was to determine whether selected Htx, presenting with normal hemodynamic and cardiac systolic and diastolic functions on both side of the heart, show a normalization of their BNP plasma values., Methods: Of a cohort of well-being 26 Htx, we selected 12 patients with normal hemodynamics and left and right heart systolic and diastolic functions and compared their circulating BNP, cyclic guanosine monophosphate (cGMP) (the BNP second messenger) and endothelin-1 (ET) values with that of 12 age-, body mass index- and mean arterial pressure-matched controls. Cardiac function determination by echodoppler included cardiac filling pressures assessment using tissue Doppler imaging. Blood samples for biological and hormonal determinations were drawn at rest, within 15 min before echocardiography., Results: As selected, hemodynamic and left and right heart systolic and diastolic functions were located in the normal range in Htx. Plasma ET value was also similar in Htx and controls (20.7 +/- 0.9 vs. 19.6 +/- 0.9 fmol/mL). However, circulating BNP, like cGMP, was still significantly increased after heart transplantation, when compared with controls (33.8 +/- 8.5 vs. 4.0 +/- 0.9 pg/mL, p = 0.002 and 8.2 +/- 1.1 vs. 4.4 +/- 0.3 nmol/L, p = 0.003) for BNP and cGMP, respectively, in Htx and controls. Interestingly, the sole correlation observed was between BNP and cGMP (r = 0.85, p < 0.0001) after heart transplantation., Conclusions: After heart transplantation, BNP remained increased despite the normalization of hemodynamic and cardiac systolic and diastolic functions. This suggests that such endocrine heart stimulation should not be viewed only as a hemodynamic marker in Htx. Further studies will be useful to investigate the role of pro-inflammatory cytokines and whether elevated BNP still possesses antifibrotic properties, further supporting the interest of enhancing its activity after heart transplantation.