RESUMO
OBJECTIVE: Brain natriuretic peptide (BNP) and endothelin-1 (ET-1) have been shown to be markers of left ventricular (LV) function. To determine the feasibility of using serial assays of these neurohormones in the assessment of cardiac status in the left ventricular assist device (LVAD) setting, we examined the relationship between LV function, myocardial morphology, and plasma levels of these hormones in LVAD recipients. METHODS: Plasma BNP and ET-1 levels were serially assayed in 19 end-stage congestive heart failure (CHF) patients before and after LVAD implantation with various devices (i.e., MicroMed DeBakeyVAD/DVAD, Novacor/NVAD, TCI Heartmate/TCI, Thoratec/TVAD). Echocardiography performed correspondingly at the time points of the hormonal assays and immunohistochemical collagen staining of left ventricular tissue samples, derived from six non-failing hearts as well as from LVAD patients at the time of device insertion and removal, were then contrasted. Patients were grouped according to device used and etiology of heart disease (ischemic or dilated cardiomyopathy, ICM/DCM). RESULTS: LVAD therapy significantly improved LV ejection fraction (EF%: 21 +/- 3.8% to 28.11 +/- 3.57%), cardiac output (CO: 3.49 +/- 1.3 to 7.3 +/- 0.2 l/m), and left ventricular end-diastolic diameter (LVEDD: 6.68 +/- 0.92 versus 4.79 +/- 1.54 cm, P < 0.0001) in all patients. Absolute BNP and ET-1 plasma levels remained significantly lower in all patients after LVAD implantation (both P < 0.001). The NVAD group exhibited the most BNP reduction and EF% increase (P < 0.0004 and P < 0.038, respectively). Average collagen levels were reduced in all patients (P < 0.0005). Among the devices, the NVAD group demonstrated the most evident change (P < 0.0036), while there was comparable reduction in the DCM and ICM groups (both P < 0.03). In general, postoperative BNP and ET-1 trends exhibited a notable parallelism with both manifesting bi-phasic tendencies and an inverse proportionality to corresponding EF% measurements. CONCLUSIONS: Device selection appears to influence the cardiac morphological and neurohormonal expressive tendencies exhibited by recipients. Plasma BNP and ET-1 levels correlate with both LV function and myocardial morphological improvement. Alterations in the levels of these hormones during LVAD support may be real-time indicators of prevailing myocardial autocrine/paracrine activity and as such may be of potential use in future algorithms of cardiac assessment and therapeutic decision-making with regard to transplant urgency and/or possible device explantation.
