The time course of natriuretic hormones as plasma markers of myocardial recovery in heart transplant candidates during ventricular assist device support reveals differences among device types

Background: The natriuretic hormones ANP and BNP are expressed differently in the myocardium. Both hormones have compensatory diuretic activity during heart failure. Mechanical stretch of the myocardial walls induces the expr ession of these hormones. In failing human myocardium, both ANP and BNP are transcribed in the ventricular myocardium in high amounts. We measured the plasma concentrations of ANP and BNP in patients supported by various vent ricular assist devices (VADs) at various times. We analyzed the time course s of ANP and BNP to determine (1) the time scale of their down-regulation a s a marker of putative myocardial recovery, (2) their steady-state levels u nder VAD support and (3) differences caused by various VAD devices. Methods: We analyzed ANP and BNP using commercially available radioimmune a ssays. We analyzed the time courses of patients supported by Thoratec (R) ( THO) LVAD (n = 8), TCI Heartmate (R) (TCI) (n = 6), Novacor (R) (NOV) (n = 7), and Lionheart (R) (LIO) (n = 3). Results: Patients supported with NOV and some patients with TCI showed down regulation of BNP to a steady-state level at 30 to 50 days, following a sin gle exponential decay. In contrast, patients supported by THO or 1.10 did n ot reveal a determined time course of the natriuretic hormones. Only a few patients reached normal plasma values during VAD support. Conclusion: The time courses of ANP and BNP differ among VAD types because of construction and/or driving mode, which might be important when consider ing patients for weaning from VAD without heart transplant.