Brain natriuretic peptide is produced both by cardiornyocytes and cells infiltrating the heart in patients with severe heart failure supported by a left ventricular assist device

Background: Brain natriuretic peptide (BNP) is a cardiac neurohormone synthesized in cardiac ventricles. as a result of increased wall stress. Left ventricular assist device (LVAD) support in patients with end-stage heart failure results in reduced wall stress and therefore may change BNP levels in the heart. Methods: BNP plasma levels were measured in 17 patients with end-stage HF before LVAD implantation and at 1 week, 1 month, and 3 months after LVAD support. BNP-messenger RNA (mRNA) expression in cardiac biopsy specimens of 27 patients before and after LVAD support was determined by quantitative polymerase chain reaction. Immunohistochemistry (IHC) and IHC-double staining was used in biopsy specimens from 32 patients before and after LVAD support to localize the BNP protein expression in the heart. Results: BNP plasma levels significantly decreased from 1,872 +/- 1,098 pg/ml before implantation to 117 +/- 91 pg/ml at 3 months after LVAD implantation. This decrease in plasma levels was accompanied by a significant decrease in mRNA expression (relative quantity) in the heart. IHC and IHC-double staining showed BNP immunoreactivity in the cardiomyocytes, endothelial cells, infiltrating T cells, and macrophages. Conclusions: The significant decrease in serum BNP concentration after LVAD support coincides with a decrease in BNP mRNA and protein expression in the heart. BNP is produced in the left ventricle not only by cardiomyocytes but also by endothelial cells, T cells, and macrophages. Unloading of the left ventricle by 4 LVAD results in decreased BNP expression in the heart and plasma and may play an important role in the reverse remodeling process of the heart.