BNP rises in heart failure due to what mechanism?

• A. Infection
• B. Myocardial infarction
• C. Ventricular wall stretch leading to natriuretic peptide release
• D. Renal failure

Answer: (C)

BNP increases in heart failure because the ventricles are chronically stretched by elevated filling pressures. This wall tension stimulates the ventricular myocytes to synthesize and secrete BNP. The hormone then acts to relieve the strain by promoting vasodilation, natriuresis and diuresis, and by dampening the renin-angiotensin-aldosterone and sympathetic systems, which helps reduce preload and afterload. So the rise in BNP mainly reflects the amount of stretch and pressure the heart is experiencing. Other conditions can alter BNP levels, but the primary mechanism in heart failure is ventricular wall stretch triggering release.