Changes in circulating levels of atrial natriuretic factor (ANF) during orthotopic liver transplantation in humans

Abstract

Atrial natriuretic factor (ANF) is a 28 amino acid peptide secreted by the atrial cardiocytes. Clearance is via the lung (50%) and the liver (25%). The main stimulus to ANF secretion is atrial distension but vasoconstrictors, sympathetic stimulation, catecolamines and tachycardia are able to enhance its circulating blood levels. ANF blood concentrations were measured during orthotopic liver transplantation in six postnecrotic cirrhotic patients. Significant increases in ANF blood levels occurred at the end of the anhepatic phase (P < or = 0.02 vs baseline) associated with low cardiac filling pressures (P < or = 0.02 vs baseline) and increased systemic vascular resistances (P < or = 0.02 vs preanhepatic phase). Aldosterone blood levels showed a similar behaviour, increasing significantly (P > or = 0.001 vs baseline) at the end of the anhepatic phase. ANF fell after reperfusion of the graft and returned towards baseline values at the end of the procedure. Since most of the total body clearance of ANF is performed by the lungs, its sharp increase at the end of the anhepatic phase could be considered a counterregulatory response to vasoconstricting stimulation and to fluid-sparing mechanisms in the presence of relative hypovolaemia. Its decrease after reperfusion could be related to volume normalization and partly to the enhanced clearance performed by the newly grafted liver.

The photoplethysmographic amplitude to pulse pressure ratio can track sudden changes in vascular compliance and resistance during liver graft reperfusion

“…[ 25 ] During the anhepatic phase in liver transplantation, sympathetic activation and elevation of systemic vascular resistance are caused by decreased cardiac output related to vascular clamping. [ 26 ] Therefore, this effect may influence the calculation of the PPG amp /PP ratio even if PPG amp shows insignificant changes during reperfusion.…”