Plasma concentrations of atrial natriuretic peptide in patients with artificial and transplanted hearts

Plasma atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay 1 to 12 days after operation in six patients with artificial hearts. The mean levels were significantly higher in artificial heart recipients (58.2 pg.ml-1) than in controls (12.6 pg.ml-1). The mechanism underlying the raised values is not clear, although it is suggested that elevated atrial pressure may have been the stimulus for higher ANP release. In 3 patients plasma ANP concentrations were also measured 1 to 5 days after orthotopic transplantation. In all of them ANP concentrations had increased by 20 to 74% despite lower right atrial pressure. An increase in atrial tissue mass may have contributed to the raised plasma ANP after orthotopic transplantation. It also suggests that the functioning sympathetic nervous system is not a necessary condition for ANP release.