Changes in plasma atrial natriuretic peptide concentration during heart transplantation

Examination of changes in plasma atrial natriuretic peptide (ANP) concentrations during heart transplantation may provide important information about factors influencing plasma ANP in patients with severe heart failure. Serial changes in plasma ANP during heart transplantation, and atrial content of ANP in native and donor atria, were measured in 12 patients. Preoperative plasma ANP was elevated in all patients (387 ± 77 pg/mL), whereas atrial content of ANP in native atria was reduced (0.36 ± 0.082 μg/mg protein). Preoperative plasma ANP did not correlate with hemodynamics, but was negatively correlated with creatinine clearance (r = -0.76, P < .01). Intraoperative plasma ANP prior to transplantation was strongly correlated with intraoperative plasma ANP alter transplantation (r = 0.84, P < .001). Although postoperative plasma ANP was reduced from preoperative plasma ANP by 75%, these two measurements were also significantly correlated (r = 0.70, P < .02). Postoperative plasma ANP was not correlated with hemodynamics, but was negatively correlated with both creatinine clearance (r = -0.65, P < .05) and content of ANP in the native atria (r = -0.75, P < .01). Multiple linear regression analysis suggested that up to 85% of the variability of early postoperative plasma ANP could be accounted for by the variability in these latter two parameters. The decrease in native atrial ANP content, in the context of elevated plasma ANP concentration, is consistent with prior animal studies suggesting that severe heart failure induces cellular adaptations favoring accelerated ANP synthesis and secretion (with resultant reduction in tissue content). The significant correlations between pretransplant and posttransplant measurements of plasma ANP suggest that factors that influence variability in plasma ANP between patients prior to heart transplantation remain important determinants of variability in plasma ANP in the first 24 hours after transplantation. These factors appear to be independent of the acute changes in atrial size and myocardial function that accompany heart transplantation, and may involve more slowly adapting biologic mechanisms regulating ANP synthesis, secretion, and clearance in patients with severe heart failure.