Atrial natriuretic peptide and N-terminal atrial natriuretic peptide in plasma reflect right ventricular volumes following coronary artery surgery.

Abstract

Atrial natriuretic peptide (ANP) and the more stable N-terminal fragment (N-ANP) of prohormone are peptides, released in equimolar amounts from cardiac myocytes in response to atrial stretch or ventricular overload and myocardial ischaemia. Protection of the right ventricular (RV) myocardium during ischaemia in cardiac surgery is difficult, especially in patients with severe right coronary artery (RCA) disease. This prospective study was designed to ascertain a possible relationship between changes in plasma ANP/N-ANP concentration and RV function in RCA-diseased patients. Plasma ANP and N-ANP concentrations and RV function, measured by fast-response thermodilution, were determined serially in 15 patients with total RCA stenosis and in another 15 with no significant RCA disease (controls) before, during and after coronary surgery. The RV ejection fraction was lower and the RV end-systolic volume index higher in the RCA-diseased patients than in the controls (P < 0.05) on the second postoperative day, and both ANP and N-ANP were higher in the RCA patients (P < 0.05) from 6 h after cardiopulmonary bypass till the second postoperative day. At the same time the changes in N-ANP concentrations from the levels before induction of anaesthesia correlated with RV ejection fraction and RV volume indexes, but not with heart rate or parameters indirectly reflecting left-sided loading. Right atrial pressure did not differ between the groups nor did it increase significantly during the study. The relationships found between N-ANP and RV volume indexes and RV ejection fraction suggest ventricular expression of ANP: ANP release may be stimulated by RV distension, the more so the poorer the RV function.