OBJECTIVE: To study the variations of the atrial natriuretic peptide (ANP) introduced by extracorporeal circulation (ECC) during cardiac surgery, and to test the hypothesis that there is a correlation between the ANP plasma levels, right atrial pressure (RAP), left atrial pressure (LAP), diuresis and natriuresis. METHOD: Study of a cohort of 15 patients submitted to myocardial revascularization using ECC. The intervals of the observation times were: t0= 10 minutes before ECC (control value); t1= 10 minutes after total flow in ECC; t2=30 minutes into total flow in ECC; t3= end stage of ECC at a nasopharingeal temperature of 36º C; and t4= 30 minutes after ECC has ended. RESULTS: The ANP, LAP and RAP values varied significantly (p<0.001). The ANP dropped from t0 to t1 (NS), and then rose progressively until t4(p<0.001). The LAP and RAP were reduced (p <0.001) between t0 and t1, rising progressively until t4 (p<0.001). The urinary Na+ rose between t0 and t3 (p<0.001) with a drop at t4. The diuresis increased progressively at all times considered (p<0.001). A significant correlation was found between ANP and the diuresis volume at t0, correlation coefficient of 0.535 (p=0.040) and at the time equal to t2 between ANP and RAP, a correlation coefficient of 0.590 (p=0.021). CONCLUSION: The ANP concentrations present variations during revascularization surgery with ECC, favoring the idea that they are related to atrial pressures and, at the end of ECC, they have an important function in sodium excretion and the volume of diuresis.
Atrial natriuretic factor; Cardiac surgery; Extracorporeal circulation
