Elevated plasma atrial natriuretic peptide levels after occlusion of the thoracic aorta

Study objective: The influence of occlusion of tbe thoracic aorta by an int raluminal balloon on plasma atrial natriuretic peptide (ANP) levels was eva luated in humans, Methods: The changes in plasma ANP and plasma norepinephrine levels, and he modynamic parameters were measured in 10 patients under general anesthesia undergoing regional chemotherapy treatment involving the 15-min inflation a nd subsequent deflation of an intra-aortic, balloon. Results: The hemodynamic changes observed were similar to those seen during aortic clamping and declamping in patients undergoing vascular surgery. Pl asma ANP levels (median +/- SD) measured 1 min after inflation (146 +/- 117 pg/mL) and 1 min after deflation (168 +/- 139 pg/mL) of the aortic balloon were significantly higher than baseline values (83 +/- 55 pg/mL), with a m ean increase, respectively, of 92% and 97% (95% confidence intervals [CI], 50 to 147% and 53 to 152%). Plasma ANP levels were still, elevated 30 min a fter deflation (121 +/- 94 pg/mL), a 56% increase (95% CI, 21 to 100%), alt hough the hemodynamic parameters had already returned to their baseline lev els, There was no evidence that the hemodynamic variables were associated w ith changes in plasma ANP levels (all, p values > 0.30), In addition, there was no evidence of an association between plasma ANP and plasma norepineph rine levels at an, of die four individual sampling points (p > 0.17), Thirt y minutes after deflation, however, norepinephrine levels were higher than baseline values. Conclusions: The changes in plasma ANP levels after aortic occlusion and re institution of blood non may be dependent on parameters other than atrial s tretch and pressure.