Circulatory support during crossclamping of the descending thoracic aorta. Evidence of improved organ perfusion.

The need to support the distal circulation during aortic crossclamping and the subsequent effects on hemodynamics and organ perfusion prompted our review of 51 patients who underwent repair of aneurysm of the descending thoracic aorta from 1983 through 1987. Forty-three patients had aneurysms originating distal to the left subclavian artery, and eight had aneurysms involving the distal aortic arch and the proximal descending aorta; 10 patients had emergency operation for aneurysm rupture. Three different techniques were used: Seventeen patients had left atrial-distal aorta arterial bypass with a centrifugal pump, 18 patients had a Gott shunt, and 16 patients had no circulatory support during aneurysm repair. Location and type of aneurysm, age, sex, diabetes, preoperative hypertension, and serum lipid levels were similar in the three groups. Duration of crossclamping was 54 +/- 12 minutes for left atrial-aortic assist, 45 +/- 5 for the shunt group, and 34 +/- 4 for patients without circulatory support. With crossclamping, all groups had similar and significant increases in heart rate (p less than 0.03). Proximal systolic blood pressure did not change during left atrial-aortic assist, but a transient increase occurred in patients with shunts (p less than 0.01), and a sustained increase occurred in patients without circulatory support (p less than 0.05). With crossclamp release, arterial pH and capillary pulmonary wedge pressure decreased significantly (p less than 0.05) in patients without shunt or bypass. Postoperative renal function did not vary significantly when circulatory support was used, but serum creatinine rose transiently in patients with unsupported aortic crossclamping. We conclude that support of the distal circulation during thoracic aortic crossclamping stabilizes hemodynamics and prevents systemic acidosis and renal ischemia. Further, our data suggest that the centrifugal pump may provide better protection than a passive shunt.