COMPARISON STUDIES OF PASSIVE AND ACTIVE SHUNTING DURING CROSS-CLAMPING OF THE DESCENDING THORACIC AORTA

The effects of passive (no pump) and active (using centrifugal pump) shunting on hemodynamics and metabolisms during cross-clamping of the descending thoracic aorta were compared in mongrel dogs. In Group I (control), the aorta was cross-clamped for 2 hours without shunting; in Group II (passive), a temporary shunt was placed between the left common carotid and left femoral arteries during cross-clamping; and in Group III (active), left heart by-pass, matching flow to that in group II, was performed. Hemodynamic and metabolic parameters were recorded prior to cross-clamping and following every 30 min for 4 hours. All animals in Group I suffered from hemodynamic instability, metabolic abnormal and neurologic injury and died within 12 hours. Hemodynamic changes were unstable in Group III than II, and three dogs in Group III, but none in Group II, suffered from neurologic injury. Metabolic changes between Group II and III were not significant. We conclude that passive shunting is superior to active shunting for aortic by-pass.