THE SIGNIFICANCE AND PREVENTION OF AIR EMBOLI WITH THE TOTAL ARTIFICIAL-HEART

Embolism remains a significant complication of the total artificial he art (TAH). The ineffectual deairing of the TAH can allow embolization of the retained air. The standard needle aspiration of TAH air (Group A) was compared with a new protocol (Group B) that included standard n eedle TAH aspiration plus simultaneous pumping of the TAH against an o ccluded ascending aorta and main pulmonary artery with vacuum applied to a needle in the proximal aorta and pulmonary artery. There were 4 c alves in each group. There was no premortem evidence of systemic or pu lmonary emboli. Both groups of animals were electively terminated less than 2 weeks postoperatively. Postoperative mean aortic and pulmonary artery pressures were recorded for each animal. Animals in Group B ha d a significant decline in pulmonary artery pressures (43 +/- 12 vs. 3 3 +/- 8 mm Hg) 1 h after TAH implantation when compared with Group A. All other aortic and pulmonary artery pressure differences between Gro ups A and B were not statistically significant within 24 h of the oper ation. Group A animals had a 75% incidence, and Group B animals had 10 0% incidence of TAH thrombus. This very small thrombus was found exclu sively at the inflow valve-TAH housing interface. Evaluation of the ki dneys postmortem was used to identify embolic injury. All animals in G roup A had evidence of acute, hemorrhagic injury, but none of the Grou p B animals had similar injury. Half of the animals in each group had small, fibrotic chronic renal cortical injury, which did not develop d uring TAH implantation. The more vigorous deairing protocol (Group B) significantly decreased early postoperative pulmonary hypertension. Th e absence of acute hemorrhagic renal injuries appeared to be associate d with improved TAH deairing. Chronic renal injuries were not associat ed with the TAH, which makes them poor indicators of TAH emboli. Impro ved TAH deairing can provide beneficial effects for the recipient.