The Significance and Prevention of Air Emboli with the Total Artificial Heart

Abstract

Embolism remains a significant complication of the total artificial heart (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 needle TAH aspiration plus simultaneous pumping of the TAH against an occluded ascending aorta and main pulmonary artery with vacuum applied to a needle in the proximal aorta and pulmonary artery. There were 4 calves in each group. There was no premortem evidence of systemic or pulmonary 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 had a significant decline in pulmonary artery pressures (43 & 12 vs. 33 & 8 mm Hg) 1 h after TAH implantation when compared with Group A. All other aortic and pulmonary artery pressure differences between Groups A and B were not statistically significant within 24 h of the operation. Group A animals had a 75% incidence, and Group B animals had 100% incidence of TAH thrombus. This very small thrombus was found exclusively at the inflow valve-TAH housing interface. Evaluation of the kidneys postmortem was used to identify embolic injury. All animals in Group A had evidence of acute, hemorrhagic injury, but none of the Group B animals had similar injury. Half of the animals in each group had small, fibrotic chronic renal cortical injury, which did not develop during TAH implantation. The more vigorous deairing protocol (Group B) significantly decreased early postoperative pulmonary hypertension. The absence of acute hemorrhagic renal injuries appeared to be associated with improved TAH deairing. Chronic renal injuries were not associated with the TAH, which makes them poor indicators of TAH emboli. Improved TAH deairing can provide

Comparison of LionHeart LVAD-Implanted Calves Based on Renal Infarctions

“…During work with total artificial hearts, Murray et al 10 identified small, chronic fibrotic scars, without evidence of acute infarction in the kidneys of 50% of calves (4/8) with the Utah 100 and Jarvik 7 total artificial hearts after 12 days of support. The average number was three lesions per animal, and each lesion was less than or equal to 6 mm in diameter at the cortex.…”

Continuous-flow total artificial heart port-to-port connection technique using dedicated de-airing sleeve

“…1,5 Air embolism remains a significant complication of the total artificial heart, caused by ineffectual de-airing of the blood pump, which allows embolization of the retained air. 2 The entrained air may cause immediate issues, such as a drop in pump pressure rise, flow rate, and power, especially if more air than the impeller can handle is entrapped. This may cause air cavitation and impeller rubbing that in turn may damage the impeller surface and make pump biocompatibility a concern.…”

“…The negative effects of air deposition into the circulatory system such as multi-organ functional deterioration have been previously reported in the literature. 1,2 The current techniques of de-airing and prevention of air entrapment are limited to basic attempts of careful device-to-conduit connection, priming of connection lines, and proper device manipulation to avoid excessive air engagement into circulation during connection. These techniques are imperfect, and the risk of air embolism remains since the access to atmospheric air is never fully limited during the actual device-to-conduit connection process.…”

Deairing Techniques for Double‐Ended Centrifugal Total Artificial Heart Implantation

“…Protamine was administered to reverse the systemic heparinization, per our standard protocol. The chest was closed, and the animal was transferred to a chronic care unit for postoperative monitoring . After termination of each experiment, the animals were sacrificed, and thorough muiltiorgan analyses and post‐explant pump evaluations were performed in all cases.…”