Lactic Acid and Metabolic Analysis of Human Donor Hearts Preserved with Organ Care System

Abstract

<h3>Purpose</h3> Primary graft dysfunction (PGD) is the most common cause of early death in patients of heart transplantation (HTx) and the requirement of ECMO is one of the definitive criteria of PGD. The Organ Care System (OCS) offers ex-vivo donor heart perfusion and currently, the decision to use the OCS preserved donor heart for HTx depends upon the lactate trend and the ventricular contractility. We performed a metabolic analysis of the OCS perfusate samples to predict donor hearts that may develop PGD following HTx. <h3>Methods</h3> Between February 2013 and September 2019, 204 donor hearts procured from the donation after brain death was assessed using OCS. 53 hearts were declined for HTx based on lactate trend and ventricular contractility (No Tx); whereas in the remaining 152 hearts that were transplanted, 42 recipients required ECMO following HTx (Tx with ECMO) while 109 recipients did not require ECMO (Tx without ECMO). <h3>Results</h3> The proportion of unfavourable lactate trend and high ‘end lactate' was significantly higher in the hearts declined for the HTx (no Tx group); however, there was no difference between ‘Tx with ECMO' and ‘Tx without ECMO' groups. The rate of fall of lactate was higher in the ‘Tx without ECMO' compared to the ‘Tx with ECMO'; however, did not reach statistical significance. Coronary blood flow was significantly low in the ‘No Tx' group compared to the other two groups. O2 content, O2 delivery and O2 return were significantly low in the No Tx group and these markers were higher in ‘Tx without ECMO' compared to ‘Tx with ECMO', although not statistically significant. The diastolic pressure and the coronary vascular resistance fell after 30 minutes of OCS perfusion in the donor hearts that did not suffer PGD whereas it remained high in the donor hearts that suffered PGD. <h3>Conclusion</h3> The rate of fall of arterial lactate offered more valuable information compared to the overall lactate trend and end lactate in the prediction of PGD after HTx. Hearts declined for the HTx based on the unfavourable lactate trend, high-end lactate and suboptimal ventricular contractility are justified by the metabolic analysis that showed significantly low CaO2, DO2 and Oxygen return in the declined hearts. Hearts procured from donors after brain death and preserved with OCS that show consistently high coronary vascular resistance may develop PGD requiring ECMO.