Relationship Between Lactate Trend and Cardiac Power Output During Ex Vivo Heart Perfusion

Abstract

<h3>Purpose</h3> Assessment of myocardial viability during normothermic ex-vivo perfusion (NEP) currently stands on lactate trend in Langendorff mode (LM). The relationship between lactate trend and myocardial performance during NEP in working mode (WM) has been poorly investigated. <h3>Methods</h3> Eighteen porcine hearts were enrolled in 3 groups: beating heart (BH) procurement followed by 4-hour cold storage (CS group, n=6); BH procurement followed by 4-hour of hypothermic ex-vivo perfusion (HEP) (HP group, n=6); and donation after controlled-circulatory death followed by 4-hour of HEP (DCD group, n=6). All hearts were then instrumented for NEP in Langendorff mode for 30 minutes, and switched to working mode (WM) for 2 hours. Mean aortic pressure (MAP) and cardiac output (CO) were continuously monitored. Cardiac Power Output (CPO) was calculated as follows: CO x MAP / 451. Lactate level was measured every 30 minutes in the perfusate. <h3>Results</h3> After 30 minutes of LM, median myocardial lactate extraction (MLE) was 0.06 (IR: -0.05 - 0.14), 0.22 (IR: 0.02 - 1.06) and 0.08 (IR: 0.002 - 0.087) respectively in HP, CS, DCD groups (p =0.36). Lactate levels were significantly different between the 3 groups during WM perfusion (p=0.01), but MLE trends were similar between the 3 groups (p=0.13). Median CPO were significantly higher in CS (2.51 mL/min/g (IR: 2.43-2.91)) and HP (3.50 (IR: 2.96-4.10)) groups compared to DCD group (0.93 (IR: 0.86 - 1.19) (CS vs DCD p< 0.01, BH vs DCD p< 0.001, CS vs HP p=0.68). MLE at 30 min of LM was not correlated to CPO in WM (r= 0.39, p=0.09). CPO was not correlated to MLE during WM (r= 0.14, p=0.30) (Figure 1). <h3>Conclusion</h3> Favorable lactate trend was not associated with myocardial performance in a working EVP mode. Myocardial extraction of lactate during LM was poorly correlated with cardiac power output during WM perfusion. New biomarkers correlated with myocardial viability and performance are waranted.