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

Purpose 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. Methods 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. Results 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). Conclusion 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. 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. 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. 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). 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.