Myocardial Work Index Correlates with Cardiac Performance During Ex Vivo Heart Perfusion

Abstract

<h3>Purpose</h3> A reliable approach for functional assessment of the donor heart during ex vivo perfusion (EVP) prior to transplantation is currently lacking. We sought to investigate the relationship between echocardiographic myocardial work index (MWI) and cardiac performance during EVP. <h3>Methods</h3> Eighteen piglets were allocated in three groups: beating heart (BH) procured after cardioplegia followed by 4-hour static cold storage (BH-S group, n=6); BH procured after cardioplegia followed by 4-hour hypothermic perfusion (BH-P group, n=6); donation after controlled-circulatory death followed by 4-hour hypothermic perfusion (DCD group, n=6). After 4 hours of preservation, all hearts were instrumented for blood perfusion (37°C) in Langendorff mode for 30 minutes, then switched to working mode (WM) for 2 hours. Surface echocardiography was performed during WM perfusion for measurement of left ventricular ejection fraction (LVEF) and MWI. Pressure-volume loops were simultaneously recorded using left ventricular conductance catheter. Cardiac output was measured using external sensor. <h3>Results</h3> Mean cardiac output generated during WM perfusion was different between groups (1200±573 mL/min for BH-S group, 1592±193 for BH-P group, 676±234 for DCD group, p<0.001), as well as MWI (respectively 441±393 mmHg%, 652±158, 292±122, p<0.001). Global MWI was correlated with measured cardiac output (r=0.85, p<0.001), maximum dP/dt (r=0.77, p<0.001), minimum dP/dt (r=-0.69, p<0.001), stroke work (r=0.75, p<0.001) and Tau (r=-0.62, p<0.001). Systolic parameter maximum dP/dt was correlated with cardiac output (r=0.73, p<0.001) (Figure 1). Echocardiographic LVEF (r= 0.49, p=0.018) and global longitudinal strain (r=0.67, p<0.001) were less associated with MWI. <h3>Conclusion</h3> Noninvasive assessment of MWI was feasible in our preclinical model of EVP. MWI was strongly correlated with cardiac performance in perfused hearts resuscitated after either prolonged hypothermic preservation or after controlled-circulatory death.