Dialysis preserves heart function during ex situ heart perfusion

Abstract

Background: Ex situ heart perfusion (ESHP) has been used to optimize donor organs before heart transplantation. However, cardiac function often deteriorates with the development of myocardial edema. The use of dialysis during ESHP could assist in cardiac preservation.

Methods: Male Yorkshire pig hearts were subjected to ESHP for 8 hours with or without dialysis. Hearts were supported during nonworking mode and working mode, and pressure-volume loops and coronary vasomotor function were evaluated. Finally, tissue biopsies were assessed for mitochondrial function, oxidative stress, and inflammation.

Results: Adding dialysis to ESHP significantly enhanced cardiac function, with improved preload recruitable stroke work at 4 hours (64.09 ± 20.13 vs 35.08 ± 13.52, p = 0.010) and 8 hours (64.31 ± 9.08 vs 23.30 ± 19.25, p = 0.0002), maximal elastance at 8 hours (24.67 ± 10.75 vs 10.62 ± 8.471, p = 0.0477), and end diastolic pressure volume relationship at 8 hours (644.7 ± 566.68 vs 86.63 ± 72.05, p = 0.0187). Coronary vasomotor function improved in the dialysis group in endothelium dependent (LogIC50 -7.39 ± 0.25 vs -2.22 ± 0.76, p < 0.0001) and independent (LogIC50 -6.11 ± 0.19 vs -4.79 ± 0.11, p < 0.0001) vasorelaxation. Dialyzed hearts also had reduced sensitivity to endothelin-1 (LogEC50 -7.94 ± 0.5 vs -8.54 ± 0.06, p = 0.0449) and significant changes in endothelin receptor-related protein expression related and oxidative stress.

Conclusions: The combination of dialysis with ESHP improves myocardial and coronary vasomotor preservation and may allow for longer perfusion times.

Keywords: DCD; dialysis; ex situ heart perfusion; heart function; heart transplantation.

Figure 1

A: Experimental design; B: Dialsys ESHP setup diagram. The perfusate is stored in the reservoir and pumped into the oxygenator and heater through the centrifugal pump. Perfusate is split into the dialysis circuit and the heart circuit. In the dialysis circuit, a roller pump pushes perfusate into the dialysis filter and subsequently back into the reservoir. Dialysate flows in a countercurrent fashion against the perfusate and is directed into a waste bag. In the heart circuit, perfusate is directed into the aorta in a retrograde fashion during nonworking mode. Venous return is drained from the pulmonary arteries into the reservoir. In working mode, the perfusate is split between the aorta and left atrial line.

Figure 2

Changes in weight over duration of ex situ heart perfusion (ESHP control blue) and with dialysis (red). Data are shown as mean ± SD.

Figure 3

Changes in perfusate over duration of ex situ heart perfusion (ESHP) in control (blue) and with dialysis (red). (A): Potassium concentration; (B) Sodium concentration; (C) Hematocrit; (D) Lactate concentration. Data is shown as mean ± SD.

Figure 4

Coronary vasomotor function with ex situ heart perfusion in control (blue) and dialysis (red). (A) endothelial-dependent vasomotor function; (B) Endothelialindependent vasomotor function; (C) Vasospasm sensitization. Data is shown as mean + SD.

Figure 5

Immunoblotting of coronary and left ventricular tissue from ex situ hearts perfused for 8 hours. (A, B) Quantification of endothelin A (ETA in A) and endothelin B (ETB in B) normalized to GAPDH from immunoblot shown in (E). Left anterior descending artery was utilized for this analysis. (C) Ratio of normalized ETA/ETB. (D) Quantification of AMDA normalized to GAPDH in immunoblot shown in (E). *p < 0.05, **p<0.01. Data are shown as mean ± SD. AMDA, asymmetric dimethyl arginine; ETA, endothelin A; ETB, endothelin B. LV left ventricle. Coro coronary.

Figure 6

Quantification (A-D) and immunoblotting (E) for markers of oxidative stress and apoptosis signalling in LV after 8 hours of perfuion in control (blue) and with dialysis (red). Quantifiation of catalase (A); p53 (B); CC3 (C); iNOS (D). Representative immunoblot of LV lysate using the indicated antibodies. *p < 0.05. CC3, cleaved caspase 3; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; iNOS, inducible nitric oxide synthase.