Abstract 786 Autoregulation of coronary microvascular flow after hypothermic, crystalloid machine perfusion of donor hearts

Introduction

DCD hearts are exposed to a warm ischemic period within the donor, followed by reperfusion with warm donor blood during transportation. Warm ischemia followed by reperfusion induces coronary microvascular dysfunction. The novel histidine-tryptophan-ketoglutarate (HTK)-N preservation solution was developed for the particular purpose of preserving the coronary endothelial function.

Purpose

To investigate the effect of hypothermic machine perfusion (MP) of DCD hearts with blood, HTK, and HTK-N solution on the autoregulation of coronary microvascular flow.

Methods

In a porcine model of DCD, native control hearts (Control, N=4) and DCD hearts (DCD group, N=6) were harvested and underwent 60 min of microcirculatory monitoring by Laser-Doppler-Perfusion (LDP), while the perfusion pressure was adjusted in steps of 20 mmHg from 20 to 100 mmHg. In three groups, DCD hearts were maintained for 4 h by MP with blood, HTK, or HTK-N (all N=7-9) before microvascular assessment. Additionally, the total coronary flow was measured.

Results

Relative LDP (RLDP) was lower in the DCD group than in control hearts (1.1±0.2 vs. 1.6±0.3; p=0.055). After HTK-N perfusion, RLDP was majorly improved compared to the DCD group (1.5±0.3 vs. 1.1±0.2; p=0.055). After MP with blood (1.3±0.5; p=0.885) or traditional HTK solution (1.2±0.4; p=0.980), RLDP was minorly improved compared to the DCD group. Total coronary flow during microvascular assessment did not differ between the HTK (811±156 ml) and HTK-N (824±151 ml) perfusion groups.

Conclusion

Both HTK and HTK-N perfusion affect the total coronary flow similarly, but only MP with the novel HTK-N solution improves the autoregulative function of the coronary microvasculature in DCD hearts. Total coronary flow does not depict the actual supply of the myocardium in DCD hearts.

Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5
Autoregulation of coronary microvascular flow after hypothermic, crystalloid machine perfusion of donor hearts
L. Saemann¹, F. Hoorn², Y. Guo¹, S. Korkmaz-Icöz³, G. Veres¹, M. Karck², A. Simm¹, F. Wenzel⁴, G. Szabó¹
¹Universitätsklinik und Poliklinik für Herzchirurgie, Universitätsklinikum Halle (Saale), Halle (Saale); ²Klinik für Herzchirurgie, Universitätsklinikum Heidelberg, Heidelberg; ³Universitätsklinikum Heidelberg, Heidelberg; ⁴Fakultät Medical and Life Sciences, Hochschule Furtwangen, Villingen-Schwenningen;
Introduction DCD hearts are exposed to a warm ischemic period within the donor, followed by reperfusion with warm donor blood during transportation. Warm ischemia followed by reperfusion induces coronary microvascular dysfunction. The novel histidine-tryptophan-ketoglutarate (HTK)-N preservation solution was developed for the particular purpose of preserving the coronary endothelial function. Purpose To investigate the effect of hypothermic machine perfusion (MP) of DCD hearts with blood, HTK, and HTK-N solution on the autoregulation of coronary microvascular flow. Methods In a porcine model of DCD, native control hearts (Control, N=4) and DCD hearts (DCD group, N=6) were harvested and underwent 60 min of microcirculatory monitoring by Laser-Doppler-Perfusion (LDP), while the perfusion pressure was adjusted in steps of 20 mmHg from 20 to 100 mmHg. In three groups, DCD hearts were maintained for 4 h by MP with blood, HTK, or HTK-N (all N=7-9) before microvascular assessment. Additionally, the total coronary flow was measured. Results Relative LDP (RLDP) was lower in the DCD group than in control hearts (1.1±0.2 vs. 1.6±0.3; p=0.055). After HTK-N perfusion, RLDP was majorly improved compared to the DCD group (1.5±0.3 vs. 1.1±0.2; p=0.055). After MP with blood (1.3±0.5; p=0.885) or traditional HTK solution (1.2±0.4; p=0.980), RLDP was minorly improved compared to the DCD group. Total coronary flow during microvascular assessment did not differ between the HTK (811±156 ml) and HTK-N (824±151 ml) perfusion groups. Conclusion Both HTK and HTK-N perfusion affect the total coronary flow similarly, but only MP with the novel HTK-N solution improves the autoregulative function of the coronary microvasculature in DCD hearts. Total coronary flow does not depict the actual supply of the myocardium in DCD hearts.
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