# Technical challenges and prospects for ex vivo heart perfusion: a republication of the review published in Japanese journal of artificial organs

## TL;DR

This paper reviews different methods for preserving donor hearts outside the body, comparing their effectiveness and energy use.

## Contribution

The paper introduces a new left ventricular assist device mode that improves heart function preservation during ex vivo perfusion.

## Key findings

- The resting mode is the simplest perfusion method used clinically.
- The working mode improves myocardial metabolism but increases energy consumption.
- The LVAD mode provides better cardiac function preservation than other modes.

## Abstract

Ex vivo heart perfusion (EVHP) has been clinically utilized for the preservation and functional assessment of donor hearts before heart transplantation. In the field of EVHP research, perfusion methods are often referred to as “modes”. This manuscript describes the characteristics of the EVHP modes that have been proposed to date. The resting mode (Langendorff mode) involves cannulation of the aorta and exclusive coronary perfusion. It is the simplest EVHP mode, and all currently available clinical EVHP systems employ this perfusion method. In contrast, the working mode allows perfusate inflow from the left atrium, thereby generating preload and enabling cardiac output. In our experimental studies, the working mode demonstrated enhanced myocardial metabolism compared with the resting mode; however, it was also associated with increased energy consumption due to cardiac contraction. To address this issue, we developed a left ventricular assist device (LVAD) mode, in which cardiac contraction is supported by a LVAD pump operating in the working mode. LVAD mode was associated with significantly better cardiac function than the resting and working mode. The preservation of cardiac function during EVHP is considered to be greatly influenced by the perfusion mode. Further development of optimized modes will be essential for the effective preservation and evaluation of donor hearts in the future. This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2024 (Vol. 53, No. 3, pp. 210–215).