# Improved Rat Heart Preservation Using High-Pressure Gaseous Perfusion with Oxygen–Xenon Mixture

## TL;DR

A new method called HIPPER for preserving rat hearts using gas mixtures shows better results than traditional cold storage.

## Contribution

HIPPER, a high-pressure gaseous perfusion method using oxygen–xenon mixtures, is introduced as a novel heart preservation technique.

## Key findings

- HIPPER preserved rat hearts better than static cold storage, with higher resuscitation success rates.
- Hearts preserved with HIPPER showed significantly higher heart rates and ventricular pressures than controls.
- Infarct size was significantly reduced in the HIPPER-preserved hearts compared to traditional methods.

## Abstract

Background: To address limitations in static cold storage (SCS) of donor hearts, we developed the High-Pressure Gaseous Perfusion without Fluidic Preservation Media (HIPPER) method, along with the necessary equipment for its application. Methods: 33 Wistar rat hearts were split into five groups: (Control) static cold storage (SCS) in HTK solution, (Exp) HIPPER using oxygen–xenon gas mixtures of varying ratios (“Gas-A”: 1/9, “Gas-B”: 9/1, and “Gas-C”: 1/1), and (Air) HIPPER using air. Hearts were preserved for six hours, followed by a one-hour Langendorff assessment. Results: Beating was restored in 4/10 Control hearts, 15/15 Exp hearts across all gas mixtures (p = 0.001 Control vs. Exp), and 6/8 Air hearts. Among resuscitated hearts, the mean heart rates (in bpm) were 131 ± 10 (Control), 164 ± 21 (Air), and 226 ± 13 (Exp) (p = 0.001 Control vs. Exp; p = 0.015 Exp vs. Air). The mean left ventricular pressures (in mmHg) were 31 ± 5 (Control), 45 ± 9 (Air), and 73 ± 7 (Exp) (p = 0.002 Control vs. Exp; p = 0.014 Exp vs. Air), with dP/dT max/min showing consistent trends (p < 0.006 Control vs. Exp and Air vs. Exp). Infarct size in Exp group was also significantly reduced, averaging 39.6 ± 6.6% (Control), 12.6 ± 3.3% (Air), and 6.3 ± 0.7% (Exp) of total myocardium area (p < 0.014 for Control vs. all). Conclusions: as evidenced by both quantitative and qualitative data, HIPPER consistently outperformed SCS following six hours of storage of rat heart regardless of the gas mixture, highlighting its potential as a more robust preservation method.