There is no suitable solution to preserve hearts for longer than 5 h between donor explant and recipient implant. Lifor is a fully artificial preservation medium containing both a nonprotein oxygen and nutrient carrier (nanoparticles) and cellular nutrients, including amino acids and sugars. We proposed that recirculated Lifor solution would satisfactorily preserve guinea pig isolated hearts perfused at low flow with no added O2 at room temperature for 10 h. Hearts were isolated from 21 guinea

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... igs and perfused with Krebs-Ringer (KR) solution (97% O2 and 3% CO 2 ) at 37°C. Heart rate, inflow and outflow O 2 tension, coronary flow, left ventricular pressure (LVP), and maximal and minimal rate of change in LVP (dLVP/dt) were measured. After baseline measurements, hearts were perfused with recirculated Lifor or ViaSpan equilibrated with room air at 15% of control flow at 26°C for 10 h. Hearts were then perfused at 100% flow with KR for 2 h at 37°C. A time control (untreated) group was perfused only with KR solution for 15 h. Lifor arrested and protected hearts against diastolic contracture and maintained a low O2 extraction. Compared with time controls, Lifor led to a higher developed LVP and coronary flow; %O 2 extraction and cardiac efficiency were similar between these two groups. Hearts similarly treated with ViaSpan exhibited diastolic contracture and lower %O2 extraction during treatment and, upon reperfusion with KR, exhibited continued diastolic contracture, no return of heart rate or contractility, low coronary flow, low %O2 extraction, and marked infarction. For long-term cardiac protection, a suitable preservation solution recirculated at low flow and room temperature without supplemental O2 would reduce the support apparatus required for transport. Lifor was far superior to ViaSpan in meeting these requirements.