Electron microscopic changes and edema after nine hours' perfusion of isolated canine hearts

In a comparative study, we investigated whether or not removed and non-beating hearts could be preserved in vitro by continuous perfusion with oxygen-carrying solutions (blood, perfluoro-carbon emulsion) and simultaneous substitution with specific substrates. We used 18 mongrel dogs subdivided into 2 groups (1st group: perfluorocarbon emulsion; 2nd group: blood); the perfusion time was 9 h. In addition to parameters to control the medium of the perfusion solution, we measured parameters that would allow us to assess the success of the extended perfusion. These parameters were high-energy phosphates and, in particular, electron optical analysis. At the end of the perfusion period, electron optical analysis revealed a mild and reversible ischemic reaction by the myocardial cells in both groups. However, statistical analysis showed (1) a significant increase in the ischemic reaction for both groups over the perfusion period (P = 0.02), and (2) a significant, even more pronounced ischemic reaction in the subendocardial myocardium (P = 0.025). It should be noted that distinctly interstitial edema developed during the perfusion period and that this would appear to be a fairly critical problem with extended continuous isolated heart perfusion.