Introduction: Lactate has been stated as an accurate predictor of heart function in donation after brain death. This has also been adopted for donation after circulatory death (DCD). Nevertheless, strictly relying on lactate to classify a DCD heart as transplantable or not during ex vivo blood perfusion (EVBP) has been criticized in recent years. Thus, we developed novel prediction parameters based on myocardial microcirculation in previous porcine Langendorff experiments. Here, we verified the models in canine orthotopic heart transplantation (HTx) and suggest a prediction model to calculate the load-independent ventricular contractility after HTx.
Materials and Methods: The hearts (n = 7) were maintained by EVBP for 4 hours. We measured lactate and monitored myocardial microcirculation in the left-ventricular (LV) anterior wall during EVBP using a Laser-Doppler Perfusion (LDP) needle probe, and computed prediction parameters based on LDP shifts. The previously identified LDP shift of main interest was the shift between the first and last 30-minute perfusion interval, thus called First-to-Lastinterval shift. After four hours, the hearts were transplanted, and the load-independent LV-end-systolic pressure volume relationship (ESPVR) was determined using a conductance catheter. Considering that reaching at least 80% of the donor-LV-ESPVR is acceptable to maintain circulation in the recipient, we also calculated the sensitivity and specificity of the model to predict that 80% of the donor-LV-ESPVR will be reached after heart transplantation (HTx).
Results: A combination of the LDP shift and venous lactate in a linear model showed the highest r (0.95) and r² (0.90) for LV-ESPVR and thus served best for a prediction model. The respective, exemplary formula to predict the LV-ESPVR that will be reached in the recipient after HTx is: LV-ESPVR = 1.166 l/mmol*Lacven +5.638 mmHg/ml*First-to-Lastinterval shift –4.468. The model resulted in a sensitivity of 100% and a specificity of 83.3% to predict that at least 80% of the donor-LV-ESPVR will be reached after HTx.
Conclusions: We conclude that the LV-ESPVR after orthotopic HTx with DCD can be predicted by combining the microcirculatory parameter First-to-Lastinterval shift during, and the Lacven at the end of EVBP in a linear model, and that such a model may lead to a reduction of unjustified decline of suitable DCD hearts during EVBP. However, the prediction formula may need to be refined based on larger datasets.
