Tissue perfusion pressure as a physiologic indicator of renal failure risk after heart transplantation

Mean arterial pressure (MAP) guides hemodynamic management following heart transplantation, yet renal failure remains common. Tissue perfusion pressure (TPP), defined as MAP minus critical closing pressure, predicts acute kidney injury in non-transplant cardiac surgery. We hypothesized that postoperative TPP predicts continuous renal replacement (CRRT) requirement after heart transplantation.

We analyzed all adult heart transplants at a single institution (01/2020-06/2025) and excluded multiorgan transplants, congenital heart disease, and patients requiring post-transplant extracorporeal membrane oxygenation support. Hourly TPP, MAP, and organ perfusion pressure (OPP; MAP - central venous pressure) were analyzed over 72 h. Patients were stratified by post-transplant CRRT use. Predictive performance was compared using net reclassification improvement (NRI) across sequential 24-hour epochs.

Of the 269 patients included, 47 (17.5%) required CRRT. Those needing CRRT more likely had circulatory death donors (55.3% vs 38.3%, p=0.035) using direct procurement and perfusion (14.9% vs 6.3%, p=0.037). Pre-transplant creatinine was greater in the CRRT group (1.5mg/dL vs 1.2, p=0.002). In the CRRT group, the median and mean TPP, OPP, and MAP within the first 72 h were all lower (p < 0.01). Mean TPP demonstrated better prediction of CRRT compared to OPP (NRI 0.49, 95% CI 0.23-0.76, p<0.001) and MAP (NRI 0.39, 95% CI 0.11-0.68, p=0.007) within 24 h post-transplant. After 24 h, the predictive powers of median TPP, OPP, and MAP were similar.

Early postoperative TPP independently predicted the need for CRRT after heart transplantation and demonstrated superior risk reclassification compared with conventional pressure-based hemodynamic metrics.