# Renal vessel–assisted anastomosis improves the abdominal heart transplant model in rats without bilateral lower limb ischemia

## TL;DR

A new surgical method for heart transplants in rats avoids kidney and limb problems by using kidney blood vessels for connections.

## Contribution

A novel renal vessel–assisted anastomosis method is introduced to improve rat heart transplant models without causing limb ischemia.

## Key findings

- Lower limb ischemia causes acute kidney dysfunction and reduced survival in rats.
- The renal vessel–assisted method reduces bleeding and improves 7-day survival in heart transplant models.
- The new method avoids complications like paraplegia and anastomotic bleeding.

## Abstract

The traditional method of heterotopic abdominal heart transplantation (HTx) involves cross‐clamping the inferior vena cava, which inevitably leads to bilateral lower limb ischemia (LI). This study first aimed to investigate the impact of LI on renal function in rats subjected to unilateral nephrectomy (UNx). Second, a modified method utilizing renal vessel–assisted anastomosis in rats with left UNx was compared with the traditional method for abdominal HTx.

Male Sprague–Dawley rats were utilized as subjects for both experimental phases. In experiment 1, the animals were divided into four groups: sham operation group; LI group—rats undergoing occlusion of the abdominal aorta and vena cava below the renal vessels; UNx group—rats with left UNx; and LI + UNx group. All operated animals were monitored for up to 7 days for biochemical markers, renal histopathology, and survival rates. In experiment 2, we introduced the renal vessel–assisted method as the experimental group and compared it against the traditional method as the control within rat heterotopic HTx models. We assessed operative characteristics, echocardiography results, histological findings, and graft survival.

First, LI resulted in acute kidney dysfunction characterized by a decrease in 7‐day survival rates and creatinine clearance rates in both the LI and LI + UNx groups compared to the sham operation and UNx groups. Particularly, histopathological damage in the kidney and liver did not exhibit significant effects during this period. Second, the implementation of the renal vessel–assisted method significantly reduced bleeding volume at suture sites and enhanced the 7‐day survival rate compared to the traditional method.

Acute kidney injury was induced by LI postoperation in treated rats. The renal vessel–assisted method demonstrated its effectiveness as a superior alternative that mitigates complications associated with the traditional method.

A modified heterotopic heart transplantation (HTx) in rats was reported to improve the surgical success rate, in which the donor's vessels, the brachiocephalic trunk (BT) and the pulmonary artery (PA), were sutured to the recipient's left renal artery (RA) and left renal vein (RV). First, the abdomen of recipient rats was opened, and the left renal vessels were exposed. After the donor heart was positioned on the left renal bed, the BT of the donor aorta was sutured end to end to the RA. The PA–RV was anastomosed in an end‐to‐side manner with running sutures; this method increased the success rate of HTx model in rats mainly due to the reduced suture time and operational complications, including anastomotic bleeding and paraplegia in recipient rats.