With a widening gap between supply and demand of organs, living-donor kidney transplantation (LDKT) has substantially increased in efforts to expand the donor pool. This has led to a surge in living-donor kidneys (LDK) with anatomical variations, specifically, multiple renal arteries (MRA) (1, 2). Kidneys with MRA are common in renal vascular anatomy, occurring at an incidence of 18–43% in potential kidney donors (3). When encountered during LDKT, they often require complex back-table reconstructions, which has been associated with a higher risk of post-transplant vascular and urologic complications (1, 4, 5). However, with improvements in reconstruction and anastomosis techniques, allografts with MRA have been shown to be successfully transplanted with similar surgical and clinical outcomes compared to allografts with a single renal artery (6–8). Examples of these improvements include the use of interposition grafting (9, 10) and side-to-side anastomoses to create a wide lumen (11, 12). Additionally, routine use of low-molecular weight dextran and optical magnification have helped to minimize postoperative complications and made it easier to construct microvascular anastomosis during LDKT (6–8).

Although long-term graft and patient survival have been shown to be similar for single and multiple arteries, the impact of the type of arterial reconstruction method for MRA has rarely been investigated and warrants additional study (12, 13). Performing multiple anastomoses is often associated with poor visibility, difficult suturing (14), thrombosis, and bleeding (15). Additionally, multiple anastomoses are associated with a prolonged warm ischemia time (WIT), which has been shown to have a detrimental effect on both early graft function and long-term graft survival in LDKT (16–21). In this study, we describe in detail 18 different surgical techniques for reconstruction of MRA during LDKT, with the main goal of creating a single renal artery ostium for allograft implantation in efforts to facilitate construction of the in situ vascular anastomosis, minimize recipient WIT, and reduce post-operative complications. We evaluated recipient and donor demographics, operative data, early outcomes such as delayed graft function (DGF), development of any post-operative vascular, urological, or other complication within 12 months post-transplant, and graft survival.

We retrospectively reviewed the medical records of all LDKT recipients with laparoscopically procured MRA kidneys at our institution between March 2008 and July 2021. This study was approved by the University of Miami Institutional Review Board and follows the ethical principles (as revised in 2013) of the Helsinki Declaration. All patients gave written informed consent prior to enrollment.

All donors underwent comprehensive nephrologic evaluation including their medical history, physical examination, renal function assessment, and urinalysis. Evaluation of the donor renal vascular anatomy was performed using computed tomography angiography (CTA). Thus, the presence of multiple vessels was known before surgery. All donors referred to us were considered suitable based on their vasculature. The approach for reconstruction of MRA and the availability of deceased donor vessels for interposition grafting reconstruction were determined before surgery.

All recipients began Aspirin 81 mg daily on post-operative day 3 and remained on this regimen indefinitely. To monitor development of vascular and/or urological complications, baseline Doppler Ultrasound (DU) was performed after surgery, and then repeated at 1, 3, and 12 months post-operatively. If there were any vascular or urological concerns, further imaging with magnetic resonance angiography and/or Tc99m MAG-3 renal scintigraphy was performed.

Recipient and donor baseline demographics and operative data appear in Table 1. Seventy-three LDKT recipients of MRA donor allografts were evaluated. Median recipient age was 48.8 (range 2.3–77.1) years, and 67.1% (49/73) recipients were male. Black and Hispanic participants comprised 12.3% (9/73) and 42.5% (31/73) of the transplant recipients, respectively. The majority of transplant recipients, 93.2% (68/73), received a primary kidney transplant; only 6.8% (5/73) were retransplants. The percentage of recipients who received a left donor kidney was 94.5% (69/73); 5.5% (4/73) received a right donor kidney. The percentage who received a kidney with two RA and three RA was 83.6% (61/73) and 16.4% (12/73), respectively. A double-J ureteral stent was placed in only 4.1% (3/73) of the patients. A JP drain was placed in 20.5% (15/73) of the patients. Median total operative time was 296 (range 206–483) minutes. The median warm ischemia time for anastomosis of a single artery ostium was 27 (range 20–42) minutes, and for two separate anastomoses it was 31.5 (range 21–33) minutes. Median estimated blood loss was 40 (range 10–300) ml.

The types of reconstruction are detailed in Table 2. Renal artery reconstruction was performed in 95.8% (70/73) of patients; reconstruction was not performed in three patients. A single renal artery ostium was created in 94.5% (69/73) of patients. Two separate renal artery anastomoses were implanted in 5.5% (4/73) of patients. Interposition grafting was performed in seven cases (9.6%).

Recipient outcomes are listed in Table 3. Median length of hospital stay was 4 (range 3–67) days. Median follow-up among 67 patients who were alive with a functioning graft as of the last follow-up date (31 July 2021) was 30.4 (range: 0.3–151.2) months post-transplant. Median preoperative creatinine was 6.0 (range 0.9–22.6) mg/dl, which decreased to 1.1 (range 0.25–2.0) mg/dl at 3 months. At 6 and 12 months post-transplant, the median creatinine remained stable at 1.1 mg/dl.

None of the 73 patients had DGF or developed a postoperative vascular or urological complication. Since the main concern with lower pole artery reconstruction is the risk of developing a postoperative urological complication, it was reassuring that no such complication was observed in any of the patients. Thus, there were no differences in clinical outcomes between those who received an upper pole artery vs. lower pole artery reconstruction.

Two patients (2.7%) developed a nonsurgical post-operative complication during the first 30 days (12 months) post-transplant, including C. difficile colitis/sepsis at 4 days post-transplant (N = 1) and acute respiratory distress syndrome (ARDS) at 6 days post-transplant (N = 1). The patient who developed c. difficile colitis/sepsis died of that infection (with a functioning graft) at 0.8 months post-transplant. The patient who developed ARDS did not experience graft loss.

One patient (1.4%) developed graft failure due to acute T-cell-mediated rejection (TCMR) at 41.8 months post-transplant. Five patients have died with a functioning graft: cardiovascular event in two patients (at 4.4 and 7.9 months post-transplant, respectively), infection in two patients (death due to C. difficile colitis/sepsis in one patient at 0.8 months post-transplant, and death due to sepsis in one patient at 125.2 months post-transplant), and ruptured aortic aneurysm in one patient (at 5.2 months post-transplant).

Kidney transplantation is the treatment of choice for patients with ESRD. However, donor organ shortage has prevented the wider application of this treatment. This has prompted surgeons to utilize each donor organ they encounter in a maximal and favorable manner, such as kidney grafts with MRA (7, 25). Up until recently, renal artery multiplicity was viewed as a contraindication for transplantation due to its greater technical demand and association with a higher incidence of vascular and urological complications (1, 4, 5). Additionally, prolonged total operative times and ischemia times were thought to add unnecessary risk to the recipient (7, 26). However, with recent advances in surgical reconstruction and anastomoses techniques, transplantation of allografts with MRA is no longer considered to be a surgical restriction and has been shown to provide comparable post-operative and clinical outcomes to allografts with a single renal artery (5, 7, 8, 27, 28).

Several reconstruction techniques of MRA have been described in the literature with the common goal of minimizing ischemic insult and avoiding vascular complications. Transplantation of MRA in LDKT is often achieved by performing multiple arterial anastomoses without reconstruction. In a retrospective study by Hwang et al, sequential arterial anastomoses of MRA were performed in 81.1% of their cases with MRA; the remaining grafts with MRA were implanted with single anastomosis by either conjoining the renal arteries into a single lumen or ligating the accessory polar artery (29). Vaccarisi et al explained that in cases of MRA, they did not consider the opportunity to perform vascular reconstruction to unify the ostium, and all anastomoses were created separately in succession without kidney reperfusion (30). Popov et al mentioned that when dealing with two arteries of unequal size, it is preferable to anastomose them separately rather than to perform bench surgery, thereby decreasing the risk of compromising the lumen of the larger renal artery (31).

Although multiple anastomoses techniques like those described can provide good long-term outcomes, they are often associated with poor visibility and difficult suturing (14). We believe it is advantageous to create a single arterial lumen from MRA while in cold preservation, as it facilitates in situ vascular anastomosis and minimizes recipient warm ischemia time (WIT). Additionally, we prefer to revascularize simultaneously, because sequential revascularization requires added WIT and increases the risk of troublesome bleeding (14).

Prolonged WIT has been shown to have a detrimental effect on early graft function and long-term graft survival in LDKT (16–21). A study by Khan et al showed that WIT greater than 45 min was a risk factor for poor early graft function; they also reported that longer WIT was likely attributed to performance of multiple anastomoses in MRA donors (19). Similarly, Marzouk et al reported that an anastomosis time greater than 29 min was associated with an increased need for dialysis and length of stay, as well as slower recovery of kidney function (20). Additionally, Weissenbacher et al demonstrated that an anastomosis time greater than 30 min significantly affects long-term graft outcome and leads to inferior patient survival (21). In this current study, we describe in detail 18 different techniques for reconstruction of MRA in LDKT with the goal of minimizing both WIT and the risks associated with performing these complex anastomoses. Surgical loupes at 3.5× magnification were used for the reconstructions, which have been shown to increase the ease of performing anastomosis and yield better results in living-donor transplantation (32).

Of the reconstructions where a single renal artery lumen was created (N = 69), we report a median WIT of 27 min. In the four cases where vessels were implanted with two arterial anastomoses, the median WIT was 31.5 min. Our median WIT for creating a single inflow orifice is acceptable compared to the reported published literature (19–21, 33). We report no incidence of DGF nor vascular or urological complications in any of our patients during the first 12 months post-transplant.

Our main goal of the study was not reached in these four cases, because the accessory polar artery was located too far from the main renal artery to be safely reconstructed into a single lumen. Therefore, the accessory polar artery was anastomosed separately to other suitable vessels located a shorter distance away from it compared with the main renal artery. The use of interposition grafting to extend the length of the polar arteries (which we implemented in seven cases of short arteries) was not an option for achieving a single lumen in these specific cases, as it would have required too long of a graft, increasing the risk of complications. Nevertheless, the use of interposition grafting in LDKT has been shown to be a useful standard method for grafts with MRA (9, 10, 34). A study by Hiramitsu et al (10) describe the usefulness of arterial reconstruction using the recipient’s own internal iliac artery for MRA grafts. They report no significant differences in complication incidence or perioperative and postoperative graft function of the interposition group at 60 months of follow-up compared to the conjoined group and the end-to-side method group. A few reports in the literature describe the use of donor gonadal vein as a conduit for renal arteries in LDKT with no vascular complications noted during short-term follow-up of these cases; however, long-term patency and safety remain unclear (9, 35–37). In our cohort, interposition grafting was performed in seven cases with various conduits such as recipient inferior epigastric artery, recipient internal iliac artery, deceased donor external iliac artery, and donor gonadal vein with no observed vascular or post-operative complications as of last follow-up.

When dealing with deceased donor kidney grafts with MRA, we also perform vascular reconstructions with the goal of creating a single arterial orifice in efforts to minimize ischemic insult. We commonly transplant MRA from deceased donors with the use of a Carrel aortic patch. If the renal arteries are located too far apart from the aorta and result in a case of long Carrel patch, we trim the Carrel patch and anastomosis it end-to-end to create a shorter carrel patch (38), or we perform a back-table vascular reconstruction into a single ostium for the same reasons as indicated in this manuscript.

Limitations of our study include the lack of comparison to outcomes for LDKT of single renal arteries. Additionally, sample sizes for certain subgroups of patients were relatively small, limiting our ability to show significant differences between the WIT of single and multiple arterial anastomoses. Another limitation of our study includes the fact that this was an evaluation of consecutively transplanted living donor recipients performed at a single center by a single, highly experienced transplant surgeon. While the chances of achieving such successful anastomoses without post-operative complications being an issue requires a surgeon who is highly experienced in performing such techniques, these techniques can be easily duplicated and incorporated by other transplant surgeons to expand their surgical armamentarium.

Complex reconstruction techniques to create a single renal artery ostium for graft implantation anastomosis in allografts with MRA shows good clinical outcomes and acceptable WIT, with no increased post-operative vascular or urological complications. These techniques can be applied by other transplant surgeons when faced with vessel multiplicity to avoid potential complications associated with multiple arterial implantations.