Renal transplantation is the best management for chronic kidney disease. Worldwide estimates associate 735000 deaths annually with chronic kidney disease [1].

With the changes in the population composition and increase in incidence of diabetes mellitus, cases of renal failure are expected to rise in the Indian population. The prevalence of ESRD between 151 and 232 per million has been estimated by an Indian based study [1].

These factors coupled with the increasing focus on development of organ transplantation in the country mean that renal transplantation is set to become an increasingly common surgery.

In spite of the thrust on increasing organ transplantation, demand for organs far outstrips the availability of organs. Therefore it is important to achieve optimal outcomes in transplant surgery. The presence of multiple vessels in the kidney graft is a surgical challenge as it involves ex vivo vascular reconstruction [2].

Multiple renal arteries pose a technical challenge to the surgeon. Suboptimal reconstruction which compromises vascular patency will result in decreased nephron mass which in turn diminishes the benefit of transplantation and decreases graft survival. Transplant Renal Artery Stenosis (TRAS) accounts for 75% of all vascular complications. Its incidence varies from 1-23%. It is apparent 3 months -2 years after transplant but may present any time after transplant. It usually presents as refractory hypertension with graft dysfunction [2].

This prospective observational study aims to study factors that conceivably affect the patency of the renal vessels in grafts that have multiple renal arteries. Although many studies have previously been done about the incidence, site and etiological factors of TRAS, But there is paucity of literature comparing technical factors associated with vessel reconstruction in cases of multiple renal arteries.

Thus this study evaluated the incidence of Transplant Renal Artery Stenosis (TRAS) and graft characteristics after declamping in renal transplant recipients with multiple renal arteries.

Aim of the Study

To evaluate the incidence of Transplant Renal Artery Stenosis (TRAS) and graft characteristics in renal transplant recipients with multiple renal arteries: A Prospective Observational Study.

• Type of Study: Prospective observational study

• Study Period: 1^st July 2016 onwards till October 2017

• Follow up: 90 days

Sample Size

We included all 25 patients’ recipients of multiple renal artery graft kidney who underwent renal transplant after 30 the June 2016 were included in this study. The patients in whom serum creatinine levels were ≤1.5 after follow up for 90 days were selected for CT Angiography of graft kidney.

Inclusion Criteria

Patients with live donor renal transplant with multiple renal arteries:

• Having completed at least 3 months of post-transplant follow up

• And with at least five recorded values of serum creatinine ≤1.5 during the 90 day period

Exclusion Criteria

• Patients of live donor renal allograft transplant with single renal artery

• Patient of with creatinine level >1.5 on less than 5 occasions even if they have grafts with more than one artery

Methodology

All patients with donor having multiple renal arteries were identified (after CT Angiography of donor) and enrolled into the study. Written informed consent and case Record form were entered for all enrolled patients. This selected group of patient was also followed intra operatively. Lap donor nephrectomy was performed for all patients in Department of Renal Transplant Surgery, PGIMER. Bench reconstruction of multiple renal artery graft kidney was done mainly into 3 types:

• Double barreling

• Y graft

• End to side anastomosis

After bench reconstruction the graft kidney was transplanted into right iliac fossa of the recipient. During transplant of renal graft into recipient cold ischemia time, presence of atheromas in recipient vessels and difference in diameter of recipient and donor vessels were noted.

Renal artery of graft was anastomosed to internal iliac artery or external iliac artery of recipient as end–end anastomosis or end-side anastomosis depending upon the feasibility of surgery. After declamping of recipient of the graft was observed for any colour changes, turgor and diuresis. Difficulty in positioning of graft kidney if any was also noted.

KTR were followed post operatively for 90 days on outpatient basis and those patients with creatinine levels <=1.5 during the entire period of follow up was identified. These patients were called for CT angiography. Prior to CT angiography these patients were hydrated with 1.5 litres of normal saline and 1200mg of N acetyl cystiene was administered intravenously and two doses of N acetyl cysteine were administered orally after interval of 12 and 24 hours post CT Angiography.

CT Angiography of transplant kidney was done to find out any evidence of TRAS (cut off taken as >50% luminal narrowing.) Patient was followed with serum creatinine levels on 4^th day after CT Angiography to see for any rise in serum creatinine (>0.5mg/dL rise compared to pre CT angiography creatinine levels) further follow up was continued as per previously established outpatient visits schedule. Various pre op & intra op parameter recorded were analysed to see any association with stenosis of renal artery. 

In Department of Renal Transplant Surgery from 1^st July 2016 till October 2017 forty one multiple Renal Artery Transplants were done .These cases were followed in the outpatient department for a period of 90 days. Out of these 25 cases which fulfilled the inclusion criteria were enrolled in this study.

Of the 25 patients one case (4%) had three renal arteries on both sides and one case (4%) had triple renal arteries on right side. Rest 24 cases (96%) had two renal arteries on left side, 11 cases (44%) had double renal arteries on right side whereas 12 cases (48%) had single renal artery on right side. Left side kidney was consistently chosen for Lap Donor Nephrectomy in all cases (Table 1).

Table 1: Incidence, Technique for Arterial Reconstruction and Arterial Anastomosis 

Loupe was used by operating surgeon in 7 cases (28%) whereas in rest of 18 (72%) surgeries loupe was not used. The p value (0.755) indicates that the use of loupe was not a significant risk factor in determining the time of surgery (Table 2).

Table 2: Use of Loupe during Surgery

There was presence of atheroma in donor renal vessels in one case (4%). During recipient surgery atheromas were noted in Internal Iliac artery of one (4%) of the recipients. Prolene 6-0 was used as suture material for reconstruction and anastomosis in all the surgeries (Table 3).

Table 3: Donor and Recipient Renal Vessels Atherosclerosis

After declamping graft kidney was observed for colour changes, consistency and diuresis. In one (4%) colour of the kidney was dusky while in rest of cases graft was pink in colour after decamping. The consistency of graft was soft in three cases (12%) while it was firm in rest of 22 cases (88%). Initial diuresis was brisk in 23 cases (92%) except for 2 cases (8%) in which it was slow. There was no difficulty in positioning of kidney during recipient surgery in any of the cases. Positioning of kidney was done to ensure no kinking of reconstructed renal arteries (Table 4).

Table 4: Graft Characteristics after Declamping

There was no incidence of stenosis in graft kidney renal artery as evident from CT Angiography done after a period of more than 90 days post operatively. Cut off criteria for stenosis was taken as more than 50% reduction in vessel diameter. Creatinine levels on 4th day after CT angiography showed no significant rise (cut off value taken as >0.5mg/dL rise of pre CT angiography levels) in any of the cases. Hence there was no evidence of CIN in any of the cases taken in this study (Table 5).

Table 5: CT Angiography of Transplanted Kidney

In the present study, various technical factors which may affect the patency of graft renal artery in renal transplant recipients with multiple renal arteries were analyzed as multiple renal arteries pose a technical challenge to operating surgeon. However no vascular complication was found. In this study the incidence of TRAS after 90 days after transplant was found to be nil. In addition the study group did not have any increase in associated complications due to multiple renal arteries.

In contrast higher incidence of ATN, urinary leak and technical ureteric obstruction has been reported by Alam et al. [3]. Similar findings were observed by Mazurcchi et al who reported equal incidence of vascular, urological and other surgical complications [4]. As per study conducted by Fervenza et al. [5] the incidence of TRAS in single renal artery transplant varied from 1-23% and period for diagnosis ranged from 2-45 months [5].

In the present study left sided Lap Donor Nephrectomy was done in all cases. The reasons for choosing the left side were due lower glomerular filtration rate (n = 1), stone in right kidney (n = 1), short right renal vein (n = 5) and surgeons preference (n = 5) in 12 (48%) cases despite the presence of single renal artery on right side. In their studies Hung et al. [6] compared 100 cases of LDN, 83 cases with single renal artery and 17 cases of multiple renal artery transplants and found comparable immediate and long term allograft outcome between multiple and single renal artery graft. 

In this study left sided kidney was chosen for donor nephrectomy in all the 25 patients (100%) inspite of presence of single renal artery in 12 patients (48%). No incidence of TRAS was found. No correlation could be established between the presence of multiple renal artery (on left side) and TRAS. The reason for choosing multiple artery left kidneys even in presence of single artery in right kidney is the presence of a longer vein on left side. The recent introduction of a vascular stapling device has resulted in increased use of right side kidneys when left side kidney has multiple arteries.

In study conducted by Marques et al in 46% of patients, symptoms of stenosis was caused due to recipient atherosclerosis, mostly proximal to anastomosis [7]. In this study only one case (4%) there was presence of atheromas in donor renal artery which was excised and one case (4%) had presence of atheromas in recipient internal iliac artery which were removed by end arterectomy. There was no evidence of TRAS in any of these patients on CT Angiography.

Loupe was used in 6 cases (24%) and 19 cases (76%) were done without use of loupe. No TRAS was found in any of the patients operated with or without the use of loupe. The use of loupe for surgery could not be proven to have direct or additive effect on future graft function & occurrence of TRAS. 

Patel et al. [8] in their study of 831 transplants (584 cadaveric, 247 live donor) found that 72 patients were symptomatic for hypertension and renal dysfunction. Amongst these 72 patients TRAS was seen in 14 patients out of 45with end to side anastomosis and 12 patients out of 27 with End to End anastomosis [8]. In this study in 19 cases (76%) end to end anastomosis was done and in 6 cases (24%) of patients end to side anastomosis was done. No evidence of TRAS was found in any case was found as the study group involved only live donors and the group included in this study was had no renal dysfunction (with post-transplant serum creatinine level ≤1.5mg/dL). This study kidney appeared dusky after declamping in one case (4%) and pink in rest of 24 cases (96%).The consistency of graft kidney after declamping was soft in 3 cases (12%) and firm in rest of 22 cases (88%).Diuresis seen in graft kidney after declamping was slower in 2 cases (8%), whereas it was brisk in all other 23 cases (92%). Hung et al had reported delayed graft function in their study comparing multiple renal artery vs single renal artery live donor transplants [6].

There was no incidence of TRAS in this study group. No significant correlation could be established between graft kidney characteristics and occurrence of TRAS. The dusky appearance, soft consistency and slower diuresis in patients after declamping of graft kidney could not be proven to have direct, additive effect on future graft function and occurrence of TRAS.

In the present study serum creatinine done on 4^th As per study conducted by Parfrey et al. [9] the risk of CIN varies from 12-26% in those with preexisting renal disease and diabetes mellitus. Haider et al. [10] found that incidence of CIN in renal transplant patients was 5.6% in those having high baseline eGFR more than 70mL/min and use of hypo osmolar contrast.

In this study no evidence of TRAS was detected on CT Angiography and hence no association could be attributed between various factors being taken into consideration in this study like number of renal arteries, surgical skill of operating team, arterial reconstruction technique, type of anastomosis (end to end/end to side), use of Loupe during surgery, time taken for LDN and recipient surgery, atherosclerosis in donor and recipient vessels, graft characteristics after declamping and time taken to reach lowest creatinine levels.

In conclusion, there was no evidence of TRAS was found in any case. There was no evidence of TRAS in any of cases on CT Angiography Hence no association could be established between occurrence of TRAS and various factors in patients with multiple renal artery live donor transplants with reconstruction.

Limitations of this Study

• Statistically not adequately powered. Clinically evident TRAS for main renal arteries is 1-12% although TRAS incidence for multiple renal arteries is not known. This was an initial study conducted in Department of Renal Transplant Surgery, PGIMER to look for evidence of TRAS in multiple renal artery transplants (live donor only) in group with serum creatinine ≤ 1.5mg/dL

• There was a negative selection bias towards TRAS because renal dysfunction is a prominent feature of TRAS and all patients with serum creatinine ≥1.5 were excluded in view of ethical considerations for an initial study

• However in case of 8 patients with serum creatinine ≥ 1.5mg/dL who were not chosen for CT Angiography, CDUS workup too showed no evidence of TRAS. This study has demonstrated no incidence of TRAS and CIN after CT Angiography. Further study can be undertaken to find out incidence of TRAS in patients with creatinine levels >1.5 mg/dL and association of TRAS with the technical factors evaluated in this study

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10. Haider, M. et al. “Incidence of Contrast-Induced Nephropathy in Kidney Transplant Recipients.” Transplantation Proceedings, vol. 47, no. 2, Mar. 2015, pp. 379–383.