Transplant Renal Artery Stenosis (TRAS)

Question 1

Introduction

Answer 1

A 62-year-old male with a history of ESKD secondary to hypertension presents to
the emergency department 14weeks after a deceased donor kidney transplant.

The donor kidney anatomy was notable for two arteries: a main artery and a much smaller inferior pole artery. The two arteries were 15mm apart on a common aortic patch; however, due to their distance apart, the smaller artery was anastomosed to the main artery.

Blood pressure (BP) after transplant ranged between 130/80 and 160/90. At the time of transplant discharge from the hospital, the patient was on nifedipine 60mg twice daily and metoprolol 50mg twice daily.

On presentation to the emergency department, the patient complained of being unwell over the last week. BP was 225/115, HR 89. He reported headaches, newonset dyspnea, and oliguria.

Over the last 3weeks before presentation, his transplant nephrologist had titrated up his antihypertensives, and he was now on
nifedipine 90mg twice daily, metoprolol 100mg twice daily, and clonidine 0.1mg
three times a day.

Question 2

Diagnostic Investigations of TRAS

Answer 2

1. Ultrasound Duplex transplant kidney
   - Peak systolic velocity > 250cm/s
   - Tardus parvus arterial waveform
2. CT angiogram of transplant kidney
   - Non-invasive, uses less iodinated contrast
3. MR angiogram
4. (Gold standard) Digital subtraction angiogram (DSA)
   - Diagnostic and therapeutic - stenting at the same setting

Question 3

Management of TRAS

Answer 3

Immediate Management
1. Stabilize hypertensive emergency
- Antihypertensives

Definitive Management
1. Rarely continue medical therapy with serial ultrasound Doppler
- If hypertension well managed, no complications, < 70% stenosis

2. Percutaneous transluminal angioplasty with stent placement
   - Complications: renal artery dissection, stent restenosis, thromboembolism, haematoma, pseudoaneuysm at puncture site
3. Open surgical revision if unsuccessful
   - Surgical bypass of stenotic segment using internal iliac artery as conduit
   - Endarterectomy with excision and reimplantation of renal artery to common iliac artery

Question 4

Epidemiology of TRAS

Answer 4

Up to 10% of all transplant recipient
Occurring between 3 -24 months

1-5% of post-transplant hypertension
75% of all post-transplant vascular complications

Question 5

Pathophysiology of TRAS

Answer 5

1. Narrowing of renal artery resulting in Renal hypoperfusion
2. Activation of RAAS system
3. Refractory hypertension, fluid retention or overload, allograft dysfunction

Question 6

Risk Factors of TRAS

Answer 6

1. Atherosclerosis disease in donor
2. CMV infection
3. Delayed graft function
4. Transplant of Paediatric kidney in adult recipient
5. Iatrogenic
   - Kinking or twisting of renal artery at time of wound closure
   - Poor procurement technique
   - Clamping of vessels
   - Trauma to donor and recipient arteries during cold ischaemic time
   - Suture technical failure
6. Immune mediated endothelial injury
   - Progressive intima proliferation -> long diffuse stenosis, occurring late

Question 7

Location of TRAS

Answer 7

Near anastomosis of renal artery to iliac artery
- Can be short, diffuse or multiple sites
- Can occur at different times

Question 8

Clinical Features of TRAS

Answer 8

1. Presence of risk factors
2. Occurring 3-24 months post-transplant
   (immune mediated may be longer)
3. Poorly controlled hypertension
4. Rising creatinine
5. Hypertensive emergency features and failure symptoms
   - Headache
   - SOB/dyspnoea (from APO)
   - Oliguria
6. Transplant site bruit