Diagnostic Ultrasound - Abdomen and Pelvis

Transplant Renal Artery Stenosis
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Diagnoses: Kidney Transplant
• Renal torsion or graft malposition may result in functional
arterial stenosis
• May be initially evaluated with CTA or MRA
• However, may need confirmatory angiography to
determine functional significance
• Be wary of diagnosing flow-limiting stenosis in absence of
post-stenotic flow disturbance
Pseudo Renal Artery Stenosis
• Stenosis proximal to renal artery causing diminished flow
• Diffuse atherosclerosis in aorta, common or external iliac
artery
Transplant Arteriovenous Fistula
• Typically intrarenal area of color aliasing and tissue
vibration
• High-velocity low-resistance waveform
• Post biopsy
PATHOLOGY
General Features
• Etiology
○ Surgical injury during harvesting or transplantation
– Anastomotic technical problems, reaction to suture,
clamp injury
– Angulation, kink or twist
– Mechanical compression resulting in turbulent flow
○ Immune-mediated vascular damage from rejection
○ Neointimal hyperplasia
○ Older renal donors are more likely to have renal artery
stenosis
○ More common in living renal donor transplants: No patch
of donor aorta
○ Predisposing recipient factors include atherosclerosis,
diabetes, obesity, increasing age
Gross Pathologic & Surgical Features
• Arterial wall fibrosis → luminal narrowing
• Diffuse arterial disease from cell mediated immune injury
Microscopic Features
• Surgical injury, inflammation, arterial wall fibrosis, thrombus
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Any time after transplantation but peaks at 6 months
and usually within 3 years
– Hypertension is the principal symptom; newly
developed, progressive, or resistant to therapy
– Acute renal failure
– Progressive decline in renal function
□ Renal failure after ACE inhibitor
– Bruit in vicinity of transplant/iliac artery
– Heart failure
– Volume overload
– Flash pulmonary edema
Demographics
• Epidemiology
○ Most common graft vascular complication
– 2-10% of transplants
Natural History & Prognosis
• Main cause of graft loss given current success of
antirejection therapy
• Increased patient morbidity and mortality if untreated
• Excellent prognosis with successful treatment of
stenosis/surgical revision
Treatment
• Percutaneous transluminal angioplasty
○ ± stent
– 5-10% complication rate
• Surgical repair second line
• Iliac stenosis may also be treated with angioplasty and
stent
DIAGNOSTIC CHECKLIST
Consider
• Curves and kinks mimicking transplant renal artery stenosis
Image Interpretation Pearls
• Look for focal elevation in peak renal artery velocity
compared to iliac artery velocityandpost stenotic
turbulence
SELECTED REFERENCES
1. Chen W et al: Transplant renal artery stenosis: clinical manifestations,
diagnosis and therapy. Clin Kidney J. 8(1):71-8, 2015
2. Gaddikeri S et al: Comparing the diagnostic accuracy of contrast-enhanced
computed tomographic angiography and gadolinium-enhanced magnetic
resonance angiography for the assessment of hemodynamically significant
transplant renal artery stenosis. Curr Probl Diagn Radiol. 43(4):162-8, 2014
3. Rodgers SK et al: Ultrasonographic evaluation of the renal transplant. Radiol
Clin North Am. 52(6):1307-24, 2014
4. Glebova NO et al: Endovascular interventions for managing vascular
complication of renal transplantation. Semin Vasc Surg. 26(4):205-12, 2013
5. Kobayashi K et al: Interventional radiologic management of renal transplant
dysfunction: indications, limitations, and technical considerations.
Radiographics. 27(4):1109-30, 2007
6. Li JC et al: Evaluation of severe transplant renal artery stenosis with Doppler
sonography. J Clin Ultrasound. 33(6):261-9, 2005
7. de Morais RH et al: Duplex Doppler sonography of transplant renal artery
stenosis. J Clin Ultrasound. 31(3):135-41, 2003
8. Patel U et al: Doppler ultrasound for detection of renal transplant artery
stenosis-threshold peak systolic velocity needs to be higher in a low-risk or
surveillance population. Clin Radiol. 58(10):772-7, 2003
9. Loubeyre P et al: Transplanted renal artery: detection of stenosis with color
Doppler US. Radiology. 203(3):661-5, 1997
10. Baxter GM et al: Colour Doppler ultrasound in renal transplant artery
stenosis: which Doppler index? Clin Radiol. 50(9):618-22, 1995
11. Gottlieb RH et al: Diagnosis of renal artery stenosis in transplanted kidneys:
value of Doppler waveform analysis of the intrarenal arteries. AJR Am J
Roentgenol. 165(6):1441-6, 1995