3. Renal transplant recipient who noticed worsening pedal oedema, deterioration of his blood pressure and rise of his S Cr especially after commencing ACEi (angiotensin-converting enzyme inhibitor). A duplex scan of the transplant artery is shown below.
- Will you explain the Duplex scan findings?
- What is your management?
Thank you All for your replies. There is another important finding on the doppler image that suggests RAS. See where the cursor is and explain this blush of colour. There is a reward for the correct answer
Dear Dr Ahmed,
This is a mosaic colour pattern indicating blood flow turbulence (abnormal and rapid blood flow will cause turbulence in the duplex study as in examination of AVF).
References:
1) Patrick Stone. Acquired arteriovenous fistula of the lower extremity. http://www.uptodate.com © 2022 UpToDate (accessed on 2 November 2022).
Excellent, well done.
The peak velocity is maximal (over 180 cm/s is considered), here 2.69 relevant to 269 cm/s) and the dotted line over the green area where there is resistance (green). The flow seems compromised where the Red (left) shows low flow there. (?!)
Green : area of turbulence
Excellent, well done.
Color doppler is showing turbulent flow in a post-stenotic area, which is a sign of renal artery stenosis
Excellent, well done.
Excellent, well done.
Tardus-parvus waveform distal to the arterial stenosis.
No, there is no obvious Tardus-Pravus, but there is turbulence at the site of the stenosis
All these findings support the diagnosis of transplant renal artery stenosis.
References :
Pini A, Faggioli G, Pini R, Mauro R, Gallitto E, Mascoli C, Grandinetti V, Donati G, Odaldi F, Ravaioli M, La Manna G, Gargiulo M. Assessment and Management of Transplant Renal Artery Stenosis. A Literature Review. Ann Vasc Surg. 2022 May;82:13-29. doi: 10.1016/j.avsg.2022.01.011. Epub 2022 Jan 31. PMID: 35108560.
This recipient has Renal Artery Stenosis (RAS)
History pertaining:
pedal edema
worsening of BP on ACEi
rise in creatinine
The markers for RAS are
turbulent flow at the anastomosis (Mosiac color pattern)
Raised Peak Systolic Velocity (PSV) at the anastomosis: 269cm/s
turbulent blood flow at the anastomosis site
the dopper ultrasound suggests renal artery stenosis the colour green area (turbid area) and RI is 0.64
I learned here: mosaic turbulent flow presented by green and yellow colors in doppler study.
The renal doppler findings are low systolic peak with parvas et tardus pattern in the renal arteries…There is also low normal RI of 0.64 secondary to decreased perfusion….
The cursor is pointing to the lesion where the Peak Systolic velocity is 269cm/sec and indicating severe RAS…
Green color shows turbulence at the anastomotic site
Although the color duplex is very sensitive and specific for RAS, one should exclude other causes like high tacrolimus levels.. The patient should have basic chemistry checked to detect worsening azotemia… Blood pressure medication check list to see for increasing requirements…
Further imaging studies maybe needed to localize the stenosis to find out about location of the stenosis… CT renal angiography will localize the stenosis, but there is risk of contrast induced nephropathy to it..Spiral CT gives 3D images of the vessels..MR renal angiogram is superior to CT renal angio in terms of sensitivity and specificity and it does not involve iodinated or gadolinium exposure….
Conservative mangement of RAS is indicated for hemodynamically insignificant stenosis PSV < 180cm/sec and RI > 0.50; This is where no intervention is needed when there is no worsening of azotemia or hypertension or pulmonary edema…Low dose ACEi can be used, but they need constant monitoring of renal functions and potassium every alternate day initially..It also required to start the patients on antiplatelets and statins
Indications of angioplasty and stenting are when BP is not controlled, renal functions deteriorating and significant stenosis when PSV > 180cm/sec…PTA is the first treatment of choice when there is short segment of stenosis…The success rate is 70-90%…However the recurrence rate is 10 – 30% in 1 year which reduces after the placement of a stent
Tight diffcult lesions not amenable to PTA require surgical re construction ..
The above patient needs PTA and renal stenting in view of hemdynamically significant stenosis and if CT renal angio shows more than 70%
The finding of this duplex
PSV more the 2.6 (high)
RI 0.6
Turbulent flow
This findings associate with Ras
Doppler criteria for significant stenosis include the following:
(a) velocities greater than 200 cm/s or a focal frequency shift greater than 7.5 KHz (when a 3-MHz transducer is used),
(b) a velocity gradient between stenotic and prestenotic segments of more than 2 : 1,
(c) marked distal turbulence (spectral broadening).
What is your management?
We should stop ACEI and monitor blood pressure with continuing treatment if necessary with CCB or Beta blockers
Sometimes we need perform MRA not only to confirm the diagnosis but also to indicate the possibility need of angioplasty
Even if these findings exist, when the patient is clinically doing well, only conservative monitoring is performed [24]. When treatment is necessary, percutaneous transluminal angioplasty with or without stent placement is nowadays accepted as the initial treatment of choice [28]. Clinical success in the form of improvement or definite treatment has been reported in 73% of patients.
https://www.hindawi.com/journals/isrn/2013/480862/
The scenario and doppler study suggestive of transplant renal artery stenosis (TRAS).
stop the ACEi
Start other anti hypertensive drug like calcium channel blocker
if failed for renal artery stent
High PSV with turbulent blood flow in the renal artery suggestive of renal artery stenosis
Diagnosis likely is transplant renal artery stenosis as is evident from the history of worsening of blood pressure,pulmonary edema and creatinine after starting ACEIs and findings of duplex showing RI of main renal artery -0.64( low RI) ,Blunted systolic upstroke (Tardus-parvus waveform),-PSV : 2.69 m/s and -PSV : 2.69 m/s.Diagnosis is confirmed via invasive angiography .CTA or MRA can help.After the diagnosis made ,then first step in management will be to stop ACEIs or ARBs and treatment of stenosis will depend on the time of presentation..If if occurs in the first month,then surgical revision requires and after 1 month PTA with or without stent AVF placement or open revascularizationif all above measures failed.Medical therapy will be continued along with this and included antihypertensives and aspirin and lipid lowering if needed.
REFERENCE:
Kolofousi C, Stefanidis K, Cokkinos DD, Karakitsos D, Antypa E, Piperopoulos P. Ultrasonographic features of kidney transplants and their complications: an imaging review. ISRN Radiol. 2012 Dec 2;2013:480862.
–
Renal artery stenosis . Confirm with MRA renal artery. refer vascular surgeon for stenting if diagnosis confirmed.
Diagnosis likely is transplant renal artery stenosis as is evident from the history of worsening of blood pressure,pulmonary edema and creatinine after starting ACEIs and findings of duplex showing RI of main renal artery -0.64( low RI) ,Blunted systolic upstroke (Tardus-parvus waveform),-PSV : 2.69 m/s and -PSV : 2.69 m/s.Diagnosis is confirmed via invasive angiography .CTA or MRA can help.After the diagnosis made ,then first step in management will be to stop ACEIs or ARBs and treatment of stenosis will depend on the time of presentation..If if occurs in the first month,then surgical revision requires and after 1 month PTA with or without stent AVF placement or open revascularizationif all above measures failed.Medical therapy will be continued along with this and included antihypertensives and aspirin and lipid lowering if needed.
REFERENCE:
Kolofousi C, Stefanidis K, Cokkinos DD, Karakitsos D, Antypa E, Piperopoulos P. Ultrasonographic features of kidney transplants and their complications: an imaging review. ISRN Radiol. 2012 Dec 2;2013:480862
Duplex scan
Peak systolic velocity : 2.96 high.
Resistive index : 0.64 low normal
turbulent blood flow
All above and the clinical findings suggesting transplant renal artery stenosis.
Management
Angiography with or without percutaneous transluminal renal angioplasty.Stents are used in cases of inadequate response to balloon angioplasty due to elastic recoil
bbas Ghazanfar, Afshin Tavakoli, Management of transplant renal artery stenosis and its impact on long-term allograft survival: a single-centre experience, Nephrology Dialysis Transplantation, Volume 26, Issue 1, January 2011, Pages 336–343,
this is a duplex examination of renal graft artery showing peak systolic velocity of 2.6 m/s with resistive index of 0.6 suggesting graft artery stenosis
to confirm the diagnosis we need MRA , CTA or angiography. if confirmed the diagnosis endovascular stenting is the treatment of choice
Duplex scan findings:
There is turbulent flow (likely in post stenotic segment) s/o of renal artery stenosis. Use of ACE inhibitor leading to worsening pedal odema, rise in serum creatinine also points to the same
Management:
Clinical:
High BP, worsening oedema and rise Cr after commencing ACEi
Image:
Ø The peak systolic velocity is 2.69 m/s HIGH
Ø RI=0.64 LOW
Ø Mosaic/ green colour wave = turbulant flow
All together confirm TRAS
Further image is angiography MRA
Stop the ACEi used another antihypertensive like CCBs
Percutaneous transluminal angioplasty/stenting or surgical intervention (vascular surgeon involvement is crucial)
Will you explain the Duplex scan findings?
High PSV 2.69 m/sec, RI 0.64, Turbulent flow. All are suggestive of renal graft artery stenosis.
What is your management?
1- Confirm by CTA or MRA.
2- Discontinue ACE.I or ARBs.
3- Control BP with other agents like CCBs.
4- Angioplasty and stenting if indicated after consulting IR.
The presence of turbulence blood flow in the site of anastomoses with PSV more than 1.8-2.0m/s and RI=0.6 indicate the presence of TRAS.
The diagnosis is confirmed by renal angiography but it’s invasive and Carry the risk of CIN.
Management started by medical treatment by removal of the ACEi as it contraindicated in TRAS as well as bilateral RAS or unilateral RAS in solitary kidney. Change the anti hypertensive medication to another choice like CCB .
Percutaneous transluminal angioplasty with stenting . If these measures failed, then surgical intervention by resection of the stenotic part and revascularization .
This turbulent flow with low RI make the renal artery stenosis is a definite diagnosis but should be confirmed by CT angiogram and we should stop the ACEI
Will you explain the Duplex scan findings?
Picture suggestive of transplant renal artery stenosis
PSV(MAX) 269 cm/s.
RI of 0.64 within normal range.
The green color indicate presence of turbulence of blood flow in the stenotic transplant renal artery.
Patients with TRAS usually present with worsening or refractory hypertension, fluid retention and/or graft dysfunction without evidence of rejection .
Similar to bilateral renal artery stenosis or unilateral stenosis in a solitary kidney, the renin–angiotensin–aldosterone system (RAAS) is activated in TRAS.
This leads to sodium and fluid retention, and patients may develop edema, congestive heart failure or recurrent bouts of pulmonary edema.
Acceleration time in the transplant renal and intrarenal arteries ≥0.1 s, peak systolic velocity in the transplant renal artery >200 cm/s and a ratio of peak systolic velocity in the transplant renal-to-external iliac arteries >1.8 are used to diagnose TRAS.
Elevated peak systolic velocity in the transplant renal artery is the most sensitive Doppler criterion for the detection of high-grade TRAS.
Recognition of TRAS is important because it is potentially treatable. There are three treatment modalities: medical therapy alone, percutaneous transluminal angioplasty and surgical revascularization each with medical therapy.
What is your management?
Stop ACEi.
shift to another antihypertensive agent with tight control of blood pressure.
Follow up of graft function
If no improvement percutaneous transluminal angioplasty to be considered.
reference
Wei Chen, Liise K. KaylerClin.
Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy. Kidney J. 2015 Feb; 8(1): 71–78.
This doppler study shows an elevated PSV (more than 2.5 m/sec), RI= 0.64, and mosaic pattern due to turbulent flow.
ACE inhibitors are contraindicated in transplanted kidney with TRAS and should be stopped.
Treatment includes angioplasty ±stent or surgery. Percutaneous balloon angioplasty is effective in 80% of patients. In those with recurrent stenosis, placement of stent is useful. In the case of resistant hypertension or recipient’s arteriosclerosis disease, surgery should be considered. But fibrous scaring around the site of transplant, makes it difficult.
reversed wise pattern? if I see it I will think of RAS
High systolic velocity
RI normal
green dotes mark to turbulent flow ( I learned from here)
management:
stop ACEI
control BPr with another alternative such as calcium blocker or labetalol if v.high Bpr
Ct angio for confirmation and may be with angioplasty
or surgical correction
This is a case of transplant renal artery stenosis.
Duplex scan showed –
– High peak systolic velocity 269cm/s
– Low resistivity index 0.64 in the renal artery.
Management:
– Stop ACE inhibitor
– CT angiography to confirm the diagnosis
– Percutaneous angiography with stenting
the doppler ultrasound finding is PSV is 2.69 m/s and if it is more than2.5m/s with sensitivity and specificity of 100 and 95% respectively of stenosis.
resistance index 0.64.
mosaic color indicates Turbid blood flow and this indicates renal artery stenosis.
Risk factors for renal artery stenosis in the transplant recipient
1-operative techniques such as trauma.
2-atherosclerosis disease.
3-CMV infection.
4-delay graft function.
the ultrasound usually is a non-invasive technique and the diagnosis confirm with MRA or CCT with intravenous contrast.
management
1- hold ACE and start calcium channel blockers such as amlodipine.
2-hyperlipidemia should be correct if present.
3- screening of CMV infection by PCR and treatment should be commenced as there is an association between the RAS and CMV infection.
4-percutaneous balloon angioplasty and the success rate is 80% and 20% develop restenosis
angioplasty with or without stenting.
5- surgery of extensive fibrosis and scaring around the transplanted kidney make surgery correction of a RAS difficult
reference
UpToDate
Transplant renal artery stenosis, it presents with HTN, salt and water retention and graft dysfunction, it may lead o flash pulmonary edema and hypertensive crisis.
The duplex scan is showing high peak systolic velocity 269cm/s and low resistivity index 0.64 in the renal artery.
Management:
Stop ACE inhibitor
CT angiography to confirm the diagnosis
Invasive arteriography provides a definitive diagnosis and is therapeutic as allow treatment with percutaneous transluminal angioplasty with or without stenting to avoid recurrence and the need for reintervention.
Baird DP, Williams J, Petrie MC, Smith JR. Transplant Renal Artery Stenosis. Kidney international reports. 2020 Dec;5(12):2399.
This duplex images showed turbulance flow with typical presentation of RAS ,with high PSV and low RI
This doppler ultrasound shows high PSV and Low normal RI with turbulence flow is suggestive of RAS.
DOPPLER SCAN FINDINGS AS FOLLOW:
1. Peak systolic velocity is 2.69 m/s, more than 1.8–2.0 m/s, suggestive of TRAS.
2. The color green indicates strong blood flow velocities and turbulences around the renal artery’s ostium.
3. RI=0.64
Findings are highly indicative if TRAS.
Unfortunately, the best diagnostic procedure for TRAS—renal artery angiography—is an invasive technique and has the risk of causing CIN.
The first step in management is to switch from the offending ACEi medication to a different one, ideally a CCB.
The subsequent renal imaging consists of a renal angiography and MRA to confirm the diagnosis.
Confirmation is necessary before proceeding with surgical treatment. Renal angioplasty with stent placement or open surgical resection of stenotic segment.
This doppler scan shows high blood flow velocities and turbulences suggestive of renal artery stenosis.
Management
Three different treatment methods are available:
1. Medical management may be used to control hypertension with unknown effect on kidney function. This approach is indicated if the degree of stenosis is not considered hemodynamically significant or the risk of percutaneous intervention is considered high for graft loss, or both.
2. Surgical intervention with revascularization. This is considered a major operation with graft loss following vascular reconstruction approaching 30% with a recurrence rate of ∼12%. There is also an increased risk of ureteral injury with surgery. Surgical correction is the preferred method for treatment of kinking of the proximal transplant renal artery.
3. Percutaneous endovascular management using transluminal angioplasty (PTA) or metallic stent placement, or both.
Rajan DK, Stavropoulos SW, Shlansky-Goldberg RD. Management of transplant renal artery stenosis. Semin Intervent Radiol. 2004 Dec;21(4):259-69. doi: 10.1055/s-2004-861560. PMID: 21331137; PMCID: PMC3036233.
Mosaic coloure pattern indcation of RAS.
we will mange either reopening or re vasculraztion
and keep patient well hydrated and to be on anticoagulonat
The clinical scenario is in favor of transplant RAS
Worsening edema, BP getting uncontrolled and rise of creatinine after introduction of ACEI indicates TRAS.
Doppler also showing Increased PSV and low RI and turbulent blood flow
These findings go with transplant renal artery stenosis.
Doppler ultrasound shows turbulent flow and RI is 0.64 and maximum velocity is 2.69m/s which consist of post transplant renal artery stenosis.
Patient history :
uncontrolled HTN
LL edema ( salt retaining )
rising creatinine after starting ACEI
so highly suspected Transplant renal artery stenosis
Duplex findings :
PSV is 2.69 m/s
RI : 0.64
turbulent flow ( post the stenotic part)
So mostly TRAS
## (Transplant renal artery stenosis (TRAS) is the narrowing of the transplant renal artery, impeding blood flow to the allograft. It accounts for 1–5% cases of post-transplant hypertension)
## most frequently in the first 6 months
Diagnosis :
1- Duplex sonography :
Intial tool – performed safely regardless of renal function
Criteria for diagnosis :
– Elevated peak systolic velocity in the transplant renal artery is the most sensitive (peak systolic velocity in the transplant renal artery >200 cm/s)
– a ratio of peak systolic velocity in the transplant renal-to-external iliac arteries >1.8
– Acceleration time in the transplant renal and intrarenal arteries ≥0.1 s
2- Invasive angiography: conventional or digital subtraction angiography (But invasive + risk of CIN )
3- CT angiography : accurate and non-invasive diagnosis of TRAS (but risk of CIN )
4- Magnetic resonance angiography (MRA).
5- Isotope renography :
Good sensitivity (75%) may be predictive of physiologically meaningful renal artery stenosis
Low specificity (67%)
Treatment :
A- Medical :
antihypertensive medications can be used to control blood pressure
B- Interventional :
Indications :
uncontrolled hypertension
worsening renal function
progression of stenosis
1- Percutaneous transluminal angioplasty with stent placement :
First line
2- Open revision surgery :
considered as a rescue therapy and reserved for cases of unsuccessful angioplasty
include :
1- resection and revision of the anastomosis
2- saphenous vein bypass graft of the stenotic segment
3- localized endarterectomy and excision/reimplantation of the renal artery
References
Chew LL, Tan BS, Kumar K, et al. Percutaneous transluminal angioplasty of transplant renal artery stenosis. Ann Acad Med Singapore. 2014;43:39–43.
Shames BD, Odorico JS, D’Alessandro AM, et al. Surgical repair of transplant renal artery stenosis with preserved cadaveric iliac artery grafts. Ann Surg. 2003;237:116–122.
Browne RF, Tuite DJ. Imaging of the renal transplant: comparison of MRI with duplex sonography. Abdom Imaging. 2006;31:461–482.
Srivastava A, Kumar J, Sharma S, et al. Vascular complication in live related renal transplant: an experience of 1945 cases. Indian J Urol. 2013;29:42–47.
Patient has renal artery stenosis is suggested by clinically and by duplex which shows high peak systolic velocity ,turbulent flow normal resistive index
Confirm the diagnosis by CTA
Treatment
May need angioplasty with or with out stenting
Will you explain the Duplex scan findings?
Spectral doppler showed spectral broadening(increased spectral ranges under the curve) with velocity acceleration up to 269 cm/s. RI of 0.64 considered to be within normal. The green color reflects the turbulence of blood flow in the stenotic region of the transplant renal artery. The doppler findings are consistent with the diagnosis of TRAS.
What is your management?
· The first intervention, to hold ACEi. To shift for another antihypertensive agent.
· If no improvement or no reversal of KFT to baseline, percutaneous transluminal angioplasty of the transplant renal artery has to be considered.
-Duplex scan finding
RI 0.6
PSV is high 2.69 m/sec, indicative of Transplant renal stenosis with turbulence flow
The waves represent inverted waves
-Stop ACEI , another antihypertensive as CCB can be used to control BP
The definitive diagnosis of TRAS requires the use of invasive angiography: conventional or digital subtraction angiography. Conventional angiography uses large amount of iodinated contrast, and a risk of developing contrast-induced AKI. Digital subtraction angiography uses a smaller amount of contrast material.
Transcutaneous luminal angioplasty with stent insertion is the treatment of choice , surgical revascularization if needed
-Reference
Chen W, Kayler LK, Zand MS, Muttana R, Chernyak V, DeBoccardo GO. Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy. Clin Kidney J. 2015 Feb;8(1):71-8.
The changes described suggest renal artery stenosis. There is an area of flow turbulence after the region where the thrombosis occurred.
Non-invasive tests such as computed tomography angiography or magnetic resonance imaging can be used, but the risk-benefit of using contrast should be considered with the worsening of renal function in this patient.
Selective angiography can be diagnostic and therapeutic, considering the need for stent implantation in this region and stenosis correction, but there are no data that support angioplasty being superior when compared to surgical revascularization.
Transplant renal artery stenosis
The current case is a typical case of TRAS based on the following criteria:
It’s associated with poorer transplant outcomes and CV complications including post-transplant HTN and early treatment causes reverse those negative outcomes.
TRAS may occur at any time after kidney transplantation but is generally diagnosed between 3- and 24 months post-transplantation (risk factors include: Immunological factors leading to vascular endothelial dysfunction that can cause TRAS. Other transplant-related risk factors have been reported including cytomegalovirus (CMV) infection)
Diagnosis of RAS
Diagnosis: Renal artery angiography remains the gold standard diagnostic test for TRAS, but it is invasive and can lead to CIN.
Carbon dioxide (CO2) angiography can mitigate some of the risks of CIN, but, in most cases, small amounts of IV contrast are still required to attain sufficiently detailed images.CTA and MRA are diagnostic with sensitivity and specificity of 100% and the US is the best screening modality if done by an experienced radiologist (6), peak systolic velocity of ≥2.5 m/second detected by Doppler is associated with a sensitivity of 100%, and specificity of 95%
Treatment
Three therapeutic options for TRAS are pharmacological therapy alone or pharmacologic therapy in addition to renal artery angioplasty with stenting or surgical revascularization
• Medical antihypertensive therapy may be utilized to control blood pressure. Statins and acetylsalicylic acid may also be part of pharmacological therapy although there is no clear evidence for this use specifically in TRAS
• Indication for intervention
Patients with worsening serum creatinine and/or uncontrolled HTN attributable to TRAS
There is no randomized controlled clinical trial (RCT) comparing the efficacy of angioplasty ± stenting vs. surgical revascularization vs. pharmacological therapy alone in the kidney transplant population
References
1. Bruno S, Remuzzi G, Ruggenenti P. Transplant renal artery stenosis. J Am Soc Nephrol 2004; 15:134.
2. Audard V, Matignon M, Hemery F, et al. Risk factors and long-term outcome of transplant renal artery stenosis in adult recipients after treatment by percutaneous transluminal angioplasty. Am J Transplant 2006; 6:95.
3. Humar A, Matas AJ. Surgical complications after kidney transplantation. Semin Dial 2005; 18:505.
4. Loubeyre P, Abidi H, Cahen R, Tran Minh VA. Transplanted renal artery: detection of stenosis with color Doppler US. Radiology 1997; 203:661.
5. O’neill WC, Baumgarten DA. Ultrasonography in renal transplantation. Am J Kidney Dis 2002; 39:663.
6. Baxter GM, Ireland H, Moss JG, et al. Colour Doppler ultrasound in renal transplant artery stenosis: which Doppler index? Clin Radiol 1995; 50:618.
7. Sankari BR, Geisinger M, Zelch M, et al. Post-transplant renal artery stenosis: impact of therapy on long-term kidney function and blood pressure control. J Urol 1996; 155:1860.
8. Fervenza FC, Lafayette RA, Alfrey EJ, Petersen J. Renal artery stenosis in kidney transplants. Am J Kidney Dis 1998; 31:142.
9. Ruggenenti P, Mosconi L, Bruno S, et al. Post-transplant renal artery stenosis: the hemodynamic response to revascularization. Kidney Int 2001; 60:309.
10. Henning BF, Kuchlbauer S, Böger CA, et al. Percutaneous transluminal angioplasty as first-line treatment of transplant renal artery stenosis. Clin Nephrol 2009; 71:543.
11. Rosenthal, JT. Chapter 7. In: Handbook of kidney transplantation, 2nd ed, Danovitch, GM (Eds), Little, Brown, and Company, Boston 1996. p.130.
Will you explain the Duplex scan findings?
1. Peak systolic velocity is (max) = 2.69 m/s [ normal not more than 180 m/s].
2. Resistive index is normal –low normal 0.64
3. Evidence of turbulent blood flow – in our case by (green) dots shown
All these findings support the diagnosis of transplant renal artery stenosis.
What is your management?
MRA and CTA are widely used for TRAS screening/diagnosis the stenosis, however a selective angiography remains the ‘gold standard’ diagnostic investigation.
Either percutaneous transluminal angioplasty alone (PTA) or percutaneous stent deployment (PTS) or both are done by studies and are of proven benefit depends on interventionalist openion, and the site of stenosis at the anastomosis site that would be traumatic, infectious [CMV] or procedure related usually early post transplantation (3-6 months).
DSA associated with atherosclerotic renal artery stenosis, old age, DM… etc usually occurs later post transplantation.
References :
Pini A, Faggioli G, Pini R, Mauro R, Gallitto E, Mascoli C, Grandinetti V, Donati G, Odaldi F, Ravaioli M, La Manna G, Gargiulo M. Assessment and Management of Transplant Renal Artery Stenosis. A Literature Review. Ann Vasc Surg. 2022 May;82:13-29. doi: 10.1016/j.avsg.2022.01.011. Epub 2022 Jan 31. PMID: 35108560.
I have no idea and experience of reading the Duplex sonography. We usually discuss the pattern with Sonologist with clinical perspective and usually don’t discuss technical intricacies of the pattern
So there is no point copying answer from other colleagues or Google when even its beyond my basics.
But I have gone through most answers and replies of tutors and added to my knowledge.
Duplex results: PSV 269 cm/s, RI 0.6, turbulent flow, all suggestive of renal artery stenosis. This is supported with deterioration of creatinine and HTN after initiation of an ACEi.
· Acute deterioration of graft function or severe hypotension associated with the use of ACEI or ARB should raise the suspicion of RAS.
· Accelerated or refractory hypertension and peripheral edema in the absence of proteinuria also can happen.
· Color Doppler ultrasound is highly sensitive, noninvasive and may help as initial imaging study to diagnose RAS
· Transplant renal artery stenosis should be suspected in any patient with the combination of hypertension, edema, allograft bruit, and erythrocytosis
Management is stopping ACEi, giving another antihypertensive drug, aspirin and a statin.
Will you explain the Duplex scan findings?
The Doppler shows PSV of 2.6m/s.
RI of 0.6.
Which suggest Post transplant RAS.
Whats your management ?
When suspicion for transplant renal artery stenosis is high on the basis of findings at duplex US,
further evaluation with MR angiography, carbon dioxide angiography, or angiography
with iodinated contrast material may be performed .(1)
Carbon dioxide angiography is a useful tool for transplant recipients, as it allows both
diagnostic evaluation and therapeutic intervention while reducing the required volume of
iodinated contrast material .
Treatment :
When transplant renal artery stenosis is hemodynamically significant, endovascular
techniques including percutaneous transluminal angioplasty and stent placement are
first-line treatments, followed by surgery in refractory cases or in the setting of complex
arterial anatomy.
References :
1_Wei Chen et al .Transplant renal artery stenosis: clinical manifestations, diagnosis and
therapy. Clin kidney j. 2015 Feb; 8(1): 71–78.
Thank you, please see my question above.
_Duplex shows:
_ PSV more 269cm/sec
_RI 0.6
_ green or mosaic color wave is suggestive of turbulant flow as in post stenotic dilataion
_together with clinical worsening of protinuria and hypertension with ACEi are suggestive of transplant renal artery stenosis
Management
_ stop ACEi as antihypertensives (contraindicated in such case of solitary kidney) , substitute it with CCB as antihypertensive.
_ MRA to confirm diagnosis.
_percutaneous transluminal renal artery angioplasty.
_ use of stations and antiplatelet to control hypertension and protinuria.
Thank you, please see my question above.
·Will you explain the Duplex scan findings?
1. The peak systolic velocity is 2.69 m/s ((Significant renal artery stenosis (RAS) is present, if peak systolic velocity >1.8–2.0 m/s))
2. The green color shows high blood flow velocities & turbulences near the ostium of the renal artery.
3. RI=0.64: (PSV-EDV)/PSV ((2.69-0.97)/2.69))
Explanation:
Transplant RAS
////////////////////////////////////
·What is your management?
Step 1:
Exclude other differential diagnoses of worsening BP & rise of serum creatinine in kidney transplant patients, including CNI toxicity (measurements of trough levels)
Step 2:
Further imaging studies:
Although Color Doppler USS is easily available, inexpensive, & no radiation is needed, however, it depends on the operator’s experience & skill.
It may also be difficult in patients with multiple arteries; therefore, the surgeon must be consulted whether or not multiple arteries or anastomoses had been present.
Spiral CT gives 3-D images of the vessels (may be superior to selective angiography) & the does not need artery puncture & less contrast used.
MRA: is even superior to spiral CT (sensitivity: 67% – 100%, specificity:75% – 100%) & does not involve ionizing radiation or iodinated contrasts ; however, it is costly & not widely available.
Arteriography: gives the definitive diagnosis of RAS; however, it needs large amounts of radio-contrast medium that may cause ARF particularly in patients with renal dysfunction.
Treatment
A. Conservative:
·Useful in hemodynamically insignificant stenoses (PSV <180 cm/s; RI >0.50), where no intervention is needed & pharmacologic treatment is usually enough to control BP; low-dose, short-acting ACEi are effective & can be safely used if serum creatinine & serum potassium are normal (both must be re-checked within 7-10 days after the start of ACEi).
·It is also reasonable to use statins & ASA as part of the conservative treatment.
B. Angioplasty & Stenting.
Indications:
-BP can no longer be controlled
-Renal function is progressively deteriorating
-Noninvasive procedures suggest the progression of the stenosis.
PTA can restore kidney perfusion in 70-90% of cases. PTA is the 1st-choice therapy for short, linear stenoses relatively distal from the anastomosis.
PTA is less effective & has a higher risk of complications for stenoses at the anastomosis.
PTA carries a recurrence rate of 10-33% over 6-8 months; however, the recurrence may be largely decreased when the PTA is combined with the placement of a stent.
C. Surgery
Indications:
Unsuccessful angioplasty
Severe stenosis not amenable to PTA.
Techniques include:
Resection & revision of the anastomosis
SV bypass graft of the stenotic segment
Patch graft
Localized endarterectomy.
Success rate: 63-92%
Recurrence rate: 12%.
N.B:
Prompt intervention (regardless of the procedure) is mandatory in stenosis >70%.
References
1. Bernd Krumme and Markus Hollenbeck. Doppler sonography in renal artery stenosis—does the Resistive Index predict the success of intervention? Nephrol Dial Transplant (2007) 22: 692–696 doi:10.1093/ndt/gfl686
2. SIMONA BRUNO, GIUSEPPE REMUZZI, and PIERO RUGGENENTI. Transplant Renal Artery Stenosis. J Am Soc Nephrol 15: 134–141, 2004
Thank you, please see my question above.
Three different treatment methods are available:
Roberts J P, Ascher N L, Fryd D S, et al. Transplant renal artery stenosis. Transplantation. 1989;48:580–583. [PubMed] [Google Scholar] [Ref list]
Hohnke C, Abendroth D, Schleibner S, Land W. Vascular complications in 1,200 kidney transplantations. Transplant Proc. 1987;19:3691–3692. [PubMed] [Google Scholar] [Ref list]
Benoit G, Moukarzel M, Hiesse C, Verdelli G, Charpentier B, Fries D. Transplant renal artery stenosis: experience and comparative results between surgery and angioplasty. Transpl Int. 1990;3:137–140. [PubMed] [Google Scholar] [Ref list]
Thankyou
The patient renal transplant recipient presented with pedal edema, high BP, and elevated SCr after using ACEi and a duplex scan was used to assist in the investigation.
The duplex scan showed the following result:
1) Peak systolic velocity of about 269 cm/s
2) Resistive index RI of 0.64
3) S/D of 2,78
Based on the above, the patient has renal artery stenosis. So the diagnosis is Transplant renal artery stenosis and it can occur after 6 weeks post-transplantation. With the use of ACEi, there is worsening renal function with elevated serum creatinine. So worsening kidney function it caused a decrease in renal blood flow and as such causes fluid retention and elevated BP.
The likely step in managing this critical situation is as follows:
1) Stop the ACEi medication
2) Control blood pressures
3) Use other antihypertensives like CCB etc.
4) Will need a surgical consultation
5) Will need further investigations like sincitiography or isotope renography
6) Will need vascular angioplasty
7) May need to so open vascular surgery if angioplasty fails and revascularization of the vessel.
Reference:
Handbook of kidney transplantation sixth edition by Dr, Gabriel Danovitch.
Thankyou
Is there a role PSV max ie compare with velocity in iliac vessels.?
Explain the Duplex scan findings
The diagnosis will be Transplant renal artery stenosis – indicates moderate renal artery stenosis.
What is your management?
References:
Ruochen Qi, Guisheng Qi, Dong Zhu, Jina Wang,Diagnosis and Treatment of Early Transplant Renal Artery Stenosis: Experience From a Center in Eastern China, Transplantation Proceedings,Volume 52, Issue 1,2020
C.H. Su, J.D. Lian, H.R. Chang, et al.
Long-term outcomes of patients treated with primary stenting for transplant renal artery stenosis: a 10-year case cohort study
World J Surg, 36 (2012), pp. 222-228
D.M. Biederman, A.M. Fischman, J.J. Titano, et al.
Tailoring the endovascular management of transplant renal artery stenosis
Am J Transplant, 15 (2015), pp. 1039-1049
F.P. Hurst, K.C. Abbott, R.T. Neff, et al.
Incidence, predictors and outcomes of transplant renal artery stenosis after kidney transplantation: analysis of USRDS
Thankyou but what could be the explanation of no difference in patients and graft survival after PTA stunting is it due to other comorbid conditions?
*The above Renal transplanted duplex showed: Resistivity index :
– RI of main renal a. ( 0.64).
-SD : 2.78
-Blunted systolic upstroke (Tardus-parvus waveform).
-PSV : 2.69 m/s
*By history: patient had worsening edema with worsening of blood pressure and worsening of serum creatinine after giving ACEIs, conclusion from both history and duplex suggest picture of renal artery stenosis post transplant (TRAS). TRAS occurs most frequently in the first 6 months post-transplanted with a percent 1-5%.
*Diagnosis of RAS with : US and duplex considered only screening for TRAS but; Invasive angiography consider the definitive method for TRAS diagnosis and possible intervention could be done. Also; MRA and CTA could help.
*Management directed first to stop ACEIs medication and control blood pressure with diuretics , CCBs or BBS.
Then, Endovascular Percutaneous transluminal PT Angioplasty with drug eluting stent fixation showing clinical success rate about 77% especially in short distal lesions , if failed then; open revision surgery should be considered.
References:
1. Zand MS, Muttana R, Chernyak V,etal.,:Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy. Clin Kidney J. 2015 ;8(1):71-78.
2. Leong KG, Coombs P, etal.,: Renal transplant ultrasound: The nephrologist’s perspective. Australas J Ultrasound Med. 2015 ;18(4):134-142.
3.Seratnaheai A., Shah A.,etal.,: Management of TRAS. Angiology, 2011;62(3): 219-224.
Thankyou well done
The Duplex scan of the transplant renal artery in the index patient shows:
a) Peak systolic velocity (PSV) of 269 cm/s
b) Resistive index (RI) of 0.6 4
c) S/D of 2.78
The patient had worsening of serum creatinine as well as fluid retention (edema and worsening of blood pressure) on initiation of ACE inhibitors. The clinical picture with the Duplex imaging is suggestive of Transplant renal artery stenosis (TRAS).
A PSV in the transplant renal artery of >200cm/s (most sensitive marker for TRAS), acceleration time in the transplant renal artery and intrarenal arteries >0.1 second, and a ratio of PSV in the transplant renal artery to that of external iliac artery of >1.8 is used to diagnose TRAS (1). Relatively reduced RIs are seen in TRAS.
An absolute PSV of 340-400 cm/s at the anastomosis site has been suggested as a more reliable cutoff for TRAS (2). In addition, delayed or blunted systolic upstroke at spectral analysis (tardus-parvus waveform) may be seen.
Considering the moderately high values of PASV, it seems that the patient is having mild to moderate TRAS.
The management includes confirmation of the diagnosis and treatment.
The confirmation for TRAS can be done using CT or MR angiography (without Gadolinium), MRA being the preferred modality due to absence of radiation and ionizing contrast use (3).
Treatment of TRAS, once confirmed, includes (1):
a) Stopping the ACE inhibitors
b) Control of blood pressure (using calcium channel blockers, beta blockers and diuretics).
c) Revascularization using percutaneous transluminal angioplasty with stent placement or surgical revascularization (if angioplasty is unsuccessful) in of worsening of renal function, uncontrolled hypertension, or progression of stenosis.
Considering the moderate degree of TRAS, the patient should become better with discontinuation of ACE inhibitors and BP control.
The other issue in this patient is with respect to the reason behind starting ACE inhibitors in him. If there is proteinuria, then the patient might require a kidney biopsy to pinpoint the cause of proteinuria and take appropriate action.
References:
1) Chen W, Kayler LK, Zand MS, Muttana R, Chernyak V, DeBoccardo GO. Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy. Clin Kidney J. 2015 Feb;8(1):71-8. doi: 10.1093/ckj/sfu132. Epub 2014 Dec 9. PMID: 25713713; PMCID: PMC4310434.
2) Sugi MD, Joshi G, Maddu KK, Dahiya N, Menias CO. Imaging of Renal Transplant Complications throughout the Life of the Allograft: Comprehensive Multimodality Review. Radiographics. 2019 Sep-Oct;39(5):1327-1355. doi: 10.1148/rg.2019190096. PMID: 31498742.
3) Leong KG, Coombs P, Kanellis J. Renal transplant ultrasound: The nephrologist’s perspective. Australas J Ultrasound Med. 2015 Nov;18(4):134-142. doi: 10.1002/j.2205-0140.2015.tb00220.x. Epub 2015 Dec 31. PMID: 28191257; PMCID: PMC5024974.
Thank you, agree it is a case of TRAS
Duplex US:
TRAS is the most frequent vascular complication post transplant with incidence 1023%.
TRAS manifest between 3 mon -12 years, but most frequently in first 6 months.
Risk factors of TRAS development include:
Diagnosis of TRAS:
Treatment of TRAS:
References:
Dear Dr Ban,
I like your logical approach and well structured reply. yes, I agree that it is not clear enough to say tardus parvus.
Ajay
Will you explain the Duplex scan findings?
The duplex scan finding is suggestive for might suggest moderate TRAS,
Given, the history of:
– Worsening HTN after ACEi use.
– Deterioration in renal function.
– Duplex finding of RI: 0.64 and PSV; 2.69 m/s= 269cm/s.
TRAS:
-It accounts for 1–5% cases of post- transplant hypertension
-TRAS occurs most frequently in the first 6 months, but it can present at any time.
-Patients with TRAS have activated RAAS and usually present with worsening or refractory hypertension, fluid retention and/or allograft dysfunction without evidence of rejection.
-TRAS should be a differential diagnosis of a kidney transplant recipient with hypertensive crisis and flash pulmonary edema.
-Doppler sonography is commonly used as a screening tool for TRAS, whereas angiography provides a definitive diagnosis.
Finding suggestive for RAS includes:
Doppler ultrasonography is the procedure of choice to evaluate graft perfusion before and after revascularization.
The term pseudo transplant renal artery stenosis (TRAS) refers to thrombosis or stenosis of iliac artery or aorta proximal to transplant renal artery.
-Color Doppler study appearance of focal color aliasing noted at stenotic segments.
-Spectral Doppler study:
– PSV in main renal artery >300 cm/sec
– Ratio of PSV in transplanted main RA and external iliac artery greater than or equal to 1.8 are highly suggestive of significant stenosis .
– Indirect criteria are low RI <0.56 sec.
– Acceleration time >0.07 sec
– Acceleration index <3 meter
– Intrarenal tardus–parvus waveform
What is your management?
-Discontinue ACEI.
– Control BP, can use diuretics, BB or CCB.
– Confirm the diagnosis of TRAS by CT-angio or MRA
– Percutaneous transluminal angioplasty with stent placement is generally the first-line therapy to correct hemodynamically significant stenosis in TRAS, especially for lesions that are short, linear and distal to the anastomosis, reported an overall clinical success rate of 76.9%
– Open revision surgery is considered as a rescue therapy and reserved for cases of unsuccessful angioplasty
References:
– Kajal Patel*, Nitin Patel, Shruti Mehta, et al.Radiology; USG and Colour Doppler of Post Renal Transplant Complications. Journal of Urology and Nephrology. 2022; 3(3)
– Wei Chen et al Transplant renal artery stenosis: clinical manifestations, diagnosis, and therapy. Clin Kidney J. 2015 Feb; 8(1): 71–78.
Thankyou well done
You are right it is mild to moderate as the numbers are not as high as a classical case though the S/D is 2,78
The US with clinical finding of the recipient (sp. after commencement of ACEi) goes with the diagnosis of TRAS (transplant renal artery stenosis).
A complication that commonly occur durin3 3 and up to 2 years post transplantation.
Sequelle;
Degree of Stenosis;
Diagnosis;
Management;
Can be treated conservatively or by revascularization.
Refferences;
Kasiske BL, Anjum S, Shah R, et al. Hypertension after kidney transplantation, Am J Kidney Dis, 2004, vol. 43 (pg. 1071-1081)
2Aguera Fernandez LG, Zudaire JJ, Isa WA, et al. [Vascular complications in 237 recipients of renal transplant from cadaver], Actas Urol Esp, 1992, vol. 16 (pg. 292-295)
3Bruno S, Remuzzi G, Ruggenenti P. Transplant renal artery stenosis, J Am Soc Nephrol, 2004, vol. 15 (pg. 134-141)
Thankyou .Al is acceptable except using ACE I or ARBs ashy risk if he is controlled by other agents , what is the indication to use them (proteinuria)!
Will you explain the Duplex scan findings?
PSV is high 2.69m/s (269cm/s)
RI is 0.64 (slightly reduced)
High blood flow velocities (green colour)
Theses Doppler features and the clinical features are consistent with RAS
RAS here is not severe (moderate):
1. PSV is not very high
2. RI is not very low (severity of RAS correlates with lower RI test)
3. PSV detected with angle of 53
Doppler criteria for significant stenosis include:
1. Velocities greater than 200 cm/s or a focal frequency shift greater than 7.5 KHz (when a 3-MHz transducer is used)
2. A velocity gradient between stenotic and prestenotic segments of more than 2 : 1
3. Marked distal turbulence (spectral broadening)
What is your management?
Invasive renal angiography is the gold standard of diagnosis (conventional or digital subtraction angiography)
Non-invasive tests are duplex sonography, isotope renography, CT angiography and contrast-enhanced MRA
Stop the offending drug (ACEIs)
Stenosis in the first postoperative month: surgical revision of the anastomoses
Stenosis after 1 month:
1. Percutaneous transluminal angioplasty with stent placement, especially for lesions that are short, linear and distal to the anastomosis. Success rate is 73%
Complicatins are renal artery dissection, stent restenosis, thromboembolism, hematoma and pseudoaneurysms at the puncture site
2. Open revascularization: when unsuccessful angioplasty. Success rate is comparable to percutaneous transluminal angioplasty but there is a high risk of surgical complications
Both with medical therapy (diuretics, beta blockers, alpha-beta blockers, and calcium channel blockers). Aspirin and cholesterol-lowering medication (if the cause is atherosclerosis)
References
1. Chen W, Kayler LK, Zand MS, Muttana R, Chernyak V, DeBoccardo GO. Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy. Clin Kidney J. 2015 Feb;8(1):71-8. doi: 10.1093/ckj/sfu132. Epub 2014 Dec 9. PMID: 25713713; PMCID: PMC4310434.
2. Gabriel M. Danovitch. Handbook of Kidney Transplantation. Sixth edition, 2017
3. Leong KG, Coombs P, Kanellis J. Renal transplant ultrasound: The nephrologist’s perspective. Australas J Ultrasound Med. 2015 Nov;18(4):134-142. doi: 10.1002/j.2205-0140.2015.tb00220.x. Epub 2015 Dec 31. PMID: 28191257; PMCID: PMC5024974.
4. Kolofousi C, Stefanidis K, Cokkinos DD, Karakitsos D, Antypa E, Piperopoulos P. Ultrasonographic features of kidney transplants and their complications: an imaging review. ISRN Radiol. 2012 Dec 2;2013:480862. doi: 10.5402/2013/480862. PMID: 24967275; PMCID: PMC4045518.
5. Bernd Krumme, Markus Hollenbeck, Doppler sonography in renal artery stenosis—does the Resistive Index predict the success of intervention?, Nephrology Dialysis Transplantation, Volume 22, Issue 3, March 2007, Pages 692–696.
Well done but what about the ACEi?
Stop ACEIs
This is likely a diagnosis of TRAS based on new-onset hypertension that worsens with the use of ACEI, salt and water retention due to renin-angiotensin system activation that explained his edema and accelerated hypertension with worsening graft dysfunction without rejection, usually they have recurrent flush pulmonary edema, heart failure, which is called Pickering Syndrome to honor Thomas G. Pickering, who first defined it(1)
the doppler US of this patient further confirms the presence of high PSV> 2.6 with low RI and S/D 2.78 which is highly suggestive of TRAS and needs to be confirmed by digital subtraction angiogram to assess the significance of the stenosis severity, length, and the anatomical site to the vascular anastomosis
Transplant renal artery stenosis is one of the causes of hypertension in the early post-transplant period usually in the first 6 months however it can occur at any time after renal transplantation (2).
The prevalence of anastomotic kidney transplant artery stenosis is hard to evaluate due to inconsistencies in the definition of hemodynamically significant lesions and the use of different diagnostic modalities including color doppler US (CDU), MRI, and CT Angio. Wong et al. reported that the prevalence of TRAS increased from 2.4 to 12.4% after the introduction of color Doppler ultrasonography (CDU) in 1985, most centers used CDU as screening imaging for TRAS however its sensitive in 95% and specifically 80% for the screening of TRAS and it’s noninvasive but operator dependent and in high suspicion index case need to be confirmed either by MRA renal or contrast CT -Angio, the MRA use limited if GFR < 30ml/min due to the risk of NSF, and CT angio also associated with radiation exposure and contrast-induced AKI risk.
The pathogenesis of TRAS is complex and involves non-immunological and immunological factors
What is your management?
Stop ACEI and optimize blood pressure and pulmonary edema with other medical therapy including loop diuretics and CCB or BB
Further confirmation by either MRA or CT Angio and if confirmed significant stenosis will advise for renal angioplasty with or without stenting depending on the segment of the stenosis, angioplasty is successful in more than80% and 20% there is a risk of restenosis.
Surgical revascularization is limited for those symptomatic and failed renal angioplasty including resection and revision of the anastomosis, saphenous vein bypass graft of the stenotic segment, localized endarterectomy, and excision/reimplantation of the renal artery.
Complications that should be addressed include the risk of vascular dissection, hematoma, pseudoaneurysm dilation at the puncture site, thromboembolism
References
1. Messerli FH, Bangalore S, Makani H, et al. Flash pulmonary edema and bilateral renal artery stenosis: the Pickering syndrome. Eur Heart J. 2011;32:2231–2235.
2. Wei Chen et al Transplant renal artery stenosis: clinical manifestations, diagnosis, and therapy. Clin Kidney J. 2015 Feb; 8(1): 71–78.
3.de Morais RH, Muglia VF, Mamere AE, et al. Duplex Doppler sonography of transplant renal artery stenosis. J Clin Ultrasound. 2003;31:135–141
4.Chew LL, Tan BS, Kumar K, Htoo MM, Wong KS, Cheng CW, Teo TK, Irani FG, Choong HL, Tay KH. Percutaneous transluminal angioplasty of transplant renal artery stenosis. Ann Acad Med Singap. 2014 Jan;43(1):39-43
Thankyou Saja for diagnosis and management .