Renal Color Doppler Ultrasound.
After studying this presentation one will be able to perform and interpret ultrasound.
This presntation in my opinion is best short analog to text.
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Role of color doppler ultrasound in rvhtn
1. Role of Color Doppler Ultrasound
in Renovascular Hypertension
Dr. Muhammad Bin Zulfiqar
Alnoor Diagnostic Centre
2. Agenda
• Introduction of renovascular hypertension
• Normal Anatomy
– Kidney
– Renal Arteries
• Parenchymal Echogenicity grades
• Basic Technique of Renal Doppler
• Normal Renal Artery Doppler
• Doppler in Renovascular Hypertension
3. Definition
• Secondary elevation of blood pressure
produced by variety of conditions interfering
with arterial circulation of kidney tissue
causing renal tissue ischemia
4. Renovascular Hypertension
• Most common secondary form of
hypertension
• Not easily recognizable clinically
• Significant renal artery disease (> 60 %
stenosis) has been found in 7 % of population
Braunwald heart disease 7th ed.page 977
5. Misconception
• Renal artery stenosis always cause
hypertension
• Revascularization always reverse or improve
hypertension as hypertension my be comorbid
with renal artery stenosis
• Renovascular hypertension means
atheromatous or fibromuscular disease
6. Normal anatomy of the kidney
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Renal parenchyma: cortex & medullary pyramids
Renal sinus: arteries, veins, lymphatics, collecting system, & fat
Renal hilum: Concave, in continuity with renal sinus
7. Anatomy of renal arteries
RRA: Usually passes posterior to inferior vena cava
LRA: Usually courses posterior to left renal vein
Multiple renal arteries in 25% (inferior polar artery from aorta)
8. Arterial blood supply to the Kidney
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
Segmental artery
Apical, upper, middle, lower, posterior
Interlobular artery
Between renal pyramids
Glomerular arteriole
Main renal artery
Arcuate artery
Between cortex & medulla
9. Classification of renal parenchymal echogenicity
4 types based of US appearance
Hypoechoic compared to liver
Isoechoic compared to liver
Hyperechoic compared to liver
Isoechoic to renal sinus
Normal
Normal
Pathological
Pathological
Grade 0
Grade I
Grade II
Grade III
10. Kidney parenchyma compared to liver parenchyma
Hypoechoic Isoechoic
Hyperechoic
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.
11. Abdominal aorta
• Normal abdominal aorta 1.5 – 2.5 cm
• Ectatic aorta 2.5 – 3 cm
• Aortic aneurysm > 3 cm
• Annual growth of aneurysms 0.33 cm/year
between 4 & 5.5 cm
* Bhatt S et al. Ultrasound Clin 2008 ; 3 : 83 – 91.
12. Technical points
• Fasting for at least 6 hours before the exam
• Duration of the examination: 30 – 45 min
• Rare failure: Non-cooperative patient – Gas
• Intestinal preparation: not necessary
• Operator-dependent technique
• Slow learning curve
• Most complex & difficult Doppler examination
13. Sites for pulsed Doppler of renal arteries
Aorta
Ostium of main renal artery
Trunk of main renal artery
Hilum of kidney
Upper pole of kidney
Middle pole of kidney
Lower pole of kidney
14. Norma right renal artery
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Transverse gray scale image
Right main renal artery
Transverse color Doppler image
Right main renal artery
15. Norma left renal artery
Gray scale image Color Doppler image
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Proximal main left renal artery Proximal main left renal artery
16. ‘‘banana peel’’ or “Isikoff” view
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Isikoff MB et al. Am J Roentgenol 1980 ; 134 : 1177 – 1179.
Origins of right & left renal arteries
Gray scale image
Origins of right & left renal arteries
Color Doppler image
Longitudinal transhepatic view in Left lateral decubitus
17. Normal right renal artery
Coronal images of IVC
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
RRA is the only vessel to course laterally under the IVC
Often slightly indents the IVC
18. Limits in visualization of main renal arteries
• Obesity
• Overlying bowel gas
• Dyspnea
• Shadowing from arterial calcifications
• Cardiac arrhythmias
• Poor angle of Doppler insonation
• Accessory renal arteries (small size)
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Expert sonographers detect 80 – 90% of main RA
CEUS improves success rate to 95%
19. Normal segmental & interlobar renal arteries
Normal segmental renal arteries (long arrows)
Color Doppler image of the kidney
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Normal inter-lobar renal arteries (short arrows)
26. Renal artery stenosis
Atherosclerosis
> 90%
FMD
< 10%
Age After age of 50 Young
Gender More common in males More common in females
Location Proximal 1 cm of main RA
Branching points
Middle of renal artery
Others (carotids)
Post-stenotic
dilatation
Rare Frequent
27. Clinical risk factors for Renovascular HTN
• Abrupt onset of severe HTN: diastolic >120 mm Hg
• Accelerated or malignant HTN: grade III or IV retinopathy
• HTN refractory to appropriate three-drug regimen
• Onset of hypertension before age 30 or after age 60
• HTN with rapidly progressive renal failure
• Renal failure that develops in response to ACE inhibitor
• HTN associated with upper abdominal bruit
• Episodes of recurrent severe HTN & pulmonary edema
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
28. Renal artery stenosis
Direct signs
Focal color aliasing
Color bruit
Turbulence
PSV > 180 cm/sec
Renal Aortic Ratio > 3.5
Indirect signs
AT > 0.07 sec
Δ RI (right – left) > 5 %
Parvus tardus pattern
Significant stenosis
(50 – 85% diameter reduction)
Sensitivity: 79 – 91%
Specificity: 73 – 97%
Severe stenosis
(> 85 % diameter reduction)
Sensitivity: 95%
Specificity: 97%
29. Renal artery stenosis / Direct criteria
Non-significant stenosis (< 50% diameter stenosis)
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Plaque in anterior wall of LRA
PSV: 148 cm/sec
Color Doppler US Power Doppler US
Better visualization of plaque
30. PSV: 293 cm/sec – RI : 0.91
Controversial indication of PTA2
Aliasing in left renal artery
Retro-aortic course of LRV
1 Schäberle W. Ultrasonography in vascular diagnosis. Springer-Verlag, Berlin, 2nd edition, 2011.
2 Jaeger KA et al. Ultraschall in Med 2007 ; 28 : 28 – 31.
Renal artery stenosis / Direct criteria
31. Renal artery stenosis / Renal Aortic Ratio
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Small right kidney (8.4 cm) PSV (aorta): 102 cm/s
PSV (RRA): 465 cm/s High grade stenosis of RRA
RAR: 4.5
32. Indirect criteria
• Loss of early systolic peak
• Distal to stenosis velocity of renal artery
decreases
• Tardus Parvus pattern
• Acceleration time > 0.07 sec
• RI values also decrease down to 0.45 to 0.5
• Difference between RI values of both kidneys
> 5-10 %
33. Renal artery stenosis / Indirect criteria
Schäberle W. Ultrasonography in vascular diagnosis.
Springer-Verlag, Berlin, 2nd edition, 2011.
PSV: 85.7 cm/s
EDV: 47.2 cm/s
RI: 0.64
Left renal hilumRight renal hilum
PSV: 125 cm/sec
EDV: 58.1 cm/s
RI: 0.75
Δ RI (right – left) > 0.05 → RA stenosis in side of lower RI
34. Renal artery stenosis / Indirect
criteria
Right kidney Left kidney
Δ RI (right – left) > 0.05 → RA stenosis in side
of lower RI
36. Fibromuscular dysplasia
Moniliform aspect of RRA
Typical FMD in middle third of RRA
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
PSV 250 cm/sec
No parallelism of RRA walls
37. Etiologies of renal artery dissection
Stenotic or occlusive lesion
• Atherosclerosis
• Fibromuscular dysplasia
• Extension of aortic dissection
• Marfan syndrome & Ehlers-Danlos syndrome
• Trauma & iatrogenic causes
• Idiopathic
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.
38. Coarctation of abdominal aorta
Severe hypertension in a 6-year-old boy
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Bilateral & symmetric
tardus parvus waveform
Sagital view of aorta
Severe narrowing at level of CA & SMA
39. Guidelines for diagnosis of RAS
• Recommended as screening test
Duplex US followed by
CT angiography (except RF) & MR angiography
• Not recommended as screening test
Captopril renal scintigraphy
Plasma renin activity
Captopril test
Selective renal vein renin measurements
Hirsch AT et al. J Am Coll Cardiol 2006 ; 47 : 1239 – 1312.
40. Micro-aneurysms
Contraindication of renal biopsy (bleeding)
• Location Distal branches of cortex
Segmental arteries rarely
• Size 1 mm, 2-3 mm rarely
• Cause PAN (micoaneurysms in 100%)
• Clinic Fever – Abdominal pain – Hematuria – RF
• Diagnosis Arteriography – Not visible by Doppler
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
41. Renal Doppler in nephropathies
• Acute tubular necrosis
• Tubulo-interstitial nephropathy
• Micro-angiopathy
• Nephro-angiosclerosis
• Diabetic nephropathy
Glomerulo-nephritis
(↑ RI in end stage disease)
Elevated RI Normal RI
43. Advantages of Renal Doppler in
Renovascular Hypertension
• Cost effective
• Easily available
• No contrast
• Excellent depiction of renal vasculature with
high accuracy
• Physiological information
• Best for follow up after revascularization
procedure
44. Take Home Message
• Evaluation of direct doppler criteria in
renovascular hypertension is possible in thin,
lean, cooperative and fully prepared patients.
• But even in unfavorable circumstances indirect
signs are sufficient to document renovascular
hypertension with high accuracy.
Hinweis der Redaktion
The normal adult kidney is bean shaped with a smooth convex contour anteriorly, posteriorly, andlaterally.
Medially, the surface is concave and known as the renal hilum.
The renal hilum is continuous with a central cavity called the renal sinus.
The collecting system (renal pelvis) lies posterior to the renal vessels in the renal hilum.
● The right renal artery is longer than the left, and passes posterior to the IVC.
● The left renal artery has a more horizontal course to the kidney.
One of the most complex and difficult sonographic examination.
Even expert sonographers detect only 80–90 per cent of renal arteries.
Ultrasound contrast agents improve the technical success rate to 95 per cent.
Because of the high prevalence of hypertension in the general population and the low incidence of RVH among these patients (0.5%–5%), however, screening all hypertensive patients is neither practical nor cost effective.
Screening for RAS is thus recommended only for enriched patient populations considered to be at high risk for RAS.
The clinical criteria most predictive of RAS are listed in Box 1. In such patient populations the prevalence of RVH increases to
approximately 20% to 30%.
PSV is recommended, may be combined with RAR (and ΔRI) to improve specificity.
In vascular medicine, a reduction in diameter of 50% is commonly regarded as hemodynamically significant and should not be equated with clinical relevance.
End organ damage may have already occurred in patients who have a small kidney with a thin, echogenic renal cortex or an RI greater than 0.8 in the intraparenchymal renal arteries, and that improvement of blood pressure or renal function is less likely following intervention in such patients.