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Renal Vascular DiseasePresented By: Syed Shoaib MuhammadSubject:Applied Doppler, Vascular Doppler.

Topics:AnatomyCausesNormal Renal artery Doppler indicesRenal Artery StenosisFibromuscular dysplasia (FMD)Nutcracker SyndromeReferences.

Anatomy of the Kidney.

Renal parenchyma:cortex & medullary pyramids

Renal sinus:arteries, veins, lymphatics, collecting system, & fat

Renal hilum:Concave, in continuity with renal sinus

Anatomy of the Kidney.

Segmental arteryApical, upper, middle, lower, posterior

Interlobular arteryBetween renal pyramids

Glomerular arteriole

Main renal artery

Arcuate arteryBetween cortex & medulla

Glomerular arteriole

Anatomy of the Kidney.

Anatomy of the Kidney.

Left lobe of liver Right lobe of liver DuodenumBile ductBody of pancreas Spinal columnRight renal arteryAortaSuperior mesenteric artery Vena cavaLeft renal veinSplenic vein

The left renal vein is physiologically compressed between the aorta and the superior mesenteric artery. It is slightly congested proximal to the compression site.

Anatomy of the Kidney.

Normal renal artery waveform. Arterial flow to the kidney shows typical low-resistance features with well-maintained diastolic flow throughout the cardiac cycle, a broad systolic peak, and a gradual transition between systole and diastole. Also note the sharp, well- defined early systolic peak and the steep early systolic slope. Faint venous flow from an adjacent vein is seen below the baseline.3D power Doppler view of the intra renal arteries shows multiple segmental arteries in the renal hilum branching into lobar and interlobular arteries.

Causes:

Renal artery stenosis Fibromuscular dysplasia (FMD) Nutcracker syndrome Renal vein thrombosis Aneurysm & pseudo-aneurysm Arterio-venous communications Renal mass Miscellaneous indications > 95 % of cases

Normal Renal artery Doppler indicesPulsatility Index (PI)0.7 1.4Resistive index (RI)0.56 0.70Peak systolic velocity (PSV)60 140 cm/s (< 180 cm/s)Systolic/Diastolic ratio (S/D) 0.26 0.4Renal Artery/Aortic Ratio (RAR) < 3.5 RI (right left) < 0.05Acceleration Time (AT)< 0.07 secAcceleration Index (AI)> 3.5 m/s2

Renal Artery Stenosis: Stenosis of the renal artery is due to atrerosclerotic disease in the vast majority of patients, or to fibromuscular dysplasia of the arterial wall in the younger, generally female patient. RAS may cause hypertension and may eventually cause renal failure. It is frequently bilateral, and is responsible for up to 15% of patients who require long-term dialysis. It is associated with aortic aneurysm, neurofibromatosis or can be traumatic in origin.

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

Renal Artery Stenosis:

Color flow Doppler of the aorta in coronal view. There is marked atheroma of the aortic wall. The origin of the right renal artery is demonstrated beneath the inferior vena cava.

Renal Artery Stenosis:

Direct signsFocal color aliasingColor bruit TurbulencePSV > 180 cm/secRenal Aortic Ratio > 3.5

Indirect signsAT > 0.07 secAI < 3 m/s2 RI (right left) > 5 %

Pulsatility Index (PI)0.7 1.4Resistive index (RI)0.56 0.70Peak systolic velocity (PSV)60 140 cm/s (< 180 cm/s)Systolic/Diastolic ratio (S/D) 0.26 0.4Renal Artery/Aortic Ratio (RAR) < 3.5 RI (right left) < 0.05Acceleration Time (AT)< 0.07 secAcceleration Index (AI)> 3.5 m/s2

Normal Values Renal Artery Stenosis:

Direct criteriaPlaque in anterior wall of LRA

PSV: 148 cm/sec Renal Artery Stenosis:

Indirect criteria

PSV: 85.7 cm/sEDV: 47.2 cm/sRI: 0.64Left renal hilum

Right renal hilumPSV: 125 cm/secEDV: 58.1 cm/sRI: 0.75 RI (right left) > 0.05 RA stenosis in side of lower RI Renal Artery Stenosis:

Right Renal ArteryPSV : 465 cm/sRight Renal ArteryPSV : 246 cm/s Renal Artery Stenosis:

Renal Artery Stenosis:

Renal Artery Stenosis:

Fibromuscular Dysplasia (FMD):Fibromuscular dysplasia is a condition in which at least one of your arteries has an abnormal cluster of cells growing in the artery wall. This cluster causes the artery to narrow, which can cause damage to the organs that receive blood through the narrowed artery. Fibromuscular dysplasia can cause a number of complications, such as high blood pressure and a bulging area of the artery.Fibromuscular dysplasia appears most commonly in the arteries leading to the kidneys.

Fibromuscular Dysplasia (FMD):

Fibromuscular Dysplasia (FMD):

Nutcracker Syndrome:Nutcracker syndromeis a vascular compression disorder, and refers tothe compression of the left renal vein between thesuperior mesenteric artery (SMA) and aorta. This can lead to renal venous hypertension, resulting in rupture of thin-walled veins into the collecting system with resultant hematuria.

Renal VeinCompression

Nutcracker Syndrome:SMAIVCAorta

Nutcracker Syndrome:

Due to Nutcracker syndrome backward pressure caused vericocele.

Renal vein thrombosis:Bland renal vein thrombosis is a relatively rare event in adults. It occurs in the settings of dehydration, coagulopathy, trauma, and certain renal parenchymal processes that cause the nephrotic syndrome such as membranous glomerulonephritis. It may also occur secondary to inferior vena cava thrombosis or ovarian vein thrombosis.

Renal vein thrombosis. Transverse gray-scale (A) and power Doppler view (B) of the left renal vein show an intraluminal thrombus (arrow) that only partially occludes the vessel. The aorta (A) and the inferior vena cava (lVC) are also seen. Renal vein thrombosis:

A

B

Renal vein thrombosis:

References: