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Adv. Vas. Son.

Test 3 Abdominal Doppler Renal

How many people in the United States have Renovascular HTN? Estimated to affect 50,000,000 people
Up to what % of HTN PTs have underlying renal disease? 6% have underlying renal disease
In severe diastolic HTN PTs , up to what % are related to renal artery stenosis? 40% are related to renal artery stenosis
What are the causes of Renovascular HTN? Atherosclerosis, usually in the Prox renal A (Most common etiology), Fibromuscular Dysplasia (FMD), Dissection &/or extension of an aortic dissection
What are the indications of Renovascular HTN? Uncontrolled HTN, Especially in younger PTs, Decreasing renal function
Result from stenosis with Renovascular HTN: There is a ↓ in blood pressure & flow w/in kidney, Casues release of Renin into blood stream, Renin is converted into angiotensin II w/ vasoconstriction, sodium & water retention
Renal artery stenosis should be suspected with: Sudden onset or worsening chronic HTN, Unexplained renal insufficiency, HTN in children
Duplex ultrasound is used to detect renal artery stenosis by: Providing anatomical as well as hemodynamic function info, Low cost w/out risk of ionizing radiation or use of nephrotoxic contrast agents
Atherosclerosis facts: Most common, Lesions often affect origin & prox 3rd of vessel, More common men than women, Bilateral 30% of the time
Risk factors for Atherosclerosis: Age, HTN, smoking, diabetes, hyperlipidemia, past history of coronary &/or peripheral arterial disease
Medial Fibromuscular Dysplasia facts: 2nd most common cause of Renovascular disease, Non-atherosclerotic disease affects mid-to-distal segment of vessel (fibrous thickening of vascular walls), Occurs in women 25-50 (90%), Often bilat, Associated w/HTN,
How does Medial Fibromuscular Dysplasia appear on ultrasound or angiogram? "String of beads" appearance
What occurs in the mid to distal segments of renal arteries and can also occur in the carotid arteries? Renal Fribromuscular Dysplasia
If renal artery stenosis is detected distal to the origin in mid segment what should be suspected? Fibromuscular Dysplasia (FMD)
What are some other less common disease processes that can impact renal artery include: Aortic dissection, Aneurysms of main or segmental renal arteries, Aortic coarctation proximal to renal arteries, Arteriovenous fistulae, Arteritis, Extrinsic compression by tumor or other mass
Kidney are what type of organs? Retroperitoneal organs
Where are the kidneys located? Between 12th thoracic and 3rd lumber vertebrae, The Right kidney is inferior to the Left
What is NORMAL kidney length? Width? Length 9-13 cm, Width 5-7cm, May decrease with age
What is the Renal Hilum? Area through which renal artery, vein, & ureter enter the kidney
What is the Renal Sinus? Cavity which contains the renal artery & veins & collecting system, Appears brightly echogenic on sonographic imaging (mostly fat, fibrous tissue)
Renal Parenchyma Medulla: Contains 12-18 renal pyramids (triangular shaped)
Renal Parenchyma Cortex: Outermost area of kidney (lies beneath renal capsule), Some cortical tissue extends between medullary pyramids (columns of Bertin)
What may be used as an acoustic window to the left kidney? Spleen
Segmental renal arteries are branches of the what? Main renal artery they enter through the renal hilum
Interlobar arteries arise from the what? Segmentals; they penetrate the renal parenchyma and run between the renal medullary pyramids
Arcurate arteries branch from where? The Interlobars and turn at the cortico-medullary junction to course parallel to cortex surface
Interlobular arteries (cortical branches) extend where? Into the cortex
Renal Arteries facts: Arise lateral or posterolateral from the abdominal aorta, Left usually more superior than right, Right renal A courses posterior to the IVC & right renal V, RRA has a longer course than left
After entering the renal hilum the renal arteries do what? Divide into segmental branches that give rise to interlobar, arcuate, and interlobular arteries within parenchyma
Renal Veins facts: Course anterior in renal hilum (renal A lies between V & ureter), Right has a short course from kidney to IVC, Left courses anterior to the aorta; Posterior to SMA (has much longer course than right)
Horseshoe kidney anomaly: Kidneys are joined at lower poles, Isthmus lies anterior to Aorta at level of 4th or 5th lumbar vertebrea
Duplicate renal artery anomaly: Often arise from aorta below main renal artery, Course to polar surfaces of kidney
Other Kidney Anomalies: Right renal artery superior to the IVC, Bifid left renal vein, Retroaortic left renal vein
What is the NORMAL renal length? 9-13 cm
Renal length > 2-3 cm compared to contralateral kidney indicates what? Compromised flow in smaller kidney
How do you measure the kidney? Pole-to-pole
Accessory Renal Arteries facts: May arise from aorta, above or below the main renal As, On right side they may pass anterior IVC, Often evaluated best by using longitudinal oblique view of aorta, can also use TRV of kidney, Power Doppler helpful
What are the only low resistance vessels distal to the SMA? Renal Arteries
NORMAL Renal Aorta findings include what: Anechoic lumens w/ smooth arterial walls, Spectral Doppler of Prox Ao will demonstrate rapid sys upstroke, sharp sys peak, & forward diatolic flow, PSV between 60 &100 cm/s, Distal to renal As, Ao waveform has slightly lower Vel & more triphasic flow
What should you identify? Areas of aneurysm dilation, dissection, &/or atherosclerotic plaque
NORMAL Renal Artery shows: Anechoic lumen with smooth walls
NORMAL Spectral Doppler demonstrates what: Rapid sys upstroke, Slightly blunted peak, Forward diastolic flow (high diastolic vel), Early sys peak often seen on upstroke to systole, PSV=90-120 cm/s, EDV exceeds 1/3 of PSV value, R <0.70 (Low Res)
PSV and EDV decreases throughout what? Length of artery and into parenchyma
Renal Artery stenosis of less than hemodynamic significance facts: Represents < 60% stenosis, MAy see atheosclerotic plaque on Bmode, Color is helpful in identifying regions of disordered flow & narrowing of lumen, ↑ in PSV up to 180 cm/s, No ↓ in flow distal to lesion, No post stenotic turbulence
Flow reducing Renal Artery stenosis facts: Representa >60% sten, PSV ↑es significantly above 180 cm/s, Post-sten turbulence is present, Low flow in distal renal artery, RAR > 3.5
With >80% stenosis, changed include: Delayed systolic upstroke, Loss of early systolic peak (ESP), PSV decreased distally
Renal Artery Stenosis facts: Look for regions of Vel ↑ & post stenotic turbulence, Carefully map these regions w/ spectral doppler, Record peak systolic vel from the waveform demonstrating max vel
Renal-Aortic Ratio (RAR) facts: A high measured vel in Renal may be false due to a hig >70º Doppler angle-Beware! Calculate the Renal/Aortic peak systolic vel ratio (RAR)
How do you calculate RAR? Highest Vel obtained in the renal artery divided by the peak vel from the aorta taken prox to renal level (near SMA)
What are the pitfalls to using RAR? Aortic PSV >100 cm/s may underestimate stenosis significane, Aortic PSV <40cm/s may overestimate stenosis significance
RAR >3.5 is consistent with what? >60% stenosis
Renal artery occlusion facts: Confirmed by using optimized spectral, color, & power doppler, Absence of flow in the main renal A, Multiple planes & approaches may be required, Low Vel Doppler signals are usually noted in the renal parenchyma, Small kidney size may suggest occlusion
PSV <10 cm/s is consistent with: Chronic renal artery occlusion
How small must the kidney be to suggest occlusion? <8cm
Elevated blodd urea nitrogen (BUN) and serum creatinine also indicate what? Medical renal disease
How does NORMAL parenchymal signals demonstrate? Continuous high diastolic flow
Parenchymal (medical) disease results in impedance to arterial inflow facts: Flow & Vel is reduced, Resistance in main renal & paraenchymal renal vessels ↑es , RI >08 indicates ↑ed renovascular resistance/medial renal disease, Diastolic to systolic ratio <0.3
What is NORMAL RI? <0.7 is indicative of normal flow in parenchyma
How is Diastolic to systolic velocity ratio calculated? EDV divided by PSV
What is NORMAL EDR? >0.2
How is RI calculated? Subtracting EDV from the PSV, then divide by PSV
Direct assessment Renal Artery Doppler Limitations: Depth of renal arteries, Motion of respiration, intra-abdominal gas, Obesity, Previous abdominal surgery, High techinical failure rates (12-25%), Accessory renal As (Polar As found in >20% of PTs), Poor Doppler angles, Long exam time (1-2 hrs)
For Renal Hilar Evals what are the Doppler techniques? Use highest TD freq possible (3-5 MHz), Larger Doppler sample vol (gate @ 3-5mm), Adjust sweep speed, Vel scale set to lowest reading that does nto alias, Low wall filter, Color flow used to located renal parenchymal vessels
Acceleration time (AT) >0.1 indicates what? Proximal renal artery disease
>60% main renal artery stenosis facts: Prolonged AT>0.1 sec, Tardus-Parvus waveform, Loss of early systolic peak (ESP), Flattened systolic upslope, Abnormally low RI, Reduced color flow in kidney, unilaterally
Pitfalls of indirect assessment: Accessory renal As, AT may remain normal in PTs w/ elevated renovascular resistance, Stenosis in the 60-79% range may not affect hilar waveform, No distinction between renal A occlusion & renal A sten
Other arterial disease that may cause delayed systolic upstroke? Aortic coarctation or Aortic stenosis
Indirect hilar assessment is a good toll but should not be the sole indicator of renal artery stenosis because: Requires meticulous technique, Accuracy drastically improves @ >70%, If RI >0.8 comparison to contralateral kidney is essential, If indirect result is positive or equivocal-main renal As should be scanned directly
Where are renal stents most likely to be placed? In ostium or proximal segment
Where are renal stents most readily visualized? From cross-sectional image of aorta at the level of the renal artery origins
What improves visualization for stents? Harmonic &/or compound imagining
Slight velocity increased are expected due to what? Reduction in arterial compliance
Features to look for that indicated restenosis with stents: Focal vel increases, Poststenotic turbulence, Dampening of distal waveform
Increased PSV without poststenotic turbulence often a result of what> Stent characterisitics
Normal renal veins have what? Anechoic lumens and respiratory phasicity on Doppler
Continuous, nonphasic low vel flow will be noted in the presence of what? Thrombosis
Abnormalities of renal veins include: Acute thrombus, Partial venous obstruction, Recanalization, collateralization, and extrinsic compression (Bmode and doppler must be optimized to identify this abnormalities)
What are other features of renal vein thrombosis: Renal atrophy, Increased renal parenchymal echogenicity, High vel in vein in the presence of compression
What is Left renal vein compression by mesentery or SMA? Nutcracker syndrome
With Renal Vein thrombosis what may PTs present with? Acute renal failure with pain and hematuria or suspicion of renal cell carcinoma with tumor extension
Absence of spectral, color, or power doppler signal suggests what? Renal vein thrombosis
Retrograde, blunted diastolic flow in renal artery suggests what? Renal vein thrombosis
Created by: EmilyGriffin
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