Chapter 25: The Renal Vasculature Flashcards
the slop of the systolic upstroke (kHz/s) divided by the transmitted frequency
acceleration index
the time interval between the onset of systole and the initial compliance peak
acceleration time
A Doppler spectral waveform recorded immediately distal to a flow-reducing stenosis. The waveform exhibits decreased peak systolic velocity and disordered flow during systolic deceleration and diastole as a result of the pressure-flow gradient associated with the lesion
poststenotic signal
The highest peak systolic renal artery velocity divided by the peak systolic aortic velocity recorded at the level of the celiac and/or superior mesenteric arteries. The ratio is used to identify flow limiting renal artery stenosis
reanl-aortic velocity ratio
narrowing of the renal artery most commonly as a result of atherosclerotic disease or medial fibromuscular dysplasia
renal artery stenosis
a tiny tube inserted into a stenotic renal artery at the time of arterial dilation (angioplasty). The stent, usually a metallic mesh structure, help to hold the artery open
renal artery stent
the outermost area of the kidney tissue lying just beneath the renal capsule, the fibrous covering of the kidney
renal cortex
the area through which the renal artery, vein, and ureter enter the kidney
renal hilum
the middle area of the kidney lying between the sinus and the cortex. The medullary tissue contains the renal pyramids
renal medulla
the opening of the renal artery from the aortic wall
renal ostium
a medical disorder affecting the tissue function of the kidneys
renal parenchymal disease
the ratio between the peak systolic velocity recorded in the proximal or midsegment of the renal artery compared to the PSV recorded in the distal segment of the renal artery
renal-renal velocity ratio
the central echogenic cavity of the kidney, It contains the renal artery, renal vein, collecting, and lymphatic systems
renal sinus
The visible indentation at the base of the neck where the neck joins the sternum
suprasternal notch
the prominence of the pelvic bones noted in the lower abdomen
symphysis pubis/ pubic bones
usually ostial or proximal; any segment of main renal; parenchymal arteries; acoustically homogenous or heterogenous; smooth or irregular surfaced; high-velocity with poststenotic turbulence if >60% diameter-reducing stenosis; low velocity if stenosis is preocclusive
atherosclerosis
mid-to-distal renal artery; parenchymal arteries; segmental narrowing and dilation of the renal artery; alternating regions of forward and reversed flow; high velocity compared to proximal arterial segment
medial fibromuscular dysplasia
focal or entire length; intraluminal echoes of varing echogenicity dependent on chronicity; kidney length <8-9cm; absent Doppler signal in imaged artery; low-velocity, low-amplitude signals in the renal parenchyma
Occlusion
Renal artery stenosis is the most common cause of:
secondary hypertension
chronic renal insufficiency
incident end-stage renal disease
Narrowing of renal artery
renal artery stenosis
most commonly the result of atherosclerotic disease or medial fibromuscular dysplasia
renal artery stenosis
The kidneys are located _______ in dorsal abdominal cavity between 12th thoracic and 3rd lumbar vertebrae
retroperitoneally
Normal kidney length
9-13 cm
Most common kidney anomaly
horseshoe kidney
Kidneys joined at lower poles by isthmus of tissue which lies anterior to aorta at level of 4th or 5th lumbar vertebrae
horseshow kidney
Renal artery supply:
distal aorta
common iliac artery
inferior mesenteric artery
most common congenital anomaly of the urinary tract
duplication of the renal collecting system
two pelvicalyceal units are present with ureters that insert separately into the bladder
complete duplication of the renal collecting system
renal pelvis is bifid with either a single ureter or two ureters that converge along their course to the bladder
partial duplication of the renal collecting system
two parts of renal parenchyma
medulla
cortex
triangular shaped; carry urine from cortex to renal pelvis
renal pyramids
outermost area of kidney; lie just beneath the renal capsule; area where urine is produced
renal cortex
cortical tissue; lies between medullay pyramids
columns of Bertin
How many medullary pyramids are located in the kidney?
12-18
located halfway between the suprasternal notch and symphysis pubis curring through lower border of first lumbar vertebrae, ninth costal cartilages, and pyloris
transpyloric plane
The ______ are located approximately 2 cm below transpyloric plane arising from anterior, lateral, or posterolateral wall of the abdominal aorta
renal arteries
The ___ renal artery orginates slightly more cephalad than the ____ renal artery.
left
right
courses on a slightly inferior path from the posterolateral aortic wall, passes posterior to the left renal vein, and is crossed by inferior mesenteric cein
left renal artery
courses anterolaterally and then moves posterior to IVC and right renal vein
right renal artery
arise from aortic wall below main renal artery; course to polar surfaces of kdineys
accessory polar renal arteries
At the level of the _____ the renal artery divides into large anterior and small posterior branches
renal hilum
The renal arteries give rise to:
interlobar, arcuate, and interlobular arteries
courses anteriorly from renal hilum with ureter arising posteriorly; short course from hilum of kidney to IVC
right renal vein
courses anteriorly from renal hilum with ureter arising posteriorly; courses anterior to the aorta just below origin of superior mesenteric artery
left renal vein
primary cause of renal artery stenosis
atherosclerotic disease
Renal artery disease primarily affects ____ and _____.
ostium
proximal third of renal artery
second most common curable cause of renovascular disease
medial fibromuscular dysplasia
cmoonly affects mid-to-distal segments of renal artery; lesions produce segmental concentric narrowing and dilation, resulting in “string of beads” appearance
medial fibromuscular dysplasia
Patient preparation
fast for 8-10 hours
extrinsic compression
“nutcracker syndrome” or mesenteric compression syndrome
______ arteries enter the renal hilum
accessory
_______ course to surface of kidney
polar renal arteries
only low-resistance vessels distal to SMA
renal arteries
If a difference in renal length greater than 1 cm is found it is suggestive of:
compromised flow on side with smaller kidney
Most common predisposing factor to renal vein thrombosis
primary renal disease
stabilized gas microbubbles that strong enhance echoes from moving blood cells due to difference in compressability and density
contrast-enhanced imaging
Doppler waveform of normal renal artery
rapid systolic upstroke
sharp systolic peak
forward diastolic flow
The PSV in the renal artery ranges from ___ to ___ cm/s
74 to 127
Distal renal artery PSV
70-90 cm/s
renal sinus PSV
30-50 cm/s
renal cortex PSV
10 - 20 cm/s
increase in renal artery PSV approaching 180 cm/s
Narrowing of renal artery by 30-60%
PSV increases significantly about 180 cm/s
Renal artery stenosis >60%
If the degree of renal artery narrowing exceeds ___% the systolic upstroke will be delayed, compliance peak is lost, and PSV will decrease distally
80
PSV ranges in the proximal abdominal aorta
60-100 cm/s
absense of flow in main renal artery
renal artery occlusion
PSV in cortex less than ____ cm/s in renal artery occlusion
10
Increased vascular resistance associated with _____ diastolic flow
decreased
amount of arterial impedance is dependent on:
age
region of renal arterial system
RI is normally highest in the _____
renal hilum
RI is normally lowest in the _____
interlobar arteries
The normal diastolic to systolic velocity ratio in the kidney is ______
less than 0.3
The normal acceleration index is less than ____
3.78
The acceleration index is found by taking the ______ divided by ______
slope of systolic upstroke
transmitted frequency
time internal between onset of systole and initial compliance peak
acceleration time
The normal accleration time is greater than ____ ms
100
ratio of highest renal artery PSV in the aortic PSV at level of mesenteric arteries
renal-aortic ratio
In >60% diameter reduction the RAR is less than
3.5
In significant renal artery stenosis the RAR is greater than
3.5
Renal artery PSV greater than 180 cm/s is an indicator of:
renal artery stenosis
kidney appears more echogenic
renal atrophy
vein most often dilated; respirophasic flow absent; kidney usually enlarged
acute renal vein thrombosis
left renal vein compressed by mesentary or SMA; high velocity signal associated with color bruit noted in vein as crosses anterior to aorta
nutcracker syndrome
most common cause of renal artery stenosis with lesions occurring most frequently in ostium or proximal segment of renal artery
atherosclerotic plaque
If a patient has an RI greater than ___ the patient is unlikely to benefit from renal revascularization.
0.8
associated with renal atrophy; successful revascularization is unlikely if the renal length is less than __ cm
9
PSV greater than 400 cm/s; cortical EDV 5 cm/s or greater;
high risk progression to renal atrophy
__% of pediatric hypertension cases occur secondary to another abnormality.
85
Up to 70% of pediatric cases of renal artery stenosis are caused by:
fibromuscular dysplasia
second most common type of childhood renal disoder
multicystic renal dysplasia
In a neonate the pole to pole length of kidney is ____
less than 4 cm
Which of the following is NOT a limitation of contrast angiography?
a. detailed anatomic information
b. lack of hemodynamic information
c. no identification of functional significance of renal artery disease
d. invasive with possible nephrotoxic contrast
b
Which of the following is true regarding duplex ultrasound assessment of the renal vasculature?
a. provides anatomic information
b. provides hemodynamic information
c. painless and noninvasive
d. all of the above
d
What is the normal length measurement of the kidney?
9-13 cm
What are kidneys that are joined at the lower poles by an isthmus of tissue that lies anterior to the aorta?
horseshoe kidneys
Why is the renal sinus normally brightly echogenic on a songraphic image?
fat and fibrous tissue in the sinus
What the triangular shaped structures within the inner portion of the kidney that carry urine from the cortex to the renal pelvis?
renal pyramids
What is the most common congenital anomaly of the urinary tract?
duplication of the renal collecting system
The right renal artery usually courses _____ from the aorta, then passes ______ to the inferior vena cava
anterolateral, posterior
Which vessel courses anterior to the aorta but posterior to the superior mesenteric artery and anterior to both renal arteries?
left renal vein
In which of the following renal artery segments does atherosclerotic disease in the renal artery typically occur?
a. origin to proximal third
b. distal renal artery just before entering the kidney
c. mid-to-distal segment
d. interlobar arteries within the renal parencyhma
a
Which of the following patients would be suspected of fibromuscular dysplasia in the renal artery?
a. an 85 year old diabetic male
b. a 66 year old female with a hisotry of well-controlled hypertension and smoking
c. a 25 year old male with chronic asthma
d. a 32 year old female with poorly controlled hypertension
d
What is the most appropriate transducer for use in the evaluation of the renal arteries?
2-5 MHz curved linear
At which level is a spectral Doppler waveform with peak systolic velocity needed from the aorta for us in the renal-aortic ratio
proximal, at the level of the celiac and superior mesenteric arteries
To identify the renal artery ostia from a midline approach, an image is obtained from which location?
transverse, slightly inferior to the superior mesenteric artery
Which of the following is an ultrasound modality that has a low angle dependence that may be helpful in identifying duplicate renal arteries?
a. color-flow Doppler
b. power Doppler
c. spectral Doppler
d. pulse inversion Doppler
b
Using which angle of insonation are flow patterns within the kidney parenchyma typically obstained with a spectral Doppler?
0 degrees
When comparing renal length from side to side, how much of a difference suggests compromised flow in the smaller kdiney?
3 cm
Which of the following describe normal spectral Doppler waveform characteristics in the renal artery?
a. high resistance, minimal diastolic flow with velocities in the range of 90 to 120 cm/s
b. low resistance, high diastolic flow with velocities in the range of 90 to 120 cm/s
c. low resistance minimal diastolic flow with velocities in the range of 10 to 120 cm/s
d. high resistance high diastolic flow with velocities in the range of 50 to 70 cm/s
b
A patient presents to the vascular laboratory for a renal artery duplex evaluation. During the examination, velocities in the right renal artery origin reach 175 cm/s with no evidence of poststenotic turbulence. Velocities on the left were 100 cm/s. What do these findings suggest?
right renal artery stenosis less than 60%
Which of the following spectral Doppler waveform changes will NOT occur distal to a hemodynamically significant stenosis of the renal artery?
a. delayed systolic upstroke
b. loss of compliance peak
c. decreased peak systolic velocity
d. increased peak systolic velocity
d
Which of the following findings within the kidney are consistent with renal artery occlusion?
a. kidney length of greater than 10 cm, velocities less than 10 cm/s in the renal cortex
b. kidney length of less than 9 cm, velocities less than 10 cm/s in the renal cortex
c. kidney length greater than 13 cm with no detectable flow within the renal parencyhma
d. kidney length less than 9 cm, velocities greater than 20 cm/s in the renal cortex
b
A patient presents to the vascular lab with suspected acute tubular necrosis. Which of the following findings on the renal artery duplex examination would be consistent with this condition?
a. renal artery velocities greater than 180 cm/s, EDR of 0.35
b. renal artery velocities greater than 180 cm/s, RI of 0.6
c. renal artery velocities of 70 cm/s, EDR of 0.19
d. renal artery velocities of 70 cm/s, RI of 0.5
c
What is measured to determine acceleration time?
onset of systole to the early systolic peak
During a renal artery duplex ultrasound examination, proximal aortic velocities of 100 cm/s, proximal right renal artery velocities of 200 cm/s, and proximal left renal artery velocities of 400 cm/s were found. Which of the following describes these findings?
a. right RAR 2.0 = 2.0, less than 60% stenosis; left RAR = 0.4, less than 60% stenosis
b. right RAR = 0.2, more than 60% stenosis; left RAR = 0.4, more than 60% stenosis
c. right RAR = 2.0, less than 60% stenosis, left RAR = 4.0, more than 60% stenosis
d. right RAR = 0.2, more than 60% stenosis; left RAR = 4.0, less than 60% stenosis
c
Which of the following may result in misinterpretation of the hilar acceleration time?
a. elevated renovascular resistance
b. systemic arterial stiffness
c. renal artery stenosis in the 60-79% range
d. all of the above
d
Under which conditions is the renal-to-aortic ratio likely inaccurate?
a. the abdominal aortic velocities are between 75 and 90 cm/s
b. the abdominal aortic velocities are over 100 cm/s or below 40 cm/s
c. the renal artery velocities exceed 300 cm/s
d. the renal artery velocities are below 100 cm/s
b
During renal duplex evaluation, the left renal vein near the hilum is noted to have continuous, nonphasic low-velocity. What do these findings suggest?
proximal renal vein thrombosis
A patient presents to the vascular lab for follow up after renal artery stent placement. Velocities within the distal segment of the stent reach 250 cm/s. At other follow ups at 6 and 12 months, velocities in the distal remain 250 cm/s. What are these findings consistent with?
increased velocity because of size mismatch from the stent to native vessel
Which of the following represents renal duplex findings that demonstrate a high risk for renal atrophy and likely unsuccessful renal vascularization?
a. renal artery PSV less than 400 cm/s and cortical EDV greater than 10 cm/s
b. renal artery PSV greater than 400 cm/s and cortical EDV less than 5 cm/s
c. renal artery PSV greater than 160 cm/s and cortical EDV less than 10 cm/s
d. renal artery PSV greater than 200 cm/s and cortical EDV less than 5 cm/s
b
Patients with sudden onset of chronic hypertension, azotemia, unexplained renal insufficiency, or pulmonary edema should be evaluated for ______.
renal artery stenosis
In most patients, renal artery disease is correctable with treatment planning providing _____ for hypertension and stabilization of renal function in patients with chronic renal failure.
control or cure
Because of the ______ of the contrast agents, computed tomography angiography is often reserved for use as secondary confirmatory study.
nephrotoxicity
The kidneys are located ______ in the dorsal abdominal cavity between the 12th thoracic and third lumbar vertebrae. The kidney
retroperitoneally
For the purpose of sonographic examination of the kidney, it is divided into ___ main areas.
4
The renal arteries can be identifited approximately ___ below the ______ plane, with the left renal artery slightly more cephalad than the right.
2cm
transpyloric
Duplicate main renal arteries that enter the kidney through the renal hilum or accessory polar renal arteries are present in ____ of patients.
12-22%
Owing to the location of the inferior vena cava, the right renal vein has a ____ course, and the left renal vein typically courses ____ to the aorta.
short
anterior
The second most common curable cause of renovascular disease is ______, which occurs most commonly in women aged 25 to 50 years.
medial fibromuscular dysplasia
Elevating the examination table, keeping the patient close to the sonographer’s side, and not overextending the arm are all ways to maintain _____ positioning.
correct ergonomic
Extrinsic compression of the left renal vein may result in ______ syndrome.
mesenteric compression/nutcracker
_____ imaging, derived from grayscale, B-mode imaging, utilizes shorter pulses and provides visualization of moving vascular reflectors, independent of insonation angle and does not depend on Doppler shift.
B-flow
A useful approach to identify the ostia of the renal arteries that involves having the patient in a decubitus position and imaging the aorta in a longitudinal plane to view the renal arteries from the lateral aortic walls is termed the _____ approach.
banana-peel
_____ Doppler is valuable in identifying duplicate renal arteries because of its lower angle dependence and sensitivity to low flow states.
power
An alternate position to access the distal segments of the renal arteries is in the ____ position, with the patient’s midsection flexed over a pillow.
prone
In addition to evaluation of the renal vasculature, the ____ should be examined for cortical thinning, renal calculi, masses, cysts, or hydronephrosis.
kidney
Accuracy of renal length is enhanced by averaging ____ separate measurements
3
In the presence of renal vein _____, renal artery waveforms demonstrate retrograde, blunted diastolic flow components.
thrombosis
Improved diagnostic accuracy has been shown in the kidneys, liver, mesenteric, and peripheral vessels with the use of _____.
CEUS
The proximal aorta demonstrates rapid systolic upstroke and ____ flow during diastole, whereas the distal abdominal aorta demonstrates a _____ flow pattern that reflects the elevated vascular resistance of the lower extremities/
forward
multiphasic
An early _____ peak is often seen on the upstroke to systole in a normal renal artery/
systolic
When the degree of renal artery narrowing exceeds __%, the systolic upstroke is delayed, the compliance peak is lost, and the PSV will decrease distally/
80
With chronic renal artery occlusion, the PSV in the cortex will be less than ___ cm/s, and pole-to-pole length of the kidney will be less than ___ cm
10
9
When parenchymal disease is present, increased renovascular ______ is demonstrated throughout the kidney, characterized by ______ diastolic flow.
resistance
decreased
Indirect renal hilar evaluations use ______ index or time to provide assessment of renal artery stenosis.
acceleration
Current diagnostic criteria for identification of renal artery stenosis are based on the _______ ratio greater than ____
Renal-aortic
3.5
With nutcracker syndrome, a ______ signal with associated color bruit is noted int he left renal vein as it crosses anterior to the aorta.
high-velocity
When evaluating a stented renal artery, velocity _____ are typically identified, making identification of stenosis difficult.
increases
When evaluating pediatric patients for renal artery disease, it is important to note that the _____ is normally higher in children than in adults.
velocity
The most common cause of renal artery stenosis in the pediatric patient is ______.
fibromuscular dysplasia
