What are the mesenteric vessels?
- Celiac
- Common hepatic
- Splenic
- SMA
- IMA
What are the two vessel that form the celiac axis?
The common hepatic and splenic.
What is the first major branch of the abdominal aorta?
The celiac axis.
Where does the celiac axis arise from?
It arises off anteriorly, about 1-2 cm below the diaphragm.
What 5 things does the celiac axis supply?
- Stomach
- Duodenum
- Liver
- Pancreas
- Spleen
Where does the superior mesenteric artery arise from?
- It arises approx. 1-2 cm below the celiac axis.
- Runs anterior and parallel to the aorta.
What 4 things does the SMA supply?
- Pancreas
- Duodenum
- Small intestine
- Colon
What is the most distal branch?
Inferior mesenteric artery.
Where is the IMA located?
- Usually located approx. 1-3 cm proximal to aortic bifurcation.
- Arises from the anterior surface of the aorta at 1 o’clock.
What does the IMA supply?
- The colon
Approx. how many people are affected by common anatomical variants in the mesenteric vessel?
Approx. 20% of general population.
What is the most common (17%) mesenteric vessel variant?
Right hepatic artery originates from an artery other than celiac artery.
What are the 4 most common mesenteric anatomical variants?
- Replaced right hepatic artery originating from the SMA (10-12%)
- Replaced common hepatic originating from the SMA (2.5%)
- Common hepatic originating from the aorta (2%)
- Common origin of celiac and SMA (<1%)
What should be done for patient preparation?
- NPD after midnight
- Supine with head slightly elevated
What are some normal mesenteric doppler waveforms in the aorta?
High resistance
What are some normal mesenteric doppler waveforms in the celiac?
Low resistance
What are some normal mesenteric doppler waveforms in the SMA?
High resistance IF fasting.
What are some normal mesenteric doppler waveforms in the renals?
Low resistance.
What are some normal mesenteric doppler waveforms in the IMA?
High resistance IF fasting.
What are some indications for chronic mesenteric ischemia?
- Abdominal pain/cramping associated with eating
- Abdominal bruit
- Post-prandial pain
- Unintended weight loss
In IAC Protocol, what vessels must be assessed?
- Abdominal aorta
- Celiac axis
- Common hepatic artery
- Splenic artery
- SMA origin
- Proximal SMA
- IMA
What must be documented in a mesenteric duplex: IAC protocol?
- Highest PSV
- Document patency of celiac and SMA
- Document any conditions of the aorta or great vessels
What is the mesenteric duplex IAC protocal in the celiac artery and what should be documented?
- Document patency
- Look for high velocities or distrubed flow in the celiac, splenic or hepatic artery.
- Note common hepatic flow direction
- Measure PSV in celiac, splenic and hepatic arteries.
- Document any flow distrubances
- If stenotic abnormal flow signals are found in the proximal celiac axis, have the patient take a deep breath and hold his breathwhile you take another sample in the celiac axis.
What is the mesenteric duplex protocol for the SMA?
- Document patency
- Look for high velocities or distrubed flow along as much of the artery as can be seen.
- Measure PSV in vessels and in any stenotic areas: assess post stenotic flow pattern.
What is the mesenteric duplex protocol in the IMA?
- Locate the IMA if possible
- Document the patency.
- Measure the PSV
- Document any stenosis and post stenotic flow pattern.
What does a normal SMA and IMA signal look like?
High resistance.
What does a low resistance signal in the SMA and IMA indicate in a FASTING patient?
Mesenteric ischemia.
What indicates a celiac artery stenosis?
- PSV measuring >200 cm/s
- Post-stenotic turbulence
What indicates a celiac artery occlusion?
- Absence of flow
- Flow in the common hepatic artery is frequently reversed.
What is normal in the celiac artery?
- <125 cm/s
- Low resistance waveform.
What indicates greater than/ equal to 70% stenosis?
- >200 cm/s
What is normal in the SMA?
- <125 cm/s
- High resistance waveform.
What is abnormal that indicates greater than/ equal to a 70% stenosis?
- >275 cm/s
What indicates an occlusion in the SMA?
- Absence of flow prominent IMA may indicate hemosignifcant SMA stenosis or occlusion.
What indicates a celiac occlusion?
- Absence of flow
- Reversed common hepatic artery flow
What is the diagnostic criteria and interpretation in the IMA?
- No commonly accepted velocity criteria
- Velocities and doppler waveforms dependent on celiac artery and SMA
- Assessing for post-stenotic turbulence when elevated velocities are obtained is crucial.
Why might a progressive occlusion of the mesenteric vessels may be relatively asymptomatic?
The gut has remarkable ability to develop compensatory collateral flow.
When mesenteric symptoms do occur, what is expected?
2 out of the 3 major splanchnic vessels are usually occluded or highly stenosis.
What are some risk factors for mesentric pathology?
- Hypertension
- Diabetes
- Smoking
- High cholestrol.
- Female
- Age
Who is more prone susceptible to MALS?
More common in younger women
Who is more susceptible to chronic mescenteric ischemia?
Elderly.
What are some mesenteric duplex indications?
- Abdominal pain/cramping associated with eating.
- Abdominal bruit
- Post-prandial pain
- Unintended and/or unexplained weight loss.
- Visceral Artery aneurysm
- Other gastrointestinal symptoms
- Post-op
What is the cause of chronic mescenteric ischemia?
Atherosclerosis and thrombosis.
What is the cause of acute mesenteric ischemia?
Embolism
What is the cause of non-occlusive disease?
Low cardiac output
What is the cause of mesenteric vein thrombosis?
Hypercoaguability
What is the cause of MALS?
The celiac trunk is compressed by the median arcuate ligament which can cause subsequent fibrosis of lumen may occur.
What is the clinical manifestations of acute mesenteric ischemia?
Sudden onset of abdominal symptoms and rapid progressions to a life-threatening conditions.
What are the symptoms of acute mesenteric ischemia?
- Abdominal pain
- Bowel evacuation
- Abdominal distention
- fever
- dehydration
- GI bleeding
- Shock
- Acidosis
- Death
What is usually involved in acute mesenteric ischemia?
SMA
What is the morality rate of acute mesenteric ischemia?
70%
What vessels does chronic mesenteric ischemia?
It typically involves atleast 2 of the 3 major vessels.
What are the symptoms of chronic mesenteric ischemia?
- Unintended weight loss
- Fear of food
- Post-prandial pain
- Patient avouds food because of pain
- Diarrhea
What is MALS caused by?
It is caused by compression of the median arcuate ligament.
How does MALS normalize?
With a deep breath (inspiration)
MALS is typically found in who?
Younger women.
What should you do whenever you find an abnormal celiac signal?
Have the patient take a deep breath and then evaluate the celiac again with them holding their breath.
What two types of doppler waveforms should you compare in MALS?
- Deep inspiration
- Complete exhalation
Descrie visceral aneurysm?
- Rare
- Most common site is the splenic artery
Describe a dissection?
- Causes include:
- athersclerosis
- FMD
- mycotic infection
- trauma
- connective tissue disorders
- Most common site is SMA
What PSV in the celiac artery indicate a ≥70% stenosis?
PSV ≥ 200 cm/s
What PSV in the SMA indicates a ≥70% stenosis?
PSV ≥ 275 cm/s
What EDV in the celiac artery indicates ≥50% stenosis?
EDV ≥55 cm/s
What EDV in the SMA indicates a ≥50% stenosis?
EDV ≥45 cm/s
What are treatment options in mesenteric pathology?
- Angioplasty and stent placement
- Arteriotomy
- Vein patch
- Decompression of median arcuate ligament
- Surgery:bypass or endarectomy
- Bypass: uses either vein or prosthetic material
In mesenteric treatment options, what are different options for bypass grafts?
- Supraceliac aorta
- Infrarenal aorta
- SMA to celiac
- Celiac to SMA
- Iliac to SMA
Where should you obtain velocity measurements in a stent/bypass graft?
- Inflow artery
- Proximal anastomosis
- Proximal graft or stent
- Mid graft or stent
- Distal graft or stent
- Distal anastomosis
- Outflow artery
What is the underlying cause for 6% of hypertensive patients?
Renal disease.
What is the overall accuracy for indentifying and categorizing a stenosis?
80-90%
What are some other image modalities?
- MRA
- CTA
Which organ is a highly specialized organ that functions to regulate volume and chemical composition of the body fluids?
Kidney
What are some of the functions of the kidney?
- Reguate volume and chemical composition of body fluids.
- Produce hormones that regulate BP and make RBC
- Maintain stable levels of electrolytes
- Excrete waste
Where is the kidney located?
- Located in the retroperitoneum.
- Dorsal abdominal cavoty
- @ level of 12th thoracic and 3rd lumbar vertebrae
What is the kidney surrrounded by?
Fibrous capsule within the perirenal fat.
What is a normal kidney length?
8-13 cm
What happens to the kidneys as one ages?
It decreases in size with age.
In the kidney, what is the hilum?
It is apoint of entry/exit for renal artery, renal vein, and ureter.
In the kidney, what is the sinus?
Cavity containing renal artery, renal vein, and collecting and lymphatic system.
In the kidney, what is the parenchyma?
It is the tissue that the renal is comprised of.
What does the parenchyma consist of?
- Cortex
- Medulla
What does the glomerulus do?
It filters the blood.
What does the tubule?
It reabsorbs and secretes fluid and electrolytes to adjust the urinary composition as necessary to maintain homeostasis of bodily fluids.
Where is the glomeruli located?
It is located in the cortex of the kidney (outer one third of the kidney)
What does the inner 2/3 of kidney consist of?
It consist of dark, striated areas (pyramids) and intervening renal columns.
Together they comprise the medulla.
Where is the renal hilum found?
It is found medially and is the point of entry for the arteries, veins, nerves and the exist of the ureter.
What is a dromedary hump?
- It is a focal bulge
- Most oftenly seen in left kidney
- Normal kidney appearance
What is a horseshoe kidney?
- Usually connected at the lower poles
- Occurs in <1% of population
What is a common kidney variant?
Hydroplastic kidney
What is a hydroplastic kidney?
It is a congenitally small kidney that may be normal or incompletely developed.
What is hydronephrosis?
It is a partial or complete urinary tract obstruction.
Which segements of the kidney does hydronephrosis affect?
- Bladder
- Ureter
- Urethral
- Intrarenal
- stones
What are the symptoms of renal calculi?
- Loin pain
- Hematuria (blood in urine)
- UT obstruction
What are the duplex characterisitcs of renal cysts?
- Hypoechoic
- Have thing, smooth. and clearly defined margins
- Exhibit acoutstic enhancement posterior to the cyst
- Increase incidence with (50% over 50)
What kind of disease is polycystic kidney disease?
Autosomal-dominant.
What causes polycystic kidney disease?
Genetics condition
What is polycystic kidney disease predipose a patient to?
End-stage renal disease.
What symptoms are associated with polycystic kidney disease?
- Loin pain
- Headaches
- Hematuria
What other cyst are usually common with PKD?
Hepatic cyst
How do renal masses present themselves on duplex?
- B-mode: demonstrates echoes within lumen
- Color image demonstrates color flow within mass
What is the protocol for doing a renal exam?
- Measure the kidney length
- Obtain signals from the distal renal artery and the renal vein
- Obtain doppler signals from the mid, upper and lower poles of the kidney.
- measure PSV/EDV
- RI
- Document any incidental findings
What is Acceleration Index (AI)?
It is the slope of the systolic upstroke divided by the transmitted frequency
What is Acceleration Time (AT)?
It is the time interval between the onset of systole and the initial compliance peak.
What does the resistive index (RI) indicate?
It indicates the state of the parenchyma in the kidney
What does a low RI indicate?
Low resistance flow
What does a high RI indicate?
It indicates high resistance flow which indicates renal parenchymal disease
What RI signifies medical renal disease or renal parenchymal disease?
>.8
What does RI give information about?
Intra-renal flow.
May be within normal limits even with a hemodynamically significant RAS
How do you find the RI?
- use 0° to isonate arteries within kidney
- Obatin doppler signals and measure PSV and EDV in upper, mid. and lower poles.
- Some labs may require the cortex and medulla
- Average together for final number
What are the characterisitics of acute renal failure (ARF)?
- Normal size kidney size and texture
- High resistance flow in kidney
What are the characterisitics of chronic renal failure?
- Small kidney size
- Thinning of the cortex and diffuse chnages in kidney texture
- High resistance flow in end stages
It is estimated that how many people in the US population have hypertension?
50 million
How many hypertensive patient have an underlying renal disease?
6%
Renal artery disease represents the most common correctable cause of ____________
Hypertension
What can cause renal ischemia?
A stenosis or occlusion of the main renal artery
What does a renal ischemia from a renal stenosis/occlusion trigger?
It triggers the renin-angiotensin mechanism to increase flow to the kidney.
Renal artery stenosis can cause or contribute to what?
Renal insuffieciency by causing renal parenchymal damage.
What are 4 clinical maifestations observed in renal artery stenosis?
- Asymptomatic “incidental RAS”
- Renovascular hypertension
- Ischemic nephropathy
- Accelerated CV disease
- CHF
- Stroke
- Secondary aldosteronism
Where does the renal artery originate?
Inferior to SMA
Which renal is longer?
RRA is longer in length than the LRA
how does the right renal courses in regards to the RRV and IVC?
RRA courses posteriorly to RRV and IVC
How does the LRA course in regards to the LRV?
LRA courses posteriorly to LRV
Where does the LRV course?
It courses between abdominal aorta and SMA
Duplicate main arteries and polar accessory renals occur in _______ of patients/
12-22%
What is the most common variant?
Most renal arteries arise below the main renal artery and terminate at polar surfaces of kidney instead of hilum.
Where can accessory renal arteries arise from?
The aorta or iliac arteries.
In which renal do these variants more commonly occur in?
Occurs more frequently on the left than right.
WHat is included in a patients clinical history?
- HTN
- Abnormal urinalysis
- Hematuria
- CHF
- Renal failure
- Flash pulmonary edema.
What are some renal vasculature pathology?
- Athersclerosis-stenosis or occlusion
- Fibromuscular dysplasia
- Embolism
- Aneurysm
- AV fistula
- External compression
- Vasculitis
What are some common risk factors for renal disease?
- Age
- Hypertension
- Diabetes
- SMoking
- Hyperlipidemia
- Obesity
- Coronary artery disease
- Race
- Family Hx
What are some indications for a renal exam?
- Sudden onset or worsening of chronic hypertension
- Elevated BUN levels (blood-urea-nitrogen), azotemia.
- Cystic kidney disease
- Atrophic kidney
- Aneurysm
- Pre- and/or post-intervention
- Abdominal bruit
- Hypertension ina young patient.
How should you preform a renal artery duplex?
- Patient supine
- Evaluate the aorta, sma, and celiac arteries
- Obtain representative doppler signals from each.
- DOcument any abnormalities
- Obtain aortic PSV at level of SMA
- Used to calcuate the renal-aortic-ratio (RAR)
Where does the RRA arise from in relation to the aorta?
Arises from the anterior aorta at about 10-11 o’clock.
Below LRV
Where does the LRA arise from in relation to the aorta?
It arises from the posterior/lateral aorta about 4-5 o’clock.
Where do you want to assess each renal artery from?
From its origin to the hilum of the kidney.
Where do you want to obatin represenative doppler signals in the renals?
- Ostium
- Proximal
- Mid
- Distal
What do you want to look out for when scanning a renal artery?
Look for areas of high velocity or flow distrubances that may he related to a stenosis.
How do you want to preform a renal exam on a patient in a lateral decubitus position?
- Measure the kidney in long
- Obtain signals from the renal parenchyma in the upper, mid, and lower poles using 0 degree insonation.
- Obtain angle-corrected velocities in the distal renal artery and a doppler signal from the renal vein.
What is a normal PSV in the renal arteries?
90-120 cm/sec
What happens to the PSV and EDV from the renal artery to cortex?
It decreases.
Typical velocities for distal RA?
70-90 cm/s
Typical velocities for the renal sinus?
30-50 cm/s
Typical velocities for renal cortex?
10-20 cm/s
What is a hemodynamically significant renal artery stenosis considered to be?
60% or greater
How do you calculate the Renal Aortic Ratio?
PSV of renal artery/ PSV of aorta =RAR
- PSV of aorta usually 80-100 cm/s
- Velocities in aorta that are above or below the mean may make RAR inaccurate
What is normal diagnostic criteria in the renal arteries?
- Sharp upstroke with low resistance forward flow in diastole
- Peak systolic velocities of less than 180 cm/s
- Renal/aortic ratio less than 3.5
What is the diagnostic criteria for a hemodynamically insignificant stenosis of less than 60%?
- Peak systolic velocity of 180 cm/s or greater.
- Renal/aortic ratio of less than 3.5
What is the diagnostic criteria that is hemodynamically significant disease of 60% or greater?
- Renal/aortic ratio of 3.5 or greater
- PSV greater than 180 cm/s
- Post-stenotic turbulence.
What is the diagnostic criteria of a renal artery occlusion?
- No arterial signal in renal artery
- Kidney size of less than 8 or 9 cm
- If flow detected in kidney, usually less than 10 cm/s
What is FMD?
- Non-athersclerotic disease
- May affect bilateral renal arteries, but more common on right
- Typically affects younger females (25-50 Y/O)
- Affect internal carotid arteries
- Mid and distal segments
- Affects ICA
- Mid and distal segments
- “string of beads” appearance
When is FMD suspected?
- When velocities increase in the mid/distal portions of the RA
- Criteria is similar to other arterial segements
- PSV doubles the proximal arterial segments PSV
What is an indirect method of detecting renal artery stenosis?
- Obtain signals from the different poles of the kidney and evaluate for acceleration time
- Normal signals have rapid acceleration time
- Patients with renal artery stenosis will have a slower acceleration time, described as the tardus parvus waveform.
Describe renal artery aneurysms
- More often saccular than fusiform
- Typically occurs before reaching the parenchyma
What is nutcracker syndrome?
It is the compression of the left renal vein as it passes between the SMA and aorta
What does Nut cracker syndrome for to the venous velocities and diameter?
- Increased venous velocities at site of compression
- Venous diameter may be increased distal to compression point
What are the symptoms associated with nutcracker syndrome?
- May be completely asymptomatic
- Microhematuria
- Left flank pain
What are some therapeutic options for renal disease?
- Medical therapy
- anti-hypertensive medication
- Surgical
- Endarectomy
- Bypass
- Aorto-renal
- Hepato-renal
- Spleno-renal
- Endovascular
- Angioplasty
- Stent
What are some anti-hypertensive medicatiom?
- Diuretics
- ACE inhibitors
- Beta-blockers
- Calcium-channel blockers
What do diuretics?
Increase urine production to remove water and sodium
What do ACE inhibitors?
Angiotensin is an enzymes that, when activated, causes blood vessels to constrict.→Results in high BP and strain on heart→ACE inhibitors prevent this by dialating blood vessels and lowering BP
What do beta blockers do?
blocks beta receptors
What do calcium channel blockers do?
SLows the rate in which calcium passes into the heart muscle and into the vessel walls.
This relaxes the vessel, lowering the BP
