If a high grade stenosis or occlusion is seen in a renal artery how will the contralateral waveform appear?
It will still be a low resistance waveform
... [Show More] but it will appear weakened or dampened.
How can increased resistance be determined?
Checking Parenchymal Resistance Ratio and the Resistive Index
Where should waveforms be obtained when checking renal resistance?
Waveform and peak velocity measurements in the upper and lower pole
PR? What is it? Equation? Normal value?
Parenchymal Resistance Ratio
End Diastolic Velocity Divided by the Peak Systolic Velocity
Normal is >0.2
RI? What is it? Equation? Normal Value?
Resistive Index
Peak Systolic Velocity minus the End Diastolic Velocity Divided by the Peak Systolic Velocity
Normal <0.75
What Peak Systolic Velocity Measurement Indicates diameter stenosis of the SMA greater than or equal to 70%?
Fasting PSV equal to or greater than 275 cm/sec indicates a 70-99 % diameter stenosis
What PSV indicates a diameter reduction of the Celiac Artery equal to or greater than 70 %?
PSV equal to or greater than 200 cm/sec indicates a 70-99% diameter reduction
What can cause extrinsic compression of the celiac artery?
Median Arcuate Ligament during exhalation
When Inhalation occurs the diaphragm moves back down and compression is released.
What are the branches of the celiac artery? Type of resistance seen in the vessels? Does eating affect the waveforms?
Splenic and Hepatic Arteries
All low resistance
Not affected by eating
Most common post-op complications after a liver transplant? (4)
1. Hepatic artery occlusion causing a hepatic infarct
2. PV Thrombosis
3. Pseudoaneurysm Formation
4. IVC thrombosis
If a low resistance waveform is seen in a peripheral artery what could this indicate? (3)
1. The limb is being exercised.
2. There is an arterial obstruction in the limb
3. There is an arteriovenous fistula and the waveform is being taken proximal to the fistula.
What is the peripheral vascular system?
The veins and arteries that supply the extremities.
Post operative extremity weakness in the calf muscle with foot drop, parasthesia and pain with passive motion of the muscle would indicate what diagnosis? Treatment?
Compartment Syndrome
Treatment: Fasciotomy where the fascia is surgically split to relieve pressure
Increased renal artery flow resistance following a transplant indicates? (4)
1. Acute rejection
2. Renal Vein Thrombosis
3. Infection
4. Tubular Necrosis
What is an AVF? Causes?
Arteriovenous Fistula
Abnormal connection between an artery and a vein
Causes- Congenital and Traumatic
Describe the flow patterns of an AVF.
Artery will become less pulsatile with lower resistance( increased diastolic component)
At the point of connection will see higher velocities and turbulence
Vein becomes pulsatile
Treatment for a pseudoaneurysm?
Compression-When the neck is uniformly and completely compressed in order to cause thrombosis of the site- Size and location must be taken into account and also need to know if the patient is on an anticoagulant makes it less likely to work- Know this causes the patient substantial discomfort and usually no pain meds are given. The pain of the procedure increases the blood [Show Less]