RVT - Registered Vascular Technologist Abdominal Vascular Duplex Exams Questions and Answers 1 — Questions and Answers
Question 1: A patient with refractory hypertension is referred for a renal artery duplex exam. The peak systolic velocity (PSV) in the suprarenal aorta is 80 cm/s. The highest PSV obtained in the proximal right renal artery is 300 cm/s. What is the calculated Renal-Aortic Ratio (RAR), and what is the most likely interpretation?
- RAR is 3.75, suggestive of a hemodynamically significant stenosis (>60%). (Correct answer)
- RAR is 0.27, which is within normal limits.
- RAR is 3.75, which is within normal limits.
- RAR is 2.50, suggestive of a non-hemodynamically significant stenosis (<50%).
Correct answer: RAR is 3.75, suggestive of a hemodynamically significant stenosis (>60%).
The Renal-Aortic Ratio (RAR) is calculated by dividing the highest peak systolic velocity (PSV) in the renal artery by the PSV of the aorta at the level of the renal arteries. In this case, 300 cm/s ÷ 80 cm/s = 3.75. A widely accepted criterion for a hemodynamically significant stenosis of 60% or greater is an RAR of 3.5 or higher.
Question 2: When measuring the maximum diameter of an abdominal aortic aneurysm (AAA) via duplex ultrasound for surveillance, which of the following is the standard, most reproducible technique?
- Anterior-posterior diameter measured from inner wall to inner wall in a sagittal plane.
- Anterior-posterior diameter measured from outer wall to outer wall in a transverse plane. (Correct answer)
- Lumen diameter only, excluding any mural thrombus, in a transverse plane.
- Transverse diameter measured from outer wall to outer wall in a sagittal plane.
Correct answer: Anterior-posterior diameter measured from outer wall to outer wall in a transverse plane.
The standard protocol for measuring an abdominal aortic aneurysm is to obtain the maximum anterior-posterior (AP) diameter from the outer wall to the outer wall. This measurement should be taken in a transverse plane, ensuring the calipers are perpendicular to the long axis of the aorta. This technique is the most accurate and reproducible for serial surveillance and clinical decision-making.
Question 3: A 40-year-old patient presents with post-prandial epigastric pain. During a mesenteric duplex exam, the celiac artery PSV is 140 cm/s during quiet inspiration. When the patient performs a deep expiration, the PSV increases sharply to 360 cm/s with associated post-stenotic turbulence. These findings are most characteristic of:
- Atherosclerotic celiac artery stenosis.
- Celiac artery dissection.
- Median Arcuate Ligament Syndrome (MALS). (Correct answer)
- Superior Mesenteric Artery (SMA) syndrome.
Correct answer: Median Arcuate Ligament Syndrome (MALS).
Median Arcuate Ligament Syndrome (MALS) is caused by extrinsic compression of the celiac artery by the median arcuate ligament of the diaphragm. This compression is most pronounced during expiration, leading to a significant, transient increase in velocity. The velocity normalizes or improves during inspiration as the diaphragm moves and relieves the compression. Atherosclerotic disease would not vary with respiration.
Question 4: A patient with a history of chronic liver disease undergoes an abdominal duplex exam. Which of the following findings is the most specific indicator of severe portal hypertension?
- A main portal vein diameter of 14 mm.
- Splenomegaly with a spleen length of 15 cm.
- A continuous, non-phasic waveform in the hepatic veins.
- Hepatofugal (reversed) flow in the main portal vein. (Correct answer)
Correct answer: Hepatofugal (reversed) flow in the main portal vein.
While an enlarged portal vein diameter (>13 mm) and splenomegaly are common findings in portal hypertension, the most specific and definitive sign of severe disease is hepatofugal flow in the main portal vein. This indicates that the resistance within the liver is so high that blood flow has reversed its normal direction and is flowing away from the liver through collateral pathways.
Question 5: A patient with ascites, hepatomegaly, and abdominal pain is referred for an abdominal vascular duplex exam. Which of the following findings would be most consistent with a diagnosis of Budd-Chiari syndrome?
- Absence of detectable flow or visualization of thrombus within the major hepatic veins. (Correct answer)
- A highly pulsatile, 'to-and-fro' waveform in the main portal vein.
- Markedly elevated velocities (>400 cm/s) in the superior mesenteric artery.
- A patent Transjugular Intrahepatic Portosystemic Shunt (TIPS).
Correct answer: Absence of detectable flow or visualization of thrombus within the major hepatic veins.
Budd-Chiari syndrome is a condition defined by the obstruction of hepatic venous outflow. The primary diagnostic finding on duplex ultrasound is the direct evidence of this obstruction, such as thrombosis, stenosis, or complete absence of flow in one or more of the major hepatic veins. The other findings are related to different pathologies.
Question 6: A patient with a history of 'food fear' and significant weight loss is evaluated for chronic mesenteric ischemia. In a fasting state, which of the following duplex findings would be most indicative of a hemodynamically significant (>70%) stenosis?
- A low-resistance waveform in the superior mesenteric artery (SMA).
- A peak systolic velocity (PSV) of 150 cm/s in the celiac artery.
- A peak systolic velocity (PSV) greater than 280 cm/s in the superior mesenteric artery (SMA). (Correct answer)
- Retrograde flow in the common hepatic artery.
Correct answer: A peak systolic velocity (PSV) greater than 280 cm/s in the superior mesenteric artery (SMA).
The most widely accepted duplex criterion for a hemodynamically significant stenosis (>70%) in the superior mesenteric artery (SMA) is a peak systolic velocity (PSV) of ≥275 cm/s in a fasting state. A low-resistance waveform in a fasting SMA is a normal post-prandial finding, not a sign of stenosis. A celiac PSV of 150 cm/s is normal. Retrograde common hepatic flow indicates celiac occlusion, but elevated PSV in the SMA is a direct measure of its own stenosis.
RVT - Registered Vascular Technologist Abdominal Vascular Duplex Exams Questions and Answers 1
A patient with refractory hypertension is referred for a renal artery duplex exam.
The peak systolic velocity (PSV) in the suprarenal aorta is 80 cm/s.
The highest PSV obtained in the proximal right renal artery is 300 cm/s.
What is the calculated Renal-Aortic Ratio (RAR), and what is the most likely interpretation?