RVT Peripheral Arterial Physiologic Testing 3 — Questions and Answers
Question 1: Which statement BEST describes the Windkessel effect and its importance in peripheral arterial testing?
- It refers to venous pooling that affects ABI accuracy
- It is the elastic recoil of large arteries that dampens pulsatile flow and maintains diastolic pressure (Correct answer)
- It describes the collateral recruitment response to arterial occlusion
- It is the pressure gradient measured across a stenosis during exercise
Correct answer: It is the elastic recoil of large arteries that dampens pulsatile flow and maintains diastolic pressure
The Windkessel effect is the storage and release of energy by elastic vessel walls, sustaining forward flow during diastole and contributing to normal triphasic waveform morphology.
Question 2: A 68-year-old woman has rest pain and an ABI of 0.38. Her toe pressure is 22 mmHg. According to TASC II criteria, this patient most likely has:
- Claudication (Fontaine stage II)
- Critical limb ischemia (Fontaine stage III-IV) (Correct answer)
- Mild peripheral arterial disease
- Non-occlusive mesenteric ischemia
Correct answer: Critical limb ischemia (Fontaine stage III-IV)
Critical limb ischemia is defined by rest pain or tissue loss with ankle pressure <50 mmHg or toe pressure <30 mmHg, consistent with this patient's findings.
Question 3: When performing thigh PVR measurements, which error would MOST likely cause falsely elevated thigh pressures?
- Using a cuff that is too large for the thigh circumference
- Using a cuff that is too narrow relative to thigh circumference (Correct answer)
- Performing the test in a cold room
- Measuring immediately after exercise
Correct answer: Using a cuff that is too narrow relative to thigh circumference
A narrow thigh cuff requires higher pressure to compress the underlying artery, producing falsely elevated pressures—a cuff width of at least 40% of limb circumference is needed for accuracy.
Question 4: On a PVR tracing, which feature represents the dicrotic notch, and what does its absence indicate?
- The initial upstroke; absence indicates venous reflux
- A small notch on the downstroke; absence indicates loss of arterial compliance or significant disease (Correct answer)
- The peak of the waveform; absence indicates arterial calcification
- A secondary positive wave; absence indicates cardiac arrhythmia
Correct answer: A small notch on the downstroke; absence indicates loss of arterial compliance or significant disease
The dicrotic notch on the descending limb of the PVR waveform represents aortic valve closure; its absence distal to a stenosis reflects dampening of pulsatility.
Question 5: A patient's right ABI is 0.85 and left ABI is 0.72. The right arm pressure is 130 mmHg and the left arm pressure is 118 mmHg. Which arm pressure should be used to calculate both ABIs?
- Average of both arm pressures (124 mmHg)
- Right arm pressure (130 mmHg) (Correct answer)
- Left arm pressure (118 mmHg)
- Either arm pressure is acceptable
Correct answer: Right arm pressure (130 mmHg)
The higher brachial pressure is always used as the denominator in ABI calculations to avoid overestimating the index and missing disease.
Question 6: Which treadmill protocol is MOST commonly used for standardized ABI exercise testing in peripheral arterial disease evaluation?
- Bruce protocol at 12% grade, 2.5 mph
- Gardner protocol at 0% grade, variable speed
- Standard PAD protocol at 2 mph, 12% grade for 5 minutes (Correct answer)
- Naughton protocol at 3.5 mph, 5% grade
Correct answer: Standard PAD protocol at 2 mph, 12% grade for 5 minutes
The standard PAD treadmill protocol uses 2 mph at 12% grade for up to 5 minutes, providing a reproducible physiologic stress to unmask exercise-induced ischemia.
Question 7: What is the physiologic explanation for the brief paradoxical increase in ABI sometimes seen immediately after exercise in a patient with claudication?
- Arterial vasodilation increases cardiac output and systemic pressure (Correct answer)
- Post-exercise brachial artery vasospasm falsely lowers the denominator
- Collateral vessels temporarily dilate beyond their capacity
- Cardiac output decreases, reducing peripheral resistance
Correct answer: Arterial vasodilation increases cardiac output and systemic pressure
Immediately after exercise, cardiac output and brachial pressure may transiently rise due to sympathetic activation, which can briefly elevate the ABI before ischemic vasodilation reduces ankle pressures.
RVT Peripheral Arterial Physiologic Testing 3
Which statement BEST describes the Windkessel effect and its importance in peripheral arterial testing?