Peripheral Arterial Physiologic Testing Flashcards

A patient presents with claudication. The right brachial pressure is 140 mmHg and the left brachial pressure is 130 mmHg. The right posterior tibial artery pressure is 70 mmHg and the right dorsalis pedis artery pressure is 65 mmHg. What is the correct Ankle-Brachial Index (ABI) for the right leg?

Answer: 0.50

To calculate the ABI, the highest ankle pressure on one side is divided by the highest of the two brachial pressures. In this case, the highest right ankle pressure is 70 mmHg (from the posterior tibial artery) and the highest brachial pressure is 140 mmHg. Therefore, 70 / 140 = 0.50. This value indicates moderate to severe peripheral arterial disease.

A patient undergoes a segmental pressure study. The following resting systolic pressures are obtained: Right Brachial: 150 mmHg, Right High Thigh: 130 mmHg, Right Above Knee: 125 mmHg, Right Below Knee: 120 mmHg, Right Ankle: 115 mmHg. Which of the following is the most likely location of significant arterial disease?

Answer: Right iliofemoral arteries

A pressure drop of more than 20-30 mmHg between adjacent segments is considered significant for arterial occlusive disease. In this case, there is a 20 mmHg pressure drop between the brachial pressure (inflow) and the high thigh, indicating a likely stenosis in the aortoiliac or common femoral artery segment. The subsequent drops down the leg are less than 20 mmHg.

Which of the following is a primary purpose for performing an exercise stress test in a patient with suspected peripheral arterial disease (PAD) and a borderline resting ABI?

Answer: To unmask a hemodynamically significant stenosis that is not apparent at rest.

Exercise increases blood flow demand in the lower extremities. In a patient with PAD, a stenosis that is not flow-limiting at rest may become significant during exercise, causing a drop in ankle pressures. This helps to confirm the diagnosis and assess the functional severity of the disease when resting studies are inconclusive.

While performing a Doppler assessment of the femoral artery, a technologist observes a waveform with a sharp systolic upstroke, followed by a brief period of flow reversal in early diastole, and a final phase of low-level forward flow in late diastole. How would this waveform be best characterized?

Answer: Triphasic

A normal, high-resistance peripheral artery at rest exhibits a triphasic waveform. This pattern consists of: 1) rapid antegrade flow during systole, 2) transient retrograde flow in early diastole due to vessel wall compliance and peripheral resistance, and 3) a smaller, brief antegrade flow in late diastole as the vessel wall recoils.

A patient with diabetes and suspected digital ischemia undergoes photoplethysmography (PPG) of the great toe. The resulting waveform is severely dampened with a delayed upstroke and a rounded peak. What is the most likely interpretation of this finding?

Answer: Significant proximal arterial occlusive disease

Photoplethysmography (PPG) assesses changes in blood volume in the capillary beds. A normal PPG waveform has a sharp systolic upstroke and a dicrotic notch. A dampened, rounded waveform with a slow upstroke indicates poor arterial perfusion, which is characteristic of significant proximal (upstream) arterial stenosis or occlusion that reduces pulsatile flow to the digits.

When performing pulse volume recordings (PVRs), what is the standard cuff inflation pressure used to sense volume changes in the limb segment without occluding arterial inflow?

Answer: 65 mmHg

For pulse volume recordings (PVRs), also known as air plethysmography, the cuffs are inflated to a pressure high enough to conform to the limb and detect volume changes, but low enough not to compress the arteries. A standard pressure of 60-65 mmHg is typically used for this purpose.