What is pulse volume recording?
Pulse volume recording, or PVR (also called plethysmography) is a test that measures blood flow in the leg arteries. PVR can be used to diagnose PAD in the legs, determine how severe the disease is, and find the general location of the blockage. The PVR test is fast and painless, and does not require entering the body.
PVR is often done together with segmental blood pressure measurement, and is sometimes performed at the same time as an ankle-brachial index test (ABI).
How does PVR work?
Blood does not flow through the body with continuous, uninterrupted flow. Instead, with each beat of the heart blood is pushed through the body in “pulses.” The PVR test uses pressurized cuffs to monitor how these pulses travel through the legs, allowing doctors to find blood flow problems that may be caused by PAD. Because the pulsing of blood is measured at several different parts of the leg, PVR can also show roughly where the blockages are.
Who might have pulse volume recording?
Although an ABI is easier to perform than PVR and is enough to diagnose PAD on its own, your doctor may request a PVR test if she or he wants additional information on what parts of your legs are most affected by PAD. Information about where your arteries are most affected may be used to help develop a treatment plan, or to identify areas to examine more closely with more detailed tests.
One advantage of PVR is that the test can detect blood flow problems in women with stiff (incompressible) arteries. If you have stiff arteries (common in elderly women, or women with long-standing diabetes or severe kidney disease), an ABI or segmental pressure measurement often does not give an accurate reading.
In patients with severe PAD, PVR can also predict if a limb has enough blood flow to survive, or if amputation may be required. It is also used after procedures to make sure the leg is getting enough blood.
How do I prepare for the test?
You should not smoke or participate in strenuous activities for 24 hours before the test. You should take any medications and eat and drink as you normally would.
What happens during the test?
A pulse volume recording may be performed in a doctor’s office or in a specialized vascular testing facility. The procedure takes about 30 to 45 minutes.
You will be lying flat during the test. The technologist will place pressurized cuffs (similar to blood pressure cuffs) on your legs, and they will be hooked up to a machine called a pulse volume recorder. Usually, one or two cuffs are placed around your thigh, another on your upper calf, and one just above the ankle. An additional cuff above your elbow provides an idea of blood flow in a healthy limb.
The cuffs are inflated and continuously monitor your arteries as the blood pulses through them. The recording machine converts these measurements into a waveform (a continuous line of peaks and valleys) that represents the movement of blood through your arteries.
In some cases, you may be asked to exercise on a treadmill or to rise up onto your toes repeatedly using your calf muscles before the test. This helps to bring out PAD symptoms that occur only during exercise, when the leg muscles need more blood than usual.
The PVR test is often performed together with segmental pressure measurement, and sometimes at the same time as an ABI.
What do the results mean?
The results of the pulse volume recording can tell doctors whether PAD has narrowed or blocked blood flow in the arteries of your legs, as well as how severe your PAD is.
In healthy arteries, the tracing of the pulses (called the waveform) will have high, sharp peaks, indicating that blood is flowing smoothly. If your arteries are narrowed by PAD, the notch will disappear and the peaks will become smaller and flatter, indicating that blood is having trouble flowing into the leg.
Pulse volume recording tracings of blood flow in the legs. As PAD gets worse, the blood flow peaks become smaller and more irregular.
Because there are several cuffs around different parts of your leg, doctors can use the different recordings to determine where the blockage is. For example, if the pulse volume recording is normal in your thigh, but abnormal in your upper calf, the blockage is probably located between the two (in the knee area).
An example of a PVR readout.
This person has PAD in the right iliac artery in the abdomen (left side of the readout).
Notice how the peaks on the left side of the readout are shorter and more irregular than those on the right.
How accurate is pulse volume recording?
Pulse volume recording is 90% to 95% accurate at diagnosing PAD. It is especially useful for diagnosing PAD in the upper legs, and may be less accurate when the blockages are near the ankle.
What happens next?
If your PVR shows evidence of blockages in your legs caused by PAD, your doctor will use the information to develop a treatment plan that includes getting your PAD risk factors under control. See Overview of PAD Treatment (coming soon) for more.
Your doctor may also order further tests to get a more detailed look at the arteries, such as an ultrasound, MR angiogram, CT angiogram, or contrast angiogram.