How to Interpret Ankle-Brachial Index (ABI) Waveforms | medmastery (2023)

FAQs

What are the waveforms of ankle-brachial index? ›

Normal, triphasic ankle-brachial index (ABI) waveforms feature a sharp upstroke to the tallest peak (blood flow acceleration during systole), a pit (reversal of flow during early diastole), and a second peak (forward flow during late diastole).

biphasic which occurs in more distal blood vessels as the result of ventricular systole and the elasticity of the blood vessels; monophasic which occurs when the flow of blood is no longer pulsatile. All three types of blood flow occur in healthy subjects.

The Doppler waveform of the lower extremity arteries at rest is classified as a high pulsatility waveform and is characterized by a triphasic flow pattern [9].

A monophasic waveform has slow, blunted antegrade systolic flow, which continues into diastole. Monophasic arterial waveforms are always abnormal and are often seen downstream from stenoses or in collateral vessels formed around the occlusive disease.

Health care providers calculate ABI by dividing the blood pressure in an artery of the ankle by the blood pressure in an artery of the arm. The result is the ABI. If this ratio is less than 0.9, it may mean that a person has peripheral artery disease (PAD) in the blood vessels in his or her legs.

What does a high ankle-brachial index mean? An ABI ratio higher than 1.4 could mean the blood vessels in your limbs are stiff because of advanced age or diabetes. Researchers have found that people with an ankle-brachial index higher than 1.4 had twice the risk of cardiovascular death.

The ABI is calculated as the higher pressure at the ankle divided by the higher of the left and right arm pressures. An ABI ratio above 0.90 is normal, 0.71-0.90 indicates mild obstruction, 0.41-0.70 indicates moderate obstruction, and <0.40 indicates severe obstruction.

The ankle-brachial index test compares the blood pressure measured at the ankle with the blood pressure measured at the arm. A low ankle-brachial index number can indicate narrowing or blockage of the arteries in the legs. Ankle-brachial index testing might be done before and right after walking on a treadmill.

Abnormal or unhealthy ABI values are 0.9 or lower and 1.41 and higher. These values indicate that you have different blood pressure levels at the two points of measurement, and thus that you have a high possibility of having narrowed arteries, blood clots, or venous insufficiency.

What is an abnormal ABI reading? ›

INTERPRETATION OF ABI RESULTS

PAD is graded as mild to moderate if the ABI is between 0.4 and 0.9, and an ABI less than 0.40 is suggestive of severe PAD [19]. An ABI value greater than 1.3 is also considered abnormal, suggestive of non-compressible vessels.

Biphasic waveform indicates mild to moderate disease and monophasic flow indicates significant disease. Duplex scanning can be added to further localize occlusive disease. Some practitioners choose to perform pulse volume recordings (PVR) instead of or in addition to arterial Doppler.

The biphasic type describes a two-phase Doppler waveform with an extension of the reverse flow phase during the whole diastole and the disappearance of the forward flow phase during diastole, in comparison with the triphasic type. Tri- and biphasic types are considered normal.

Although monophasic and biphasic machines are successful in performing defibrillation, the latter is considered a better option. They are more convenient, accurate, effective, and cost less and are able to prevent further damage to the heart.

Normal wave: 1-2 Oscillations before returning to baseline is deemed normal. Over-dampened: Air bubbles, kinks, clots, spasms, stopcock closed/loose connections, or no volume or low pressure in pressure bag and tubing. This can underestimate systolic pressure and/or overestimate diastolic pressure.

Most waves of 8 Hz and higher frequencies are normal findings in the EEG of an awake adult. Waves with a frequency of 7 Hz or less often are classified as abnormal in awake adults, although they normally can be seen in children or in adults who are asleep.

Low-resistance spectral waveforms are characterized by a slower increase in flow velocity with the onset of systole and a gradual decrease in velocity during diastole with continued forward flow throughout the cardiac cycle (Fig. 39.4B).

The main difference between monophasic and biphasic shock delivery is that a monophasic electrical current moves in a single direction while a biphasic current is bidirectional (moving in a straight line and then reversing its direction).

Blunted waveforms were characterized by the absence of the characteristic peak of the systolic signal and the elevated end-diastolic flow velocity (fig. 1).

Monophasic has most commonly been used to describe abnormal waveforms with a single phase found distal to a hemodynamically significant arterial obstruction,^18,25 but has also been employed to characterize abnormal blood flow proximal to a significant obstruction and from normal extremities following exercise and ...

What is the hallmark symptom of peripheral arterial insufficiency? ›

The most characteristic symptom of PAD is claudication which is a pain in the lower extremity muscles brought on by walking and relieved with rest. Although claudication has traditionally been described as cramping pain, some patients report leg fatigue, weakness, pressure, or aching.

Normal cut-off values for ABI are between 0.9 and 1.4. An abnormal ankle-brachial index- below 0.9-is a powerful independent marker of cardiovascular risk.

A normal ABI value is 1.10 to 1.40. This is because among individuals without PAD, lower extremity arterial pressures increase with greater distance from the heart, due to increasing impedance with increasing arterial taper, resulting in higher systolic pressures at the ankle compared with the brachial arteries.

On the other hand, an ABI of 0.5 means that only 50% of the blood is reaching the ankles, and 50% is blocked by PAD.

Normal ABI will range from 0.9-1.3; 0.5-0.8 indicates no significant PAD or mild PAD; < 0.5 indicates severe PAD or critical ischemia, in which case compression therapy is contraindicated. If the ABI is > 1.3, the result is unreliable and those patients should also be evaluated before considering compression.

ABI values and what they mean: 1.0 - 1.4 - could indicate calcification in the vessels. . 9 - 1.4 - normal range - no treatment is necessary.

The ankle-brachial index (ABI) is the ratio of the systolic blood pressure (SBP) measured at the ankle to that measured at the brachial artery. Originally described by Winsor¹ in 1950, this index was initially proposed for the noninvasive diagnosis of lower-extremity peripheral artery disease (PAD).

In general, a toe pressure of 70 to 110 mmHg or TBI > 0.5 to 0.75 is considered normal and anything below is diagnostic of PAD. A toe pressure lower than 30 mmHg or TBI < 0.2 is considered severely ischemic and diagnostic of critical limb ischemia (CLI).

Arterial Doppler Ultrasound

A Doppler ultrasound uses sound waves to produce images that highlight blood flow in the leg arteries. This test detects and evaluates any blockages caused by plaque buildup.

A graft is used to redirect blood flow around a blocked or narrowed artery. A graft can be a blood vessel from another part of the body or a synthetic substitute. In some cases, angioplasty or surgery may be necessary to treat peripheral artery disease that's causing claudication: Angioplasty and stent placement.

Is arterial insufficiency the same as venous insufficiency? ›

Venous insufficiency refers to a breakdown in the flow of blood in our veins, while arterial insufficiency stems from poor circulation in the arteries. Left untreated, both conditions may lead to slow-healing wounds on the leg.

Initial evaluation begins in the office setting with a thorough history and physical examination. Typical symptoms of venous insufficiency include aching, pain, tightness, skin irritation, pruritus, heaviness, tingling, muscle cramps, and cosmetically unsatisfying varicose veins.

Introduction: The Ankle-Brachial Index (ABI) makes it possible to identify patients with peripheral artery disease (PAD). Intermittent claudication (IC) is the first major symptom of PAD, although many patients with an ABI ≤ 0.9 do not exhibit IC, and the range of ABI among those who do have IC is very variable.

Calculating toe brachial pressure index

Divide the toe's systolic pressure by the brachial systolic pressure in the arm with the higher pressure. A toe brachial pressure index (TBPI) less than 0.64 warrants further evaluation and testing.

A TBI value less than 0.5 suggests proximal arterial disease of moderate severity, while an index less than 0.2 and toe pressures less than 30 mm Hg are consistent with critical ischemia and poor potential for healing.

It has been recognized for some time that systolic pressures at the level of the ankles can also be elevated in comparison to pressures measured in the arm. This is usually attributed to calcification of the arteries, which prevents arterial compression and results in a falsely elevated pressure measurement.

The aim of this review was to compare biphasic with triphasic oral contraceptive pills. Our a priori hypotheses were that biphasic and triphasic pills have similar contraceptive efficacy but that triphasic oral contraceptives cause fewer side effects, give better cycle control, and have higher continuation rates.

The normal (“triphasic”) Doppler velocity waveform is made up of three components which correspond to different phases of arterial flow: rapid antegrade flow reaching a peak during systole, transient reversal of flow during early diastole, and slow antegrade flow during late diastole.

Biphasic pills provide in succession 2 estrogen-progestagen combinations in increasing doses. Triphasic pills provide a continuous dose of estrogen combined with a progressively increased dose of progestagen from week to week.

A normal ankle-brachial index is between 1.0 and 1.4. Normal. Stiff blood vessels in your limbs may be from advanced age, diabetes or calcification. Borderline.

What are normal values for ABI? ›

A normal ABI value is 1.10 to 1.40. This is because among individuals without PAD, lower extremity arterial pressures increase with greater distance from the heart, due to increasing impedance with increasing arterial taper, resulting in higher systolic pressures at the ankle compared with the brachial arteries.

The ankle-brachial index (ABI) provides objective data about arterial perfusion of the lower limbs. The ABI refers to the ankle to arm systolic blood pressure ratio; a normal ABI is 1.0–1.4. ABI values above 1.4 indicate noncompressible arteries.

It has been recognized for some time that systolic pressures at the level of the ankles can also be elevated in comparison to pressures measured in the arm. This is usually attributed to calcification of the arteries, which prevents arterial compression and results in a falsely elevated pressure measurement.

Toe/Ankle Pressure (TBI/ABI) have proven to be an accurate option for the diagnosis of PAD in patients at risk for falsely elevated ankle-brachial index (ABI) values, as vessels in the toes are usually not affected by calcification. The procedure is similar to an ABI test but requires small cuffs and a sensitive probe.

However, the ABI may be unreliable and termed 'non-compressible' when the infrapopliteal arteries cannot be compressed by a blood pressure cuff.

If blood flow is normal in the lower extremities, the pressure at the ankle should equal or be slightly higher than that in the arm with an ABI of 1.0 or more. An ABI less than 0.9 indicates LEAD.