Arterial Duplex: An Overview

Introduction:

Blood vessels are vital anatomical structures of the body. They mainly comprise arteries and veins. Arteries carry blood from the heart to the peripheral parts, and veins carry them back to the heart. Any condition affecting this circulatory network is known as vascular disease. Vascular diseases may affect the arteries, veins, or lymphatic channels. Vascular diseases include various conditions like partial or complete blockage of vessels, blood clots, engorged veins, and others. Prompt diagnosis is key to successful management and preventing any fatal consequences.

What Are Peripheral Artery Diseases?

Peripheral artery disease (PAD) is a vascular disease affecting the arteries of the upper or lower extremities (arms or legs). It is a common condition of adulthood affecting both the male and female populations equally. PAD refers to the narrowing of the peripheral arteries due to plaque buildup in the arterial walls. Plaque comprises cholesterol, calcium, and other substrates from the blood. However, gradually as they deposit in the blood vessels, they get calcified and harden over time. This results in the total or partial obstruction of the arteries. This is also known as atherosclerosis.

When the blood supply to the arms or legs is compromised, it could result in symptoms like severe pain, weakness, or numbness in the affected part. The pain would be severe enough to restrict an individual’s daily activities. The damage could be critical if the peripheral arteries are completely blocked, resulting in tissue death (gangrene) and amputation of the affected part.

What Are the Risk Factors for Peripheral Artery Diseases?

The risk factors associated with PAD are given below:

• Smoking and tobacco products are considered significant risk factors for PAD.

• Systemic diseases like diabetes, hypertension, high cholesterol, and bleeding disorders.

• Elderly individuals over 50 years of age.

• Family history of cardiovascular diseases.

• Obesity.

How Can Peripheral Artery Disease Be Diagnosed?

Individuals with PAD may not notice the symptoms until it is aggravated. However, diagnosing PAD early is essential to avoid the following consequences:

• People with PAD usually have atherosclerosis in other body parts, such as the heart or kidney. Hence they are more prone to developing stroke, heart attack, and renal diseases.

• The PAD could be severe enough to result in non-healing ulcers on the legs or foot, resulting in gangrene. This would lead to amputation of the foot or the leg.

Hence PAD should be diagnosed promptly to avoid any disabilities or fatalities. A detailed medical history and physical examination would be the initial step. Various diagnostic tests such as ankle-brachial index test (comparing the blood pressure in legs and arms), angiography, and blood tests may be needed to assess the severity of PAD. However, vascular ultrasound is more precise in determining the blood circulation through the arteries and any associated abnormalities.

What Is a Duplex Ultrasound?

Duplex ultrasound is a non-invasive procedure to see the blood flow through the arteries and veins. This procedure uses high-frequency sound waves to create images of the arteries. When combined with a Doppler ultrasound, this technique can evaluate the movement (both speed and volume) of blood through the arteries. Duplex ultrasound can precisely determine the size and severity of obstruction, dilatation of vessels, or vessel aneurysms (abnormal enlargement).

What Are the Types of Duplex Ultrasound?

Various types of duplex ultrasound are based on the blood vessels to be examined. They are given below:

• Arterial and Venous Duplex Ultrasound of the Abdomen: To evaluate the abdominal blood flow.

• Carotid Duplex Ultrasound: To evaluate the carotid artery.

• Duplex Ultrasound of the Extremities: To look at the blood vessels in the arms or legs.

• Renal Duplex Ultrasound: For the blood vessels in the kidney.

What Is an Arterial Duplex?

An arterial duplex is a painless and non-invasive imaging procedure used to see the arteries of the arms, legs, abdomen, and pelvis. It can evaluate the blood flow and thereby helps to detect any obstruction or block in the arterial flow. This procedure uses high-frequency sound waves to capture the images. In addition, an arterial duplex can provide information on the location, extent, and severity of PAD, guiding treatment planning.

Where Is Arterial Duplex Indicated?

The major indications for arterial duplex are mentioned below:

• To detect and assess the severity of obstruction in peripheral arteries in symptomatic patients.

• Patients who experience severe leg pain while walking but decrease at rest (intermittent claudication).

• Patients with abnormal ankle-brachial index.

• To detect aneurysms and dilatation of arteries.

• In cases of trauma, to evaluate the arterial viability.

• In diabetic foot patients.

• Delayed wound healing in the leg with no pulse present.

• To grade a vascular trauma.

• To map the arteries before any surgical procedure involving major arteries.

• To follow up on cases of atherosclerosis that have been treated.

• To monitor the sites of surgical interventions such as angioplasty, stent, bypass, or thrombolysis.

What Is the Working Principle Behind Arterial Duplexes?

An arterial duplex uses the same principle as that of ultrasound by using high-frequency sound waves to capture the images of the arteries. These sound waves are emitted into the body through a small device known as a transducer. These sound waves, which are inaudible to the human ear, bounce back upon hitting certain internal structures. These returning sound waves are captured by the transducer and processed by a computer based on the amplitude, frequency, and time taken by these waves to return. These images, once processed, can be visualized on a screen as real-time images. The duplex procedure encompasses a Doppler procedure along with ultrasound. Hence the term duplex (two-mode) is used. The Doppler can also measure the speed and volume of blood flowing through the arteries.

What Are the Instructions Before the Procedure?

• Patients undergoing abdominal arterial duplexes are required to fast for six to eight hours, as abdominal gas can interfere with the quality of images. However, they can take their regular medications with a sip of water.

• Arterial duplexes of arms and legs do not require any special instructions.

• Patients should wear loose and comfortable clothes. In addition, they should remove their jewelry and valuables before the procedure.

• Patients should carry their recent medical test reports and prescription medicines for the procedure.

• Any history of allergy should be reported to the doctor before the procedure.

How Is Arterial Duplex Performed?

• The patient is asked to change into a hospital gown and lie on the examination table.

• The area to be examined is uncovered, and a clear gel is applied over the skin.

• The transducer is moved back and forth over the area to be examined. The radiologist may apply firm pressure while moving the transducer to control the blood flow.

• The images are visible on the monitor, which is then examined by the radiologist.

• The entire procedure takes roughly around 60 to 90 minutes.

How Are the Results Interpreted?

The results of the arterial duplex are assessed for the following parameters:

Atherosclerosis:

• The patency of the arteries is assessed.

• The blockage is classified as lesser than 50 %, greater than 50 %, greater than 75 %, and complete occlusion.

• The site and size of the occlusion are determined.

Blood Flow:

• Speed and volume of blood flow through the arteries are assessed.

• Narrowing of arteries, if any, is detected.

Aneurysms:

• The site, size, and extent of aneurysms can be detected.

What Are the Instructions After the Procedure?

An arterial duplex is a relatively simple procedure; hence, no special instructions are required. Therefore, patients can continue with their routine activities.

What Are the Benefits of This Procedure?

• It is an ideal tool to screen PAD.

• It can precisely describe the location, extent, and severity of the disease and hence guide the early and non-invasive treatment approach.

• It is a valuable tool for monitoring disease progression and the effectiveness of the treatment.

• Non-invasive and well tolerated by the patient.

• Cost-effective as compared to other invasive procedures.

What Are the Risks Associated With This Procedure?

Ultrasound has no known risks associated.

Conclusion:

An arterial duplex is a simple, non-invasive, and cost-effective procedure to examine arterial blood flow and associated abnormalities. PAD is a common condition affecting the majority of the population. Severe forms of PAD are associated with grave damage. Hence, early diagnosis is mandatory in patients with PAD to avert any disabilities or fatal consequences.