The Importance of ABI (Ankle Brachial Index) Test
The Ankle Brachial Index (ABI) test is used to evaluate the blood flow in the peripheral arteries or to assess the stiffness of the arteries. It is primarily used to detect peripheral arterial disease (PAD), which refers to the narrowing of the arteries in the legs. This condition increases the risk of stroke and coronary artery disease.
Peripheral Arterial Disease (PAD)
PAD occurs when the arteries in the legs become narrowed or blocked due to a buildup of fatty deposits or arterial stiffening. This condition affects the body’s circulatory system and can restrict blood flow to the legs. On average, 12% of people across all age groups suffer from PAD. Less than 3% of people under 60 years old are affected, but the prevalence increases to more than 20% in those over 70 years old. PAD is common among both men and women. Even if there are no symptoms, individuals with PAD have a higher risk of dying from heart disease and stroke, even if they have no prior symptoms or history related to heart or brain conditions.
Symptoms of Peripheral Arterial Disease
In most cases, individuals with PAD detected through the ABI test do not exhibit symptoms until the artery becomes significantly blocked, leading to inadequate blood supply to the affected organ. The most common symptoms include:
✔ Pain while walking, sometimes accompanied by leg cramps, which improves after rest. This is referred to as Intermittent Claudication.
✔ Muscle weakness in the affected leg.
✔ Numbness or coldness in the lower leg or foot, especially when compared to other parts of the body.
✔ Skin color changes, such as darkening or shiny skin.
✔ Hair loss or slower hair growth on the legs and feet.
✔ Weak or absent pulses in the feet.
✔ Pain or cramps during activities that require arm usage, such as knitting, writing, or general daily tasks.
As the disease progresses, pain may occur even while resting or lying down, significantly affecting the quality of life. Temporary relief can be achieved by dangling the legs off the side of the bed or walking around the room.
Who Should Get the ABI Test?
Individuals who should get the ABI test include:
✔ People over 65 years old.
✔ People over 50 with a history of diabetes or smoking.
✔ People under 50 with diabetes and additional risk factors such as obesity, high blood pressure, and smoking.
✔ People with high cholesterol.
✔ Those with a family history of PAD, heart disease, or stroke.
✔ Individuals with elevated levels of Homocysteine or Lipoprotein, which are associated with arterial stiffness and contribute to conditions like high blood pressure, heart disease, stroke, and chronic conditions.
Principle of ABI Testing
ABI is a diagnostic test used to assess the total body vascular health by comparing the ankle pressure to the arm pressure on each side. This helps to identify arterial blockages. The normal ABI value is 1.0 or higher, indicating healthy arteries. A value below 0.9 indicates possible blockage. In cases where an angiogram (X-ray with injected dye) is performed, about 95% of patients with ABI values lower than 0.9 show peripheral arterial disease.
The severity of PAD is classified based on the ABI values:
- ABI values between 0.5 – 0.8 suggest chronic pain and muscle weakness during exercise.
- ABI values below 0.5 indicate a critical condition, where the tissue in the affected leg may die due to a lack of blood supply, requiring urgent treatment.
What to Do Before and After the ABI Test
Before the test:
- The patient should lie flat with the arms and legs at heart level, and remain as still as possible.
- Do not talk, touch the cuff, or move your limbs during the test, as this could affect the accuracy of the results and increase the time required for measurement.
During the test:
- If the patient experiences any discomfort or unusual symptoms, the procedure will be stopped immediately.
- The test is not suitable for patients with metal implants in their arms or legs, as this can interfere with accurate measurement.
In conclusion, the ABI test is an essential screening tool for assessing the risk of peripheral arterial disease (PAD), which can significantly impact overall health, especially in individuals with additional risk factors such as age, diabetes, smoking, and family history of vascular diseases. Early detection and treatment can help prevent more serious complications, including heart attack and stroke.
