Peripheral artery diseases (PAD) are a group of disorders characterised by narrowing of, or obstruction in, the arteries supplying to the hands and the legs. Atherosclerosis, narrowing of arteries due to deposition of fats in the wall, is the leading cause of PAD is individuals above the age of 40. Other causes of PAD are thrombosis, embolism, vasculitis, fibromuscular dysplasia and trauma. PAD may also be an early warning of deposition of fat occurring in the arteries supplying to other organs like the heart or the brain.
Causes of PAD
The major cause of PAD is atherosclerosis. This condition is caused due to deposition of fats and cholesterol into the wall of your arteries leading to a narrowing of its lumen, which in turn reduces the blood flow. Although atherosclerosis is generally discussed in association with the heart, this condition can also affect blood vessels in other parts of your body like the limbs and the brain leading to subsequent symptoms. PAD of the lower limb is more common than the upper limb.
There are several conditions which may increase the likelihood of PAD like:
- High blood cholesterol levels
- Renal insufficiency
- Family history of stroke or heart disease or PAD
- Age over 50
Symptoms of PAD
More than 50% of the patients with PAD are asymptomatic. The signs of PAD are:
- Pain, aching and a sense of fatigue in your limb while exercising which gets relieved on resting (claudication)
- Aching and pain in your leg during sleep(when kept in a horizontal position), and relief when kept in a vertically downward position
- Feeling of numbness or cold in your foot or toes compared to the other leg
- Ulcers in your leg that won’t heal
- Reduce growth of hair in the affected limb compared to the other limb
- Slow growth of toe nails in the affected limb
- Shiny skin on your affected leg
- Change in colour of your leg
Diagnosis of PAD
To diagnose PAD your doctor will first like to do a thorough physical examination in which might include looking for pulses in different parts of your limb, listening to the pulse with a stethoscope and looking for signs of reduced blood supply, like change in colour of your leg or ulcers which aren’t showing signs of healing. Other tests that your doctor may order for are:
- Ankle: Brachial Index (ABI): in this test the doctor will measure the blood pressure in your arm and your leg with the help of a cuff and a special probe to compare them. An imbalance in their values may point towards PAD.
- Treadmill test: used to assess the severity of the narrowing of the arteries, the doctor will measure your ABI after you’ve walked on a treadmill.
- Transcutaneous oximetry: this test is used to get an idea about how much oxygen reaches the periphery of your limb, which directly correlates with the extent of narrowing of the artery.
- Ultrasound: Using special technique, like the Doppler ultrasound your doctor will be able to identify the vessel involved and the severity of the disease.
- Coronary CTA: by injecting a dye into your blood vessels during this procedure your doctor will be able to directly visualise the flow of blood through the arteries, and identify the affected area.
- Catheter angiography: more invasive than angiography, this procedure can also be used for treatment as well as diagnosis. A thin tube called a catheter is inserted into your artery in the groin and a dye is injected to visualise the artery. If required the narrowing can be corrected simultaneously.
- Blood tests: to check for the levels of lipids and cholesterol in your blood.
Complications of PAD
When the initial symptoms of PAD are ignored, the disease may gradually lead to:
- Critical limb ischemia: ulcers and gangrene due to insufficient blood supply to the tissue in the limb. They become fertile ground for infection which can spread to other parts of the body. The death of the tissue (gangrene) may require amputation to prevent infection from affecting the whole limb.
Treatment of PAD
Your treatment will depend upon the severity of your symptoms. The treatment aims to prevent cardiovascular events, improve the limb symptoms, and reduce the risk of developing critical limb ischemia.
- Discontinuing cigarette smoking
- Supervised exercise training for 30-40 minutes, 3-5 times a week for atleast 12 weeks, for patient with claudication lead to an improvement in symptoms
- Control of blood pressure by taking anti hypertensive medications like ACE inhibitors.
- Statins: for maintaining a normal lipid profile. (an abnormal lipid profile leads to increased risk for development of PAD)
- Anti coagulant therapy: aspirin or clopidogrel are prescribed to reduce the chances of lot formation which may narrow the artery
- Medication to control blood sugar
- Cilostazol: increases the blood supply to the limb by dilating the artery
- Pentoxifylline: increases the amount of oxygen that the tissue receives, hence partially compensating for the narrowing of the artery
- Percutaneous Transluminal Angiography (PTA): a small tube(catheter) with a balloon is inserted into the narrowed artery, the balloon is then inflated to flatten the fat deposit narrowing the artery. In some cases your doctor might also put a mesh in the artery to ensure that it remains open.
- Bypass surgery: your doctor might choose to create a new path for the blood to flow around the affected area with the help of a graft. The graft can be a vessel from your body of it could be made from a synthetic material.
Prognosis of PAD
The prognosis depends heavily on the extent of pre existing atherosclerosis (narrowing of artery) in the heart and the brain. Individuals with PAD have a 15-30% 5 year mortality and about a 2-6 fold increase in chances of death due to coronary artery disease compared to individuals without PAD. Nearly 70-80% of non diabetic patients remain symptomatically stable. Deterioration might occur in the remaining 20-30%, of which some will develop critical limb ischemia. Approximately 25-30% of patients with critical limb ischemia undergo amputation within a year.