This is part 2 of our interview with Dr Benjamin Chua from the Vascular Interventional Centre about the risk factors and symptoms associated with Peripheral Artery Disease (PAD), how it is diagnosed and treated, plus the latest advancements in PAD management. For part 1, please click here.
Q: How is PAD diagnosed?
The physician will usually start with a physical examination which involves palpating the foot and feeling for an arterial pulse. The physician will also check for other physical indicators such as temperature; the affected foot often feels cooler than the unaffected foot. A bluish or purplish hue could indicate reduced circulation in the area.
This is followed by an ankle-brachial pressure index (ABPI) or ankle-brachial index (ABI) test to measure the ratio of the blood pressure at the ankle to the blood pressure in the upper arm (brachium). If the blood pressure (BP) in the leg is significantly lower than the arm it could indicate blocked arteries and PAD. If there is lower BP in the leg a duplex ultrasound maybe used to locate any narrowed or blocked arteries. Blood tests looking for signs of diabetes, kidney disease and high cholesterol may also be performed.
The improved resolution of modern duplex ultrasound images makes them highly accurate and as they do not involve any radiation and can be done in the clinic, most physicians will use them instead of a CT or MRI scan for diagnostic purposes. However, CT or MRI scans or a catheter angiogram might be required if the physician thinks the patient may need a physical intervention. An angiogram involves injecting contrast dye into the affected arteries, and taking X-ray images to see where blockages are located. If blockages are detected, the doctor may then opt for some form of intervention such as a catheter procedure to open up the vessel and improve blood flow. These procedures are similar to those used on the heart.
Q: How is PAD treated and managed?
A diagnosis of PAD indicates patients are at higher risk for heart attack and stroke, not just leg pains and mobility problems. Therefore, the primary treatment objective is to prevent stroke and heart attack. The treatment will also take into consideration the patient’s overall cardiovascular health, any other illnesses, current medication, age, and lifestyle.
The first step in managing your PAD will usually be lifestyle changes which are also intended to improve your general cardiovascular health. Smoking cessation, a healthy diet, weight loss and a regular exercise regimen are all typically recommended. More walking is highly recommended, which is ironic for a disease whose first symptom is pain when walking.
The second step is assessing and managing any co-morbidities to reduce their potential impact on the PAD. PAD is often associated with coronary artery disease (CAD), diabetes, high blood pressure and elevated cholesterol and other age-related chronic conditions. In general, the older the patient, the more likely there are to be multiple comorbidities.
The third step is medication. The main purpose of medication is to reduce the risk of heart attack and stroke and prevent complications. Some patients may receive medication to manage pain and improve mobility and overall quality of life.
Antiplatelet drugs which stop blood cells called platelets from sticking together and forming harmful clots are prescribed to reduce the risk of stroke and heart attack. Aspirin and clopidogrel are the most commonly prescribed antiplatelets. Some patients may receive an antiplatelet drug and a vasodilator which widens blood vessels in the legs and can help to reduce claudication, a condition in which cramping pain in the leg is induced by exercise, typically caused by obstruction of the arteries.
Patients with concomitant conditions such as high blood pressure or high cholesterol or some form of cardiovascular disease (CVD) may also be prescribed anti-hypertensive or statin medications to manage those conditions. These drugs can also benefit the PAD.
In the last couple of years the use of novel oral anticoagulants (NOACs) for treating CAD and PAD has become more popular in the United States and Europe; the low-dose rivaroxaban with aspirin regimen came to prominence after the publication of the COMPASS study. I would say it is suitable for patients with high-risk, symptomatic CAD and PAD, until we see more research to identify for which other patient groups it might benefit.
For advanced PAD that is limiting mobility and causing severe pain, some form of endovascular or surgical procedure – the same sorts that are used for heart disease – may be needed. Endovascular surgeries are minimally invasive procedures that involve inserting thin tubes called catheters into a blood vessel to repair it. A variety of devices, including cameras, balloons and stents, can be introduced to the blood vessel via the catheter.
The most common procedure is a balloon angioplasty. It involves temporarily inserting and inflating a tiny balloon where your artery is clogged to help widen the artery. Angioplasty is sometimes combined with a stent to help prop the artery open and decrease its chance of narrowing again.
Occasionally an atherectomy might be performed instead of angioplasty. It also uses a catheter but this time with a laser or tiny blade on the end that removes the plaque from the walls of the artery as it moves past the blockage.
The most severe PAD may require bypass surgery. This is very similar to heart bypass; it involves a surgeon taking a section of the patient’s healthy vein, or a synthetic replacement, and using it to create a bypass around the blocked section of the leg artery.
Q:What are some of the latest advances in the management of PAD?
There have been some promising developments in recent years.
In terms of technology, better techniques combined with smaller wires and low-profile balloons stents have now made it possible to treat even the smallest blocked arteries below the knee and in the foot. This is especially relevant in diabetics as these smaller below the knee and foot arteries are the ones usually affected in PAD. Another advancement in technology is the use of better angiography imaging to better locate and evaluate the arterial lesions. Perfusion imaging evaluates the blood flow in the foot before and after intervention. We also use less contrast per procedure which is much better for patients. One of the risks of excess contrast use is the development of acute kidney failure, especially in diabetic patients.
Another promising technology is lithoplasty balloon catheters which use shockwave energy bursts to crack the surface of the plaque, which is particularly useful for harder plaques with large amounts of calcium in them. This makes the blood vessel easier to inflate with a balloon and also allows for better absorption of any drug applied to the cracked surface of the plaque.
Q: What steps can we take to avoid developing PAD or manage it if we already have it?
The advice for managing PAD and avoiding PAD – or any cardiovascular disease – are the same. Don’t smoke, exercise regularly and eat a healthy, balanced diet; something like the “Mediterranean diet”.
A recent study showed that the countries bordering the Eastern Mediterranean, home of the “Mediterranean diet” had the lowest incidence of PAD. There is also increasing evidence that switching to a diet that supplies more of your protein from plant sources such as beans, grains and nuts as you get older, is good for cardiovascular health.
Dr Chua is a Senior Consultant Vascular Surgeon, and the Medical Director of the Vascular & Interventional Centre at Farrer Park Medical Centre.