Leg Attack! Understanding Peripheral Arterial Disease

When you hear of “blocked arteries”, the first thing that probably comes to mind is a heart attack or a stroke. In both instances, blood flow to vital organs (the heart and the brain, respectively) is interrupted by blockage in the arteries. These blockages are caused by the accumulation of fatty plaques along the inner walls of the arteries. But what you may not know is that these fatty plaques could occur in any artery in the body. When these plaques form on arteries feeding other parts of the body, peripheral arterial disease (PAD) happens.

What is PAD?

PAD is the formation of fatty plaques in the arteries that could lead to blood flow to other parts of the body being slowed down or completely blocked. PAD usually affects the arteries nourishing the legs, but may also affect the vessels to other organs. Factors such as advancing age, smoking, high blood pressure, diabetes and high blood cholesterol all contribute to the development of PAD. Patients with PAD are also at high risk of a heart attack or stroke.

Given the strong connection between PAD and diabetes, most of the studies among Asians involved patients with diabetes. These studies showed that up to 10% of the population may be affected by PAD. However, studies from other parts of the world suggest that up to 1 in every 5 adults aged 65 years or older could have PAD.

Leg pain is one of the most common symptoms of PAD. The specific type of pain seen in patients with PAD is called “intermittent claudication”. This leg pain affects the calves and, in worse cases, even the thighs and the buttocks. The pain can be induced by even light exercise, and is relieved by rest. This pain is caused by the lack of oxygen-rich blood in the leg muscles, with its intensity ranging from mild to severe.

Other symptoms of PAD include:

• Skin on the feet that is cool to touch
• Skin redness or colour changes
• Changes in skin texture (skin may be brittle or shiny)
• Thinning of leg hair
• Thickened nail beds
• Foot sores that take a long time to heal

When an artery gradually progresses to being completely blocked, the body develops alternative arteries (collaterals) for blood to bypass the blockage. The patient may suffer from stable claudication or leg pain while walking. In reality, there is no need for surgery as limb loss due to the growth of bypass collaterals is uncommon. However, this group of patients have a much higher chance of dying from a heart attack or stroke, and therefore control of the risk factor is paramount.

However, critical limb ischaemia (i.e., a leg attack) occurs when the leg develops a non-healing ulcer or gangrene, requiring special attention and intervention to open up the blocked arteries and thus save the leg. In patients with severe PAD, afflicted arteries could be widespread, including those leading to the heart and brain, consequently causing a heart attack or stroke. A “leg attack” also increases the risk of these complications.

In some patients with PAD, leg pain is not present, leading to delayed diagnosis. PAD can be detected in asymptomatic patients through a thorough physical examination by a medical professional. This examination includes a blood pressure check on both the arm and the ankles. A significantly lower blood pressure at the ankles compared to the blood pressure at the arm suggests the presence of PAD. If you have risk factors for PAD, inform your physician so that blood pressure could be taken in these two areas. Your doctor may also recommend other tests such as ultrasound, computerised tomography (CT scan) or magnetic resonance imaging (MRI) to determine the presence of PAD.

Treatment and prevention of PAD

The treatment and prevention of PAD include interventions to address associated diseases such as hypertension, high blood cholesterol and diabetes, all of which contribute to PAD. Interventions to improve blood flow are also crucial. These interventions include the following:

Lifestyle interventions
These include quitting smoking and adopting a healthy diet that is low in cholesterol, fat and sodium, but high in dietary fibre. Exercise is imperative, though it may be difficult to start exercising if your legs hurt. The key is to exercise gently and progress slowly. For example, you could start walking until your legs hurt, then rest. Slowly increase the distance you walk each day. A gradual increase in your amount of exercise will not only improve blood supply to your leg muscles, but also condition the rest of your body to gain strength.

Good foot care and skin care to prevent leg ulcers
Check your feet and legs regularly for wounds and ulcers. Keep your feet clean and moisturise your feet and legs to keep your skin healthy.

Treatment of conditions predisposing to or aggravating PAD
If you have hypertension, diabetes or high blood cholesterol, ensure that you continue taking your prescribed medication and follow up with your physician regularly. In some instances, your doctor may also prescribe blood thinners to lower the risk of blood clots, as well as the risk of a heart attack or stroke.

Procedures for advanced PAD
In severe cases where the collateral vessels are insufficient to nourish the leg, your doctor may recommend special interventions to widen the blood vessels and improve blood flow. These procedures may include angioplasty, stenting, and atherectomy to remove any blockages. Surgery may also be recommended to re-route blood flow around blocked arteries.

As with most diseases, prevention is better than cure. Therefore, it is important to sustain a healthy lifestyle and ensure early treatment for any medical condition that may lead to PAD. These small steps towards maintaining healthy blood vessels could take you miles away from PAD.

Article is contributed by Clinical A/Prof Jack Tan, Honorary Secretary of the Singapore Heart Foundation. He is also the Deputy Chief Executive Officer and Senior Consultant at the National Heart Centre Singapore.