PAD is a type of atherosclerosis that involves the blood vessels supplying circulation primarily to the legs (less likely in the arms). It is a common condition and studies have shown that PAD can be identified in 5% of individuals between 60-69 years of age and in 15% of individuals who are 70 years of age or older. PAD prevalence increases with age and is more common in individuals who smoke or have one of the risk factors described. PAD risk is increased in patients who have had a heart attack or stroke or who have had any vascular surgery, including angioplasty.
Symptoms of Peripheral Artery Disease
Claudication: Claudication comes from the Latin word for “limp.” It is defined as pain, tiredness or weakness in the muscles of the calf, thigh or buttocks that occurs with exercise (walking), which is then relieved when you rest or stop the activity. Symptoms of claudication result from the muscles’ increased demands for oxygen during physical activity that cannot be met due to reduced blood flow from narrowed or blocked arteries. As a result of impaired circulation, leg muscles will tire or become painful (cramping or weakness). Symptoms of claudication are very repeatable and often occur after the same type of activity (walking, climbing stairs or a hill) and do not occur in the muscles of the foot. It can often be managed medically and, in most cases, there is a low risk of amputation. Pains in the leg that are not brought on by exercise but instead occur during rest or after prolonged standing or sitting are not generally related to vascular disease. There may be many other causes of leg pain (arthritis, back problems, neuropathy).
Critical Limb Ischemia (CLI):When the degree of blockage from PAD becomes severe, pain may occur without exercise and manifests in the foot, especially the toes (not the calf, hip or thigh). This is known as critical limb ischemia (CLI), and as the name implies, is an urgent condition that requires prompt consultation with a surgeon, as there is significant risk of amputation (unlike claudication). In general, patients will experience a burning pain occurring most often at night, which can be relieved by sitting up, hanging your foot over the side of the bed or sometimes even by walking. With CLI, the foot may lose color when it is elevated or become deep red or purple when you stand or sit. Small areas of dead tissue (gangrene) may develop, usually on the toes or other pressure points on the foot. In most severe cases, sores or ulcers may develop on the foot from minor injury—either on the toes or at sites of pressure (sole of foot or heel). If you develop a sore on the foot, especially if it does not heal quickly, you should be checked immediately for PAD.
Diabetic neuropathy (nerve pain) can sometimes be confused with CLI and the conditions can sometimes coexist. However unlike the pain of CLI, diabetic nerve pain usually occurs in both feet, is not made better by hanging your foot down and is not associated with changes in color of the foot.
Diagnosis of Peripheral Artery Disease
Although most patients with PAD have no symptoms, it can be easily and painlessly diagnosed in the doctor’s office and is painless. The process involves measuring the systolic blood pressure at the ankle with a Doppler probe and a blood pressure cuff, then comparing that reading to the highest blood pressure taken in either arm. The ratio of these pressures is called the Ankle/Brachial Index (ABI) and a normal ABI is 0.9 to 1.2. Generally, the lower the ABI, the more severe the PAD. For example, when an ABI is performed and the result is generally less than 0.45, you may have critical limb ischemia (CLI), a severe form of PAD that may result in amputation if left untreated. You should discuss an ABI screening—which is more accurate than feeling for a pulse in the foot—with your physician after you reach the age of 55, or earlier if you smoke, have diabetes or high cholesterol. This can be done as part of your regular examination or in a vascular laboratory.
Prevention Strategies and Medical Management of PAD
Specific management strategies for symptomatic PAD differ depending on the severity of the symptoms—whether you have claudication or CLI. Patients with PAD are likely to have coronary artery disease or carotid artery disease, even if they are asymptomatic. Since stroke and death are common in patients with PAD, it is important to look for evidence of these conditions in all patients with PAD.
Medical Management of Claudication
It is important to remember that patients whose only PAD symptom is claudication are not in immediate danger of amputation. Only about 15-20% of patients whose only symptom is claudication will eventually progress to the point where amputation might be a concern. In fact, patients with claudication are more likely to have a heart attack than to have an amputation. Therefore the goals of treatment are symptom relief, identification of silent atherosclerosis in other areas (heart, carotid arteries), and general treatment of atherosclerosis to prevent worsening of the condition or problems of myocardial infarction or stroke. Management techniques include:
- Stop Smoking—smoking cessation is critical with PAD.
- Supervised Exercise—regular exercise on a treadmill, while it is time consuming, has been shown to be equivalent to or better than angioplasty or bypass for most patients with claudication. For this strategy to be effective, patients need to work up to 45 minutes per day at a speed of 2.5 miles per hour using a 10% incline for 3-5 times per week. Since many patients are often initially too physically limited, we recommend that this is done in short segments that add up to 45 minutes over the course of the day. Patients who do not have access to a treadmill should walk as briskly as possible for as long as they can to total 45 minutes. This should be done as often as possible but no less that 3-4 times per week. This routine works by building up tolerance in your leg muscles. While you may get pain when you walk, you cannot damage your muscles by walking as long as possible. More than 60% of patients will see symptom improvement when combining smoking cessation and exercise.
- Antiplatelet Agents – because of the risk of heart attack and stroke, all patients should be on an agent that reduces platelet clumping. The two most common agents are Aspirin (81 or 325 mgm/day) and Clopidogrel (Plavix) 75 mgm/day.
- Cilostazol (Pletal)—this drug has been shown in blinded comparison to improve walking distance in the majority of patients. This drug works by increasing the ability of red cells to go through small arteries. Patients generally start at 50 mgm twice per day and increase to 100 mgm twice per day if tolerated. Side effects include nausea or GI upset, lightheadedness and sweating. About 60% of patients can be helped by this medication in our experience; however it is not covered by all insurance carriers and is expensive. Pletal should not be given to patients with congestive heart failure.
- Statins—there is a controlled trial that demonstrates improvement in walking for patients who take statins, even at low doses. The basis for this improvement is not known.
Medical Management of CLI
In the case of CLI, the circulation has deteriorated to the point that it must be improved rather than stabilized. The major goals in patients with CLI are to relieve pain, heal ulcers and prevent amputation. While medical management techniques are similar for claudication (see above), and smoking cessation is critical, medical management is usually not sufficient in patients with CLI. Pletal has no clear role in patients with CLI, so intervention is often required.
Intervention for Claudication
Patients who have failed in the medical management of claudication may be considered for intervention. Some patients are so incapacitated by their symptoms that they choose intervention as the initial treatment. This is acceptable as long as the patient realizes all interventions are associated with risk and that all of them are subject to failure at some future date. Patients may be treated by “endovascular” surgery (angioplasty with or without stents) or surgical bypass. The choice of intervention will be determined after discussion with the surgeon and will be based on the location and severity of the disease, the overall health of the patient and patient preference and expectations. Some things to consider prior to intervention for claudication include:
- How bad are my symptoms? Do they require intervention or can I try exercise and medication? Remember the goal of intervention is to reduce symptoms; amputation is unlikely in patients with claudication.
- Is the blockage short enough that angioplasty will give a good result? Am I willing to have a second intervention within two years if angioplasty fails?
- Am I healthy enough for surgical bypass? Am I willing to recover for 4-8 weeks from surgery knowing that this often provides a superior long-term result?
A general comparison between Angioplasty/Stent and Surgical Bypass is shown in the table below. In general, after any intervention, patients should begin an exercise program and take an aspirin and statin to reduce the risk of recurrent problems. Cilostazol should not be needed after a successful intervention.
Comparison of Angioplasty/Stent and Surgical Bypass for Claudication
|Preferred in:||Larger vessels||Smaller vessels (<4 mm)|
|Preferred in:||Shorter vessels||Longer Blockages (>20cm|
|Hospital Stay:||Outpatient or Overnight||Inpatient (3-7 days)|
|Anesthesia:||Local with sedation||General or Spinal|
|Recovery at home:||One week or less||3-4 weeks|
|Durability:||About 50% at 2 years||60-75% at 5 years|
Intervention for CLI
Since intervention is usually required for CLI, patients will need a study (ultrasound, angiogram) to determine the extent of the blockage and plan either angioplasty or surgical bypass. Furthermore, patients should be evaluated for coronary artery disease, which is present in almost all patients with CLI. When possible, any significant coronary disease should be controlled before CLI intervention. Patients with CLI are generally older and sicker than patients with claudication and their disease is more extensive. Consequently, advanced endovascular techniques may be required to achieve success in these circumstances.
Recommendations on preferred treatment of patients with CLI are evolving and treatment decisions should be made after consultation with a vascular surgeon who is experienced in both open surgical bypass and advanced endovascular techniques. A large study comparing endovascular surgery and open surgical bypass suggests that endovascular gives equal results with less complication rates for the first two years, but after that, open surgery is superior. Therefore, decisions on appropriate therapy depend on many factors including the patient’s overall medical condition. Post Intervention Care—after intervention, patients should take aspirin, Clopidogrel or both. Clopidogrel is recommended for at least 6-8 weeks, after which aspirin alone is sufficient.
Patients should be on a statin drug and should continue risk reduction, which includes no smoking and control of diabetes, cholesterol and high blood pressure. The most common problem after intervention (besides recurrence) is myocardial infarction and patients should follow up with their primary care physician or cardiologist to prevent this condition. After any intervention, patients should be seen regularly for life. Any intervention can fail, but if caught in time, the problem can be corrected. Most failures occur during the first two years after intervention. Therefore, it is recommended that patients see their surgeon after one month, and every 3-6 months thereafter for two years. If everything looks good at two years, annual follow up is sufficient. If symptoms recur at any time, you should go back to your surgeon.