People with angina also may have undiagnosed episodes of silent ischemia. In addition, people who have had previous heart attacks or those with diabetes are especially at risk for developing silent ischemia. Having an exercise stress test or wearing a Holter monitor — a battery-operated portable tape recording that measures and records your electrocardiogram ECG continuously, usually for hours — are two tests often used to diagnose this problem. Other tests also may be used. Written by American Heart Association editorial staff and reviewed by science and medicine advisers.
See our editorial policies and staff. Heart Attack. Chronic critical limb ischemia is manifested by pain at rest, nonhealing wounds and gangrene. Ischemic rest pain is typically described as a burning pain in the arch or distal foot that occurs while the patient is recumbent but is relieved when the patient returns to a position in which the feet are dependent.
Objective hemodynamic parameters that support the diagnosis of critical limb ischemia include an ankle-brachial index of 0. Intervention may include conservative therapy, revascularization or amputation. Progressive gangrene, rapidly enlarging wounds or continuous ischemic rest pain can signify a threat to the limb and suggest the need for revascularization in patients without prohibitive operative risks.
Bypass grafts are usually required because of the multilevel and distal nature of the arterial narrowing in critical limb ischemia. Patients with diabetes are more likely than other patients to have distal disease that is less amenable to bypass grafting. Compared with amputation, revascularization is more cost-effective and is associated with better perioperative morbidity and mortality. Limb preservation should be the goal in most patients with critical limb ischemia.
Atherosclerosis underlies most peripheral arterial disease. Narrowed vessels that cannot supply sufficient blood flow to exercising leg muscles may cause claudication, which is brought on by exercise and relieved by rest. For a review of the diagnosis and management of claudication, see the article by Santilli, et al. While critical limb ischemia may be due to an acute condition such as an embolus or thrombosis, most cases are the progressive result of a chronic condition, most commonly atherosclerosis.
Chronic critical limb ischemia is defined not only by the clinical presentation but also by an objective measurement of impaired blood flow.
Criteria for diagnosis include either one of the following 1 more than two weeks of recurrent foot pain at rest that requires regular use of analgesics and is associated with an ankle systolic pressure of 50 mm Hg or less, or a toe systolic pressure of 30 mm Hg or less, or 2 a nonhealing wound or gangrene of the foot or toes, with similar hemodynamic measurements.
Chronic critical limb ischemia is the end result of arterial occlusive disease, most commonly atherosclerosis. In addition to atherosclerosis in association with hypertension, hypercholesterolemia, cigarette smoking and diabetes, 3 , 4 less frequent causes of chronic critical limb ischemia include Buerger's disease, or thromboangiitis obliterans, and some forms of arteritis.
Diabetes is a particularly important risk factor because it is frequently associated with severe peripheral arterial disease. Atherosclerosis develops at a younger age in patients with diabetes and progresses rapidly. Moreover, atherosclerosis affects more distal vessels in patients with diabetes; the profunda femoris, popliteal and tibial arteries are frequently affected, while the aorta and iliac arteries are minimally narrowed.
These distal lesions are less amenable to revascularization. Atherosclerosis in distal arteries in combination with diabetic neuropathy contributes to the higher rates of limb loss in diabetic patients compared with nondiabetic patients.
The development of chronic critical limb ischemia usually requires multiple sites of arterial obstruction that severely reduce blood flow to the tissues. Ischemic rest pain is classically described as a burning pain in the ball of the foot and toes that is worse at night when the patient is in bed. The pain is exacerbated by the recumbent position because of the loss of gravity-assisted flow to the foot.
Ischemic rest pain is located in the foot, where tissue is farthest from the heart and distal to the arterial occlusions. Patients who keep their legs in a dependent position for comfort often present with considerable edema of the feet and ankles. Nonhealing wounds are usually found in areas of foot trauma caused by improperly fitting shoes or an injury.
A wound is generally considered to be nonhealing if it fails to respond to a four- to week trial of conservative therapy such as regular dressing changes, avoidance of trauma, treatment of infection and debridement of necrotic tissue.
Gangrene is usually found on the toes. It develops when the blood supply is so low that spontaneous necrosis occurs in the most poorly perfused tissues.
The presence of rest pain can sometimes be difficult to discern in patients with other chronic leg pain, such as that caused by peripheral neuropathy. Labeling a wound as nonhealing can also be a subjective assessment.
However, a number of physical findings and objective hemodynamic parameters can be used to substantiate a diagnosis of chronic critical limb ischemia. Typical physical findings include absent or diminished pedal pulses, shiny smooth skin of the feet and legs, and muscle wasting of the calves. An objective measurement of blood flow is easily accomplished with the use of a hand-held Doppler probe and a blood pressure cuff.
The cuff is then slowly deflated until the pulse is again detected. This measurement is recorded as the systolic pressure. As previously mentioned, an ankle systolic pressure of 50 mm Hg or less or a toe systolic pressure of 30 mm Hg or less suggests the presence of critical limb ischemia. Another widely used parameter is the ankle-brachial index, which is a ratio of the systolic pressure at the dorsalis pedis or posterior tibial artery divided by the systolic pressure at the brachial artery.
Patients with claudication typically have an ankle-brachial index of 0. Vascular laboratories also use Doppler probes to measure the pulse volume waveform at segmental locations in the leg arteries. A change in the Doppler waveform from triphasic to biphasic to monophasic and then stenotic waveforms can identify sites of arterial blockage.
Ischemic rest pain may be confused with night cramps, arthritis or diabetic neuropathy. Night cramps occur in the calf muscles; they usually awaken the patient from sleep and are relieved by massaging the muscle, by walking or by using antispasmodic agents. Patients with arthritis of the metatarsal bones may have pain in the foot. This pain is often experienced at night and may be relieved by standing. When they do occur, the most common is chest pressure or pain, typically on the left side of the body angina pectoris.
Other signs and symptoms — which might be experienced more commonly by women, older people and people with diabetes — include:. If you have too many cholesterol particles in your blood, cholesterol may accumulate on your artery walls. Eventually, deposits called plaques may form. The deposits may narrow — or block — your arteries. These plaques can also burst, causing a blood clot to form.
Myocardial ischemia occurs when the blood flow through one or more of your coronary arteries is decreased. The low blood flow decreases the amount of oxygen your heart muscle receives. Myocardial ischemia can develop slowly as arteries become blocked over time. Or it can occur quickly when an artery becomes blocked suddenly. The same lifestyle habits that can help treat myocardial ischemia can also help prevent it from developing in the first place. Leading a heart-healthy lifestyle can help keep your arteries strong, elastic and smooth, and allow for maximum blood flow.
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