Chronic limb threatening ischemia (CLTI), also known as critical limb ischemia (CLI), is an advanced stage of peripheral artery disease (PAD). It is defined as ischemic rest pain, arterial insufficiency ulcers, and

gangrene Gangrene is a type of tissue death caused by a lack of blood supply. Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness. The feet and hands are most commonly affected. If the ga ...

. The latter two conditions are jointly referred to as tissue loss, reflecting the development of surface damage to the limb tissue due to the most severe stage of

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems w ...

. Compared to the other manifestation of PAD,

intermittent claudication Intermittent claudication, also known as vascular claudication, is a symptom that describes muscle pain on mild exertion (ache, cramp, numbness or sense of fatigue), classically in the calf muscle, which occurs during exercise, such as walking, a ...

, CLI has a negative prognosis within a year after the initial diagnosis, with 1-year amputation rates of approximately 12% and mortality of 50% at 5 years and 70% at 10 years. CLI was conceived to identify patients at high-risk for major amputation, but the increasing prevalence of

diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

has led to a broader conception of limb threat that includes the risk of amputation associated with severely infected and non-healing

wounds A wound is a rapid onset of injury that involves lacerated or punctured skin (an ''open'' wound), or a contusion (a ''closed'' wound) from blunt force trauma or compression. In pathology, a ''wound'' is an acute injury that damages the epid ...

Signs and symptoms

Critical limb ischemia includes rest pain and tissue loss.

Rest pain

Rest pain is a continuous burning

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

of the

lower leg The human leg, in the general word sense, is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or gluteal region. However, the definition in human anatomy refers only to the section of the lower limb ex ...

feet The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...

. It begins, or is aggravated, after reclining or elevating the limb and is relieved by sitting or standing. It is more severe than

, which is also a pain in the legs from arterial insufficiency.

Tissue loss

Tissue loss is the development of arterial insufficiency ulcers or

due to

peripheral artery disease Peripheral artery disease (PAD) is an abnormal narrowing of arteries other than those that supply the heart or brain. When narrowing occurs in the heart, it is called coronary artery disease, and in the brain, it is called cerebrovascular diseas ...

Diagnosis

Critical limb ischemia is diagnosed by the presence of ischemic rest pain, and an ulcers that will not heal or gangrene due to insufficient blood flow. Insufficient blood flow may be confirmed by ankle-brachial index (ABI), ankle pressure, toe-brachial index (TBI), toe systolic pressure,

transcutaneous oxygen measurement Transcutaneous oxygen measurement (TCOM or TcPO2) is a non-invasive method of measuring the oxygen level of the tissue below the skin. Since oxygen is carried by the blood, TCOM can be used as an indirect measure of blood flow to the tissue. Since ...

(TcPo2 ), or skin perfusion pressure (SPP). Other factors which may point to a diagnosis of critical limb ischemia are a Buerger's angle of less than 20 degrees during

Buerger's test Buerger's test is used in an assessment of arterial sufficiency. It is named after Leo Buerger. The ''vascular angle'', which is also called ''Buerger's angle'', is the angle to which the leg has to be raised before it becomes pale, whilst lying ...

, a capillary refill of more than 15 seconds or diminished or absent pulses. Critical limb ischemia is different from acute limb ischemia. Acute limb ischemia is a sudden lack of blood flow to the limb, for example caused by an embolus whereas critical limb ischemia is a late sign of a progressive chronic disease.

Treatment

Treatment mirrors that of other symptoms of

, and includes modifying

risk factors In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often use ...

revascularization In medical and surgical therapy, revascularization is the restoration of perfusion to a body part or organ that has had ischemia. It is typically accomplished by surgical means. Vascular bypass and angioplasty are the two primary means of reva ...

via

vascular bypass A vascular bypass is a surgical procedure performed to redirect blood flow from one area to another by reconnecting blood vessels. Often, this is done to bypass around a diseased artery, from an area of normal blood flow to another relatively norm ...

or angioplasty, and in the case of tissue loss, wound

debridement Debridement is the medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue. Removal may be surgical, mechanical, chemical, autolytic (self-digestion), and by maggot therapy. I ...

Research

As of 2015 pCMV-vegf165, a gene-therapy was being studied in critical limb ischemia. In 2014, a trial was started to better understand the best revascularization technique for CLI. As of 2017, it had enrolled nearly half of the 2100 people needed to complete the trial. A similar study, BASIL 2 (Bypass Versus Angio plasty in Severe Ischaemia of the Leg), is being conducted in the United Kingdom.

References

External links

Cochrane Peripheral Vascular Diseases Review Group
{{Vascular diseases Hypertension