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 gan ...

. 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, an ...

, 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 ...

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

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 e ...

or feet. 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 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 dise ...

Tissue loss

Tissue loss is the development of

arterial insufficiency ulcers Arterial insufficiency ulcers (also known as ischemic ulcers, or ischemic wounds) are mostly located on the lateral surface of the ankle or the distal digits. They are commonly caused by peripheral artery disease (PAD). Characteristics The ulcer ...

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 dis ...

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, a

capillary refill Capillary refill time (CRT) is defined as the time taken for color to return to an external capillary bed after pressure is applied to cause blanching. It can be measured by holding a hand higher than heart-level and pressing the soft pad of a f ...

of more than 15 seconds or diminished or absent pulses. Critical limb ischemia is different from

acute limb ischemia Acute limb ischaemia (ALI) occurs when there is a sudden lack of blood flow to a limb. Acute limb ischaemia is caused by embolism or thrombosis, or rarely by dissection or trauma. Thrombosis is usually caused by peripheral vascular disease (athe ...

. 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, revascularization via vascular bypass or

angioplasty Angioplasty, is also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atheroscle ...

, 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