Acute limb ischemia caused by DVT is a rare and potentially fatal complication that can result in arterial circulation impairment or limb gangrene

Acute limb ischemia is typically caused by a sudden blockage of arterial blood flow, but in rare cases can be caused by deep venous thrombosis (DVT). Acute limb ischemia caused by DVT is a rare and potentially fatal complication that can result in arterial circulation impairment, tissue ischemia, or limb gangrene.

What is acute limb ischemia?

Acute limb ischemia is a condition caused by a drop in blood flow and oxygen to the limbs. Causes and risk factors include:

• Acute arterial thrombosis (blood clots)
• Embolism (broken clot)
• Arterial trauma
• Atherosclerosis (buildup of plaque in the arteries)
• Smoking
• Advanced age
• High cholesterol
• High blood pressure
• Diabetes
• Family history of cardiovascular disease
• Obesity
• Sedentary lifestyle

What is DVT?

DVT occurs when a blood clot forms in one or more of the deep veins in the body, most commonly in the legs. DVT can be a warning sign of certain medical conditions. Causes and risk factors include:

• Immobility, such as bed rest or sitting for long periods
• Recent surgery or trauma
• Coagulation abnormalities
• Having a central venous catheter
• Limb trauma and orthopedic procedures
• Childbirth within 6 months
• Hormone therapy or use of oral contraceptives
• History of miscarriage
• Age 40 or above
• Obesity
• Tobacco usage
• Previous DVT or family history of DVT
• Previous or current cancer

What are the symptoms of acute limb ischemia?

Acute limb ischemia has a wide range of symptoms, but the most common ones include:

• Marble white appearance of the skin
• Absent limb pulses on palpation
• Cold limb

Less common symptoms, which usually appear in later stages, including:

• Paresthesia (with reduced or complete loss of light touch sensation in the distal limb)
• Paralysis (with the inability to wiggle toes or move fingers)
• Muscle weakness
• Gangrene

What are the symptoms of DVT?

Some cases of deep venous thrombosis (DVT) do not present with any symptoms at all, but signs to look for include:

• Pain, swelling, and tenderness in one leg (usually the calf)
• Heavy ache in the affected area
• Warm skin around the clot
• Red skin, particularly at the back of the leg below the knee

The condition typically affects only one leg, but can also affect both legs or other parts of the body. A blood clot that breaks and travels through the bloodstream can become lodged in a blood vessel in the lung. This is called pulmonary embolism (PE) and can be life-threatening. Some people are unaware they have DVT until this occurs. 

Signs of PE include:

• Chest pain
• Coughing up blood
• Rapid heart rate (tachycardia) of more than 100 beats per minute
• Shortness of breath

What are treatment options for acute limb ischemia?

Acute limb ischemia should be treated as soon as possible because the consequences can be severe. To avoid amputation, blood circulation to the affected limb must be increased. Medication, wound care, and vascular surgery may all be used in treatment.

• Once the diagnosis of acute limb ischemia has been made, anticoagulant therapy should be started with a heparin bolus and infusion. Heparin inhibits the growth of the thrombus and reduces the likelihood of another clot forming in areas of relatively stagnant flow. 
• Doctors may recommend wound treatment for any non-healing or infected wounds.
• Pain medications and medications to control blood pressure and cholesterol may be prescribed.

Methods to restore blood flow depend on the extent and location of the occlusion, presence of collaterals, patient's comorbidities and surgical risk, and the local availability of treatment options. Although the emergency physician is not usually the one who decides on the treatment plan, knowing the options can help determine the appropriateness of transfer and inform patients of their options:

• Angioplasty: A procedure in which a catheter is inserted into the groin and threaded to the artery blockage. When the balloon is in place, it inflates to dilate (widen) the artery. A metal tube (stent) is placed in the artery to support the artery wall.
• Laser atherectomy: A catheter-based procedure that uses a laser to vaporize small pieces of plaque.
• Directional atherectomy: A procedure that physically removes plaque from the arteries by using a rotating cutting blade on the tip of a catheter.
• Peripheral bypass surgery: A surgical procedure in which a vein or synthetic graft is inserted next to the blocked artery and redirects blood through the new bypass.
• Endarterectomy: A surgical procedure in which the artery is opened and plaque from the walls of the artery is removed. This is a rare procedure reserved for arteries close to the skin's surface, such as the femoral artery.

If the doctor is unable to reestablish blood circulation, the last resort is amputation.

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What are treatment options for DVT?

The primary goal of deep venous thrombosis treatment is to keep the clot from growing any larger and causing a pulmonary embolism. Following that, the goal is to reduce the chances of developing deep venous thrombosis again. Typically, treatment consists of a combination of medications and compression.

Medications

Anticoagulants are commonly referred to as "blood thinners," but they work by interfering with the clotting process and lengthening the time it takes for clots to form. This helps prevent new blood clots from forming and keeps existing clots from growing. Anticoagulant medications commonly used include:

• Enoxaparin, which is administered subcutaneously
• Warfarin pills

Regular blood tests may be required to determine how well the anticoagulants are working and whether warfarin dosage changes are necessary. To effectively treat DVT, anticoagulant therapy should be continued for at least 3 months. It may be required on a long-term basis in some cases.

Compression stockings

These are special stockings made of elastic that support the lower legs, encourage circulation, and help reduce swelling. This pressure reduces the likelihood of blood pooling and clotting.

Although DVT cannot be avoided in all circumstances, risk factors can be reduced:

• Sitting for long periods should be avoided. Elevate your legs if you are going to be sitting for an extended period.
• Extra precautions can be taken if you are traveling long distances or are immobilized in a hospital.
• If you smoke, stop or cut back on smoking. Nicotine can cause blood vessels to shrink and reduce blood flow.
• Aim to lose weight if you are overweight. 
• Exercise regularly.
• Drink 6-8 glasses of water a day to stay hydrated and prevent clotting.

What is the prognosis of acute limb ischemia caused by DVT?

Acute limb ischemia, regardless of the underlying etiology, can lead to amputation if proper treatment is not administered. ALI necessitates both localized and systemic treatment because:

• Both the prognosis for the limb and prognosis for overall survival are dismal
• In general, DVT advances to advanced limb ischemia within 2 weeks, and it has a documented death rate of 15%-20% due to coexisting illnesses including cardiovascular or cerebrovascular disease, as well as ischemia-reperfusion injury.

Acute limb ischemia is a rare complication of DVT as is the subsequent development of venous gangrene:

• Although the incidence of venous gangrene is unknown, the annual incidence of all types of DVT in the United States has been reported to be as high as one million cases.
• Ischemic discomfort, cyanotic skin coloring, and severe extremities swelling are common symptoms.
• Venous outflow restriction causes substantial fluid sequestration in the extremity, culminating in shock. It has a death risk of 25%-40%.
• Ischemia is caused by venous hypertension and can be reversed if diagnosed early and treated aggressively.
• However, venous gangrene affects 40%-60% of patients, leading to amputation rates of 12%-50%.
• Patients had a greater rate of pulmonary embolism (12%-40%) than patients with sub-massive deep venous thrombosis. Pulmonary embolism accounts for 30% of mortality.

Early diagnosis, anticoagulation, forceful fluid resuscitation, and venous hypertension treatment are essential for the successful management of both diseases.