Anticoagulant and Lytic Therapy for Arterial Thromboembolism in Extremities

Perioperative Management

A complete history and thorough physical examination is the most important aspect of the evaluation of patients with acute limb ischemia. Specific details from the history can suggest the etiology of the process: If a patient has a history of arrhythmias, a central source of embolism should be suspected; on the other hand, if the patient has a history of previous bypass grafting, thrombosis should be suspected. Aggressive fluid resuscitation has been proved to be of paramount importance for long-term survival. Once the initial assessment has been completed and a sense of urgency has been determined, an arteriogram could be performed if it is expected that it will significantly affect the planning of the procedure and that any delays will not adversely affect the outcome of the jeopardized extremity.

Immediate anticoagulation with 100 U/kg of heparin and institution of a heparin drip at 20 U/kg per hour can prevent propagation of the thrombus. Several other anticoagulants are also clinically available in the event antibodies or resistance to heparin is suspected. Bivalirudin has been the most extensively studied and is the easiest to use with regard to therapeutic levels. Laboratory tests have little to offer in terms of preoperative diagnosis, but electrolyte and acid–base abnormalities are common and should be corrected before reperfusion. After finishing the intervention that restores blood flow to an ischemic limb, it is crucial to consider the potential deleterious effects of reperfusion and edema that could potentially create further damage and impair inflow to the affected limb. In this situation, a fasciotomy should be performed without hesitation.

Thrombolysis and Results

In the 1970s Dotter proposed the use of local catheter–directed thrombolytic therapy to avoid systemic effects of these agents and to achieve a stronger and quicker effect. In the 1980s, McNamara developed a protocol of graded intraarterial urokinase administration. Modifications of that protocol set the standard for therapy. The validation of the safety and efficacy of thrombolysis in acute limb ischemia came from the completion of prospective randomized trials comparing it to open surgical intervention. However, to date there is not a drug approved for use in the United States for pharmacologic thrombolysis for acute lower extremity ischemia, and the drugs available are used off-label.