Diagnosis and Management of Acute Limb Ischemia

Etiology

Acute limb ischemia (ALI) results from a sudden obstruction in the arterial flow to the extremity due to an embolism or thrombosis. Embolic problems result in a greater degree of ischemia than thrombosis, as the embolus characteristically lodges in a "virgin" vascular bed with no prior collateral development. On the contrary, an in situ thrombosis occurs in vessels with prior, gradual atherosclerotic narrowing that has stimulated the formation of collateral channels. The presence of these collaterals lessens the severity and rapidity of symptom development when the atherosclerotic narrowing progresses to occlusion.^[1] It is often difficult to distinguish an embolus from a thrombosis, but embolic occlusions should be suspected in patients with the following features: 1) acute onset, where the patient is often able to accurately time the moment of the event; 2) a history of embolism; 3) a known embolic source, such as cardiac arrhythmias; 4) no prior history of intermittent claudication; and 5) normal pulse and Doppler examination in the unaffected limb.

In addition to the presence of collateral channels, the location of the occlusion may also play a critical role in the severity of limb ischemia. For example, occlusion of the popliteal artery results in profound limb ischemia, since it is the only artery crossing at the level of the knee. By contrast, occlusion of the anterior tibial artery is often asymptomatic, as two other vessels -- the posterior tibial and peroneal arteries -- can function as alternate parallel channels to supply the foot.^[1]

Due to a decline in the incidence of rheumatic heart disease, advances in cardiac surgery, and the widespread use of anticoagulation for arterial arrhythmias, generalized atherosclerosis resulting in thrombosis is the most common etiology of acute peripheral arterial occlusion. The superficial femoral artery is the most common site of atherosclerotic narrowing. In addition, aggressive use of bypass grafts has resulted in a greater number of patients presenting with acute ischemia. The ever-changing nature and increasing complexity of the vascular pathology requires a multimodality approach that may involve vascular surgeons, cardiologists, radiologists, coagulation specialists, and various critical care specialists. Most importantly, this patient care team must include knowledgeable nurses and technologists who are the eyes and the ears of the physicians and provide the moment-to-moment care of this quite fragile group of patients.

Cite this: Current Options in the Diagnosis and Management of Acute Limb Ischemia - Medscape - Jan 01, 2002.

Table 1. Clinical Categories of Acute Limb Ischemia
Category	Sensory Change	Motor Change	Doppler Signals
Category	Sensory Change	Motor Change	Arterial	Venous
Viable	None	None	Audible	Audible
Threatened	Rest pain	Moderate	Inaudible	Audible
Irreversible	Anesthetic	Paralysis	Inaudible	Inaudible

Table 2. Amputation, Mortality, and Long-Term Limb Salvage With Open Surgery
Author	Year	Number	Amputation	Mortality	Limb Salvage
Campbell et al.^[7]	1998	474	16%	22%	NR
Nypaver et al.^[8]	1998	71	7%	10%	1 year: 62%
Pemberton et al.^[9]	1999	107	12%	25%	2 years: 75%

NR=not reported

Table 3. Contraindications to Use of Pharmacologic Thrombolytic Agents
Absolute Contraindications
Active bleeding disorder Gastrointestinal bleeding within 10 days Cerebrovascular event within 6 months Intracranial or spinal surgery within 3 months Head injury within 3 months
Relative Contraindications
Major surgery or trauma within 10 days Hypertension (systolic >180 mm Hg or diastolic >110 mm Hg) Cardiopulmonary resuscitation within 10 days Puncture of noncompressible vessel Intracranial tumor Pregnancy Diabetic hemorrhagic retinopathy Recent eye surgery Hepatic failure Bacterial endocarditis

Table 4. Results of Treatment With Initial Thrombolytic Therapy or Primary Operation for Acute Limb Ischemia: Multicenter, Randomized Trials
Trial	Patients	Time Period	Thrombolytic Therapy		Primary Operation
Trial	Patients	Time Period	Amputation	Death	Amputation	Death
Rochester^[10]	114	12 months	18%	16%	18%	42%
STILE^[2]	393	6 months	12%	6.5%	11%	8.5%
TOPAS-II^[11]	544	12 months	15%	20%	13.1%	17%

Table 5. Amputation, Mortality, and Patency After Percutaneous Mechanical Thrombectomy
Author	Year	Number	Device	Amputation	Mortality	Patency
Silva et al.^[14]	1998	22	Angiojet	5%	14%	NR
Wagner et al.^[13]	1997	50	Angiojet	8%	0	1 year: 69%
Reekers et al.^[21]	1996	28	Hydrolyser	11%	0	1 month: 50%
Henry et al.^[15]	1998	41	Hydrolyser	0	0	1 month: 73%
Hopfner et al.^[12]	1999	51	Oasis	17.70%	8%	6 months: 54%
Rilinger et al.^[18]	1997	40	Amplatz	5%	0	NR
Tadavarthy et al.^[22]	1994	14	Amplatz	0	0	6 months: 43%

NR=not reported

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Current Options in the Diagnosis and Management of Acute Limb Ischemia

Etiology

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