Peripheral artery disease

Background

• Peripheral artery disease = ABI <0.9
• >80% of pts are either former or current smokers
• 33% of deaths are from reperfusion injury
  • Myoglobinemia, ARF, incr CK
• Thrombosis accounts for >80% of lower limb ischemia

Diagnosis

History

• 6 P's:
  • Pain, pallor, paralysis, pulselessness, paresthesias, polar
    • Paresthesia and weakness are early findings
    • Preservation of light touch is good guide to tissue viability
    • Anesthesia and paralysis = impending gangrene
    • Absence of pulse in pt w/ chronic disease only helpful if accompanied by skin changes

Physical Exam

• Shiny, hyperpigmented skin, hair loss
• Ulceration
  • Tend to be on foot/toes, more painful than venous ulcers
• Cap refill >3sec

Work-Up

• ABI
  • Ratio of sBP of post tibial or DP to highest brachial pressure in either arm
  • <0.40 = potentially limb-threatening vascular disease
  • 0.41-0.90 = claudication
  • >1.3 = noncompressible vessel (severe vascular calcification)
• Imaging
  • Ultrasound
    • Accurate for detecting obstruction in femoral/popliteal/bypass grafts
      • Sn declines at/below the calf
  • CT (with contrast)
    • Sensitivity similar to that of aortography

DDx

• Phlegmasia cerulea dolens (severe DVT)
• Phlegmasia alba dolens (severe DVT + arterial spasm)
  • Seen in pregnant women
  • Arterial spasm is transient (do not confuse w/ arterial occlusion)

Disposition

Table 64-5 ED Therapy for Acute Limb Ischemia

Although no studies to date have established an unequivocally beneficial role of any generally administered antithrombotic agent for acute arterial occlusion, when the diagnosis of acute limb ischemia is known or suspected, the current practice is the immediate administration of IV unfractionated heparin. Weight-adjusted dosing of unfractionated heparin at an 80 units/kg bolus followed by an infusion of 18 units/kg/h rapidly achieves a therapeutic heparin level and activated partial thromboplastin time.

Supportive therapies, including the administration of analgesia and dependent positioning of the extremity, should not be overlooked. Fluid resuscitation and treatment of heart failure and dysrhythmias are sometimes necessary to improve limb perfusion.

Catheter-directed intra-arterial thrombolysis has replaced systemic thrombolysis for peripheral artery embolic or thrombotic disease.

The final recommendation is that catheter-directed thrombolysis should be considered a treatment option in patients with thrombotic or embolic disease of <14 days provided the patient is at low risk for myonecrosis or ischemic nerve damage during the time required to achieve reperfusion.1

The decision regarding the method of revascularization is a complex one.

PTA may be a better option for patients with multiple comorbidities who are at higher risk when undergoing major surgery and for those with a short life expectancy. In general, open surgery seems to be a more attractive option for patients with inflow disease and multifocal and long-segment disease. Open surgery still is the gold standard therapy and an important treatment option for patients with a favorable long-term prognosis.

The American College of Cardiology/American Heart Association 2005 guidelines included cilostazol, a phosphodiesterase inhibitor, as a Class I recommendation for the treatment of claudication in patients with obstructive arterial disease2 (avoid in patients with heart failure). Pentoxifylline is considered a second-line therapy for the treatment of claudication (Class IIb)

Source

Tintinalli