Aortoiliac Occlusive Disease Workup

Updated: Aug 21, 2017
  • Author: Khanjan H Nagarsheth, MD, MBA; Chief Editor: Vincent Lopez Rowe, MD  more...
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Workup

Laboratory Studies

Examine a serum lipid profile that includes total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides (TG). Furthermore, in younger patients or those with a strong family history of atherosclerosis at any early age, lipoprotein (a) and homocysteine levels should be determined.

If a history of diabetes exists, a glycosylated hemoglobin level (HbA1c) should be checked. Excellent control of diabetes reduces long-term complications, and the American Diabetes Association (ADA) currently recommends that the HbA1c be below 7%. [10]

If a patient has a history of thrombosis in any venous or arterial segment or a family history of a clotting disorder, an evaluation for hypercoagulability is necessary. Tests include routine prothrombin time (PT), activated partial thromboplastin time (aPTT), platelet count, factor V Leiden, factor II (prothrombin) C-20210a, anticardiolipin antibody, protein C, protein S, and antithrombin III.

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Imaging Studies

Contrast aortography is not always required, unless interventional therapy (percutaneous transluminal angioplasty [PTA]/stenting or surgical revascularization) is planned. Serum creatinine is checked to validate a baseline level prior to the use of contrast agents that may be nephrotoxic.

Computed tomography (CT) angiography (CTA) is an excellent modality for planning operative or endovascular treatments. [11] It has the advantage of producing three-dimensional images of the arterial system that are as accurate as those achieved with conventional catheter arteriography. However, the use of an iodinated contrast agent is still required to obtain the images in CTA, though direct arterial cannulation is not needed.

As an alternative to conventional angiography, the surgeon may consider magnetic resonance angiography (MRA) or arterial duplex mapping as definitive imaging studies for planning surgery. MRA is overly sensitive and may suggest significant arterial stenoses that are simply not present.

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Ankle-Brachial Index and Pulse Volume Recording

At least half of patients with peripheral arterial disease (PAD) are asymptomatic and are diagnosed only by physical examination, Doppler-derived measurement of the ankle-brachial index (ABI), or both.

An ABI lower than 0.9 clearly is abnormal and confirms the diagnosis of PAD. An abnormal ABI should alert the clinician to the fact that this group of patients is at risk for early mortality from cardiovascular causes (eg, myocardial infarction, stroke, other vascular death). The ABI also can grade the severity of PAD. Note that Doppler-derived segmental arterial pressures do not accurately reflect the severity of aortoiliac occlusive disease (AIOD).

In addition, the ABI is not very sensitive in identifying patients with mild occlusive lesions in the aortoiliac segment. A treadmill exercise stress test should be recommended for those patients with mild iliac occlusive disease who have symptoms suggestive of claudication even though the ABI is normal at rest. After exercise, the blood flow through stenotic vessels increases and the pressure decline across these lesions is augmented.

Moreover, if the blood pressure cuff is unable to compress the vessels adequately, the Doppler-derived pressures may be falsely elevated. This may occur in patients with diabetes or end-stage renal disease. In the event that supranormal (falsely elevated) Doppler-derived pressures are encountered, pulse volume recording (PVR) may be useful in evaluating leg perfusion.

The PVR waveform reflects the volume of blood in the leg during an individual cardiac cycle. A normal waveform demonstrates a brisk upstroke, a sharp systolic peak, and a downstroke with a dicrotic notch. With significant PAD, the dicrotic notch is lost, the slope of the upstroke and downstroke decline, the amplitude of the waveform is reduced, and the contour of the systolic peak is more rounded.

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Other Tests

Because an association with coronary disease in patients with PAD exists, electrocardiography (ECG) should be performed even in patients without cardiac history.

For those patients being considered for an intra-abdominal aortic procedure, pulmonary function tests are important if a history of obstructive pulmonary disease or dyspnea is present. Often, the results of this preoperative evaluation signal a need to alter the surgical approach.

An intensive preoperative cardiac evaluation is reserved for patients with newly onset angina pectoris, unstable angina pectoris, or evidence of ventricular dysfunction on dobutamine stress echocardiography. Adenosine thallium perfusion tests are not routinely performed, because of the high sensitivity and low specificity.

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