Endovascular Intervention of Aortoiliac Occlusive Disease
Sasanka Jayasuriya, MBBS, FACC, FASE, RPVI, FSCAI
William L. Bennett, MD, PhD
Key Points
Claudication, critical limb ischemia, and erectile dysfunction are symptoms related to aortoiliac occlusive disease.
Investigations including ABI ultrasound are performed to aid diagnosis, and CT angiography and MRA are helpful for lesion characterization and procedure planning.
Many techniques including contralateral and ipsilateral crossing techniques could be undertaken for crossing the lesion with reentry devices used to aid access to the true lumen.
Self-expanding stents are commonly used with 3-year primary patency being greater than 70%.
I. Introduction
Advances in transcatheter therapies have led to a shift in endovascular interventions for aortoiliac disease, even in the setting of complex lesions such as Trans-Atlantic Inter-Society Consensus Document classification (TASC) class C and D lesions in recent times.1 Patients with peripheral arterial disease suffer from multiple comorbidities, and up to 40% suffer from significant coronary artery disease. Of these patients, the subgroup suffering from aortoiliac occlusive disease (AIOD) suffers from substantial loss of quality of life owing to claudication and critical limb ischemia.11 Endovascular treatment options are a valuable alternative to high-risk open surgical procedures. However, the operators are encouraged to recognize the risks associated with aortoiliac interventions with attention to careful case selection, procedure planning, technical skill, and bailout strategies, which result in successful results.
II. Indications for Endovascular Intervention of Aortoiliac Occlusive Disease
A. Claudication is a common symptom in AIOD with complaints including claudication of the buttocks, thighs, or calf. Symptoms typically begin in the calves and proceed proximally with worsening hemodynamics. Intervention is indicated when >50% stenosis is present with lifestyle-limiting claudication (Rutherford class 2 and 3), which is not improved with medical therapy or exercise therapy. In the event of multilevel disease, inflow revascularization (treatment of AIOD) is undertaken initially.
B. Critical Limb Ischemia presenting as ischemic rest pain or vascular ulcers and tissue loss (Rutherford class 4, 5, and 6) is a strong indication for revascularization. Contrary to patients with claudication, patients with critical limb ischemia are treated with complete revascularization in an attempt to establish straight-line reperfusion to the affected angiosome.
C. Erectile Dysfunction is another indication for treatment of AIOD. The typical syndrome of buttock or thigh claudication, erectile dysfunction, and absent pulses is known as Leriche syndrome and is usually caused by AIOD.
D. Vascular Access for unrelated procedures such as endovascular aortic repair (EVAR) and transcatheter aortic valve replacement (TAVR) requiring large-diameter sheath introduction may require aortoiliac revascularization.
III. Diagnosis
A. Physical Examination performed thoroughly could suggest AIOD, although the nature and exact location of the lesion cannot be predicted. Reduced or asymmetric femoral pulses are appreciated with typical signs of chronic ischemia in the affected limb such as cold extremity, pallor, hair loss, nail atrophy, and dependent rubor.
B. The first line of physiologic testing includes noninvasive testing such as ankle brachial index (ABI), toe brachial pressures, segmental pressures, and pulse volume recording (PVR). If unilateral iliac stenosis is present, the ABI, segmental pressures, as well as the PVR would be reduced in the affected limb. However, in the setting of distal aortic or bilateral aortic disease, the ABI and segmental pressures may be reduced in a symmetrical fashion. Blunting of the pulse volume waveform bilaterally suggests distal aortic and bilateral iliac disease.
C. Imaging
1. Duplex ultrasound could be used as a method of imaging especially in patients with renal impairment. However, iliac ultrasound evaluation is technically challenging and time-consuming with poor images resulting due to body habitus, bowel gas, and calcification. A study by Ubbink et al suggested significant interobserver variability with iliac duplex imaging with 1/8 agreement on results.12 Hence, alternative imaging should be considered if more precise anatomic diagnoses are needed.
2. Computer tomography angiography (CTA) is an excellent study modality in patients with AIOD. Current generation scanners produce accurate three-dimensional imaging and are an excellent alternative to invasive angiography for planning revascularization. Benefits of CTA evaluation include a faster scan time, high spatial resolution, and ability to visualize in-stent restenosis. However, use of iodinated contrast and radiation exposure are disadvantages, and further heavily calcified vessels may reveal inaccurately more severe stenosis due to blooming artifact.
3. Magnetic resonance angiography (MRA) is another effective imaging method of evaluation in AIOD. Current high-performance MR scanners produce remarkable angiography. MRA carries the benefits of not being exposed to iodinated contrast or ionizing radiation. However image acquisition takes a long time, and patients with advanced renal disease are at risk of nephrogenic systemic fibrosis. MRA also may not accurately estimate the degree of calcification, which may change the level of complexity of an intervention.
4. Invasive angiography is the gold standard for imaging aortoiliac disease. In assessing AIOD, the initial angiogram would comprise of an anterior-posterior distal aortic angiogram run off to include both common iliac, external iliac, and common femoral arteries (CFAs). Imaging is performed by digital subtraction angiography (DSA).
Evaluation of each iliac artery is performed by contralateral oblique projection, which separates the iliac bifurcation. In the event of a long-segment occlusion, the distal anastomotic site as well as below knee run off is completed to ensure the appropriate approach is undertaken and distal embolization had not occurred during intervention.
The hemodynamic significance of an intermediate lesion can be measured by advancing a catheter beyond the lesion with gradual pullback measurements. A more accurate method is to transduce simultaneously the side branch of the sheath and a catheter, which is at least 1 French less in diameter placed across the lesion. A peak-to-peak systolic gradient greater than 10 mm Hg is considered to be hemodynamically significant. With concomitant distal disease, a pressure gradient could be induced with intra-arterial nitroglycerin injection to induce peripheral vasodilatation.
IV. Endovascular Treatment
A. Procedure Planning Planning of the procedure is a key element in endovascular treatment of AIOD. Specific patient and lesion characteristics could significantly change the approach and outcomes in intervention.
1. Lesion characteristics. Long-segment occlusions and heavily calcified vessels should be undertaken only by the experienced operator. For early career interventionalist, backup support planning is imperative. While heavy calcification is a contraindication to aortoiliac percutaneous intervention, every lesion carries the risk of perforation. Hence the availability of bailout equipment such as occlusive balloons and covered stents should be ensured.
2. Patient characteristics. AIOD intervention could be relatively fast or long and complex. Hence the candidacy for conscious sedation and support from an anesthesiologist should be assessed. Considering the higher volume of iodinated contrast used, prehydration should be undertaken to reduce contrast-induced nephropathy with special attention to the patient’s current volume status and left ventricular function. Low-osmolar or iso-osmolar contract agent use is also associated with a lower risk of contrast-induced nephropathy.
B. Access
1. Access site and sheath size are important decisions that lay the foundation to successful completion of the intervention. Complex aortoiliac intervention usually requires dual access. While angiography is performed through catheters advanced from one site, equipment would usually be delivered through a larger French sheath in an alterative site.
2. The most common site of access in AIOD is the ipsilateral CFA. However, in the event of complete occlusion of the external iliac artery, there may not be an adequate length in the patent vessel to advance the sheath. In this case, contralateral common femoral access or brachial access is considered. While radial access is more elegant,
in comparison to brachial access, the shaft length of current balloons and stents may not reach the external iliac vessels from a radial sheath. However, for the sole purpose of diagnostic angiography proximal to the occlusion, radial access could be obtained, through which a pigtail catheter placed in the descending aorta or a multipurpose catheter directed to the respective iliac artery would be useful to perform diagnostic angiography. However, if devices are to be delivered from above, brachial access is required. Left brachial access is preferred as the risk of cerebral embolization is less than with right brachial access in these patients with significant atherosclerotic disease.
3. In deciding sheath size, the smallest sheath, which would allow required equipment delivery, is the choice. However, in a heavily calcified vessel, a sheath that could deliver a covered stent as needed would be a wiser choice.
V. Common Femoral Disease
In the event of concurrent common femoral disease, a prior decision for the approach to managing this lesion is imperative. At the conclusion of the iliac intervention, the lesion in the CFA could be revascularized by atherectomy and drug coated balloon therapy or with hybrid revascularization with concomitant common femoral end arterectomy.
VI. Lesion Crossing
A. External Iliac Artery and Retrograde Approach Occlusions of the external iliac artery could be crossed by ipsilateral common femoral access, if the distal external iliac artery was patent and sheath placement was possible. Ultrasound-guided vascular access is beneficial, as femoral pulses are faint to absent. A bright-tipped sheath is used. The lesion could be crossed with an assortment of wires and backup catheters. We commonly use a 0.14″ Fielder FC (Asahi Intecc) wire with a Quickcross (Spectranetics Corp, Colorado Springs, CO) backup catheter with success in crossing the lesion in an intraluminal fashion. However, an angled Glidewire (Terumo Medical, Somerset, NJ) and a 0.35″ angled backup catheter are other options. The support catheter is advanced to the distal cap of the occlusion with gentle forward force, and the distal cap is crossed by spinning or looping the wire. As the access sheath could get displaced out of the artery when forward force is applied to cross the lesion, it should be secured manually. Subintimal crossing may be undertaken with the Glidewire, but reentering the vessel at the reconstitution site is important to prevent undue stenting and propagation of a dissection plane. Once the lesion is crossed, the backup catheter is advanced beyond the lesion and blood is aspirated to confirm intraluminal placement. A limited angiogram could be performed through the backup catheter. A stiff-bodied wire is then advanced through the backup catheter, which would be the guidewire for equipment delivery to complete the procedure. Hence this could be a 0.14″, 0.18″, or 0.35″ wire depending on the intervention planned.
B. Antegrade Approach An external iliac occlusion could also be crossed by the antegrade approach with access in the contralateral CFA or in the left brachial artery. With contralateral CFA access, the iliac bifurcation is crossed in standard fashion, and a
45 cm crossover sheath is advanced to the proximal cap of the occlusion. With angiography performed in the contralateral oblique position, the lesion is crossed as mentioned above.
With brachial access a 90 cm guiding sheath is advanced to the proximal cap of the lesion. The lesion is crossed with wire and a backup catheter, and the stiff guiding wire is placed in the CFA. With available landing room in the distal external iliac and CFAs, the wire advanced from the brachial position could be externalized through a sheath in the ipsilateral CFA. This could be exchanged to a stiff guiding wire, following which the intervention could be completed from the ipsilateral CFA.
C. Common Iliac Artery Occlusions Occlusions of the common iliac artery or common and external iliac arteries are best crossed by ipsilateral CFA access or left brachial access. Contralateral crossover sheaths usually would not be stable enough to provide the backup support or “pushability” to cross through a lesion. This is specifically true in flush occlusions of the ostial common iliac artery, although this approach could be tried as an initial strategy, as access is likely obtained for diagnostic angiography. Once the guiding sheath is usually advanced to engage the stump or in very close proximity of the lesion, which is crossed with a hydrophilic guidewire and angled backup catheter. A 0.14″ wire such as the Fielder FC (Asahi Intecc) or a 0.35″ angled Glidewire (Terumo Medical, Somerset, NJ) could be used. If brachial access was used the wire is snared out of a sheath placed in the ipsilateral CFA, thus allowing for a stiff guiding wire to be advanced to the descending aorta from the CFA, which facilitates ease of delivery of stents and correct alignment.
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