Iliofemoral peripheral vascular intervention

Key points

Patients with symptomatic lower extremity peripheral artery disease often present with classical burning, cramping pain made worse with exertion and better with rest (known as “intermittent claudication”).
The symptomatic location is typically one level below the area of arterial stenosis; however, multilevel stenoses are frequently encountered, especially in critical limb ischemia.
Endovascular intervention for symptomatic claudication has a level I recommendation for iliac interventions and a IIa indication for femoral-popliteal disease in patients not responsive to goal-directed medical therapy and supervised exercise therapy.
A complex armamentarium of devices exists for the treatment of symptomatic lower extremity peripheral artery disease, including angioplasty, stents, atherectomy devices, specialty/focal force balloons, and drug-coated devices.

Introduction

Guideline-directed treatment of the iliofemoral arterial segments is largely determined by patient presentation and response to medical therapy. First-line treatments for peripheral arterial disease include blood pressure management, antiplatelet treatment, aggressive lipid lowering with statins, and smoking cessation. Additionally, the use of cilostazol and supervised exercise therapy have been associated with significant improvement in functional status and symptoms.

When invasive treatment is indicated, endovascular approaches have become favored in many situations. A study of the Medicare population in the United States demonstrated that endovascular treatments occur at four times the rate of open surgical treatment. In recent years, technological advancements have dramatically diversified the treatment options available to achieve procedural and technical success, with an overall goal of enhancing longer-term patency. Despite these advances, durability of interventions may still be limited because of the complex array of forces caused by flexion, extension, and rotation of joints in each of these vascular segments.

Patient evaluation and noninvasive assessment

Iliac obstructive disease classically manifests as thigh and buttock claudication. It may also present with sexual dysfunction if the obstruction occurs proximal to the origin of the internal iliac artery, which supplies much of the pelvic vasculature. Iliac stenosis also frequently mimics spinal stenosis or lumbosacral spine disease (pseudoclaudication). Classically, more upright posture will worsen symptoms (i.e., walking down a hill), suggesting pseudoclaudication because of postural compression of the nerve roots involved. Pseudoclaudication can be improved with leaning forward, whereas ischemic claudication will be improved with rest. In contradistinction, femoral stenosis manifests as exertional symptoms in the thigh, calf, or foot (burning, cramping pain). Pulses will be diminished below the level of the stenosis on exam.

Pulse volume recordings (PVR) and ankle brachial indices (ABI) can be useful in determining the presence, severity, and location of vascular stenoses ( Fig. 15.1 ). In patients with equivocal testing, exercise may be added to enhance the sensitivity of the test and to garner additional prognostic data. Standardized protocols can help discern progressive disease.

Figure 15.1, Positive resting pulse volume recording in the right leg with loss of phasicity from the proximal thigh with worsening at the ankle.

Ultrasound studies are routinely ordered to investigate symptomatic patients with abnormal ABI studies when revascularization or anatomic delineation is required. Increases in peak systolic Doppler velocity are used to grade stenosis severity ( Fig. 15.2a ) and, when correlated with clinical symptoms, may trigger further evaluation and treatment. The ratio of the affected segment compared with the upstream segment is helpful in quantifying this change. Change in phase of Doppler waveforms may also be useful when interpreting ultrasound studies with proximal aortoiliac disease, which may not have been evaluated specifically on femoropopliteal-focused ultrasonography (see Fig. 15.2b ).

Figure 15.2A, Popliteal artery subtotal stenosis with velocity “step up” in stenotic area.

Figure 15.2B, Phasicity change to parvus et tardus waveform in the external iliac artery (EIA) and right mid superficial femoral (Rt SFA MID).

Claudication versus chronic limb-threatening ischemia

The distinction in patient presentation between claudication and chronic limb-threatening ischemia (CLTI; also commonly referred to as critical limb ischemia [CLI]) warrants discussion because treatment approaches and goals are very different between the groups. In patients with claudication, the primary goal is primarily symptom reduction. This goal can often be accomplished via supervised exercise programs with the addition of cilostazol. CLTI is defined as rest pain or tissue loss/gangrene lasting longer than 2 weeks and associated with abnormal hemodynamic findings. The nomenclature of CLTI has recently changed based on the Society of Vascular Surgery (SVS) guidelines from the classic term “critical limb ischemia” to emphasize the chronicity of the presentation. When CLTI is diagnosed, revascularization (either surgical or endovascular) with goal-directed medical therapy carries a level I recommendation by the 2016 American Heart Association (AHA/American College of Cardiology (ACC) guidelines. Conversely, revascularization for claudication should be performed after inadequate response to goal-directed medical treatment (strength of recommendation IIA).

An additional treatment distinction must be clarified when comparing approaches to treatment of claudication with CLTI. In patients with claudication, invasive intervention can often be approached in a stepwise manner, treating inflow (aortoiliac) lesions first before moving to outflow (femoropopliteal). The goal in CLTI, however, is restoration of in-line flow to the affected area (via surgical or endovascular means) to enhance the probability of wound healing.

Selective angiography, carbon dioxide imaging, and vascular ultrasound

Contrast angiography

Fluoroscopic angiography with use of iodinated contrast remains the gold standard for invasive assessment of peripheral arterial disease. Digital subtraction angiography (DSA) is often used to remove bony or dense tissue structures to enhance vascular visualization. A half and half mix of saline and contrast is usually used with DSA to reduce dye exposure and diminish patient discomfort associated with contrast injection into the distal vascular beds.

Carbon dioxide angiography

Carbon dioxide (CO ₂ ) angiography can enable endovascular angiography with the potential for dramatically reducing or eliminating contrast dye exposure ( Fig. 15.3A–C ). CO ₂ may also be useful for individuals at high risk for severe contrast allergies. Successive CO ₂ injections should be spaced apart by 2 to 3 minutes because multiple rapid injections can lead to intestinal ischemia. Visualization of infrapopliteal vessels may be limited with CO ₂ injections. In such scenarios, one can switch the system to contrast injections for enhanced distal vessel visualization or, in the absence of severe proximal disease, CO ₂ injection can be done via a catheter placed more distally.

Figure 15.3, (A) Co 2 tubing set up with syringe and two-way stop cock. (B) A diseased common femoral artery and proximal superficial femoral artery seen with CO 2 . (C) A diseased distal superficial femoral and popliteal artery demonstrated with CO 2 .

Intravascular and extravascular ultrasound

Intravascular ultrasound (IVUS) can aid in assessment of vascular pathology, enable accurate vessel sizing, and assist in postintervention assessment ( Fig. 15.4 ). Preintervention IVUS for vessel sizing can be especially useful in vessels at the extremes of size both large and small in which visual estimation may be challenging. IVUS can also assess the severity of vascular calcification and help determine the need for more complex treatments for lesion preparation (e.g., use of focal force balloons, lithotripsy, or atherectomy). Postintervention imaging can assess adequacy of vessel expansion, note lesion coverage, and assess complications such as dissection or intramural hematoma.

Figure 15.4, Using intravascular ultrasound (Philips, Amsterdam, Netherlands) for distal (A) and proximal (B) reference measurement. These images represent vessel sizing from the external elastic lamina measured as opposed to lumen measurement.

Intraprocedural use of extravascular ultrasound has obvious applications for vascular access. Nevertheless, it has also been used to aid in intraluminal wiring during complex chronic total occlusion (CTO) wire crossing. Experienced operators have demonstrated the feasibility of avoiding fluoroscopy during intervention, thereby reducing radiation exposure to patients and staff.

Endovascular revascularization of the iliofemoral segments

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