Endovascular Treatment of Peripheral Artery Disease

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Chapter 20 Endovascular Treatment of Peripheral Artery Disease

The concept of nonsurgical catheter-based peripheral vascular revascularization was first described by Charles Dotter1 and further advanced with the development of balloon dilation catheters by Andreas Gruentzig.2 Catheter-based revascularization has largely replaced conventional open surgery as the treatment of first choice in selected patients treated for lower-extremity ischemia.3

No single specialty program (cardiology, radiology, or surgery) offered training that satisfied the entire skill set needed to perform peripheral endovascular intervention (Table 20-1). Recognition of this unmet need for a trained cadre of clinicians to care for patients with peripheral artery disease (PAD) prompted the development of a core cardiology training symposium (COCATS-11) to codify the necessary cardiology fellowship training.4

Table 20-1 Required Skill Elements for Optimal Peripheral Vascular Intervention

Skill Element Description
Cognitive Extensive knowledge of vascular disease, including natural history, pathophysiology, diagnostic methods, and treatment alternatives
Technical Competence in both diagnostic angiography and interventional techniques, such as use and selection of balloons, guidewires, stents, and emboli protection devices
Clinical Ability to manage inpatients, interpret laboratory tests, obtain informed consent, assess risk/benefit ratio, and admitting privileges

Patient and Lesion Selection Criteria

Indications

Anatomical and Functional Criteria

Patient selection for catheter-based vascular intervention depends upon both anatomical and functional criteria (Table 20-2). Anatomical lesion criteria include ability to gain vascular access, a reasonable likelihood of crossing the lesion with a guidewire, and the expectation that a therapeutic catheter can be advanced across the target lesion (Fig. 20-1). A strategy of “provisional” (bailout) stenting, or use of a stent for a failed balloon dilation attempt (in contrast to “primary” stenting, in which stents are placed with or without balloon predilation), has become the standard of practice for shorter, more discrete lesions. Longer lesions and occlusions are better treated with primary stent placement.3,58

Availability of endovascular stents (balloon expandable and self-expanding) has significantly extended the anatomical subset of patients who may be considered candidates for peripheral vascular intervention, particularly for longer stenotic lesions and occlusions. The rate-limiting step for nonsurgical revascularization of the aortoiliac vessels is the ability to pass a guidewire across the lesion. Regardless of the balloon dilation result, the option of stent placement offers a reliable and reproducible method to recanalize these large vessels.9

Vascular access site complications following catheter-based procedures often can be treated with percutaneous therapy10 (Fig. 20-2). Patients with hypotension and a high suspicion of bleeding after common femoral artery (CFA) access require urgent diagnostic angiography from the contralateral femoral artery to determine the bleeding site. Rapid identification of the bleeding site may provide an opportunity for lifesaving hemostasis with balloon tamponade.

Functional criteria to select patients for peripheral endovascular revascularization typically include lifestyle- or vocational-limiting symptoms of claudication, critical limb ischemia (CLI; rest pain, nonhealing ulcers, or gangrene), or acute limb ischemia. Asymptomatic patients with anatomically suitable iliac artery lesions may be considered candidates for peripheral vascular intervention to facilitate vascular access, such as for intraaortic counterpulsation balloon placement or for vascular access to perform coronary intervention.

Patients with lifestyle-limiting symptoms of classical claudication or atypical claudication should first have an attempt at pharmacological therapy with cilostazol and supervised exercise training before endovascular intervention is attempted. If exercise training and pharmacotherapy are not effective, if patients are intolerant of cilostazol or cannot be treated with the drug because of heart failure (black box warning), or if a supervised exercise program is unavailable, an attempt at endovascular intervention is appropriate. In general, patients with claudication progress to limb loss at a rate of well under 5% per year, so endovascular revascularization is reserved for those patients with favorable anatomy who either fail conservative therapy and have lifestyle-limiting symptoms or have vocational-limiting symptoms. Therapeutic goals for claudicants are symptom relief, increased walking distance, and improved functionality and quality of life. For this reason, durability of the procedure becomes important; recurrent ischemic symptoms require repeated procedures.

Patients with CLI or limb-threatening ischemia (gangrene, nonhealing ulcer, or rest pain) are candidates for urgent revascularization. When considering a patient with CLI for revascularization, it is important to remember that multilevel disease (iliac, femoral, and tibial) is likely to be present and that simply improving “inflow” without addressing the more distal vascular lesions or runoff vessels may fail to solve the clinical problem. Patients with CLI (rest pain, nonhealing ulcers, or gangrene) typically have more extensive disease than claudicants and require urgent revascularization to prevent tissue loss3,11 (see Table 20-2).

Prognosis for patients presenting with CLI is poor.12 Those with tobacco abuse and/or diabetes are 10 times more likely to require amputation. Patients with CLI tend to be older, with almost 50% of patients older than 80 years undergoing amputations. Within 3 months of presentation, 12% will require an amputation, and 9% will die; 1-year mortality rate is 22%. Anatomy suitable for endovascular therapy is often present in one or more below-knee vessels. Therapy should be designed to restore pulsatile straight-line flow to the distal part of the limb, with as low a procedural morbidity as possible. The guiding principle is that less blood flow is required to maintain tissue integrity than to heal a wound, so restenosis does not usually result in recurrent CLI unless there has been repeated injury to the limb. Therefore, the emphasis is less on long-term vessel patency and more on amputation-free survival.

The Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial was a multicenter randomized trial comparing an initial strategy of balloon angioplasty to open surgery in 452 patients with CLI.13 The primary outcome was time to amputation or death (amputation-free survival). After 6 months, the two treatment strategies did not differ significantly in amputation-free survival. There was no difference between the groups for quality-of-life outcomes, but for the first year of follow-up, costs associated with a surgery-first strategy were higher than for angioplasty. For this reason, the authors concluded that a percutaneous-first strategy was the treatment of choice in patients who are candidates for either surgery or endovascular intervention.

Technical and Procedural Considerations

Preprocedure

General Measures

Prior to performing peripheral endovascular intervention, the patient should have a complete cardiovascular evaluation, with specific attention directed to the status of atherosclerotic risk factors. Atherosclerosis is a systemic disease, and appropriate risk-factor modification (tobacco-cessation counseling, treatment of lipids to target values), screening tests for cardiovascular diseases, and optimization of medical therapy should be performed.

Prior to performing lower-extremity endovascular intervention, it is necessary to objectively determine the patient’s functional status. A history, physical examination, and appropriate noninvasive testing should be obtained prior to planning peripheral endovascular revascularization. If the patient is ambulatory, a rest and exercise ankle-brachial index (ABI) should be measured, and pulse volume recordings (PVR) should be performed. Other noninvasive modalities, such as vascular ultrasound, or alternative imaging modalities, such as magnetic resonance angiography (MRA) or computed tomographic angiography (CTA), may be helpful to resolve conflicting data and are used at the discretion of the physician (Fig. 20-3). When planning lower-extremity revascularization, status of the inflow and outflow vessels relative to the target lesion must be visualized angiographically. This is usually done with invasive diagnostic angiography, but in selected patients, MRA or CTA may be very useful.

Equipment Choices

Clinical Outcomes

Aortoiliac Vessels

The current best practice, in experienced hands, for aorto-iliac lesions favors an endovascular strategy (Fig. 20-4). This recommendation is based upon the morbidity and mortality associated with major vascular surgery in patients with significant comorbidity, and the excellent outcomes available with current endovascular techniques. In a large single-center registry of 505 iliac stent procedures, the technical success rate was 98%, 8-year primary stent patency rate was 74%, and secondary patency rate was 84%.18 In a 10-year iliac stent patency study, there was no effect of age, diabetes, tobacco smoking, or hypertension on patency.19 Common iliac artery (CIA) lesions had greater long-term patency than external iliac artery (EIA) lesions. Outcomes from another series of 89 consecutive patients with symptomatic occluded iliac arteries demonstrated a 92% success rate for endovascular treatment.20 Increasing severity and complexity of lesions did not significantly alter iliac artery patency rates.

An observational study compared nonrandomized results of iliac artery stenting with surgery in patients with moderately complex lesions.21 There was no difference regarding limb salvage or patient survival out to 5 years, but vessel patency was reduced in limbs treated with stents compared to surgery. A nonrandomized retrospective comparison of endovascular intervention compared to open surgery for complex aortoiliac occlusive lesions found a shorter hospital stay, fewer postprocedural complications, and lower primary patency rates but equivalent secondary patency rates for the endovascular arm.22

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