Peripheral Artery Disease and Peripheral Artery Angiography

5 Peripheral Artery Disease and Peripheral Artery Angiography

Peripheral artery disease (PAD) refers to stenotic, occlusive, and aneurysmal diseases of the aorta and branch arteries that include the lower extremity, upper extremity, renal, mesenteric, and carotid arterial beds. PAD is a common manifestation of atherosclerosis, and its prevalence increases with age and concurrent cardiovascular risk factors such as diabetes and tobacco use. As with coronary atherosclerosis, peripheral arterial-occlusive disease has a natural history, progression pattern, and susceptibility for developing vulnerable and complex plaques. It has a strong positive correlation with cardiovascular events and mortality.

When considering patients for peripheral endovascular intervention, an accurate history and physical is important. Initial risk factor assessment should be made, screening tests for cardiovascular disease should be obtained, and patients should be medically optimized. A key component to the diagnosis of PAD is the presence of symptoms. However, less than 20% of patients with PAD report the typical symptom of intermittent claudication. Many patients present with symptoms that are not typical of claudication. The review of symptoms should include the following:

Lower Extremity Peripheral Arterial Disease

PAD involving the lower extremities is diagnosed by screening studies or physical examination. Symptoms of intermittent claudication classically start distally within a muscle group (below the stenosis) and then ascend with continued activity. Rest pain that occurs with leg elevation and is paradoxically relieved by walking may suggest severe PAD (as the effects of gravity increase arterial perfusion of muscle groups). Critical PAD may present as tissue ulceration and gangrene. The American College of Cardiology/American Heart Association (ACC/AHA) has produced guidelines that suggest that individuals with PAD present in clinical practice with distinct syndromes (Table 5-1).

Table 5-1 Individuals With Peripheral Artery Disease Present in Clinical Practice with a Variety of Distinct Syndromes

Asymptomatic: Without obvious symptomatic complaint (but usually with a functional impairment)
Classic claudication: Lower extremity symptoms confined to the muscles with a consistent (reproducible) onset with exercise and relief with rest
“Atypical” leg pain: Lower extremity discomfort that is exertional but that does not consistently resolve with rest, consistently limit exercise at a reproducible distance, or meet all “Rose questionnaire” criteria
Critical limb ischemia: Ischemic rest pain, nonhealing wound, or gangrene
Acute limb ischemia: The “five Ps,” defined by the clinical symptoms and signs that suggest potential limb jeopardy: pain, pulselessness, pallor, paresthesias, paralysis; polar as a sixth “P”)

The physical examination is the first tool in defining the location, severity, and etiology of PAD and its symptoms. Arterial pulse intensity should be assessed and should be recorded numerically as shown in Table 5-2.

Table 5-2 Gradation of Arterial Pulse

Numerical Gradation Clinical Assessment
0 Absent
1 Diminished
2 Normal
3 Bounding

Patients with lower extremity PAD can present without symptoms, with classic symptoms of claudication, or with symptoms of limb ischemia. The initial history and physical examination is very important in these patients; however, other noninvasive testing can also aid in the diagnosis of PAD.

Table 5-3 outlines some of the more important aspects of the limb examination.

Table 5-3 Physical Examination Findings of Peripheral Artery Disease

Limb examination (and comparison with the opposite limb) includes the following:

Noninvasive Diagnostic Testing

Measuring the ankle-brachial index (ABI) both at rest and after exercise is very useful, especially in individuals who have risk factors for PAD. Resting ABI may be insensitive for detecting mild aorto-iliac occlusive disease and is not designed to define the degree of functional limitation. However, it establishes the diagnosis of PAD and identifies a population at high risk of cardiovascular ischemic events. Incompressible arteries (elderly patients, patients with diabetes, renal failure) make such rest testing difficult. The toe-brachial index (TBI) should be used in individuals with noncompressible pedal pulses. Exercise ABI may be even more useful than resting ABI as this will “unmask” PAD when resting the ABI is normal. Performing segmental ABI and pulse volume recordings together with the ABI can indicate presence of multilevel occlusive lower extremity PAD.

Duplex ultrasound of the extremities is useful to diagnose the anatomic location and degree of stenosis of PAD. This type of study is recommended for routine surveillance after femoral-popliteal or femoral-tibial-pedal bypass.

Other noninvasive testing includes magnetic resonance angiography (MRA) and computed tomographic angiography (CTA). MRA of the extremities is useful to diagnose the anatomic location and degree of stenosis of PAD. The MRA should be performed with gadolinium administration. It must be noted, however, that gadolinium use in individuals with an estimated glomerular filtration rate (eGFR) less than 60 ml/min has been associated with nephrogenic systemic fibrosis (NSF)/nephrogenic fibrosing dermopathy. MRA of the extremities is useful in selecting patients with lower extremity PAD as candidates for endovascular intervention.

CTA of the extremities may be considered to diagnose the anatomic location and presence of significant stenosis in patients with lower extremity PAD. CTA may be considered as a substitute for MRA for those patients with contraindications to MRA (claustrophobia, presence of pacemaker/implantable cardioverter-defibrillator).

Endovascular Percutaneous, Catheter-Based Revascularization Techniques

Endovascular revascularization techniques have greatly advanced the management of obstructive PAD. Endovascular therapy offers several distinct advantages over surgical revascularization. The morbidity and mortality from endovascular therapy is low when compared with surgical revascularization. Unlike vascular surgery patients, these individuals often return to normal activity within 24to 48 hours of an uncomplicated procedure. Finally, endovascular therapies may be repeated if necessary, generally without increased difficulty or increased patient risk compared with the first procedure. Prior angioplasty does not preclude surgery if required later. The problems and complications associated with endovascular intervention are generally related to bleeding and vascular access.

Endovascular reconstruction options include the following:

The advantages of using percutaneous interventional procedures over bypass surgery (especially to treat chronic limb ischemia) include the following:

The efficacy of PTA versus stents for lower extremity arterial stenosis has not been demonstrated in randomized trials. PTA of distal abdominal lesions is effective; however, PTA followed by stenting offers greater advantages of larger vessel lumen gain, long-term patency (>70% at 5 years), high procedural success rates (90%), and less thromboembolism. Factors associated with a poor outcome with endovascular therapy include the following:

Iliac Artery Intervention

Iliac artery provides blood flow to the lower extremities, and permits access to the central circulation for coronary artery intervention, insertion of an intra-aortic balloon pump, other cardiac output assist devices, or treatment of vascular access site complications.

The indication to perform iliac artery intervention includes vascular access and symptomatic lower extremity ischemia. Iliac intervention may also be appropriate in patients with severe stenosis (Fig. 5-2, A and B) or occlusion of the femoropopliteal or infrapopliteal arteries and concomitant moderate iliac artery disease, in whom revascularizing the moderately stenosed iliac artery may improve the arterial inflow and lead to symptomatic improvement or salvage of the limb.

The indications for revascularization in the patient with intermittent claudication are as follows:

Endovascular treatment of significant iliac artery stenosis with claudication is indicated as follows:

Femoropopliteal Artery Intervention

Atherosclerotic occlusive disease is more common in the femoropopliteal artery than in the iliac artery. When the femoropopliteal artery is involved in a symptomatic lower extremity, complete occlusions are three times more frequent than stenosis. Table 5-4 demonstrates the morphologic stratification of femoropopliteal lesions according to the Transatlantic Inter-Society Consensus (TASC). According to the TASC recommendations, endovascular therapy is the treatment of choice for type A femoropopliteal lesions and surgery is the treatment of choice for type D lesions. Endovascular treatment is the preferred treatment for type B lesions and surgery is the preferred treatment for low risk patients with type C lesions. The patient’s comorbidities, fully informed patient preference, and the local operator’s long-term success rates must be considered when making these treatment recommendations for type B and type C lesions.

Table 5-4 Morphologic Stratification of Femoropopliteal Lesions

TASC type A femoropopliteal lesions

TASC type B femoropopliteal lesions

TASC type C femoropopliteal lesions

TASC type D femoropopliteal lesions

CFA, Common femoral artery; SFA, superficial femoral artery; TASC, Transatlantic Inter-Society Consensus.

Endovascular interventions for TASC type A femoropopliteal arterial lesions have excellent procedural success and reported patency rates that vary from 30% to 80% at 1 year. The role of primary stenting for femoropopliteal disease remains incompletely defined. Stents (and other adjunctive techniques such as lasers, cutting balloons, atherectomy devices, and thermal cryoplasty devices) can be useful in the femoral, popliteal, and tibial arteries as salvage therapy for a suboptimal or failed result from balloon dilation (e.g., persistent translesional gradient, residual diameter stenosis greater than 50%, or flow-limiting dissection). The effectiveness of stents, atherectomy, cutting balloons, thermal devices, and lasers for the treatment of femoral-popliteal arterial lesions beyond this context is not well established (Figs. 5-3, 5-4, and 5-5).

Revascularization of the femoral or popliteal arteries is reserved for patients with lifestyle-limiting claudication, ischemic rest pain, and limb-threatening ischemia. Treatment of short (<5 cm) occlusions yields better results than treatment of long (>10 cm) occlusions or stenosis. The presence of patent runoff vessels correlates with long-term benefits, reflected in the improved outcome in patients with milder symptoms. Significant residual stenosis after angioplasty correlates with a poor long-term outcome, whereas the absence of diabetes correlates with an improved patency rate. Endovascular intervention is not indicated if there is no significant pressure gradient across a stenosis despite flow augmentation with vasodilators. Primary stent placement is not recommended in the femoral, popliteal, or tibial arteries (Figs. 5-6 and 5-7). Endovascular intervention is not indicated as prophylactic therapy in an asymptomatic patient with lower extremity PAD.

Jun 5, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Peripheral Artery Disease and Peripheral Artery Angiography

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