Duane S. Pinto, M.D. Director Peripheral Angiographic Core Laboratory, TIMI Data Coordinating Center Director, Cardiology Fellowship Training Program Interventional Cardiologist Beth Israel Deaconess Medical Center Assistant Professor of Medicine, Harvard Medical School Intermittent Claudication Diagnosis and Work-up
PAD is a common disorder • Occurs in approximately 1/3 of patients • Over age 70 • Over age 50 who smoke or have DM • Strong association with CAD • Obvious associated risk of stroke, MI, cardiovascular death • Progressive disease in 25% with progressive intermittent claudication/limb threatening ischemia • Outcomes • Impaired QoL • Limb Loss • Premature Mortality
Reduced Increased Smoking Diabetes Hypertension Hypercholesterolemia Hyperhomocysteinemia Fibrinogen C- Reactive Protein Alcohol Relative Risk .5 1 2 3 4 5 6 Risk Factors for PVD: Framingham Heart Study Mean follow-up 38 years
PAD is Associated with Poor Outcomes Criqui M, et al. Circulation 1985; 71:510
Diagnostic Modalities • History • Physical • Ankle Brachial Index (ABI) • Noninvasive vascular laboratory • Angiography: MRA, CT, DSA
Initial Assessment • Identifying risk factors and symptoms • Pulse palpability • Further assessment relies on functional non-invasive testing and radiological imaging • Determine not only the anatomic, but also the physiological aberration of peripheral vascular flow.
Intermittent Claudication • Intermittent claudication (derived from the Latin word for limp) • A reproducible discomfort of a defined group of muscles that is induced by exercise and relieved with rest. • Supply ≠ Demand • Location depends upon the location of the disease. • Buttock, thigh, calf or foot claudication, either singly or in combination.
PVD Etiology • Large arteries • Atherosclerosis • Thromboembolism • Trauma • Arteritis of various types including • Buerger’s disease • Fibromuscular dysplasia • Takayasu’s
Medium and small vessel occlusions Diabetes Chronic recurrent trauma Multiple small emboli Collagen vascular diseases Dysproteinemias Polycythaemia vera Pseudoxanthoma elasticum Drug Reaction Vasospasm PVD Etiology
Specific to certain anatomical sites Cystic adventitial disease of the popliteal artery Popliteal artery entrapment Iliac endofibrosis (cyclists) Various neurovascular compression syndromes affecting the upper limb Cervical rib Costoclavicular syndrome Scalenus tunnel syndrome Hyperabduction syndrome Quadrangular space syndrome PVD Etiology
PVD Differential Diagnosis • Deep venous thrombosis • Musculoskeletal disorders • OA • Restless leg syndrome • Peripheral neuropathy • Spinal Stenosis (pseudoclaudication) • Worse with erect posture (lordosis) better sitting or lying down. • Can find relief by leaning forward and straightening the spine (pushing a shopping cart or leaning against a wall).
Location, Location, Location! • Buttock/hip • Usually indicates aortoiliac occlusive disease (Leriche's syndrome) • Some cases, thigh claudication too • Question diagnosis of bilateral disease if erectile dysfunction is not present • Thigh • Occlusion of the common femoral artery leads to claudication in the thigh, calf, or both. • Calf • Symptoms in upper 2/3 is usually due to SFA • Lower 1/3 is due to popliteal disease.
PVD History • Use of the history alone to detect peripheral arterial disease will result in missing up to 90 percent of cases. • Asymptomatic patients with abnormal ABI have 50% increased risk of cardiovascular complications Hirsch AT, et al. JAMA 2001; 286: 1317 Hooi JD, et al. J Clin Epidem 2004; 57:294
Physical Exam • Trophic Signs • Skin atrophy, thickened nails, hair loss, dependent rubor • Ulceration, gangrene • Pulse exam • May miss more than 50% • Elevation and dependency test Criqui M, et al. Circulation, 1985: 71; 516-521
Physical Exam: Elevation and Dependency Test Halperin, Throm Res. 2002; 106: V303-311
Ankle Brachial Index • Cornerstone of lower extremity vascular evaluation • Blood pressure cuffs, Doppler • Ankle (DP or PT) to brachial artery pressure
Limitations • Noncompressible vessels • Diabetes • Renal Failure • ABI >1.5 • Use toe-brachial index • Normal >0.7 • Rest pain <0.2 • Subclavian/Brachiocephalic Occlusive disease
Segmental Pressures • Pneumatic cuffs at multiple levels • Doppler pressure at pedal artery • Drop >30 mm Hg between levels • Drop >20 mm Hg between limbs • Reflects status of artery above drop in pressure • Inaccurate with calcified vessels Rose SC. J Vasc Interv Radiol. 2000; 11:1107-1114
Duplex Doppler • Non-invasive method of evaluating the blood vessels using sound waves, similar to ultrasonography and echocardiography. • Can obtain both anatomic and hemodynamic information. • Anatomical detail • vessel wall • intraluminal obstructive lesions • perivascular compressive structures
Doppler Waveform Analysis: Hemodynamic Information • Sensitivity of 92.6% and specificity of 97% (angiography gold standard) • Inaccurate at adductor canal and the aorto-iliac regions. • 95% accuracy in the detection of bypass graft stenosis, but can overestimate stenosis. Polack JF. Duplex Doppler in peripheral arterial disease. Radiol Clin N Amer 1995; 33 : 71-88.
Doppler Waveform Analysis: Hemodynamic Information • Qualitative assessment of waveform analysis • Simple Equipment • Not affected by medial calcinosis • Supplements segmental pressures
Pulse Volume Recordings • Pneumatic Cuffs at Multiple Levels • Inflated to 65 mm Hg • Extremity Volume Increases in Systole • Changes pressure in cuff • Waveform Analysis • Not Impacted by Calcification
Pulse Volume Recordings • Advantanges • Widely available • Cheap • Reproducible • Disadvantages • Technician dependent • Time Consuming • Detection of Collaterals is low • Presence of gas and calcification degrade images
Is this enough? • Noninvasive lab documents presence and severity of disease • No comprehensive anatomic information • No ability to plan interventions
Radiologic Imaging: MRA and CTA • DSA (conventional angiography) remains the gold standard for evaluation of PVD • Newer modalities that match its accuracy are rapidly evolving • It is a matter of time before imaging replaces DSA, with the invasive angiographic techniques reserved for interventional procedures
MRA: Current Technique • 3D gradient echo (fast acquisition) • Gadolinium Enhanced • 20-40 cc • Automated Scan delay • Renal arteries to toes • Stepping table or bolus chase • 45-min exam
Limitations of MRI • Uncooperative patient • Claustrophobia • Metal artifact • Pacemakers/ICDs • Lack of visualization of calcium
CTA of PVD • Multidetector CT scanner necessary (4+) • Many hospitals now have 64 Slice • Iodinated contrast volume similar to conventional angiography • 80-150 cc • Automated Scan Delay • Renal arteries to ankles • 20-minute exam • High powered post processing software crucial
CTA of PVD • Large volumes of data are generated via CTA studies and displayed in various formats to refine the analysis of study results • Maximum Intensity Projection -MIP (most common) • Shaded surface display • 3D Volume rendering
CT Limitations • With significant and dense calcifications, a false diagnosis of patency can result. • Uncooperative patient • Pregnancy • Bad Pump • Inconsistent pedal vessel visualization • Renal failure/contrast allergy
Digital Subtraction Angiography (DSA) • Gold standard of arterial imaging • Has almost totally replaced conventional cut film angiography • Compares a pre contrast image with a post contrast image using a computer, and "subtracts" elements common to both. • Prevents images of objects like bones etc from obscuring vascular details. • Contrast resolution is improved through use of image enhancement software.
Digital Subtraction Angiography (DSA) • Radiation exposure and contrast volumes are lower than conventional angiography • Images are immediately available for review. • Images are stored in digital format on computerized data storage media • Interventional procedures can be performed
Digital Subtraction Angiography (DSA) • Drawbacks precluding use as a screening modality • Technique is invasive and expensive. • Requires arterial puncture • Longer study than CT • Contrast nephrotoxicity
Medical Treatments for PAD *Survival Bias †Excepting Stroke
Workup-Take-home • Noninvasive Vascular Lab is first line evaluation in nonacute patients • ABI is easy screening test • Beware noncompressible vessels in renal failure and diabetes • Segmental limb pressures often combined with doppler waveform anlaysis • Not sufficient to plan intervention
Workup-Take-home • MRA indicated for intervention planning • MRA (gadolinium enhanced) provides excellent renal to pedal imaging • Surpasses CT in the foot • Overestimation of stenoses in small vessels • Limited by metal artifact, magnetic field, and length of study
Workup-Take-home • CTA indicated for intervention planning • CTA provides excellent renal to ankle imaging • Pedal imaging poor • Soft tissues and bone also imaged • Small vessel calcification is limitation