Vascular Evaluation (MC)

Peripheral Arterial Disease (PAD)

• Atherosclerosis is a key factor
• Atherosclerotic lesions causes blockages in the arteries
• Results in stenosis and occlusion
• Blood flow to brain, organs, and limbs is affected
• Lower extremities are often affected by PAD
• Associated with smoking, high blood pressure, diabetes, age, and hypercholesterolemia

Symptoms of PAD

• Intermittent claudication can occur
• Claudication causes limping, characterized as "claudico"
• Pain occurs while walking
• Pain is relieved by rest
• Ischemia causes pain at rest
• Can also cause ulcers or gangrene

Prevalence of PAD

• Asymptomatic PAD occurs in >50% of people with ABI < 0.9, accounting for 4-6 million cases
• Claudication affects 30-35% of with muscle pain, ache, cramps, or fatigue. Totaling 2-4 million cases
• Critical Limb Ischemia affects less than 10% with pain at rest, ulceration, or gangrene. Totaling 400,000-1 million cases

Risk Factors for PAD

• Smoking, diabetes, hypertension, hypercholesterolemia, hyperhomocysteinemia, and elevated C-reactive protein are risk factors
• Atherosclerosis is a major cause of death in the US
• Cardiovascular disease is the #1 cause of death, stroke is #3, aortic aneurysm is #13

Intermittent Claudication: Differential Diagnosis

• Pseudoclaudication
• Degenerative Joint Disease
• Diabetic Peripheral Neuropathy

Natural History of Claudication

• Non-fatal cardiovascular events occur in 20% of patients
• Mortality rate is 15%-30%, with cardiovascular causes accounting for 75%

PAD and Diabetes Mellitus

• 30 million Americans (8% of the population) have diabetes
• For every 1% increase in HbA1c, there is a 26% increased risk of PAD
• Claudication is twice as common in diabetics
• There is a 10-fold increased risk of progression to Critical Limb Ischemia (CLI)
• 10% of patients with diabetes over the age of 75 have ulceration

Natural History of CLI

• Rest pain, ulceration, and gangrene are characteristics of CLI
• 50% of CLI patients are still alive one year later with both limbs
• Amputation occurs in 25%
• Death occurs in 25%

Scope of CLI in the US

• 67% of patients with CLI undergo major amputation as their primary therapy
• Approximately 200,000 major amputations are performed annually
• Less than 50% have any vascular evaluation before amputation
• Less than 50% of all amputees regain mobility
• Over 50% of amputees die within one year

Peripheral Vascular Disease

• 15-20% of patients with diabetes mellitus (DM) will have PAD after 10 years
• 45% of patients with DM will have PAD after 20 years

Symptoms of Ischemia

• Pain in buttocks, thigh, calf, and arch
• Night ischemic pain

What is Ischemia?

• Ischemia is defined as Demand exceeding Supply
• Absolute Ischemia is the absolute amount of flow present
• Relative Ischemia involves discrepancy between available and needed flow

History and Physical Exam

• Hair presence, warm foot, normal skin color, palpation of pulses, and nail plate status should be examined
• Significant vascular disease is observed in 20% of patients, even with normal clinical findings
• Ischemia is more likely with toe or heel ulcer, unknown etiology, diminished pulses, shiny atrophic skin, infection, dependent rubor, or elevation pallor
• History should include CABG, CEA, tobacco use, MI, CVA, Angina, thigh/buttock/calf pain during walking, and previous ulcerations

When to Order Non-Invasive (NIV) Arterial Testing

• Chronic non-healing ulcer/wound
• Pre-operatively to assess healing of proposed foot surgery
• Ulcers of the digits, or boney prominences
• Symptoms of claudication

Noninvasive Modalities

• Ankle Brachial Index (ABI)
• Toe Brachial Index (TBI)
• Toe Pressure
• Segmental Pressures
• Doppler waveforms
• Photoplethysmography
• Pulse Volume Recordings

ABI/TBI

• Ankle Brachial Index (ABI) assessment includes ratio of ankle/arm systolic blood pressure
• Normal ABI is 0.9 to 1.2
• False elevation in patients with DM due to medial calcification
• ABI is a good screening test for non-diabetic patients
• Toe Brachial Index measures the ratio of hallux/arm systolic pressure
• TBI > 0.6 = low risk
• TBI < 0.2 = severe risk
• Digital vessels are less affected by calcification in DM

Ischemia – Noninvasive Assessment

• Grade 0: ABI > 0.80, Ankle SP > 100 mm Hg, TP/TcpO2 > 60 mm Hg
• Grade 1: ABI 0.60-0.79, Ankle SP 70-99 mm Hg, TP/TcpO2 40-59 mm Hg
• Grade 2: ABI 0.40-0.59, Ankle SP 50-69 mm Hg, TP/TcpO2 30-39 mm Hg
• Grade 3: ABI mm Hg

Medial Calcinosis

• Involves Tunica media, neuropathy, and elevated pressures
• Associated with Goebel and Fuessel, Edmonds

Doppler Waveform Interpretation

• Waveforms can be triphasic/biphasic/monophasic
• Normal flow appears as narrow peak, followed by one or two smaller peaks
• Faster flow results in a higher audible pitch, waveform resembles teepee
• Slower flow results in a lower pitch, igloo waveform
• As flow deteriorates, waves flatten

Photoplethysmography

• Involves transmission of IR light into tissue
• Reflection varies based on the blood content of the microcirculation
• A transducer is attached to digits for waveform readings

Diabetic vs Nondiabetic Ischemic Patterns

• In diabetic patients, ischemia is distal, affecting popliteal, 'trifurcation,' tibial, and pedal vessels
• Collateral pathways in diabetics includes internal iliac, profunda femoral, tibial
• Calcified vessel walls
• Ischemia is symmetrical