PAD Flashcards
Anatomical definition of PAD
Anatomical: Structural atherosclerotic narrowing of any non-coronary vessel which limits blood flow to the limbs
Functional definition of PAD
Functional: Arterial narrowing causing a mismatch between organ supply and demand causing intermittent symptoms of claudication and/or tissue ischemia
Classifications of PAD:
a) Lower Extremity Disease
– Typically known as PAD
– Pain in the legs with walking or at rest (severe disease)
b) abdominal
– Aortic aneurysm
– Renal artery
– Mesenteric
c) Cerebral Vascular (Carotid)
Causes: Tobacco
– Single most important modifiable cause
– Ten-fold increase in relative risk, dose related
– Exposure to 2nd hand smoke also shown to promote changes to endothelium
Causes: Diabetes Mellitus
– Increases risk 2-4 times, due to endothelial and smooth muscle cell dysfunction
– Diabetes accounts for up to 70% of nontraumatic amputations performed
– Diabetes in combination with smoking: 30% risk of amputation in 5 years
Causes: Dyslipidemia
– Elevations of total cholesterol, LDL, and TG’s all correlated with accelerated PAD
– Correction via diet and/or medications=major improvement rates of stroke, MI
All Causes:
- Tobacco
- DM
- Dyslipidemia
- Hypertension
– Especially, but not exclusively, related to stroke - Inflammatory mediators
– Homocysteine, fibrinogen, C-reactive protein, Lipoprotein (a), renal disease - Age
- gender (male)-until after 85 then more women
- ethnicity (African Americans with higher risk)
- Obesity and physical inactivity
Prevalence of PAD
- Increases with age
2. 1/3 patients 70+ or 50-69 w/hx of DM or smoking
PAD Symptoms
• Analogous to angina pectoris • Intermittent limb claudication – Dull aching muscular discomfort induced by exercise and relieved by rest – Often at discrete threshold of work • Atypical features common – Fatigue – Heaviness – Dysesthesia or cold sensation •not nocturnal cramps or restless leg
Comprehensive Vascular Exam
• Bilateral arm blood pressure (BP) • Cardiac examination • Palpation of the abdomen for aneurysmal disease • Auscultation for bruits • Examination of legs and feet
Pulse Examination – Carotid – Radial/ulnar – Femoral – Popliteal – Dorsalis pedis – Posterior tibial
Pulse Scale
• Scale – 0=Absent – 1=Diminished – 2=Normal – 3=Bounding (aneurysm or AI)
Steps towards Dx of PAD
- Obtain history of walking impairment and/or limb ischemic symptoms
- Obtain a vascular review of symptoms
• Leg discomfort with exertion
• Leg pain at rest non-healing wound gangrene - Results:
-no leg pain
-atypical
-classic claudication
-Chronic limb ischemia
-acute limb ischemia - For all of the above perform ankle-brachial index measurement
How to Perform ABI Exam
- Performed with the patient resting in the supine position
- All pressures are measured with an arterial Doppler and appropriately sized blood pressure cuff
- Systolic pressures will be measured in the right and left brachial arteries followed by the right and left ankle arteries.
What is the ABI?
The ratio of the higher brachial systolic pressure and the higher ankle systolic pressure for each leg:
ABI=(ankle systolic P)/(higher brachial Psys)
≤ 0.90 is diagnostic of peripheral arterial disease
ABI Scale
1.00–1.29: Normal
0.91–0.99: Borderline, low normal
0.41–0.90: Mild-to-moderate disease
≤0.40: Severe disease
≥1.30: Noncompressible
Hemodynamic noninvasive tests
- Resting Ankle-Brachial Index (ABI)
- Exercise ABI
- Pulse volume recordings
Pulse Volume Recordings
Measured all along the leg
-should be triphasic
Exercise ABI Testing:
- Indicated when the ABI is normal or borderline but symptoms are consistent with claudication
- An ABI fall post-exercise supports a PAD diagnosis
- Assesses functional capacity (patient symptoms may be discordant with objective exercise capacity).
Color Duplex Testing
Significant stenosis because velocities are super high and a ton of color means a lot more turbulent blood flow
Arterial Duplex US Testing
Duplex ultrasound
• diagnose anatomic location
• degree of stenosis
Duplex ultrasound of the extremities can be used to select candidates for:
(a) endovascular intervention (stent/PTA)
(b) surgical bypass
(c) to select the sites of surgical
anastomosis.
MRA
MRA has virtually replaced contrast arteriography for PAD diagnosis
•Excellent arterial picture
• No ionizing radiation
• Noniodine–based intravenous contrast medium rarely causes renal insufficiency or allergic reaction
• ~10% of patients cannot utilize MRA because of
− Claustrophobia
− Pacemaker/implantable cardioverter-defibrillator
− Obesity
CTA
- Requires iodinated contrast
- Requires ionizing radiation
- Produces an excellent arterial picture
Renal Artery Stenosis:
Causes?
Athersclerosis or Fibromuscular Dysplasia
RAS: Atherosclerotic Etiology
– Increased prevalence in pts w/ CAD, CVD, PAD
– Risk factors essentially the same for each
RAS: FMD
– Accounts for 40% cases
– Also seen in the carotid arteries
– Congenital arterial abnormality of fibrous, muscular and elastic components
- Different thing altogether: connective tissue disorder
- typically affects young women
- Any CT disease is going to affect vasculature: FMD, Marfan’s, etc.
Beads on a string*
Renovascular HTN
Caused by renal artery stenosis (kidney senses low blood flow because of the blockage)
• Thus it shoots out a lot of renin–>RAAS
• Giving them meds doesn’t do much to decrease their HTN
– Secondary to atherosclerosis – usually origin and proximal segment of renal artery
– Fibromuscular dysplasia – usually mid to distal segment of renal artery or carotid artery
– Occlusion
AAA
• Def: perm localized dilation of an artery
=/> 50% normal diameter
– Dilatation >2x size of more proximal artery
- At risk of dissection, high mortality if this occurs
- Most often occur in infra-renal aorta
AAA: Prevalence
• Abdominal: Thoracic Aneurysms
– Men 7:1
– Women 3:1
• Coexistence of other vascular dz increases incidence:
– 5% pts w/ sx CAD have AAA
– 10% pts with CVD or PAD have AAA
- AAA affects 8% older men, 1.5% older women
- 15,000 deaths/year in the US alone
- Once rupture occurs, 75-90% mortality rate
AAA Screening
• Prior to 1996, insufficient evidence for or against screening: now with
– Family History
Dx of AAA
• Ultrasound
– Aorta, look at diameter
– Renal artery, look at diameter and velocities to estimate stenosis
• MRA
• CT scan
Goal: to adequately visualize the arteries for
measurements and velocities
Carotid Artery Dz: Prevalence
- Third leading cause of death in the US
- 500,000 new strokes each year
- 160,000 strokes result in death annually
- 15-20 billion dollars per year
- 50% of patients with a stroke will have a second stroke within 5 years if untreated
Stroke: Causes
• Only 10% of strokes preceded by TIA’s • 15% from a cardiac source • >33% of strokes associated with extracranial disease (like the carotids!)
a) Definition of a stroke
b) ischemic
c) hemorrhagic
- Sudden brain damage
- Lack of blood flow to the brain caused by a clot or rupture of a blood vessel
b) ischemic=clot
- 85% of all strokes
c) hemorrhagic=bleed
- around brain
- into brain
Dx of Carotid artery Dx
- Physical examination: carotid bruit
- Suspicion leads to ultrasound of carotid arteries
- Any abnormality on ultrasound: confirm with MRA or CT
Carotid artery Dz: Tx
•Lifestyle changes (no, seriously)
- must stop smoking
•Medications
•Interventions
Two Major Goals in Treatment of PAD
- Limb outcomes
2. Cardiovascular morbidity and mortality outcomes
Two Major Goals in Treatment of PAD:
1. Limb outcomes
• Improved ability to walk – Increase in peak walking distance – Improvement in quality- of-life (QoL) • Prevention of progression to CLI and amputation
Two Major Goals in Treatment of PAD:
Cardiovascular morbidity and mortality outcomes
- Decrease in morbidity from non-fatal MI and stroke
* Decrease in cardiovascular mortality from fatal MI and stroke
Tx to Improve CV Outcomes
Must treat the underlying causes!
• Smoking cessation • Anti-platelet therapy-aspirin • Hyperlipidemia (lifestyle and/or medications) -statin: 10mg & 80mg • Hypertension • Keep Diabetes under good control • Get active, lose weight
Considerations for the Treatment of Hypertension in PAD
- Blood pressure lowering is indicated to reduce the risk of stroke, MI, CHF, CRF, and death.
- Individuals with PAD should receive hypertension treatment
Indications for Angioplasty/Stent
Indications Lower Extremities:
– Persistent limiting claudication, preventing working and/or ADL
– Rest pain
– Tissue loss/non healing ulcers
• Get the Patient walking, and they will start to heal themselves!!
- Abdominal Aorta or Renal Arteries
- Carotid Arteries
*ADL: Activities of Daily Living
PAD and Surgery
• Lower extremity arterial disease:
– Bypass (eg. Femoral to popliteal artery)
– Vein or synthetic graft used
• Abdominal Aorta
– when the risk of rupture outweighs the risk of surgery
- Normal aorta: 3cm or less
- Aneurysm: 3-4-5 cm
- At 5CM: risk of rupture»»surgery
• Carotid Endarterectomy
In regards to PAD….smoking, physical inactivity, and DM increase:
– Prevalence of PAD
– Presence of Asymptomatic disease
– Risk of amputation, low quality of life
Dx modalities for PAD
– Doppler ultrasound to evaluate velocities
– ABI/ pulse volume recordings
– MRA, angiography
U/S Evaluation of Degree of Stenosis
• 50-79% stenosis
– High systolic velocities, normal diastolic
• 80-99% stenosis
– Both systolic and diastolic velocities high
• Occlusion – signal becomes similar to external carotid signal with low diastolic velocities
What does a carotid bruit mean?
- Asymptomatic bruits do increase stroke risk (14% over 5 years) - but not always on side of bruit
- Good indicator of significant coronary disease (50-71%)
People risk for PAD
- Age: Less than 50 years with diabetes, and one additional risk factor (e.g., smoking, dyslipidemia, hypertension, or hyperhomocysteinemia)
- Age 50 - 69 years and history of smoking or diabetes
- Age 70 years and older
- Known atherosclerotic coronary, carotid, or renal artery disease
