Atherosclerotic Peripheral Disease of the Lower Extremities

Question 1

General Considerations

Answer 1

• 12% of the population of age 50 have significant ASPVD • 36% of the population of age 80 have significant ASPVD • Poiseulle’s Law

Question 2

Poiseulle’s Law

Answer 2

• 70% stenosis • Reducing the radius by one half increases energy losses by a factor of 16 (vascular resistance) • Pulsatile flow—important for optimal organ function Example: when a kidney is perfused by steady flow instead of pulsatile flow, a reduction in urine volume and sodium excretion occurs. Pulsatile flow effects the microcirculation influencing transcapillary exchange, arteriolar tone, and lymphatic flow.

Question 3

Risk Factors of LE Disease

Answer 3

Family History Obesity Sedentary Lifestyle Age Hypertension Hypercholesterolemia Diabetes Tobacco Abuse

Question 4

Causes of ASPVD

Answer 4

Genetics Tobacco Abuse Hypertension Diabetes Hyperlipidemia Increased homocysteine levels Lack of exercise Diet and obesity Female Job and environment

Question 5

Diabetic Patients and ASVPD

Answer 5

• Risk of amputation increased due to • Reduced sensation in feet • Reduced resistance to infection • Reduced arterial flow • Deformity of the foot (Charcot Joint) • Diabetics more susceptible to ischemia & infection—more likely to require amputation

Question 6

Clinical Findings

Answer 6

Claudication- monocytes, neutrophils, free radicals, lactic acidosis Leriche Syndrome Rest Pain Ischemia, gangrene

Question 7

The Six Ps

Answer 7

pulselessness paralysis pain pallor parasthesia poikilothermy

Question 8

Physical Exam

Answer 8

-bruits, thrills -skin temp -cap refill -ulcers -pulse exam -monofilament testing

Question 9

Non-invasive tests and imaging

Answer 9

Segmental limb pressures, ankle brachial indices (ABI’s), and plethysmography—waveform analysis Duplex scanning

Question 10

Contrast Studies

Answer 10

• Aortogram with runoffs—”Gold Standard” • Cat scan angiogram • MRA with gadolinium • Aortogram or CTA with renal insufficiency patient, use 50% gadolinium/50% contrast and IV mucomyst and sodium bicarbonate

Question 11

LEOD Diagnosis: Duplex Scanning

Answer 11

• Measures peak systolic & end‐diastolic blood velocities to estimate severity of stenosis • Fast arterial velocity (indicated by brighter colors on scan) indicates narrowing of artery

Question 12

LEOD Diagnosis: Angiograms

Answer 12

• Definitive method of arterial diagnosis prior to selecting intervention • Provides anatomical information about lesion • Shows surrounding anatomy including branch arteries

Question 13

Risk factor reductions

Answer 13

• Stop smoking • Diet • Cholesterol control • Hypertension control • Diabetic control • Ambulation, aerobic exercise

Question 14

Medical Management Options

Answer 14

Coated Aspirin Clopidigrel Cilostazol Heparin, Coumadin

Question 15

Aspirin

Answer 15

Inhibits cyclooxygenase activity which blocks prostaglandin metabolism and synthesis of thromboxane A2—stimulator of platelet aggregation • Mainly COX 1 (platelets), COX2 (inflammatory cells) 50:1

Question 16

Clopidigrel

Answer 16

• Blocks ADP receptor P2Y12 , an extra carboxymethyl side group • 6 times more potent than Ticlid with fewer side effects • CAPRIE trial (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events) • 8.7% risk reduction in vascular death, ischemic stroke, and myocardial infarction versus aspirin

Question 17

Conservative treatment

Answer 17

• Ambulation, aerobic exercise • Platelet inhibitors—aspirin, plavix • Multivitamins • Vitamin E, 400IU daily • Vitamin C, 1000mg daily • B‐complex vitamins with B6, B12 and folic acid • Omega 3 fish oil • Cilostazol (Pletal) • Continued close observation, i.e. symptomology, physical exam, ABI, and doppler changes

Question 18

Invasive Treatment

Answer 18

• Angioplasty • Stenting • Cryoplasty • Anthrectomy devices, laser, and brachytherapy • Bypass—veins, prosthetic grafts • Endoprosthetic devices (Viabahn)

Question 19

CryoPlasty® procedure

Answer 19

– CryoPlasty = angioplasty + Cryotherapy – Nitrous oxide used to dilate balloon to 8atm & cool balloon surface temp to -10˚C – Three theoretical effects of cooling • Altered plaque response • Reduced elastic recoil • Apoptosis

Question 20

Atherectomy devices

Answer 20

– Open arteries blocked by plaque – Plaque is cut or shaved, then removed by endoscopic catheter – Procedure is common for densely calcified lesions or total occlusions

Question 21

Excimer laser

Answer 21

– Has many medical uses, including opening vessels occluded by plaque – Commonly used for total occlusions – Flexible fiber optic catheter advanced into lesion – Laser debulks plaque to recannilize vessel – Not yet FDA approved for peripheral artery intervention

Question 22

Brachytherapy

Answer 22

– High dose gamma radiation – Segmented center balloon advanced into lesion – Patient transferred to radiology oncology for procedure

Question 23

Amputation

Answer 23

Indications • Pain • Sepsis, multiple organ failure • Hygiene

Question 24

PreOp Evaluation

Answer 24

• Cardiac clearance—stress testing • Pulmonary function testing • Beta blocker protocol

Question 25

Ankle-Brachial Index

Answer 25