Atherosclerotic Peripheral Disease of the Lower Extremities Flashcards
General Considerations
• 12% of the population of age 50 have significant ASPVD • 36% of the population of age 80 have significant ASPVD • Poiseulle’s Law
Poiseulle’s Law
• 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.
Risk Factors of LE Disease
Family History Obesity Sedentary Lifestyle Age Hypertension Hypercholesterolemia Diabetes Tobacco Abuse
Causes of ASPVD
Genetics Tobacco Abuse Hypertension Diabetes Hyperlipidemia Increased homocysteine levels Lack of exercise Diet and obesity Female Job and environment
Diabetic Patients and ASVPD
• 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
Clinical Findings
Claudication- monocytes, neutrophils, free radicals, lactic acidosis Leriche Syndrome Rest Pain Ischemia, gangrene
The Six Ps
pulselessness paralysis pain pallor parasthesia poikilothermy
Physical Exam
-bruits, thrills -skin temp -cap refill -ulcers -pulse exam -monofilament testing
Non-invasive tests and imaging
Segmental limb pressures, ankle brachial indices (ABI’s), and plethysmography—waveform analysis Duplex scanning
Contrast Studies
• 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
LEOD Diagnosis: Duplex Scanning
• 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
LEOD Diagnosis: Angiograms
• Definitive method of arterial diagnosis prior to selecting intervention • Provides anatomical information about lesion • Shows surrounding anatomy including branch arteries
Risk factor reductions
• Stop smoking • Diet • Cholesterol control • Hypertension control • Diabetic control • Ambulation, aerobic exercise
Medical Management Options
Coated Aspirin Clopidigrel Cilostazol Heparin, Coumadin
Aspirin
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