Peripheral Vascular Disease Flashcards
What are common areas of stenosis for PAD?
Aortoiliac, superficial femoral, tibial
Is it more common for PAD to present in both legs or only one?
More have both. But 40% of patients have in only one.
Think of ____ as _____ of the legs. You get leg pain on exertion that resolves with rest.
PAD, angina
Are the risk factors for PAD the same as atherosclerosis?
Yes
If you have PAD, are you more at risk for CV death?
Yes, about 6x increase risk
What are the symptoms of PAD?
Intermittent Claudication (limp)
Cramp, calf fatigue with exercise, resolves with rest.
Blood flow normal at rest, limited with exercise
No symptoms at rest, onset only with exercise.
If the disease progresses, patients can get–
Ischemic rest pain/ischemic ulcers (critical leg ischemia)
Pain in the distal foot or heel, worsened by leg elevation and improved by dependency.
Distal, painful ulcers on toes or heel.
Blood flow limited at rest and exercise.
Symptoms at rest and with exercise.
True or False: PAD is more from chronic occlusion than from plaque rupture
True
What are signs of PAD? (4 signs)
- Decreased or absent pulses
- Bruits (abdominal, femoral)
- Muscle atrophy
- In severe PAD (critical leg ischemia), pallor of feet with elevation and dependent rubor
Where do you palpate for posterior tibial artery?
behind medial malleolus
Where do you palpate for dorsalis pedis?
On top of the foot
What are the factors that affect arterial hemodynamics? (4 factors)
- Perfusion pressure
- Blood viscosity
- Arterial stenosis (radius and length. radius most important)
- Flow velocity (hemodynamic severity increases at higher flow velocities)
True or False: For flow velocity, the higher the velocity, the less narrowing it takes to cause a decrease in pressure and flow across a stenosis.
True
Even with laminar flow, when blood pressure increases, you get more _____ stress.
Shear stress
What does shear stress trigger in endothelial cells?
Dilation. from production of NO.
Collateral vessels may develop at sections of _____.
Stenosis
Do collateral vessels help much for bringing blood across stenotic lengths of vessel?
Not much. They are high resistance
What does endothelium distal to stenosis do?
Vasoconstrict, because of the turbulent flow and dropped pressure across stenosis.
What is Ankle-Brachial Index (ABI)?
Blood pressure measurement in the ankle right above the malleoli. Doppler probe detects the systolic blood pressure. You take the ratio between the systolic blood pressure in the ankle and the systolic blood pressure in the arm. In a healthy person, the systolic blood pressure should be about the same around your body. In a healthy person, the ankle is actually higher pressure than at the brachial artery.
Ratio less than 0.90 is considered abnormal
For the ABI, under what ratio is a positive finding for PAD?
0.90
For ABI, does a normal patient has a stronger systolic pressure at the brachial artery or posterior tibial?
Posterior tibial
What are implications for therapy in PAD? (name 3)
- Prevent CV events (MI, stroke, vascular death)
- Improve limb symptoms, exercise performance, and QOL
- Heal ulcers and prevent limb loss
What are treatments for PAD? (name 3)
- Surgery or angioplasty improves hemodynamics
- Exercise training improves muscle metabolism
- Drugs (cilostazol) have multiple mechanisms
What are aneurysms?
Pathological expansion of all 3 arterial layers
What is the normal aorta size in an adult? (at root, mid descending, and infra-renal)
3 cm at root
2.5 cm mid descending thoracic aorta
2 cm at the infra-renal aorta
What is the size for Abdominal Aorta Aneurysm?
> or = 3.0 cm or 50% increase in size relative to proximal normal segment
When you open up an aneurysm, what do you see?
A lot of atherosclerosis and thrombosis
What are the mechanisms of aneurysm formation? (name 4 and some physiological factors that cause them)
- Weakened aortic wall (decreased elastin and collagen)
- Inflammation (B and T lymphocytes, macrophages, cytokines, autoantigens)
- Proteolytic enzymes (Increased MMP, uPa, tPa. Decreased TIMP)
- Biomechanics stress (elastin disruption, turbulent blood flow, mural thrombus)
What is the incidence of AAA?
40-50 per 100,000 men and 7-12 per 100,000 women
How many people die annually in the U.S. from AAA?
16,000
True or False: Ruptured aneurysms are the 13th leading cause of death in the USA.
True
What are the 4 major risk factors of AAA?
- Age
- Gender
- Smoking
- Family history
For AAA, what is the 5-year rupture rate % in relation to size? (give %s)
less than 4 cm 4-5 5-6 6-7 greater than 7 cm
Size - 5 year rupture rate
less than 4 - 2% 4-5 - 2-13% 5-6 - 25% 6-7 - 35% 7 cm - 75%
At about what diameter do clinicians start to get concerned about AAA rupture?
5-6cm (25% 5 year rupture rate)
For AAA, is fixing small aneurysms beneficial?
No. Studies show that managing them is more beneficial than fixing small AAA aneurysms.
What are symptoms of AAA?
70% of patients are asymptomatic, then present with sudden death
30% present with abdominal discomfort or severe radiating pain to the back, then die
How are AAAs typically discovered?
Physician physical examination (rarely) or incidental discovery from imaging for another indication
Why is a symptom of AAA back abdominal discomfort or back pain?
Because AAA is retroperitoneal
What are the best imaging tools for AAA?
CT and MRI
Ultrasound and X-rays can work but not as well. Angiography isn’t that good for this because it only images the lumen
True or False: Imaging with CT for AAA is good for imaging and planning for intervention
True
What is the surgical procedure for infrarenal AAA? (older way)
- Cross clamp aorta below the renal arteries, cross clamp the iliacs.
- Open up aneurysm and take out gunk
- Put in tube graft
- Overlay sac like thing
What is the newer procedure for fixing infrarenal AAA?
Endovascular infrarenal aortic repair
Basically deploy catheters that open up stent like things. Can 3D print to customize fit to patient’s branch arteries
How common is aortic dissection?
~30 cases / million / yr
True or False: Aortic dissection can cause sudden death
True. 3-5% sudden deaths.
For aortic dissection, what is the mortality rate if left untreated?
1%/hour mortality x 24 hours
75% mortality at 2 weeks
90% mortality at 3 months
What are the 2 mechanisms of aortic dissection?
- Primary intimal rent/tear
2. Rupture of vasa vasorum (causing ingrowth)
What are risk factors for aortic dissection? (name 8)
- HTN (drugs e.g. cocaine)
- Inherited disorders of CT (marfan syndrome, ehlers-danlos syndrome)
- Bicuspid aortic valve
- Coarctation (congenital aorta narrowing)
- Pregnancy
- Aortitis
- Iatrogenic (surgery, arterial catheterization)
- Trauma
True or false : aortic dissections are often occlusive
True
What is the symptom of aortic dissection?
Majority of cases present with severe, tearing pain
Aortic dissection of different arteries leads to different clinical outcomes. Name 5 and the level of arterial dissection.
- Stroke (carotid)
- Syncope (vertebral)
- MI (coronary)
- Intestinal ischemia (mesenteric)
- Renal failure (renal arteries)
What is the treatment for aortic dissection? Both medically and surgically
Medical-
Control DeltaPressure/DeltaTime (beta blockers)
Control BP (nitroprusside, ACEIs, CCB)
Control Pain (narcotic analgesia)
Surgical-
Endovascular grafts. Stents.
True or False. In aortic dissection, the artery can unravel.
True
What is the 3rd most common peripheral vascular disease?
Venous Thromboembolic Disease (VTE)
What percentage of Venous Thromboembolic Disease (VTE) are asymptomatic or undiagnosed?
2/3 (66%)
Venous Thromboembolic Disease (VTE) account for what percentage of hospital deaths?
5-10%
Prophylaxis is important for preventing VTE. Without prophylaxis, what % of MI, paralytic stroke, and hip surgery patients develop VTE?
MI - 24%
Paralytic stroke - 60%
Hip surgery patients - 75%
What percentage of PE deaths had not received any prophylaxis
58%
So, it’s important to treat prophylactically.
Of patients with VTE, how many have post-phlebitic syndrome?
40-80%
What is post-phlebitic syndrome?
It is when there is damage to venous valves after treatment of thrombosis. Causes swollen area that is tender and limits activities
Where are the most common locations for acute venous thromboembolism?
Many are in legs or pelvis. Can result in pulmonary embolism
What are the visible signs of chronic VTE?
Stage 1. Swelling
Stage 2. Visible collateral vessels
Stage 3. Stasis dermatitis
Stage 4. Ulceration
What are the 3 points of virchow’s triad?
- Abnormal flow (stasis)
- Injury/Inflammation
- Coagulation factors
Typically takes more than one of these to result in thrombosis
What is thrombophilia? (4 criteria)
Propensity to clot. Any alteration in coagulation balance that:
- Increases thrombin production
- enhances platelet activation/aggregation
- mediates endothelial activation/damage
- and/or mediates fibrinolytic inhibition
What is the risk factor for severe inherited thrombophilia?
Homozygous protein C deficiency (rare)
What is the risk factor for mild inherited thrombophilia?
Heterozygous Factor V Leiden (common)
How is thrombophilia typically acquired?
Infection, inflammatory, and certain drugs (estrogens)
What Xa inhibitors are preferred for treating venous thromboembolism?
Direct Factor Xa inhibitors (rivaroxaban, apixaban, edoxaban)
- Oral
- No cofactor needed (Reversible)
- do not bind PF4 - no risk of HIT
- Inhibit free factor Xa and factor Xa in prothrombinase complex–better attenuation of thrombin generation
What are the 3 risk factors for VTE?
- Hyper coagulable states
- Venous Trauma
- Stasis
What is the most pertinent chronic risk for VTE?
Post-phlebitic syndrome
What is the most pertinent acute risk for VTE?
Acute venous and pulmonary thrombosis (morbidity)
What is the treatment for VTE?
Anticoagulation