Pretest_9_Peripheral_Vascular_Problems Flashcards
In evaluating oliguria, you want to make sure you provide enough fluid replacement such that the Swan Ganz catheter in the left atrium measures around __ mm Hg
15
Abdominal distention, fever, elevation of white blood cell count, and/or bloody diarrhea in the postoperative period should raise suspicion for
colon ischemia
What accounts for 90% of primary lymphedema?
Hypolasia of the lymphatic drainage of the lower extremity
Acute onset, persistent back pain, hypotension =
ruptured abdominal aortic aneurysm
T/F: The IMA is typically ligated at the time of an abdominal aortic aneurysm repair
True!
Which part of the colon is most likely to be affected after the rupture of an abdominal aortic aneurysm?
Sigmoid! (after repairs (and IMA ligation), the marginal artery of Drummond from the SMA and the inferior and middle hemorrhoidal vessels are responsible for perfusing tbe left colon. If SMA is stenotic or occluded, patient is screwed!)
What is the name of the artery that anastamoses the SMA and IMA?
The marginal artery of Drummond
T/F: Though Carotid arteriography remains the gold standard for quantifying carotid stenosis, it is usually performed after noninvasive testing suggests significant stenosis.
True
Even if carotid artery stenosis is asymptomatic, if it exceeds ___% reduction in diameter and the patient is in good health/good candidate for surgery, they should have carotid endarterectomy.
70% or greater
What are common causes of compartment syndrome (x3)?
- acute areterial occlusion without colalteral inflow
- rapid reperfusion of ischemic muscle
- orthopedic trauma
T/F: If a fasciotomy is indicated for compartment syndrome, only the compartment involved should be opened.
False! All 4 compartments (anterior, lateral, superficial posterior, and deep posterior)
Most patients with limb claudication will stabilize or improve with instituting a program of _______________________ daily, vs. surgical intervention
exercise, cessation of smoking, weight loss
What are indications for arterial reconstructive surgery?
rest pain, gangrene
T/F: Most antiplatelet agents work by enhancing prostaglandin synthesis.
False! Aspirin inhibits the synthesis of thromboxane A2 and the subsequent production of prostaglandins. The platelet does not have a nucleus and thus cannot remanufacture the prostaglandins necessary for its functioning.
What is the “anatomic situation” that results in subclavian steal syndrome?
atherosclerotic occlusion of the subclavian artery proximal to the vertebral artery. Ischemia results in reversal of flow in the vertebral artery, with consequent diminished flow to brain = light headed on exertion, esp with lifting of arms
Which extremity is more prone to subclavian atherosclerosis?
The left (likely due to turbulence near the more acute angle at which the left subclavian artery leaves the aorta.)
What is the treatment for subclavian steal?
carotid-subclavian bypass, subclavian-carotid transposition, or dilating/stenting of the subclavian artery by endovascular techniques
What is Leriche syndrome?
Aortoiliac atherosclerotic disease resulting in claudicatio nof hte hips, buttocks, and thighs; absent femoral pulses; and impotence
What are important collateral arterial pathways around the aortic bifucation and common iliac segmetns important in patients with aortoiliac atherosclerotic disease?
1) intercostal and lumbar arteries to circumflex iliac and iliolumbar arteries
2) superior to inferior epigastric arteries
3) superior and inferior mesenteric arteries to rectal and internal pudendal
What are important collateral arterial pathways around the external iliac arteries important in patients with aortoiliac atherosclerotic disease?
hypogastric to circumflex femoral channels
can meet metabolic needs, but not levels necessary for exercise
T/F: Reduced hypogastric perfusion can also lead to retrograde ejaculation
True
What surgical error leads to retrograde ejaculation?
Disruption of the sympathetic chain overlying the distal aorta and left iliac after dissection around those vessels during vascular reconstructions
What test is most predictive of postoperative ischemic cardiac events following peripheral vascular surgery?
1) Gated-blood pool (MUGA) scan demonstrating ejection fractions of 35% or less and reversible perfusion defects
2) Reversible perfusion defects on dipyridamole-thallium imaging
What is the preferred thrombolytic agent: urokinase or streptokinase?
Urokinase: fewer allergic reactions
Without surgical revision following lysis of a clot in acute graft occlusion, a reocclusion rate of ___% is expected within 3 months. Even with surgical revision, a rate of __% is expected within 1 year.
w/o surgery 3 months: 50%
w/ surgery 1 year: 20%
What is the difference in management of acute arterial insufficiency WITH and WITHOUT neurologic compromise?
With neurologic compromise: immediate surgical intervention
Without neurologic compromise: either surgical intervention or arteriography with directed thrombolysis
T/F: Embolectomy of the femoral artery can be performed under local anesthesia.
True
Why should the contralateral groin be prepared in a femoral embolectomy?
In case flow is not restored via simple thrombectomy and a fem-fem bypass is needed to provide inflow to the affected limb
What are the most common peripheral arterial aneurysms?
Popliteal artery aneurysms
Popliteal artery aneurysms are bilateral up to ___% of the time and are associatd with extrapopliteal aneurysms ____% of the time
bilateral: 70%
extrapopliteal: 55%
What is the most common presentation of popliteal artery aneurysms?
distal emboli
Which popliteal artery aneurysms should be treated, and how?
all symptomatic and all asymptomatic >2 cm
Treatment is surgical repair with exclusion of the aneurysm (which is left in situ) and surgical bypass
What is a normal ABI?
ankle to brachial index: 0.9-1.3
1.3 = calcifications, as in diabetes, might make value wrong
What is the etiology of mesenteric ischemia?
thrombosis, embolus, or nonocclusive ischemia due to low cardiac index or mesenteric vasospasm
What is the treatment of mesenteric ischemia?
Occlusive disease: Thromboltic therapy, operative embolectomy, or vascular bypass
non-occlusive: angiographic instillation of papaverine, nitrates, or CCBs
T/F: A negative duplex scan is sufficient to withhold anticoagulation in patients presenting with symptoms evoking DVT
True (sensitivity, specificity, and positive and negative predictive values are more than 95% in symptomatic patients)
What characterizes acute vs chronic DVTs on Duplex?
Acute = enlarged, noncompressable vein without collateral vessels Chronic = normal-sized veins with significant collaterals
Patient with HIV and hx of IVDU presents with new murmur, fever, and sever eback pain: found to have enlarged, saccular-appearing abdominal aorta below the renal arteries:
infrarenal mycotic aortic aneurysm
What are the most common etiologic agents in mycotic aortic aneurysm?
Staphylococcus or Salmonella
What are risks associated with a carotid endarterectomy?
stroke, injury to hypoglossal/vagus/marginal branch of facial nerve
What is in the carotid sheath?
common carotid artery, IJV, vagus nerve, deep cervical lymph nodes
T/F: Most physicians recommend taking aspirin after routine endarterectomy.
True
What is the first branch of the internal carotid artery?
The opthalmic artery (emboli from carotid artery –> amarousis fugax)
After a STROKE, an endarterectomy should not be performed until after a carotid duplex study is performed and the patient’s neurologic stabilizes, as early as ___ weeks after the diagnosis of stroke.
2-4 weeks
What is the treatment of acute arterial embolus in the right leg?
heprain, proceed to OR for earliest revascularization (with Fogarty (baloon catheter) embolectomy). Anticoagulants continued post-operatively. IN post op period, do CT of thoracic and abdominal aorta looking for source.
After fasciotomy is performed, it can be closed with ____________.
split-thickness graft; during recovery, PT is important.
What is the most common location for occlusive disease of the lower extremity? Which pulses would be absent?
superficial femoral artery (at the adductor hiatus). Popliteal and pedal pulses are absent. (If the femoral pulse is absent, significant aortoiliac disease may also be present)
Normally the Doppler waveform is triphasic (why?)
What happens when there is severe vascular disease?
Triphasic: rapid systolic, brief phase of reverse flow secondary to elastic recoil of vessel, diastolic flow
Becomes monophasic as vessel becomes less compliant
T/F: Though nonoperative exercise management with lifestyle modification is the therapy for patients with claudication, all should undergo an arteriogram to see how the vessels work.
FALSE. There is an inherent risk to arteriogram and has no benefit unless surgery is planned.
What is ABI in a patient with rest pain?
0.3-0.5
After the superficial femoral artery emerges from the adductor hiatus, it is the
popliteal artery
WHen do you use a reversed/in situ saphenous vein graft vs fem-pop bypass for occlusion of the superficial femoral artery?
Both used in situations where there is distal reconstitution.
IF there is also occlusion of the popliteal artery, then fem pop. IF not, then graft
IN a fem pop bypass, which artery is selected as the outflow tract?
The best one continuous with the foot (usually popliteal or anterior or posterior tibial arteries). If the tibial arteries are occluded, the peroneal artery is chosen (branch of posterior, supplies lateral compartment of leg)
Which grafts have better patency after four years: saphenous vein or PTFE (Polytetrafluoroethylene)?
saphenous (especially better in infrapopliteal bypass grafts and below-knee; in above knee the two are closer)
Single, short segment (<3 cm) iliac stenosis is ideal for what treatment?
Percutaneous transluminal angioplasty (PTA) often performed at the time of angiography
Following aortobifemoral bypass, a painful cyanotic big toe is discovered that was not present preoperatively:
“trash foot,” atheroembolization of fibrin, platelets, or dislodged atherosclerotic debris has blocked the small pedal or digital arteries and microvessels during unclamping; inaccessible to embolectomy catheters, but in the presence of patent tibial vessels and palpable pedal pusles, significant healing commonly results. Treat with heparin and antiplatelet long-term
What type of graft is used in an aortobifemoral bypass?
PTFE (polytetrafluoroethylene) or Dacron
What is the most important medical consideration prior to major abdominal revascularization?
cardiac study! should undergo stress test or cardiac catheterization, because as many as 70% of perioperative and late fatalities after peripehral vasc. surgery are due to cardiac events
__% of patients with popliteal aneurysms have AAAs.
50
__% of popliteal aneurysms are bilateral.
50-75%
Elective repair of AAAs that are ___ cm or larger in diameter is appropriate.
5 (4-5 is debatable)
Patient with impotence post AAA repair is likely due to:
1) interruption of hypogastric circulation (internal iliac artery circulation)
2) injury to autonomic nerves on the anterior surface of the aorta near the inferior mesenteric artery, which course over the aortic bifurcation
Ischemic colitis following AAA repair usually involves which segment?
rectosigmoid (due to interruption of a patent IMA in the setting of compromised colalteral flow from teh SMA and internal iliac arteries)
Vascular graft infection is usualy due to which flora?
Staph aureus or Staph epidermis (due to contamination from skin flora)
If mesenteric ischemia is suspected, the patient should undergo
a mesenteric arteriogram, with planned revascularization if appropriate
How is the MOA of heparin and LMWH different?
Heparin binds to and potentiates the actions of
antithrombin (AT) to inactivate factor Xa and prevent the
conversion of prothrombin to thrombin, as well as prevent
the conversion of fibrinogen to fibrin. LMWH also inactivates factor Xa, but less inhibits production of thrombin.
HIT can occur ___ days after heparin is first given.
5-14
Why must patients be on a hep-warfarin bridge when warfarin is first started?
It can induce a protein C deficiency (relative hypercoagulable state) when it is first started
What is the most common EKG finding found in PE? What is a characteristic finding?
most common: tachycardia
S1Q3T3 seen in 20% of patients: deep S wave in lead I, Q wave in III, inverted T wave in III
If a patient receiving anticoagulation for surgery with a long history of NSAID use then vomits 100 mL of brith red blood, what do you do?
Because UGIB is a life threatening condition, systemic anticoagulation should be discontinued. Alternate PE protection with an IVC Greenfield filter shoudl be provided. Antiulcer therapy should be instituted and UGIB workup started.
What is phlegmasia cerulea dolens?
Severe deep venous thrombosis; interruption of venous outflow from obstruction secondary to pelvic malignancy (eg advanced carcinoma of the cervix) that compromises arterial inflow. Venous gangrene.
What is the treatment of phlegmasia cerulea dolens?
anticoagulation, leg elevation, venous thrombectomy in severe cases
How are infrarenal mycotic aneurysms treated?
axillofemoral bypass is performed and then the involved intra-abdominal aorta is excised. Abx therapy for 3-6 months.
A single abdominal ultrasound to screen for AAA is recommnded for which patients?
Men age 65 to 75 with a history of smoking
Indications for elective repair of AAA include diameter >__ cm in men and >___cm in women
In patients with comorbidities (COPD, CAD), then only if >__ cm
men: >5.4cm
women: >4.5cm
comorbidities: >7 cm
Which medication increases walking distance, improves HDL cholesterol, decreases triglycerides, and improves the quality of life in patients suffering from intermittent claudication?
cilostazol (inhibtor of type 3 PDE)
How does an AV fistula affect heart rate, cardiac output, PVR, and SV?
HR: increased
CO: increased
PVR: decreased
SV: increased
