Definition of a TIA
Brief neurological deficity that completely resolves within 24 hours
Risk of another TIA if a patient with a TIA is not treated?
40% of another attack within 2 years
Work up for a patient w/hx of TIA
Physical exam for carotid bruits, focal neurologic deficit, heart disease, echo if murmur is present and duplex u/s of carotid vessels.
Carotid endarterectomy/stenting vs. aspirin in stroke prevention
3x more effective in preventing strokes over a 2 year period.
Indications for carotid endarterectomy/stenting?
Ipsilateral neurological symptoms (amaurosis fugax, TIA, stroke w/recovery) AND > 70% internal carotid stenosis. Asymptomatic carotid bruit AND > 70% internal carotid stenosis.
What are risks of carotid endarterectomy?
1-3% risk of stroke (most common cause immediate post-op is inappropriate smothing of the resected portion of the artery and emboli), hypoglossal nerve injury, vagus nerve injury and marginal branch of facial nerve injury.
What are the branches of the internal carotid artery?
What are the steps of a carotid endarterectomy?
Get a-line to carefully monitor pts BP, EEG to monitor neurologic function if under general anesthesia. 1) Incision along SCM 2) Dissect to carotid sheath 3) Protect vagus, isolate carotid artery and avoid carotid body 4) Expose ICA to level of hypoglossal nerve 5) Heparin and clamp vessel 6) Open vessel and dissect out plaque 7) Close artery w/ or w/o patch
Follow up for patients post-carotid endarterectomy
Recurrent carotid narrowing over 5 years has 13% incidence. TIA from opposite artery may still occur and pt should take aspirin, control lipids, exercise, quit smoking and exercise to decrease further atherosclerotic disease.
What are the branches of the external carotid artery.
The opthalmic artery is the first branch off the carotid. This is when an emboli travels through the opthalamic artery to the retina causing transient monocular blindness or hazy vision like a shade being pulled over the eye. Fundoscopic exam may show a bright shiny spot at the retinal artery (Hollenhorst plaque).
Location of speech center in right handed patients
Left temporal lobe
Stroke work up and tx
If the patient's TIA does not resolve within 24 hours, you can still do a carotid duplex u/s, but endarterectomy/stent is not necessary immediately. The patient should be observed for improvement and stabilization of neurologic status and then endarterectomy/stent can be considered as early as 2-4 weeks later.
Common findings in patients with acute arterial occlusions
6 P's: Pain, paresthesias, pallor, pulselessness, poikelothermia, paralysis.
Time limit for revascularization of an acute arterial thrombus in the limbs
Less than 6 hours
Tx for patient presenting with acute arterial thrombus of < 6 hours
Immediate heparin, then ballon catheter embolectomy with a Fogarty catheter as the procedure of choice. This involves 1st entering the vessel distal to the embolus and 2nd extracting the most proximal embolus 1st. More distal thrombi can be cleaned out at the same time.
What are the most common sites of arterial emboli?
10-15% in aortic saddle, 15-20% in common iliac, 40-45% in common femoral, 15% in popliteal, 5-10% in upper extremity, 5-10% in viscera or kidney and 10-15% in carotid.
Characteristics of a threatened limb, how can you treat such a limb?
Slow to intact cap refill, mild muscle weakness, mild sensory loss, inaudible arterial pulses and audible venous pulses w/doppler. Limb can be salvaged if treated promptly.
Characteristics of a limb with irreversible ischemia
Absent cap refill (marbling), profound paralysis (rigor), profound sensory loss, inaudible arterial and venous pulses on doppler.
What are the most common sources of arterial emboli
Cardiac accounts for 75%, with 50-60% due to a-fib and 20-25% due to acute MI. Aneurysm or atherosclerotic plaques from the aorta account for 10-15%. Other causes include aortic dissection and femoral artery puncture sites that disloged tunica intima and created an embolus.
What condition commonly arises after revascularization of an acutely ischemic limb?
Compartment syndrome due to acute muscular edema.
Pressures in compartment syndrome that lead to irreversible ischemic injury of muscles and nerves
How do you manage a patient with compartment syndrome?
4 compartment fasciotomy should be performed with high degree of clinical suspicion. Needle and pressure-measuring device can be done to check pressures if suspicion is not as high before performing fasciotomy. Fasciotomy is the closed w/split thickness skin graft
Long-term management of a patient recovering from compartment syndrome after 4 compartment fasciotomy
PT to maintain full ROM. Chronic warfarin anticoagulation to prevent further arterial emboli. Echo, angio, CT etc should be used to dx source of emboli once the patient has recovered.
A patient presents with intermittent claudication. If he has an arterial occlusion in his lower extremity, where will it most likely be found?
Superficial femoral artery in the adductor hiatus is the most common location of occlusive disease in the lower extremity.
What is the noninvasive workup for a patient complaining of intermittent claudication?
ABI and Doppler to detect stenotic areas and locate the level of the occlusion. Normal ABI is 0.9-1.1. In mild claudication, ABI is 0.6-0.8 and indicates single level disease. Severe claudicationi ABI is < 0.5 and indicates multilevel disease. An ABI < 0.3 is typically indicative of rest pain or tissue loss.
What is the measured BP in patients with advanced diabetes when checking ABIs?
Typically as high as the cuff is inflated, this is because their vessels have become calcified from atherosclerotic disease and are now non-compressible.
How do you interpret triphasic, diphasic vs. monophasic Doppler waveforms?
Triphasic = good vessels with phase of rapid systolic flow, reversal flow due to elastic recoil and finally a diastolic outflow phase. Diphasic = loss of the reverse flow, indicating decreased elasticity of the vessels due to atherosclerosis, can also be normal. Monophasic = severe disease with no changes.
Most common way claudication is managed?
Non-operatively with lifestyle modification (exercise, smoking cessation, lipid-lowering drugs, diet and weight loss). With this approach 1/3 get better, 1/3 stay the same and 1/3 get worse. Revascularization surgery is really only done in patients without critical limb ischemia when the claudication is an impairment to their activities of daily living. Note that you should not order an arteriogram unless you are actually planning for surgery due to the inherent risks of the test.
What is Leriche syndrome
Claudication, impotence and pulselessness indicating aortoiliac occlusive disease.