HY lecture notes:
Most common cause of carotid plaques? –> HTN –> the strong systolic impulse from the heart pounds the carotids –> endothelial damage –> atherosclerosis.
55M + BP 150/90 + TIA; next best step in Mx? –> carotid duplex USS à the first thing you want to think about is, “Does this guy have a carotid plaque that has resulted in a clot embolizing to his brain.”
80M + good blood pressure (e.g., 110/70) + stroke or TIA; next best step in Mx? –> ECG à you want to think, “Does he have atrial fibrillation with a LA mural thrombus that’s now embolized to the brain.”
80M + good blood pressure (e.g., 110/70) + stroke or TIA + ECG shows sinus rhythm with no abnormalities; next best step in Mx? –> Holter monitor –> when you first see this scenario you’re probably like, “Wait, the ECG is normal, so it’s not AF?” –> No, it is likely AF, but AF is often paroxysmal, so in order to detect it in this scenario, the next best step is a Holter monitor (24-hour wearable ECG). This means that later in the day when he sits down to have dinner and then pops into AF, the Holter monitor will pick it up.
What % of people over age 80 have AF? –> 8% of people over age 80 have AF, which is why age is a huge risk factor. In other words, if the vignette says the guy is 58, AF is probably less likely just based on shear probability, regardless of hypertensive status.” And, once again, knowing that AF is often paroxysmal is really important.
Age 50s-60s + high BP + TIA/stroke/retinal artery occlusion; next best step in Dx? –> answer = carotid duplex ultrasound to look for carotid plaques.
Age >75 + good BP + TIA/stroke/retinal artery occlusion; answer = ECG to look for AF –> if normal, do Holter monitor to pick up paroxysmal AF.
55M + good BP + carotid bruit heard on auscultation; next best step in Mx? –> answer = carotid duplex ultrasound to look for carotid plaques –> in this case, if they are obvious and explicit about the suspected etiology of the stroke, TIA, or retinal artery occlusion, then you can just do the carotid duplex ultrasound.
How to Mx carotid plaques? –> first we have to ask whether the patient is symptomatic or asymptomatic. A bruit does not count as symptoms (that’s a sign). Symptomatic means stroke, TIA, or retinal artery occlusion. According to recent guidelines: carotid occlusion >70% if symptomatic, or >80% if asymptomatic –> answer = do carotid endarterectomy.
Below these thresholds –> answer = medical management = statin, PLUS clopidogrel OR dipyridamole + aspirin.
The USMLE will actually not be hyper-pedantic about the occlusion %s (that’s Qbank). They’ll make it obvious for you which answer they want. They’ll say either 90% à answer certainly = carotid endarterectomy, or they’ll say 50% –> answer = medical management only. There’s one NBME Q where they say a guy has a bruit but is asymptomatic, and has 10 and 30% occlusion in the left vs right carotids, respectively, and he’s already on aspirin + statin, and the answer is “maintain current regimen” –> if he were symptomatic, even with low occlusion, he’d certainly need statin, PLUS clopidogrel OR dipyridamole + aspirin.
68F + diabetic + diffuse, dull abdo pain 1-2 hours after meals; Dx? –> chronic mesenteric ischemia due to atherosclerosis of SMA or IMA, not duodenal ulcer (if they want the latter, they’ll say 29M from Indonesia) –> essentially stable angina of the bowel.
68F + Hx of intermittent claudication + CABG + abdo pain 1-2 hours after eating meals; Dx? –> chronic mesenteric ischemia.
78M + Hx of AF + acute-onset severe abdo pain “out of proportion to physical exam”; Dx? –> acute mesenteric ischemia due to embolus.
16F + Hx of severe anorexia + BMI of 14 + has episode of ventricular fibrillation due to hypokalemia + now has severe abdo pain; Dx? –> acute mesenteric ischemia due to episode of decreased blood flow (should be noted that hypokalemia causing arrhythmia is most common cause of death in anorexia).
68F + diabetic + Hx of diffuse, dull abdo pain 1-2 hours after meals + now has 2-day Hx of severe abdo pain out of proportion to physical exam; Dx? –> acute on chronic mesenteric ischemia due to ruptured atherosclerotic plaque (akin to an “MI” of the bowel).
Dx of acute + chronic mesenteric ischemia? –> USMLE answer = mesenteric angiography.
Tx of acute mesenteric ischemia? –> endarterectomy might be able to restore blood flow if caught in time, but on the USMLE, they will say “IV antibiotics are administered; what’s the next best step in Mx?” and the answer is just “laparotomy.”
Tx of chronic mesenteric ischemia –> endarterectomy to clear vessel.
Tx for acute limb ischemia –> endarterectomy; but if medicinal –> heparin + oxygen + morhphine.
Question on one of the surgery or IM NBME forms where they say patient has an ischemic posterior cerebral stroke + a false lumen is visualized in one of the vertebral arteries; next best step in Mx? –> heparin –> apparently stasis can occur within arterial false lumina and heparin has utility in the Tx.
