myocardial infarction

Question 1

acute coronary syndrome classification?
and main difference between them?

Answer 1

unstable angina vs NSTEMI vs STEMI
unstable angina: normal cardiac enzymes and ECG
NSTEMI: high troponins but normal ECG
STEMI: high troponins and abnormal ECG

Question 2

etiology?

Answer 2

coronary artery disease (thrombus)
coronary artery vasospasm
coronary artery emboli

Question 3

partial vs complete coronary artery occlusion?

Answer 3

partial affects the inner 1/3 (subendocardial infarction) bcz blood supply extends from outer to inner part of the heart. Manifests as NSTEMI or unstable angina

complete causes transmural infarction. manifests as STEMI

Question 4

clinical features?
esp in diabetics/elderly?
inferior wall MI?

Answer 4

acute retrosternal chest pain lasting >20 minutes that’s characterized by squeezing pressure or tightness radiating to the left chest, shoulder, neck, jaw and epigastrium worse with exertion. symptom relief after nitrates isn’t a diagnostic criteria.
SOB, pallor, lightheadedness, N/V, sweating, tachycardia

in diabetics or elderly it can be stabbing in nature. or no chest pain in diabetics due to polyneuropathy

inferior wall MI:
bradycardia
triad of hypotension, high JVP, clear chest
explanation: inferior wall is supplied by RCA which also supplies the conduction system of the heart so they present with bradycardia

Question 5

localization of MI on ECG with involved vessel?

Answer 5

V1-V6 anterior MI, left anterior descending
v1-v1 (anteroseptal), LAD

1-aVL lateral wall, LCX (circumflex branch of left coronary artery)

II,III, aVF inferior wall, RCA

v7-v9 posterior wall (suspected if inferior wall is affected)

Question 6

diagnostic modalities?

Answer 6

ECG

Coronary angio to identify site and degree of occlusion for STEMI, NSTEMI (also for PCI treatment)

transthoracic echo to identify wall motion abnormalities

troponins

Question 7

critical management?

Answer 7

all patients with suspected ACS should be considered for PCI. door to balloon: 90 minutes).

-if unavailable: tPA/ dual antiplatelet (aspirin-clopidogrel). door to needle: 30 minutes within 12 or 6 hours.
-nitroglycerin or morphine for chest pain
-beta blockers (avoided in hypotension and acute HF)
-statins regardless of LDL levels
-ACEI is protective for heart

aspirin, ACEI, statin, BB are continued for life
modify risk factors

Question 8

complications?

Answer 8

acute left HF
arrythmias (ventricular tachyarrythmias, AV block, AF)
cardiogenic shock
left ventricle free wall rupture
interventricular septum rupture
papillary muscle rupture -> mitral regurg
ventricular aneurysm
acute pericarditis

post-MI syndrome (dressler)

Question 9

what is post-mi syndrome?

Answer 9

pericarditis, fever, dry cough, pleuritic chest pain, leukocytosis, diffuse ST elevations and high troponins occurring 10 wks after MI. treated with NSAIDs