10 Cardiac Ischemia

Ischemic Syndrome

Angina vs MI:

  • Angina: Symptoms relieved by NG; MI not relieved by NG
  • stable: unruptured plaque, blocking blood flow. RBC squeeze through. Symptoms with exertion. May have ST depression during symptoms
  • unstable angina: ruptured plaque, clot, subendothelial (ST depression) ischemia (no markers)
  • prinzmetal: transmural (ST elevation) ischemia (no markers)
  • NSTEMI: subendothelial necrosis, clot not completely obstruct artery (not transmural yet)
  • STEMI: transmural necrosis, clot completely obstructs artery, transmural

  • coronary ischemia most cause of sudden death, except with HCM in young people

Symptoms

  • angina: squeezing type of chest pain
  • lavigne sign: patient place hand over chest

  • vagus run along inferior wall of heart, can be stimulated with inferior MI

Risks

  • angina, MI in past highest risks
  • other very high risks

Cardiac Markers

  • 1 hour after chest pain: no cardiac marker, nl biomarkers

  • pt with rhabdo will have very high CK, but mostly MM

  • liver enzyme

EKG

ST depression

  • blue: small area of subendocardial ischemia
  • endocardium can get blood from ventricle. Subendo receive blood from epicardial vessels, most vulnerable to ischemia
  • in mild ischemia: subendo ischemic first
  • ischemic tissues create electric current going away from it
  • T: EKG lead looking at LV
  • At baseline: T sees current heading towards it (elevated ST baseline)
  • Heart depolarize: everything at normal baseline
  • repolarize: elevated baseline again
  • Appears to have ST depression, in reality, baseline elevation

T inversion

  • normally: subendo repolarizes first, current goes to T, create upward T wave from current heading towards it
  • subendo ischemia: subendocardium repolarizes last, reversing wave of repolarization, going away from T, inverted T

ST Elevation

  • transmural ischemia, current away from it
  • baseline: T sees current heading away, depressed baseline
  • depolarizes: everything at baseline
  • repolarizes: depressed baseline again
  • ST elevation = baseline ST depression

STEMI

  • transmural MI progression
  • Q wave after a few hours, but also represent old infarction
  • T wave invert after few days
  • normal ST
  • T wave normal, Q wave remain

  • tell which leads ischemic with transmural infarct
  • anterior wall

Progression and Complications

Overview:

  • 1st thing: coagulative necrosis: removed nucleus from cells
  • 2nd: acute inflammation with neutrophils/macrophages
  • 3rd: healing, granulation, then conversion to scars

< 4 hours:

  • congestive heart failure: blood back up and can’t pump
  • arrythmia from damaged conduction

1-7 days:

  • WBC gives yellow pallor gross color
  • complication depends on whether neutrophil or macrophages
  • neutrophil: transmural inflammation, exudate leak to pericardium, pericarditis. Only with transmural inflammation
  • macrophage: eat up all dead debris, wall = weakest, rupture

1-3 weeks:

  • granulation: blood vessels, red border from outside, from normal tissues

months:

  • scar: not as strong as myocardium, not good movement, stasis, aneurysm/thrombus

  • 1 day, 1 week, 1 month
  • 1st day: coagulative necrosis
  • after 1st day: inflammation up to 1 week, neutrophil then macrophage
  • after 1 week: granulation
  • 1 month: scar

  • subendo, mottled color

  • coagulation necrosis

  • inflammation

  • pericarditis

  • rupture

  • papillary muscle

  • scar

  • collagen, CT, type 1

  • aneurysm

  • return of blood flow: contraction band
  • return blood flow, Ca inflow into dead cells, contraction of muscle fibers, dense contraction bands
  • reperfusion: free radicals from O2 coming back. Cardiac enzyme continue to rise after open up clot

Complications

  • VTACH, can deteriorate into cardiac arrest

  • can cause tamponade if accumulation of fluid
  • inferior wall: papillary muscle with single supply from RCA
  • thrill: feel with hand
  • hypotension: blood leaks from left to right

  • US: apex with akinetic tissue, aneurysm with stasis of blood on left side
  • can have stroke if a piece breaks off
  • anterior infection: most common

  • EKG with pericarditis
  • diffuse ST elevation
  • PR depression, down going
  • autoimmune

  • like sand paper

  • extension of inflammation into pericardium

Treatment

Revascularization

  • dye with fluoroscope
  • put in stent

  • balloon first to push the plaque, then leave stent (chickenwire) in
  • PCI: going across skin to access artery
  • PTCA: lumen of artery to get to coronary artery
  • PCI: within 90 min of symptoms onset
    • more than 90 min: tpa
    • PCI unsuccessful: emergency CABG

  • systolic dysfunction: cardiomyopathy with reduced LV EF
  • hibernating myocardium: myocardium so little flow that going into hibernation
  • in valve surgery: treat blocked artery at same time

Bypass

  • bypass backup option

Medication

Prevention

  • trigger inflammation when put in
  • drug: sirolimus/tacrolimus to prevent stenosis
  • thrombosis: complete closure of stent by blood clot inside

  • endothelialization: scar tissue grew over stent

STEMI Treatment

  • 1: catheter
  • time it takes: door to balloon or needle

  • inferior MI: bradycardia and AV block already from parasympathetic stimulation. Adding beta blocker make it worse
  • usually LV infarct, RV sometimes can be infarcted
  • hypotension and then cardiac arrest

  • No intRUDIN: bivaliRUDIN is a direct thrombin inhibitor
  • Big GATOR: arGATROban and dabiGATRAN are direct thrombin inhibitors

  • ABC sportscaster grabbing fries: abciximab blocks the GP IIb/IIIa receptor preventing platelet aggregation
  • Antibody-shaped microphones: abciximab is a monoclonal IgG antibody
  • Tied game: eptifibatide and tirofiban block the GP IIb/IIIa receptor to prevent platelet aggregation
  • Broken plates: GP IIb/IIIa inhibitors can cause thrombocytopenia
  • Ketchup time: antiplatelet therapy increases bleeding time (measure of platelet function)

NSTEMI

  • damage to heart tissues but absence of EKG elevation

  • not important

Unstable Angina

  • treated just like NSTEMI