CM- Acute Ischemic Heart Disease Flashcards
What is the definition of an acute coronary syndrome? What are the 3 types?
It is an acute complication of ischemic heart disease.
- unstable angina
- non-ST segment elevation MI (NSTEMI)
- ST segment elevation MI (STEMI)
What is a myocardial infarction?
When heart muscle dies as a result of prolonged ischemia due to:
- obstructed blood flow
- increased myocardial demand
Does all myocardial ischemia result in cell death?
How much time for ischemia to cause CELL necrosis?
How much time to SEE necrosis on pathologic specimen?
How much time for ALL myocardium to be at risk of infarction?
No. The ischemia must exceed a threshold for an extended period of time to overwhelm myocardial repair mechanisms and allow necrosis to begin.
20 minutes of ischemia is necessary to cause cell necrosis.
Several hours to see necrosis on pathologic specimen.
6 or more hours for all the myocardium to be at risk of infarction.
How does the chest pain of a myocardial infarction differ from angina?
Where does the pain radiate?
It feels the same (pressure/pain) but is more severe and prolonged, lasting 20-30 minutes.
Radiates to neck, jaw, arm
What are EKG changes of ischemia?
What are the changes with myocardial injury?
Ischemia: T wave inversions, ST depression.
Myocardial injury: ST elevation
What are the EKG changes associated with NSTEMI?
- Inverted T waves, ST depression
2. no injury pattern
The EKG is diagnostic of STEMI if there is new _________ in _______________________.
As the infarct progresses, there is a loss of ____ and development of ______ in the affected leads.
new ST elevation in 2 or more contiguous leads
Loss of R wave voltage and Q waves develop
A new _____________________ in a patient presenting with chest pain suspicious of an MI is also treated as STEMI.
LBBB
IF there is ST elevation in II, III or avF, where is the infarction? What artery is likely occluded?
Inferior part of the heart- right coronary artery
If there is ST elevation in I, avL, V5, V6 where is the infarction?
lateral side of the heard- circumflex
If there is ST elevation in V1-V4, where is the infarction?
anterior part of the heart - LAD
In what type of acute coronary syndrome would the location of ST and T waves help determine the area of infarction?
The ST and T waves can help determine area of infarction for STEMI but NOT NSTEMI or unstable angina
What variation is seen on the EKG for :
- ischemia
- injury
- infarction (acute)
- Infarction (age uknown)
- tall or inverted T wave (infarct), ST depression (angina)
- Elevated ST, T wave inversion
- Q wave, ST elevation, T inversion
- Q wave, ST and T waves returned to normal
What cardiac enzymes are released when the myocytes become irreversibly injured?
Which is the preferred biomarker for diagnosing MI?
CK, CK-MB isoform
Troponin I or Troponin T (preferred for diagnosing MI)
What is the underlying pathology in most acute coronary syndromes?
A coronary arterial atherosclerotic plaque ruptures so the inner contents are exposed to circulating blood forming a compete or partial occlusion thrombus.
What increases a plaques propensity to rupture?
Multifactorial-
- cellular composition
- lipid composition
After a plaque ruptures, if there is sustained, full occlusion, what will the EKG show?
If there is partial occlusion, what will the EKG show?
Full occlusion-> transmural ischemia/injury->Infarction–> STEMI
Partial occlusion–> NSTEMI or unstable angina (differentiated by cardiac enzymes)
Unstable angina and NSTEMI both show inverted T waves and ST depression on EKG. How are they differentiated?
NSTEMI will have cardiac enzymes. Unstable angina will not.
When in the day is acute myocardial infarction most likely to occur? Why?
6am and noon with a peak incidence in the first 3 hours of waking because of increased arterial pressure, HR, adrenergic activity, vascular tone and or/platelet aggregation
What are the six things that must be done to treat an acute MI?
- reperfuse immediately for STEMI
- Limit infarct size
- stabilize ruptured plaque with antithrombotics
- relieve pain
- prevent electrical/mechanical complications
- prevent reinfarction, recurrent ischemia, heart failure
If the person has STEMI, the goal is to achieve reperfusion within ________, optimally _____.
What are the 2 options for reperfusion?
Within 120 minutes (optimally 60)
- Primary coronary intervention (PCI)
- Intravenous Thrombolytic therapy
PCI should be performed with optimal “door to balloon time” of ________________. It can restore perfusion in _________ % of cases.
Intravenous thrombolytic therapy should be “door to needle” in ________________.
90 minutes, 90-95% of cases
30 minutes
What are the 5 ABSOLUTE contraindications for thrombolytic therapy?
- active internal bleeding
- less than 2 months since cerebrovascular insult or neurosurgery
- less than 2 weeks since major surgery, organ biopsy
- less than 1 month since GI bleed
- Recent serious trauma including prolonged CPR
What are the 5 RELATIVE contraindications for throbolytic therapy?
- severe hypertension (200/110)
- recent minor trauma
- hemostatic defect
- hepatic/renal disease
- diabetic hemorrhagic retinopathy
What is the difference between PCI “bleeding risk” and thrombolytic therapy “bleeding risk”?
PCI- bleeding at the site of access (groin from the femoral entrance)
Thrombolytic- potential brain bleeds
In patients who present at a hospital without capacity to perform PCI, what is the course of action?
- Transfer to a hospital with PCI
2. Give thrombolytic therapy and THEN transfer to a hospital with PCI
Why is aspirin given for MI?
It interferes with cyclooxygenase and inhibits formation of TXA2.
It interferes with platelet activation and adhesion.
It is used in unstable angina, NSTEMI and STEMI to decrease mortality and decrease risk of reinfarction
What is “dual anti-platelet therapy”? What 2 drugs are involved and when is it used?
Aspirin and clopidogril and is used to decrease risk of stent thrombosis
What 8 drugs are given as acute therapies for MI?
- Aspirin
- Clopidogril
- Heparin
- Nitrates
- B-blocker ***
- ACE-inhibitor ***
- STatin
- Oxygen
What are nitrates given when a patients has acute coronary syndrome?
To relieve chest pain by relaxing vascular smooth muscle and dilating arteries and veins