Chapter 11: Myocardial Infarction Flashcards
A cessation of normal cardiac contractions
Cardiac arrest (asystole)
What is the most common cause of cardiac arrest?
V fib
An actual necrosis of the heart muscle starved of blood/oxygen
Myocardial infarction
What is the most sever consequence of CAD/CHD?
MI
Full-thickness infarct from
endocardium to epicardium, usually from clot in major
coronary artery
Transmural infarct
MI in which only part of wall undergoes necrosis
Subendocardial infarct
Which muscles of the heart are typically involved in an MI?
Muscles of the L ventrical and septum (because they are thicker and require larger blood supply, have greater O2 requirements)
Infarcts of the left anterior wall caused by L descending artery blockage are called what?
Widow-maker infarct
What are the 4 basic mechanisms that trigger a heart attack (MI or cardiac arrest)?
1) Sudden blockage
2) Hemorrhage
3) Arterial spasm
4) Sudden greatly increased myocardial oxygen requirements.
True or false: MI patients usually develop one or more complications.
True
What is the 5 year survival rate following an MI?
80%
What are the 3 major causes of death following an MI?
- Fatal arrhythmia
- Heart failure
- Cardiac rupture with
cardiac tamponade
What percentage of MI’s begin with angina? What percentage occur without warning?
50%; 50%
What is the most important blood enzyme test for MI dx?
Troponin T and troponin I
In what percentage of cases can you dx an MI accurately with an EKG and troponin test?
99%
How can angina pectoris be treated?
1) Rest
2) Vasodilator (e.g., nitroglycerin)
What does temporary insufficient blood supply to the heart lead to?
Angina pectoris
What does prolonged insufficient blood supply to the heart lead to?
MI
True or false: Heart muscle damaged by an MI can regenerate functional tissue.
False; undergoes scar repair and becomes non-contractile.
What are two causes of cardiac arrest?
1) asystole (less common)
2) Ventricular fibrillation
In what two ways can a heart attack be manifested?
1) Cardiac arrest
2) MI
What 4 basic mechanisms can lead to a heart attack?
1) Sudden CA blockage
2) Hemorrhage into an atheromatous plaque
3) Arterial spasm next to plaque in a CA
4) Sudden increase in myocardial oxygen need
How do women’s MI symptoms differ from men?
Women are much less likely to have chest
pain, arm/jaw pain, nausea/vomiting, or strong anxiety.
Inflammation of lining of the lungs and chest.
Pleurisy
What are two conditions whose symptoms can mimic a a heart attack
1) Heartburn/indigestion
2) Pleurisy
3) Gall bladder attack
3) Muscle strain
Partial necrosis caused by an MI
subendocardial necrosis
Necrosis through all layers of the heart caused by an MI
transmural necrosis
What two key test are able to accurately diagnose MI 99% of the time?
EKG and troponin levels
What are the three groups for Acute Coronary Syndromes?
1) Severe unstable angina (ST depression, no rise in troponins or CK)
2) Minor myocardial damage (non-STEMI, elevated troponins and CK
3) Major myocardial damage (STEMI, elevated troponin and CK)
How is severe unstable angina diagnosed? How is it treated?
1) ST depression, no rise in troponins or CK
2) Drugs
How is minor myocardial damage (non-STEMI) diagnosed? How is it treated?
1) ST depression, increased troponin (not CK)
2) Angioplasty
How is major Myocardial damage treated (STEMI)?
Total CA blockage; treated with angioplasty or thrombolytics ASAP.
Within what time period must thrombolytics be given to given to prevent irrversible tissue infarction?
within 6 hours
What is the very best treatment for an MI?
angioplasty (unblocks CA in 90% of patients)
What device can be used to treat patients who are at high risk of v-fib?
implantable cardioverter defibrillator
What implantable device senses v-fib and automatically shocks the heart?
cardioverter defibrillator
What is the percentage of MIs that are survived if patients are hospitalized?
95%
What percentage of MI deaths occur outside of the hospital?
1/3
