What is the main cause of coronary heart disease aka ischemic heart disease?
Obstructive atherosclerosis and corresponding decreased coronary blood flow.
What is the leading cause of death in the U.S. and other industrialized nations?
CHD
What are the warning signs of a heart attack?
- Chest discomfort.
- Referred discomfort (left arm, left part of jaw, etc.).
- Other signs including cold sweat, nausea, light-headedness.
Do most people who are experiencing a MI experience chest discomfort?
No. 42% of females don’t experience it, and 31% of males don’t experience it.
What are the five basic clinical syndromes of IHD?
- Angina pectoris
- Acute MI
- Sudden cardiac death
- Chronic IHD
- Acute coronary syndrome
What causes sudden cardiac death?
Lethal arrhythmia
What are the three types of angina pectoris? Describe them.
- Variant (Prinzmetal): Happens during rest.
- Stable (typical): 75% or greater coronary artery narrowing, precipitated by strenuous activity.
- Unstable (crescendo): May occur during rest or sleep. Caused by thrombi. Precursor to more serious, potentially irreversible ischemia.
What is the most common symptom of IHD?
Angina
In critical stenosis of a coronary artery, ______% of a vessel is lumen is occluded, causing angina in the setting of increased functional demand.
70-75%
90% stenosis of a coronary artery is likely to cause _______ angina.
unstable
Which portion of the right coronary artery is susceptible to atherosclerotic build up?
The entire length
Which coronary artery is known as the “widow maker?”
The left anterior descending artery.
Explain what is meant by “right dominant” with regards to coronary arteries.
The artery that perfuses the posterior 1/3rd of the septum can come from either the right coronary artery of the left circumflex branch. 80% of peeps are right dominant.
What are the 5 sequential events that occur in a typical MI?
- Disruption of a preexisting plaque.
- Platelet adhesion, aggregation to form microthrombin.
- Vasospasm triggered by released mediators.
- Thrombus formation.
- Lumen occlusion.
What is the “area at risk?”
The region of tissue downstream of an infarcted artery.
Which ventricle is more commonly infarcted?
Left
Cardiac myocytes lose their contractile ability after ____ seconds of ischemia.
60
Cardiac myocytes undergo irreversible injury after _____ to ____ minutes of ischemia.
20 to 40
What is the pattern of necrosis spread after infarction?
From the endocardium to the epicardium.
How are arrhythmias related to MIs?
MIs kill myocytes, causing electrical instability.
Name five factors that contribute to the severity of myocyte death following a MI.
- Location, severity, and rate of development of the occlusion.
- Size of the vascular bed perfused by the obstructed vessel.
- Metabolic demands of the “at risk” myocardium.
- Extent of collateral supply.
- Presence, site, and severity of the arterial spasm.
Are most MIs transmural, or subendocardial?
Transmural
Which zone of the myocardium is most vulnerable to reductions in coronary artery flow?
The subendocardial zone.
Name two major myocyte proteins that are used as diagnostic biomarkers.
TnI, TnT
What do contraction bands on a histologic slide of cardiac tissue indicate?
Transient ischemic injury
Are the following items potential complications of MI?
contractile dysfunction, arrhythmias, myocardial rupture, pericarditis, infarct expansion, mural thrombus, ventricular aneurysm, papillary muscle dysfunction, progressive late heart failure.
Yeah
What is a mural thrombus?
A blood clot that develops inside the heart chambers or a large artery.
What is the sequence of events during scar formation in the heart following a MI?
Day 1: Coagulative necrosis with edema and infiltrating neutrophils. Myocytes look wavy.
Days 3-4: Dense polymorph infiltration.
Days 7-10: Phagocytic removal of dead myocytes.
Later, granulation tissue is laid down, eventually forming a dense collagenous scar.
