Pathology: Ischemic Heart Disease Flashcards
Ischemic heart disease is also known as?
Coronary artery disease
This is an imbalance between supply (due to coronary artery stenosis or decreased PO2) of oxygenated blood to the heart and demand of oxygenated blood (increased by myocardial hypertrophy or tachycardia)
Ischemic heart disease
What does ischemic heart disease present as?
MI, angina pectoris, chronic IHD with heart failure, sudden cardiac death
What is the difference between infarction and ischemia?
Infarction is tissue death, while ischemia presents as pain because the heart isn’t getting the oxygen that it needs
What are the 2 mechanisms of insufficient coronary perfusion relative to myocardial demand? (IHD syndromes)
- Chronic progressive atherosclerotic narrowing of the epicardial coronary arteries (luminal size is narrowed)
- Variable degrees of superimposed acute plaque change, thrombosis, and vasospasm
What percentage of luminal obstruction has to be present to cause chronic stable angina (chest pain with exercise)?
75% or greater
What type of angina presents with 90% of luminal obstruction?
Chronic unstable angina (pain at rest)
What type of circulation can help combat the effects of ischemia and infarction to a certain extent?
Collateral
This type of angina is associated with pain during exercise
Stable angina
True for False: Stable angina is associated with plaque disruption
FALSE: Stable angina is usually not associated with plaque disruption
This type of angina is associated with plaque rupture complicated by a partially occlusive thrombosis and vasoconstriction causing pain at rest and of increasing frequency
Unstable angina
What is the mechanism of a MI?
Acute plaque change inducing total thrombotic occlusion causing ischemia and necrosis of the myocardium… death of heart muscle!
What is the common pathophysiologic basis for most instances of angina, MI, and sudden cardiac death?
Coronary atherosclerotic plaque disruption, thrombus formation, and myocardial ischemia
This is failure to deliver adequately oxygenated blood to tissues
Hypoxemia
This is hypoxemia along with inadequate removal of metabolites
Ischemia
Can you have hypoxemia by itself?
YES
Can you have ischemia without hypoxemia?
NO, ischemia includes hypoxemia
This type of MI involves necrosis of the full thickness of the ventricular wall
Transmural MI
This type of MI follows the distribution of a single coronary artery (often LAD, left circumflex, or RCA)
Transmural MI
In this type of MI, you have a thrombus that is superimposed on plaque resulting in complete occlusion and full thickness death
Transmural MI
A subendocardial MI is limited to what part of the ventricular wall?
Inner 1/3 to inner 1/2
Does a subendocardial MI follow the distribution pattern of a single coronary artery
NO, it may extend laterally beyond the distribution of the involved coronary artery
This type of MI is due to incomplete occlusion, with or without vasospasm
Subendocardial MI
Besides subendocardial MI, what other problems can be caused by incomplete occlusion with or without vasospasm?
Angina and sudden cardiac death
What causes a subendocardial MI?
This area is least well perfused (relies on diffusion of oxygenated blood from ventricular space)
Does the systemic BP increase or decrease with a subendocardial MI?
It decreases!
The thrombus is lysed before necrosis extends across the whole wall… this causes drop in systemic BP
Do you want a subendocardial MI or a transmural MI?
Neither, DUH… but if you had to choose you want a subendocardial one
What causes death of cardiac muscle?
Prolonged severe ischemia
If you have a MI in someone under 40, what might you be thinking caused it?
COCAINE
Are men or women at higher risk for MI?
MEN, but once women go through the change of life, their risk shoots up with rapid development of CAD (they loose the protective effects of estrogen)
Evolution of an MI
- Sudden change in atheromatous plaque exposes subendothelial collagen and necrotic plaque contents
- Platelets come to play (form microthrombi) and cause vasospasm stimulated by mediators released from platelets (TXA2- Vasoconstricts)
- Tissue factor activates the coagulation pathway
With this, the thrombus evolves and occludes vessel lumen
What defines granulation tissue?
Edema, neovascularization, fibroblast deposition
What happens grossly and microscopically at 1/2-4 hours post-MI
Gross: Nothing (might see yellow-white area of dead tissue with a TTC stain)
Microscopic: Wavy fibers at borders