CAD and MI Flashcards
What is ischemic heart disease (IHD)?
group of syndromes related to myocardial ischemia; IHD is the leading cause of death in the U.S. This also results from reduced nutrient substrates and inadequate removal of metabolites.
What is myocardial ischemia?
imbalance between oxygen supply and demand
What is the most common cause of ischemia?
reduction of coronary blood flow from atherosclerotic CAD, occurring after decades of slow accumulation of atheromas.
What are the 4 types of Ischemic Heart Disease (IHD)?
- Angina= less severe (stable, Prinzmental, unstable)
- MI= most important
- Sudden Cardiac Death
- Chronic Ischemic Heart Disease= w/heart failure
Is there clinical heterogeneity of IHD?
YES: elderly that are asymptomatic with severe atherosclerosis to young people with minimal CAD presenting with acute MI or sudden death.
On what does clinical morphology of IHD depend?
plaque changes= erosion, ulceration, fissuring, rupture, hemorrhage, superimposed thrombus
Do pts with CAD typically have more than one affected vessel?
YES >90%. Slowly developing lesions can stimulate the development of collateral circulation protecting against ischemia.
What coronary arteries are most commonly affected with CAD?
LAD, LCX, RCA
What is stable angina?
- chest pain that arises with exertion or emotional stress due to atherosclerosis of coronary arteries with >70% stenosis; decreased blood flow is not able to meet the metabolic demands of the myocardium during exertion.
- relieved by rest or nitroglycerin
What will an EKG show with stable and unstable angina?
ST-segment depression due to subendocardial ischemia.
What is unstable angina?
- chest pain that occurs at rest, usually due to rupture of an atherosclerotic plaque with thrombosis and incomplete occlusion of a coronary artery.
- high risk of progression to MI
- relieved by nitroglycerin
What is Prinzmetal angina?
- episodic chest pain unrelated to exertion, due to coronary artery VASOSPASM.
- relieved by nitroglycerin or calcium channel blockers
What will an EKG show with Prinzmetal angina?
ST-segment elevation due to transmural ischemia.
What are some influences that can affect plaques?
- intrinsic influences= plaque structure and composition itself
- extrinsic influences= BP, platelet reactivity. Plaque often cannot withstand mechanical stresses.
What are vulnerable plaques?
- plaques with large areas of foam cells and extracellular lipid.
- fibrous cap plaques, which are thin or contain few smooth muscle cells or clusters of inflammatory cells.
What are some changes that can occur to plaques?
- fissures= occur at junction of the fibrous cap and normal plaque free arterial segment where stresses are greatest.
- collagen made by smooth muscle cells can be degraded by metalloproteinases made by macrophages.
What does inflammation do to plaques?
destabilizes it
What will adrenergic stimulation do to plaques?
stress plaque by hypertension and vasospasm.
Can a minimally occluded coronary artery result in occlusion with plaque change?
YES. (Textbook number says 75% occlusion to be clinically significant).
How does inflammation lead to CAD?
initial lesion needs interaction between endothelial cells and leukocytes. Endothelial cells will then release chemokines and increase their expression of adhesion proteins (ICAM, VCAM..). T cells produce cytokines that activate macrophage filled with oxidized LDL.
As what marker may c-reactive protein serve?
a potential marker of atherosclerosis, because it is a marker of inflammation in general.
Where does a coronary thrombus typically occur?
on a disrupted plaque, causing a previously anti-coagulant surface to become pro-coagulant. These may embolize.
Of what are thrombi potent activators?
growth related signals, promoting growth of atheromas :(
What is the role of vasoconstriction in CAD?
compresses lumen increasing mechanical forces that can disrupt the plaque, augmenting the issue.