IHD, Part 1 Flashcards
what is the most common, serious, chronic, life-threatening illness in the U.S?
IHD
what % of the population has a sustained MI?
3-4%
MC risk factors of IHD
- genetic influences
- high-fat and energy-rich diet
- smoking
- sedentary lifestyle
- In the U.S, growing among low-income groups
- Primary prevention has prolonged age of disease development
What is the most MCC of myocardial ischemia?
atherosclerotic CAD
Mechanism of Myocardial Ischemia
Multifactorial
1. Generally an imbalance between oxygen supply and demand
2. Oxygen supply → determined by blood flow
- Blood flow is regulated by pressure vs. resistance ratio
- Most critical factor is radius of blood vessel
pathogenesis of IHD
- Ischemic heart disease = MI
- supply < demand
- If heart muscle is not perfused with blood, it cannot get properly oxygenated, and ischemia results
the radius of the blood vessel is influenced by what factors?
atherosclerosis hardening of vessels
vascular tone
endothelial cell dysfunction in cardiac ischemia
what are the 4 types of IHD? which are acute coronary syndrome (ACS)?
- Prinzmetal Angina
- Stable Angina
- Unstable Angina (ACS)
- Myocardial Infarction (ACS)
- stemi
-nstemi
stable, fixed plaque that reduces vessel diameter and when demand goes up, supply is limited, leading to symptoms
what is this called?
stable angina
ACS results when there is _____ and _____.
plaque rupture
thrombus formation
The amount of coronary blood flow restriction determines the severity:
- Unstable angina - no occluded blood flow → sx at rest
- NSTEMIs - partially impeded blood flow through the coronary vessels
- STEMIs - completely impeded blood flow through the coronary vessels
differences between stable vs unstable angina
- stable - Fixed stenosis
- A typical pattern; predictable
- Occurs when the heart is under stress and needs more oxygen (exercise, cold, emotion)
- Typically lasts 1-15 min
- Goes away with rest and/or NTG
- It may continue without much change for years - unstable - Caused by a transient formation and dissolution of a thrombus
- Unexpected; a change in your usual pattern of stable angina
- Occurs when blood flow to the heart is suddenly slowed by narrowed vessels or thrombus in the coronary arteries
- It may happen at rest or with light activity. It does NOT go away with rest or nitroglycerin.
- Warning sign that an MI is impending. An EMERGENCY!
After occlusion of a Coronary Artery, the myocardium evolves through various stages and degrees of severity of impairment:
ischemia –> injury –> infarct
- Present as soon as there is a decrease or complete absence of blood supply to myocardial tissue; immediate phase
- Cardiac cells can tolerate mild-moderate anoxia for a short time without greatly affecting their function
- When adequate blood flow / reoxygenation return, these cells usually return to a normal
what is this stage/degree of severity of impairment?
ischemia
- severe or prolonged, the anoxic cardiac cells sustain damage and stop functioning normally
- Damage to the cells still remains reversible so that injured cells remain viable and salvageable for some time
- Cells may return to normal or near normal after the return of adequate blood flow and reoxygenation
what is this stage/degree of severity of impairment?
injury
- Severe myocardial ischemia continues because of continued complete absence of blood supply
- The anoxic cardiac cells will sustain irreversible injury and die.
what is this stage/degree of severity of impairment?
infarct
what results in necrosis of a portion of the myocardium
irreversible myoardial injury
ACUTE MI suggests the infarct is how old?
<3-5 d