Exam 3: CAD/HTN Flashcards
what are the comprehensive risk factor profile for coronary artery disease? (5)
- dyslipidemia
- genetic factors
- traditional modifiable risk factors
- non-modifiable risk factors
- novel risk factors
what is dyslipidemia? give examples (4)
o Abnormal amount of lipids in the blood
Triglycerides, phospholipids, cholesterol, lipids
what are lipids?
fats transported in plasma in form of lipoproteins
what are lipoproteins?
- particles made of protein and fats (lipids). They carry cholesterol through your bloodstream to your cells
- a molecule consistent with water soluble molecules with a core of cholesterol and triglycerides covered by phospholipids
- it varies their contribution in atherosclerotic risks
VLDL
primarily triglycerides and protein
LDL
mostly cholesterol and protein
- contains 70% of cholesterol in circulation
- metabolic byproduct/end product of VLDL
HDL
mainly phospholipids and protein
- each 1 mg/dL increase in HDL–estimated to decrease CAD risk by 2% in men and 3% in women
Chylomicron
what we put in our mouth, the least dense of lipoproteins, primarily contain triglycerides
- not thought to be atherosclerotic but the remanence of the breakdown of their lipolysis are atherogenic
how does HDL lower CAD risk?
because of reverse cholesterol transport
CAD risk factors: dyslipidemia (3)
- elevated LDL-C
- low HDL-C
- hypertriglyceridemia
how does elevated LDL-C cause CAD?
Can penetrate arterial wall, promote atherosclerosis
Increased concentration of LDL is an indicator for coronary risk; however, the risk depends of the presence of other risk factors such as;
* Age, diabetes, CKD
how does low HDL cause CAD
HDL picks up cholesterol and brings to liver where it can be further processed; need to move oxidized LDL out of macrophages and bring to liver
* “reverse cholesterol transport”
CAD risk factors: genetic factors
o Heterozygous vs Homozygous
Homozygous familial hypercholesterolemia harder for body to remove LDL from blood
o Blacks > white
what is familial hypercholesteremia?
- these individuals have fewer or defective LDL receptors
- significant atherosclerosis and premature CAD in the absence of other risk factors unless the hypercholesteremia is treated with medication or aphaeresis at a very early age.
what is the function of LDL receptors on the liver?
the receptors are responsible for clearing and removing cholesterol from circulation
modifiable risk factors for CAD (5)
- smoking
-HTN - physical inactivity
-DM - Obesity
How does smoking contribute to CAD
lowers HDL further, reduces coronary blood flow, decreases endothelial fxn, increase vasospasm, increase plt aggregation
**leading cause of preventable death
what is the most prevalent CAD?
-HTN
**theres a relationship between BP elevation and incidence of CAD and stroke
how does DM play a role in CAD?
-increases plt aggregation
- hyperinsulinemia–>occurs in T2DM promotes smooth muscle proliferation and cholesterol accumulation in arterial wall
what are non-modifiable risk factors for CAD? (3)
- FAMILY HISTORY
**first degree family with CAD and at young age
**risk factor for having MI is inversely r/t at the age the MI occurred in the parents
**risk is greater if your father had an MI at 40 compared to him having an MI at 75
-AGE
**risk for having CAD or MI increases with age
**about 4/5 of fatal MI occurs in ppl >65
-GENDER
**the onset of symptomatic CAD is 10 years earlier in men compared to women
**the risk evens out when women reaches menopause
Novel RF (non-traditional, newer) of CAD (5)
o elevated lipoprotein (a)
**we all have lipoprotein (a) but if it is elevated, it can be a risk factor- looks like LDL and clotting factor (plasminogen) but meds don’t reduce it or lifestyle changes
**elevated levels have shown to be an important risk factor for coronary atherosclerosis, especially in woman
o elevated high sensitivity- CRP
**inflammatory factor, when elevated increases CAD
o elevated fibrinogen
o elevated LDL particle number
**this is the total #
o small, dense LDL
describe atherosclerosis
o a thickening and hardening of the vessel that are caused by the accumulation of lipid-laden macrophages within the arterial wall, which leads to the formation of a lesion called a “plaque”.
Lesions are likely to develop following endothelial injury
o Atherosclerosis is not a single disease but rather a pathologic process that can affect vascular systems throughout the body- multi-process
what is atherosclerosis the leading cause of?
CAD and cerebrovascular disease
the earliest manifestation of atherosclerosis
endothelial dysfunction
define CAD
o Narrowing or blockage of the coronary arteries, usually caused by atherosclerosis
o CAD can dimmish blood supply until deprivation impairs myocardial metabolism enough to cause ischemia
progressive process of atherosclerosis
normal–>fatty streak–>fibrous plaque–>occlusive atherosclerotic plaque <–>plaque rupture/fissure and thrombosis
which can lead to:
-unstable angina
-MI
-coronary death
-stroke
-critical leg ischemia
fatty streak
o First lesion of atherosclerosis- was first found in children when they would die suddenly
o They are consisted of lipid laden macrophages (“foam cell”), when significant amounts accumulate, they form a legion called “fatty streak”
o focal thickening of the intima
intima- first layer of the artery
media- muscle layer of the artery
o increase in smooth muscle cells and extracellular matrix.
o Smooth cells migrate and proliferate into the intima
Smooth muscle cell migrates into where the atherosclerotic lesion begins, which enlarges the lesion
o lipid deposits accumulate
o macrophages and T-lymphocytes (early damage to vessel wall).
o Aggregation of lipid thick foam cells in intima. When LDL oxidized, taken into macrophages
fibrous plaque
o The second phase
o evolves from fatty streak and increase accumulation of connective tissue.
o Increased number of smooth muscle cells laden with lipids.
o Deeper extracellular lipid pool.
o Results in further endothelial cell dysfunction, necrosis of underlying vessel tissue, and narrowing of the lumen as the lesion protrudes out from the vessel wall
Advanced (Complicated) Lesion
o Last phase
o Smooth muscle cells, numerous macrophages, T-cells, often associated with lipid core and necrotic material.
o Covered in fibrous cap (smooth muscle cells surrounded by connective tissue matrix).
o White in appearance, usually elevated and protrudes into lumen of artery
o Can compromise blood flow but often does not
o Unstable lesion is prone to rupture (type 1 MI caused by plaque rupture)
Plaque that have ruptured are called “complicated”
* Once rupture occurs, exposure to the underlying tissue results in platelet adhesion, initiation of the clotting cascade, rapid thrombus formation that may suddenly occlude the affected vessel.
- the fourth stage is the end stage of atherosclerosis, in which the artery becomes completely blocked and blood flow is severely reduced or completely blocked. This stage can be life-threatening and often requires surgery to restore blood flow, such as coronary artery bypass surgery or a heart transplant.
Compare and contrast stable and unstable atheromatous lesions.
- When lesions/plaque is covered by a cap and it is stable and dense it is considered to be “protective”
o Thick cap provides stability to the lesion
o Gradually increase in size and may partially occlude the vessel lumina - thin, no-uniform cap, macrophage-rich makes an unstable lesion, prone to rupture leads to thrombosis, hemorrhage, and/or calcification
o plaque rupture occurs because of inflammatory activation of proteinases, apoptosis of cells within the plaque and bleeding within the lesion
how does myocardial ischemia develop?
Develops if coronary blood flow or the oxygen content of coronary blood is insufficient to meet the metabolic demands of myocardial cells
How long does it take myocardial cells to become ischemic?
- Myocardial cells become ischemic within 10 seconds of coronary occlusion, after a few mins the heart loses the ability to contract, cardiac output decreases
o Cardiac cells remain viable for ~20min, under ischemic conditions > can be restored
o >20min MI