Ischemic Heart Disease Flashcards
what is ischemic heart disease?
heart problems caused by narrowed heart (coronary) arteries that supply blood to heart muscle
creates a mismatch between supply and demand
how can IHD manifest clinically
as MI and ischemic cardiomyopathy
how can death occur from IHD?
some suddenly due to acute coronary occlusion
some slowly over weeks to years due to progressive weakening of heart pumping process
what are the symptoms of IHD?
- angina
- heart rhythm problems
- Nausea, sweating, fatigue or shortness of breath, weakness or dizziness
- Reduced exertional capacity
- Leg swelling (when left ventricular dysfunction is present)
- Diaphoresis
what can angina from IHD be mistaken as?
indigestion or heart burn
what are the angina associated symptoms of IHD?
- Aching, burning, fullness, heaviness, numbness, pressure, squeezing
- Radiation in arms, back, jaw, neck, shoulder
- High or low BP
- Syncope
what heart rhythm problems may be caused by IHD?
- Palpitations (irregular heartbeats or skipped beats)
- Heart murmurs
- Tachycardia (Acute coronary syndrome ACS, Acute myocardial infarction AMI)
- Atrial fibrillation
- Ventricular tachycardia or ventricular fibrillation
- S4 gallop: A common early finding of diastolic dysfunction
- S3 gallop: An indication of reduced left ventricular function and a poor prognostic sign
what are the non-modifiable risk factors of IHD?
age
gender
family history of CVD
ethnicity
genetic evidence
previous history of CVD
what are the modifiable risk factors of IHD?
high BP
total cholesterol/ HDL cholesterol/ Lipoprotein a
smoking/ diet/ exercise/ alcohol
blood sugar/ diabetes/LVH
BMI
stress/ mental health
low socioeconomic state/ socail deprivation/ income
environment
centain medication
what are the most important risk factors to prevent over non-modifiable risk factors for IHD?
diet
who are the highest risk in high-income countries for IHD?
hypertension
cholesterol
tobacco use
what are the highest risk for IHD in low-income countries?
poor diet
low education
air pollution
low strenght
when does myocardial ischaemia occur?
imbalance between supply of oxygen (and other nutrient) and the myocardial demand
what might coronary blood flow be obstructed by?
- Atheroma
- Thrombosis
- Spasm
- Embolus
- Coronary ostial stenosis
- Coronary arteritis
what might cause a general decrease of oxygenated blood flow to myocardium?
anemia
carboxyhaemoglobulinaemia
hypotension causing decreased coronary perfusion pressure
what is atherosclerosis?
complex inflammatory process
plaques in the intima in large and medium-sized coronary arteries
also called atherogenesis
what triggers atherogenesis?
- Endothelial dysfunction
- Mechanical sheer stresses (HTN)
- Biochemical abnormalities (elevated and modified LDL, DM, elevated plasma homocysteine)
- Immunological factors (free radicals from smoking)
- Inflammation ( infection such as chlamydia, Helicobacter)
what are the features of athersclerotic plaques?
fibrous tissues
necrotic lipid rich core
foam cells
FC + infl cells
calcium
what occurs during the fatty steak phase?
dysfunctional endothelial cells + retention of lipoproteins (LDL,VLDL)
This causes:
increased expression of monocyte interaction(migration into intimal space)
Other immune cells that mediate the internalization of LDL to form foam cells
this is reversible!!
how does the plaque progress to form fibrous fatty lesions?
infiltration and proliferation of tunica media smooth muscle cells
various growth factors e.g TGF-B, FGF) create more inflammation
SMCs are recruited to luminal side of lesion to form a barrier between lesional prothrombotic factors
fibrous fatty lesions are less likely to regress than fatty streaks
what is the composition of a stable plaque?
fibrous cap composed of layers of smooth muscle cells ensconced in a substantial extracellular matrix network
it provides an effective barrier preventing plaque rupture
stable plaques have a small necrotic core
the production of TGF-B by t-reg cells and macrophages maintains fibrous cap quality by being potent stimulator of collagen production in smooth muscle cells
what makes a plaque vulnerable
unresolved inflammation causes thinning of fibrous cap
thin areas are prone to rupture exposing prothrombotic components to platelets and pro-coagulation factors
leading to thrombus formation
what happens when atherosclerotic plaque breaks through the endothelium?
what are the possible stages of presentation of coronary/ ischemic heart disease?
asymptomatic
chronic stable angina
acute coronary syndrome (unstable angina, non ST-elevation MI, ST-elevation MI)
heart failure
sudden death
what happens to the collateral vessels during acute episode hypoxia?
dilate
double by the day and reach normal coronary flow within 1 month
what happens to the collateral vessels in hypoxia for chronic atherosclerotic patients?
slow occlusion- collateral vessels can develop at same time while the atherosclerosis becomes more severe
how can an ACS occur with collaterals?
collaterals get atherosclerosis or damage is so extensive the collaterals cannot help
this can cause weaking of the heart and heart failure