Myocardial Ischaemia Epidemiology and Aetiology Flashcards
ischaemic heart disease other names (4)
coronary artery disease (CAD), coronary heart disease, heart disease, micro-vascular heart disease
heart disease that is more prevalent in women
micro-vascular heart disease
CAD symptoms (2)
none or angina pectoris
angina pectoris
chest strangling
no symptoms
silent
angina pectoris pain due to
lactate and adenosine activation of pain nerve endings
CAD mortality rates peaked in
1966
CAD mortality started to decrease after
coronary bypass surgery
Framingham study started
1945-50
CAD mortality rate linked to smoking
1955
Coronary care units set up in Australia
1960-65
Coronary bypass surgery used after MI
1970
beta blockers first used for hypertension
1975
MONICA study starts
1980-85
Framingham shows 50% increase in MI with hypertension
1980-85
Statins lower cholesterol
1985-90
Statins and ACE inhibitors available PBS
1985-90
statins most prescribed drug on PBS
2000-2005
Leading causee of disease worldwide
CHD
CHD deaths : dementia/stroke
2:1
Number of Australians dying daily from CHD
48
Cardiovascular disease with the most hospitalisations
CHD
hospitalisation for CAD
men > women
More deaths compared to hospitalisation
women
what is ischaemic heart disease
imbalance between oxygen supply and demand
Oxygen supply to the heart factors (3)
diastolic pressure, coronary oxygen resistance, carrying capacity
Oxygen demand factors (3)
ventricular wall stress, heart rate, contractility
increased muscle mass leads to
increased oxygen demand
ventricular wall stress that leads to increased oxygen consumption
intraventricular pressure (stretch) and systolic pressure (afterloading)
Ventricular wall stress that leads to decreased oxygen consumption
increased wall thickness
How heart rate increases oxygen demand
cardiac cycle energy expenditure
cardiac cycle energy expenditure
ATP splitting
ATP splitting (2)
Calcium homeostatis and cross bridge activity
how contractility leads to increased oxygen demand
increased ionotropic state (increased energy expenditure) andsympathetic modulation
when is coronary flow maximised
diastole
what determines coronary perfusion
aortic diastolic pressure
normal aortic diastolic pressure
60 mmHg
what is oxygen carrying capacity dependent on (2)
Haemoglobin levels and oxygen saturation (stability)
oxygen extraction in the heart is
maximised
what increases coronary resistance
vessel compression (maximised in systole)
vascular tone is
autoregulated
coronary resistance can lead to
vessel obstruction
Metabolic constrictor
oxygen
metabolic dilators (4)
adenosine, lactate, Hydrogen ions, carbon dioxide
Endothelial constrictors
Endothelin 1
What produces Endothelin 1 (2)
shear force and Angiotensin II stimulation
Endothelial dilators (2)
nitric oxide and prostacyclin
neural/hormonal constrictors
alpha 1 receptors
neural/hormonal dilators
beta 2 receptors
coronary dysfunction can lead to
autoregulatory failure
contributors to coronary dysfunction (3)
endothelial cell dysfunction, unopposed vasoconstriction, imbalance
what leads to endothelial cell dysfunction
nitric oxide defficiency
autoregulatory failure means (4)
increased cardiac work, irregular coronary flow, oxygen demand/supply mismatch, clots
what can cause clots in autoregulatory failure
loss of nitric oxide mediated suppression of platelet aggregation
Main features of coronary pathology (2)
atherosclerosis and thrombi formation
thrombus
clot
Normal arterial wall layers (3)
endothelial cells, elastic connective tissue, smooth muscle cells
Fatty streak features (3)
LDL cholesterol, macrophages, muscle cells
How is a fatty streak formed (3)
macrophages ingest lipids, streak forms, smooth muscle migration
Stable plaque features (4)
lipid core expansion, smooth muscle proliferation and thickening, plaque bulge, fibrous scar tissue cap
Vulnerable plaques (6)
plaque cap ruptures, collagen exposed, platelets aggregate, thrombus formation, downstream blood flow occlusion, calcifications
Anterior heart surface anatomy (7)
superior vena cava, right atrium, right auricle, left atrium, aorta, pulmonary artery, conus arteriosus, right ventricle, left ventricle
RCA
right coronary artery
LAD
left anterior descending branch of the left coronary artery
RCA runs between
right atrium and right ventricle
LAD runs between
Right ventricle and left ventricle
what is present in MI histology
calcifications
Plaque obstruction
stenosis
<70% stenosis
minimal effect on flow and compensatory dilation
70-90% stenosis
espisodic ischaemia
> 90% stenosis
basal ischaemia
100% total occlusion
thrombosis
partial transient occlusion
hibernation
partial maintained occlusion
hibernation
total transient occlusion
stunning
total maintained occlusion
stunning
hibernation
chronic metabolism suppression
hibernation recovery
Re flow
stunning
prolonged contractile depression
stunning recovery
delayed
infarct
irreversible myocardium necrosis
what causes infarct
prolonged intense ischaemia
How is excitation contraction coupling maintained
ion flow (particularly calcium) and pumps
In depolarisation of a cardiomyocyte how does calcium enter the cell
sarcolemmal T tubule L type Ca channels
what does intracellular calcium do in a cardiomyocyte (2)
stimulates myofilament contraction and activates sarcoplasmic reticular calcium release
how is intracellular calcium reuptaken
SERCA pumps and ATP
What is required for calcium to be pumped out of a cardiomyocyte
ATP
How does sodium come into a cell
in exchange for hydrogen ions (elevates cardiomyocyte pH)
how does sodium leave a cell
sodium potassium exchanger or sodium calcium exchanger
What is there a reduction of in ischaemia (3)
oxygen, pH, ATP
What is there an increase of in ischaemia (3)
hydrogen, calcium and sodium ions
what is inhibited in ischaemia (5)
calcium pumps, sodium potassium exchanger, SERCA channels, mitochondrial function, myofilament contraction
Myocardial hypoxia leads to decreased (3)
ATPase pump activity, SR Ca uptake, cell pH
Myocardial hypoxia leads to increased (2)
sodium calcium exchanger and anaerobic metabolism
reduced ATPase and SR Ca uptake coupled with increased sodium calcium exchanger leads to (3)
increased calcium in, potassium out and sodium in
increased calcium in, potassium out and sodium in leads to (2)
lipase and protease activation and altered RMP
RMP
resting membrane potential
increased anaerobic metabolism coupled with decreased cell pH leads to
chromatin clumping and protein denaturation
altered RMP can lead to
arrythmias
lipase and protease activation coupled with chromatin clumping and protein denaturation can lead to
cell death