Ischaemic Heart Disease Flashcards
what is ischaemic heart disease?
a group of syndromes, which are related pathophysiologically, which result from myocardial ischaemia
examples of IHD
- myocardial infarction
- angina pectoris
- chronic IHD with heart failure
- sudden cardiac death
what causes ischaemic heart disease?
an imbalance between the myocardial blood flow and the metabolic demand of the myocardium
what does coronary artery perfusion depend on?
- the pressure difference between the ostia and the coronary sinus
- inversely on heart rate
what reduces coronary perfusion?
- decreased aortic diastolic pressure
- increased intraventricular pressure and myocardial contraction
- coronary artery stenosis (artherosclerosis, vasoconstriction)
- aortic valve stenosis and regurgitation
- increased right atrial pressure
how can risk factors be classified?
- genetic vs acquired
- modifiable vs non-modifiable
risk factors for IHD
- hypertension
- high cholesterol (high LDL; low HDL)
- hypertriglyceraemia
- diabetes mellitus
- obesity (waist-to-hip ratio)
- smoking (duration and no of cigs per day; incl passive smoking)
- male gender (for MI/SCD); female gender (for AP)
- physical inactivity
- family history of CAD
- influenza (this brings on an acute inflammatory and vasoconstrictive episode)
- oral contraceptive
properties of lipoprotein A
- proatherogenic
- proinflammatory
- prothrombotic
risk factors for metabolic syndrome
- abdominal obesity
- triglycerides
- HDL cholesterol
- hypertension
- hyperglycaemia/diabetes
how does alcohol consumption affect IHD risk?
- light to moderate drinking decrease the risk for mortality, CAD, DM, HF and stroke
- heavy drinking increases the risk of death and CVD
how do the genders differ in CAD risk?
- men present earlier with symptoms of CAD etc
- the risk of women developing IHD increases after menopause
- oestrogen is cardioprotective because it has a lower atherogenic profile and more healthy fat distribution
how does age contribute to IHD?
- independent risk factor
- linked to the lack of modification of other more prominent risk factors
- the risk decrease over the age of 50yo as there are more competiting causes to kill you
what are the pathological components of atherosclerosis?
- central lipid core
- fibrous cap
- covered by endothelium
what is atherosclerosis?
progressive disease characterised by focal accumulation of lipid with inflammatory response
where does atherosclerosis hap[pen?
medium to large arteries
where is the lesion in atherosclerosis?
focused in the intima
how can atherosclerosis evolve?
- critical stenosis
- complicated plaque
- atheroembolism
- aneurysm formation
formation of a plaque
- starts with fat streaks depositing near the ostia of branch vessels
- fibrous tissue deposits on them
- red cells get stuck in them, forming the thrombus
gross myocardial morphological changes in IHD
- dark mottling
- yellow-tan infarct centre
- hyperaemic border
- grey-white scar
what does the infarct look pale
leakage of dehydrogenases through the damaged membrane of necrotic myocytes; that’s why it doesn’t stain
what causes dark mottling
stagnant trapped blood
complications of MI
- acute transmural MI with rupture
- rupture of the free wall and cardiac tamponade
- rupture of the interventricular septum
- complete rupture of a necrotic papillary muscle
- left ventricular aneurysm
- Dressler syndrome (fibrino-haemorrhagic pericarditis)
microscopic morphologic changes
- waviness of fibres
- coagulation necrosis
- loss of nuclei and striations
- extensive haemorrhage at the border of the infarct - hyperaemic border
- neutrophilic infiltrate
- phagocytosis of dead cells
- granulation tissue
- collagenous scar
what is an infarct?
localised area of coagulative necrosis
what does the coagulative necrosis cause?
- denaturation of structural proteins
- blockage of proteolysis of dead cells
characteristics of ischaemic cardiomyopathy
- hypertrophic myocytes
- large dark nuclei
- interstitial nuclei
