cardiovascular histology Flashcards
define atherosclerosis?
an arteriosclerosis
atheromatous deposits &
fibrosis
of inner layer of arteries
where do atheroma plaques form?
intima then protude into lumen
describe the process of atherosclerosis?
smooth endothelium damage
platelets stick to damaged endothelium
endothelium proliferates
fibrous cap fomrs on top of endothelium
choleserol deposits in core of lesion
plaque enlarges, blocking lumen of vessel
which study looked at risk factors of atherosclerosis ?
Framingham Heart Study
Risk factors have a what type of effect on risk of atherosclerosis?
MULTIPLICATIVE EFFECT
list Constitutional Risk Factors (impossible/hard to control) in atheroslcerosis?
age
gender - W: protected premenopause, risk increased post menopause
Genetics - most significant independent risk factor
what is the MOA of statins?
inhibit HMG-CoA reductase rate limiting enzyme in liver cholesterol synthesis
HTN alone increases risk of IHD by __%
DM increases risk of IHD by __%
Prolonged cigarret smoking increases risk of IHD by __%
60%
double
double
ihd is a group of conditions resulting from ….?
from myocardial ischaemia
what is the order of extent of injury?
loss of cell function
cell death
microscopic changes
gross changes
what are the 4 stages of presentation of ihd?
Angina pectoris
Myocardial infarction
Disease with heart failure
Sudden cardiac death.
pathogensis of ihd?
Predominant cause is
insufficient coronary perfusion to suffice myocardial demand
due to chronic progressive atherosclerotic narrowing of epicardial coronary arteries
and variable degrees of superimposed plaque change, thrombosis and vasospasm
what are the componesnt of a vulnerable plaque?
Lots foam cells or extracellular lipid
Thin fibrous cap
Few smooth muscle cells
Clusters inflammatory cells
why does emotional stress inc risk of sudden death?
Adrenalin increases blood pressure & causes vasoconstriction
Increases physical stress on plaque
Hence emotional stress increases risk of sudden death
Circadian periodicity to sudden death (6am-noon)
what level of stenosis is required to see symptoms?
75% stenosis or more generally needed to cause symptoms precipitated by exercise
Vasodilation cannot compensate above this level of stenosis
90% stenosis can lead to pain at rest
where do plaques tend to form in the epicardial coronary arteries?
Plaques mainly in first few cm of LAD or LCX
Entire length RCA
what are the 3 acute coronary syndromes?
STEMI
NSTEMI
Unstable angina
what is the pathophysiology of ACS?
Stable plaque becomes unstable
Due to rupture, erosion, haemorrhage etc
Generally leads to superimposed thrombus which increases occlusion
no plaque disruption in stbale angina though
which angina is caused by artery spasm?
prinzmetal
aka variant angina
what is a Warning of impending infarction?
unstable angina
what is the myocardial response to a sudden disruption to its blood supply?
Myocardial blood supply compromised leading to ischaemia
Loss of contractility within 60 seconds
Therefore heart failure can precede myocyte death
Potentially reversible
Irreversible after 20-30 minutes
most common arteries of infarct?
LAD – 50%, ant wall LV, ant septum, apex
RCA - 40%, post wall LV, post septum, post RV
LCx - 20%, lat LV not apex
after an mi, which cells are first to repond in order?
neutrophils
macrophages
angioblasts
fibroblasts and collagen
how soon after an mi do you see;
Coagulation necrosis, loss nuclei & striations, neutrophils +++
1-3 days
how soon after an mi do you see;
granulation tissue, macrophages,
new blood vessels, myofibroblasts, collagen synthesis
10-14 days
how soon after an mi do you see;
normal by histology (CK-MB also normal)
under 6 hours
what are the worst prognostic factors in MI?
Age, female, DM, previous MI
-> worse prognosis
how do you treat a hibernating myocardium?
revascularisation
list 3 complications of MI?
Contractile dysfunction – 40% infarct-> cardiogenic shock with 70% mortality rate
Arrhythmia
Myocardial rupture
Pericarditis (Dressler syndrome) 2nd or 3rd day
Infarct extension/expansion causing;
Mural thrombus
and more
Most common areas of myocardial rupture?
free wall most common,
septum less common,
papillary muscle least common
mortality in MI?
Total mortality = 30% in one year
3-4% mortality per year after first
describe the heart in chronic IHD vs heaert failure?
C IHD: Enlarged heavy heart, hypertrophied, dilated LV Atherosclerosis Maybe mural thrombi Fibrosis (microscopic)
Heart failure:
Dilated heart, Scarring & thinning of the walls
causes of sudden cardiac death?
Marked atherosclerosis (>75% stenosis) in one or more vessels usually >90%
10% non atherosclerotic cause (long QT etc)
½ have plaque rupture
what is the presentation of left vs right sided hf?
Left sided (-> SOB, pulmonary oedema)
Right sided (-> peripheral oedema, hepatomegaly, raised jvp)
aetiology of dilated cardiomyopathy?
describe the heart?
Progressive loss of myocytes
Dilated heart
Causes: Idiopathic Infective – viral myocarditis Toxic: alcohol, chemotherapy (adriamycin, daunorubicin), cobalt, iron thyroid conditions
etc
aetiology of hypertrophic cardiomyopathy?
describe the heart?
Left ventricular hypertrophy
Familial in 50% (autosomal dominant, variable penetrance)
Beta-myosin heavy chain
Thickening of septum narrows left ventricular outflow tract
aetiology of restrictive cardiomyopathy?
describe the heart?
Impaired ventricular compliance
Idiopathic or secondary to myocardial disease eg amyloid, sarcoidosis
Normal size heart – big atria
list effects of CHRONIC RHEUMATIC VALVULAR DISEASE on heart structures?
thickened valves;
Predominantly left-sided valves (almost always mitral)
Mitral > Aortic > Tricuspid > Pulmonic
Mitral alone 48%, Mitral + aortic 42%
Thickening, shortening and fusion of chordae tendineae
name the Commonest cause of aortic stenosis?
aetiology?
Calcific aortic stenosis
70s or 80s Calcium deposits outflow side cusp Impairs opening Orifice compromised Outflow tract obstruction
what are the different types of aneurysm?
True - all layers wall
False – extravascular haematoma
Causes: Weak wall
list some causes of aneurysm?
Congenital eg Marfans
Atherosclerosis
Hypertension
atherosclerotic aortic aneurysm typically occur where?
in the abdominal aorta portion (AAA) below the renal arteries
list some causes of aortic regard?
Rigidity - rheumatic, degenerative
Destruction - microbial endocarditis
Disease of aortic valve ring
-> dilatation-> valve insufficient to cover increased area:
Marfan’s Syndrome
Dissecting aneurysm
Syphilitic aortitis
Ankylosing spondylitis
