HISTO: Cardiovascular Flashcards
True or false
“In the Western world atheroma causes half of all deaths and more morbidity and mortality that any other disorder”
True
What is shown?
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Atherosclerosis
Define atheroscelrosis.
an arteriosclerosis characterized by atheromatous deposits in and fibrosis of the inner layer of the arteries
Atheroscelrosis is characterized by intimal lesions - atheroma (atheromatous plaques) - that protrude into vessel lumen
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What are the characteristics of an atheromatous plaque?
- Raised lesion
- Soft lipid core
- White fibrous cap
What are the risk factors for atherosclerosis?
- Age
- Gender
- Genetics
- Hyperlipidaemia
- Hypertension
- Smoking
- Diabetes Mellitus
What kind of effect does having multiple RFs have on risk of atherosclerosis?
Risk factors have a MULTIPLICATIVE EFFECT e.g.
- 2 risk factors increase the risk fourfold
- 3 risk factors increase the risk sevenfold
Hwo does age affect atherosclerosis risk?
Atherosclerosis progressive between 40->60 years
incidence myocardial infarction (MI) X 5
How does gender affect atherosclerosis?
Premenopausal women protected (HRT no protection)
Postmenopausal risk increases (older ages greater than men)
How do genetics affect risk of atherosclerosis?
Family history most significant independent risk factor
Some mendelian disorders (eg Familial Hypercholesterolaemia)
Most multifactorial (genetic polymorphisms -> clustered risk factors HT, DM)
What is a modifiable risk factor for atherosclerosis? How is this risk modified?
- Hyperlipidaemia (Hypercholesterolaemia)
- LDL – bad HDL – good
- Diet rich in cholesterol/saturated fat – bad
- Statins inhibit HMG-CoA reductase rate limiting enzyme in liver cholesterol synthesis - good
How does HTN affect risk of atherosclerosis?
Modifiable RF 2: HTN
- Systolic & Diastolic important
- Ht alone increases risk of IHD by 60%
How does smoking affect risk of athrosclerosis?
- Smoking
- Definite risk in men, probable in women
- Prolonged smoking doubles death rate from IHD
- Stopping reduces risk considerably
Why is DM a RF for atherosclerosis?
- DM
- Induces hypercholestrolaemia
- Increases risk of atherosclerosis
- 2 x risk IHD in DM if all other factors equal
Which of these is not a major RF for ischaemic heart disease?
- Age
- Male sex
- High alcohol
- Smoking
- HTN
High alcohol consumption is not a major RF
What are some other RFs for atherosclerosis?
- Inflammation
- Hyperhomocyteinaemia
- Metabolic syndrome
- Lipoprotein (a)
- Haemostasis (procoagulation)
- Lack of exercise
- Stress
- Obesity (Ht, Dm, low HDL)
What is the pathogenesis of atherosclerosis? (Response to Injury Hypothesis)
Response to Injury Hypothesis
- Chronic inflammatory and healing response of arterial wall to endothelial injury
-
Endothelial injury
- Lipoprotien accumulation (LDL)
- Monocyte adhesion to endothelium
- Monocyte migration into intima -> macrophages & foam cells
- Platelet adhesion
- Factor release
- Smooth muscle cell recruitment
- Lipid accumulation -> extra & intracellular, macrophages & smooth muscle cells
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How does endothelial damage occur?
Early atheroma arises in intact endothelium
Endothelial dysfunction important – increase permeability, gene expression & adhesion
- Haemodynamic disturbance -> dysfunction
- Hypercholesterolaemia -> dysfunction
- Inflammation -> vicious circle
What are the characteristics of smooth muscle proliferation in atherosclerosis pathogenesis?
- Intimal smooth muscle proliferation
- Some from circulating precursors – (have synthetic & proliferative phenotype)
- ECM matrix deposition
- Fatty streak -> mature atheroma & growth
- PDGF, FGF, TGF-alpha implicated
What are the layers seen here in an artery?
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What is the earliest lesion in atherosclerosis?
Fatty streak
- Earliest lesion
- Lipid filled foamy macrophages
- No flow disturbance
- In virtually all children >10yrs
- Relationship to plaques uncertain
- Same sites as plaques
What is seen here?
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Fatty streak
What are the characteristics of an atherosclerotic plaque?
- Patchy – local flow disturbances
- Only involve portion of wall
- Rarely circumferential
- Appear eccentric
- Composed of – cells, lipid, matrix
What sites of an arterial tree does atherosclerosis usually occur in?
bifurfations and curvatures
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What are the complications of an atheromatous plaque?
Can obstruct or rupture
At what % occlusion does stenosis usually occur in atheroma? What is the result?
>70% occlusion demand>supply OR diameter <1mm
–> Stable angina
What type of plaque disruption is this?
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Type II - eccentric ragged edges stenosis
What are 3 ways in whch atherosclerotic plaques can change?
- Rupture – exposes prothrombogenic plaque contents
- Erosion - exposes prothrombogenic subendothelial basement membrane
- Haemorrhage into plaque – increase size
Which plaques are most at risk of complications?
- Lots foam cells or extracellular lipid
- Thin fibrous cap
- Few smooth muscle cells
- Clusters inflammatory cells
- Stress -
- Adrenaline 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)
- Vasoconstriction - reduces luminal size e.g. sue to adrenergic factors, platelet factors, reduced endothelial relaxing factors, mediators from perivascular cells
What characteristics of atherosclerosis are seen here?
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Human coronary atherosclerotic plaque with a yellow core of lipid separated from the lumen by a fibrous cap. Opposite the plaque is an arc of normal vessel wall.
What is the leading cause of death for men and women worldwide?
IHD
7million/year
What does IHD refer to ?
Group of conditions resulting from myocardial ischaemia
What % of blood flow obstruction occurs fo MI to occur?
90%
long silent progression prior to symptoms
What 4 conditions can IHD present as?
- Angina pectoris
- Myocardial infarction
- Chronic IHD with heart failure
- Sudden cardiac death.
What is the pathogenesis of IHD?
Insufficient coronary perfusion relative to myocardial demand
Due to chronic progressive atherosclerotic narrowing of epicardial coronary arteries and variable degrees of superimposed plaque change, thrombosis and vasospasm
What % stenosis is require to cause chest pain during exercise vs at rest?
75% for pain precipitated by exercise
90% for pain at rest
After which level of stenosis can vasodilation no longer compensate for?
>75%
Where do atherosclerosis usually occur in IHD?
- Plaques mainly in first few cm of LAD or LCX
- Entire length RCA
What is acute coronary syndrome caused by?
Stable plaque becomes unstable
Due to rupture, erosion, haemorrhage etc
Generally leads to superimposed thrombus which increases occlusion
What is the difference between Prinzmental vs Stable vs Unstable angina?
Stable = comes on with exertion, relieved by rest, no plaque disruption
Unstable = more frequent, longer, onset with less exertion or at rest
Prinzmetal = uncommon, due to artery spasm
What is angina pectoris? Is there ischaemia?
Yes - transient ischaemia but not producing myocyte necrosis
What is MI? How common is it in the UK?
Death of cardiac muscle due to prolonged ischaemia
Incidence 5/1000 per year UK (ST elevation)
What is the most common cause of death in postmenopausal women?
MI
What is the myocardial response to MI?
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
Which artery is most commonly affected in MI?
LAD – 50%, ant wall LV, ant septum, apex
RCA - 40%, post wall LV, post septum, post RV
LCx - 20%, lat LV not apex
Which part of the myocardium does LAD supply?
- Ant wall LV
- Ant septum
- Apex
Which part of the myocardium does the RCA supply?
- Post wall LV,
- Post septum
- Post RV
What part of the myocardium does LCx supply?
- Lat LV
- NOT apex
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What is the gross pathology of the myocardium post-MI (1hr to 6 weeks)?
- Under 6 hours – normal by histology (CK-MB also normal)
- 6–24 hrs loss of nuclei, homogenous cytoplasm necrotic cell death
- 1-4 days – infiltration of polymorphs then macrophages (clear up debris)
- 5-10 days removal of debris
- 1-2 weeks granulation tissue, new blood vessels, myofibroblasts, collagen synthesis
- Weeks-months strengthening, decellularising scar
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When does loss of nuclei, homogenous cytoplasm necrotic cell death occur post MI?
6–24 hrs
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1
Which days post MI is this and what is seen?
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MI 10-14 days
granulation tissue, macrophages
How long after MI would this appearance occur?
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>2 months
What % of MI is asymptomatic?
10 – 15% asymptomatic
Common in elderly & diabetes mellitus
Which type of MI will not cause usual ST changes?
Subendocardial infarct
What time frame do most MI deaths occur in?
50% of deaths within the first hour (most do not reach hospital)
Who has worse prognosis with MI?
Age
Female
DM
Previous MI history
What is the cause or reperfusion injury post angioplasty? What are the clinical features?
Due to oxidative stress, Ca overload, inflammation
- Arrhythmias common
- Biochemical abnormalities last days -> weeks
- Thought to cause “stunned myocardium” – reversible cardiac failure lasting several days
What is a hibernating myocardium? Is it reversible?
Chronic sub lethal ischaemia -> lowered metabolism in myocytes “hibernating myocardium”
Reversed with revascularisation
What are the complications of MI? When do they usually occur?
- Contractile dysfunction – 40% infarct-> cardiogenic shock with 70% mortality rate
- Arrhythmia due to myocardial irritability & conduction disturbance
- Myocardial rupture - free wall most common, septum less common, papillary muscle least common. (At mean 4-5days, range 1-10 days)
- Pericarditis (Dressler syndrome) 2nd or 3rd day
- RV infarction
- Infarct extension – new necrosis adjacent to old
- Infarct expansion – necrotic muscle stretches ->mural thrombus
- Mural thrombus
- Ventricular aneurysm, late -> thrombus, heart failure, arrhythmia, do not rupture
- Papillary muscle rupture
- Chronic IHD = progressive late heart failure
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What is Dressler syndrome and when does it occur?
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Pericarditis post-MI = Dressler syndrome
2nd or 3rd day post MI
Complication time frames:
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What is the mortality with a year of MI?
- Total mortality = 30% in one year
- 3-4% mortality per year after first
What is chronic IHD?
Progressive heart failure due to ischaemic myocardial damage. There may be no prior infarction.
What are the gross histopathological features of chronic IHD?
- Enlarged heavy heart, hypertrophied, dilated LV
- Atherosclerosis
- Maybe mural thrombi
- Fibrosis (microscopic)
Define sudden cardiac death. What is the usual cause?
Unexpected death from cardiac causes in individuals without symptomatic heart disease or early (1hr) after onset of symptoms
Usually due to lethal arrhythmia on background of IHD in most (90%). In most cases triggered by myocardial ischaemia.
What % of sudden cardiac death is caused by atherosclerosis?
90% due to marked atherosclerosis (of >75% stenosis)
10% due to non atherosclerotic cause (long QT etc, some cases heritable)
What symptoms are usually caused by left vs right sided heart failure?
Left sided -> SOB, pulmonary oedema
Right sided -> peripheral oedema
What side of the heart does congestive heart failure affect?
Left and right
What are the causes of cardiac failure?
- Ischaemic heart disease
- Valve disease
- Hypertension
- Myocarditis
- Cardiomyopathy
- Left sided heart failure (Right)
What are the complications of cardiac failure?
- Sudden Death
- Arrhythmias
- Systemic emboli
- Pulmonary oedema with superimposed infection
What are the histopathological features of cardiac failure including gross and microscopic?
Gross: Dilated heart, scarring & thinning of the walls
Microscopy: fibrosis and replacement of ventricular myocardium
Name these types of cardiomyopathy.
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Left to right
- Normal
- Dilated
- Hypertrophic
- Restrictive
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What is the pathophysiology of dilated cardiomyopathy?
Progressive loss of myocytes –> dilated heart
What are the causes of dilated cardiomyopathy?
- Idiopathic
- Infective – viral myocarditis
- Toxic: alcohol, chemotherapy (adriamycin, daunorubicin), cobalt, iron
- Endocrine– hyper-, hypo- thyroid, diabetes, peri-partum (?)
- Genetic – haemochromatosis, Fabry’s, McArdle’s
- Immunological – myocarditis incl. Viral (hypersensitivity component
What type of cardiomyopathy is shown?
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Dilated
What is the most common cause of hypertrophic cardiomyopathy?
Familial in 50% - autosomal dominant inheritance with variable penetrance
Mutation to the beta-myosin heavy chain
What is the gross histopathology of hypertrophic cardiomyopathy (HCM)?
Left ventricular hypertrophy
Thickening of septum narrows left ventricular outflow tract
What is shown?
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Hypertroophic cardiomyopathy (left ventricular)
What are the gross histopathological features of restrictive cardiomyopathy? What is it caused by ?
- Impaired ventricular compliance
- Normal size heart – big atria
Idiopathic or secondary to myocardial disease eg amyloid, sarcoidosis
What are the features of chronic rheumatic valvular disease? Which valve is most commonly affected?
Predominantly left-sided valves (almost always mitral)
- Mitral > Aortic > Tricuspid > Pulmonary
- Mitral alone 48%, Mitral + aortic 42%
Thickening of valve leaflet, especially along lines of closure
Fusion of commissures
Thickening, shortening and fusion of chordae tendineae
What is the cause of chronic rheumatic valvular disease?
Sequelae of earlier rheumatic fever predominantly affecting left-sided vlaves (mitral)
What is the most common cause of aortic stenosis?
Calcification of the aortic valve
Affects patients aged 70-80yrs
What are the complications of calcified aortic stenosis?
- Impairs opening
- Orifice is compromised
- Outflow tract obstruction
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What are the causes of aortic regurgitation?
- 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
What is a true vs false aneurysm?
True - all layers wall
False – extravascular haematoma
What are the causes of aneurysms?
Causes: Weak wall
- Congenital eg Marfans
- Atherosclerosis
- HTN
What is shown?
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Aneurysm
- Atherosclerosis may weaken the wall of the aorta such that it bulges out to form an aneurysm.
- This typically occurs in the abdominal portion below the renal arteries, as shown here.
- Aortic aneurysms that get bigger than 6 or 7 cm are likely to rupture.