Histo Flashcards
(156 cards)
Atherosclerosis defined as
atheromatous deposits in and fibrosis of the inner layer of the arteries.
intimal lesions - atheroma (atheromatous plaques) - that protrude into vessel lumen
Stages of atherosclerosis
- Smooth endothelium damage.
- Platelets adhere to damaged tissue
- Proliferastion of endothelium
- Fibrous cap forms
- Deposition of cholesterol and enlargement of plaque with fatty core.
Atheromatous plaque definition
Raised legion, soft lipid core, white fibrous cap.
Pathogenesis of atherosclerosis
Endothelial injury
LDL accumulation
Monocyte adhesion and migration to intima forming macrophages and foam cells.
Platelet adhesion.
Fatty streak
Earliest lesion. lipid filled foamy macrophages, no flow disturbance, in all children >10y
Relationship to plaque unknow but in same sites.
Atherosclerotic Plaque
Patchy, localised flow disturbance, only involve a portion of the wall (rarely circumferential)
Composed of cells, lipid and matrix.
Critical stenosis occurs at
70% occlusion or diameter
Acute plaque changes (3)
Rupture - exposes prothrombotic plaque contents.
Erosion - exposes prothrombotic basement membrane
Haemorrhage into plaque increases size.
Reasons for a vulnerable plaque
Lots of foam cells of lipid
Thin cap
Few smooth muscle cells
Clusters inflammatory cells
Vasoconstriction effect on plaque
Reduces lumen size and increases mechanical pressure on plaque.
Due to adrenergic agonists
IHD main cause
90% due to reduced blood from from atherosclerosis.
IHD is leading cause of mortality for men and women. Due to lack of o2 to cardiac muscle less well tolerated that true hypoxia due to impaired waste clearance as well.
% stenosis of coronary arteries required to cause angina on exercise?
% stenosis to cause angina at rest?
75%
90% stenosis for pain at rest
MI pathogenesis
Loss of contractility in?
Irreversible after?
Myocardial blood supply compromised.
Loss of contractililty in 60s (so failure can precede myocyte death)
Irreversible after 20-30mins
Locations for MI
LAD 50%
RCA 40%
LCx 20%
% of asymptomatic MI
10-15% usually in elderly or DM.
Reperfusion injury cause
due to oxidative stress, Ca overload and inflammation. Arrhythmias are common
Complications of MI (6)
Mortality of MI is 30% in one year
Contractile dysfunction Arrhythmia Myocardial rupture Pericarditis RV infarction Deslers syndrome (pericarditis 2-3w post MI) Papillary muscle rupture
Chronic IHD definition
Progressive heart failure due to ischaemic myocaridal damage. May not be a prior infarction. Hypertrophies heart with dilated LV
Sudden Cardiac Death
Unexpected death in individuals without symptomatic heart disease or
Causes of sudden cardiac death
Acute MI is usually the trigger Marked atherosclerosis (>90%)
10% non atherosclerotic (long QT, HOCM)
Types of cardiomyopathy (3)
Dilated - progressive loss of myocytes
Hypertrophic
Restrictive
Causes of dilated cardiomyopathy
Idiopathic Infective Toxic - alcohol, chemo Hormonal - hyper/hypothyroid, DM, peripartum Genetic - haemochromatosis
Causes of hypertrophic cardiomyopath
Familial 50%
Causes of Restrictive Cardiomyopathy
Idiopathic or secondary to myocardial disease like amyloid or scarcoidosis.