CHD INTRO Flashcards
what are the 4 pathogenesis of IHD/ CHD
1- Atherosclerosis
2- Coronary Thrombosis
3- Coronary artery spasm
4- Coronary microvascular dysfunction
define myocardial ischaemia
- Reduced regional blood flow to the heart
- Imbalance between myodcardial demand/ supply
- Exertional demand vs. non-exertional supply ischaemia
define tissue ischaemia
reduced blood flow to an organ or tissue.
due to lack of O2 and nutrient supply.
and lack of washout of metabolic waste.
what are the types of tissue ischaemia?
reversible and irreversible tissue dammage.
what are the determinants of the extent of tissue damage caused by ischaemia? (3)
- the organ
- the duration and extent of reduced blood flow
- the existence of collateral circulation
what increases O2 demand?
wall stress
heart rate
contractility
what is the determinant of O2 supply?
near max at rest
define CHD
Coronary heart disease- pathological conditions characterised by a reduced or inadequate blood flow to the heart, usually due to an obstructive disease of the coronary arteries.
is CHD curable?
no but it can be prevented before you get it .. exercise/ diet etc
what is the single leading cause of death worldwide
CHD
(one of the leading causes of death and most common causes of premature death in the UK)
associated with high morbidity and cost
what is the 4 basic step disease process of CHD
1- Coronary artery obstruction or constriction
2- reduced regional blood flow to the heart
3- oxygen and nutrient deprivation and accumulation of toxic wastes
4- metabolic dysfunction/ contractile dysfunction/electrical instability/ myocardial cell death
what are the clinical manifestations of CHD?
1- angina pectoris (stable, variant or microvascular)
2- immediate or sudden cardiac death (do not see doctor)
3- acute coronary syndromes (acs) - see a doctor and are diagnosed- unstable angina/ acute myocardial infraction (NSTEMI, STEMI)
define Atherosclerosis
- a progressive, degenerative arterial disease characterised by asymmetric deposition of lipids and fibrous tissue on the inside walls of arteries.
- most common cause of CHD (>90%)
What is the disease process with atherosclerosis? (short)
inflammatory process, begins as a fatty streak
what is the 6 step disease process with atherosclerosis?
1- LDL deposition in sub-endothelial space
2-LDL oxidation and monocyte recruitment into sub- endothelial space
3- Macrophage differentiation +uptake of oxidized LDL
4- foam cell formation
5- SMC migration, proliferation & de-differentiation
6- fibrous plaque or atheroma
where do monocytes differentiate into macrophages?
in the subendothelial space.
what induces macrophages to release cytokines that stimulate adhesion molecule expression in endothelial cells?
modified LDL induces this
what expresses receptors that take up modified LDL?
macrophages
what expresses growth factors and proteinases?
macrophages and foam cells
what is a consequence of atherosclerosis?
1) Partial Occlusion - Stable Angina
2) Endothelial/Vascular Dysfunction - Coronary Artery Spasm
3) Ulceration/ Rupture - Coronary Thrombosis
define coronary thrombosis
unwanted formation of a haemostatic plug or thrombus or blood clot within coronary arteries
Seen in 30-90% of ACS (UA, Evolving AMI and AMI)
where does coronary thrombosis occur
usually on top of a ruptured atheroma(plaque)
what is the 4-step disease process in coronary thrombosis
1-ruptured plaque
2- contact of blood elements with collagen and tissue factor
3-platelet adhesion/activation and aggregation OR activation of the coagulation cascade with fibrin formation and deposition
4- clot
what are the consequences of coronary thrombosis?
1) Complete/Permanent Occlusion of Coronary Artery - ACS (STEMI)
2) Subtotal/Intermittent occlusion of coronary artery - ACS (NSTEMI)
3) Thrombeombolism in distal artery
define coronary artery spasm
a transient, spontaneous coronary vasoconstriction
Occurs in normal arteries, mildy atherosc sites or during ongoing thromb
what are the disease mechanisms for coronary artery spasm
1- local endothelial injury= inc reactivity to vasoconstrictors
2 abnormal release of vasoconstrictors or local imbalance in release of vasodilators and constrictors
3- smooth muscle cell hypercontraction/ hyper-reactivity
what are the consequences of coronary artery spasm?
Subtotal or Intermittent occlusion of coronary artery OR Complete focal occlusion of artery
what does GTN do?
improves blood flow through dilatation
define coronary microvascular dysfunction
damage to the inner walls of the small coronary blood vessels of the heart, leading to microvascular spasms, decreased blood flow to the heart, muscle and reduced coronary flow reserve.
What is the coronary Microvasculature
Network of small coronary blood vessles (arterioles) that branch off the large epicardial coronary arteries
what are the two types of damage that coronary microvascular dysfunction can do?
1) Structural - Microvascular remodelling
2) Functional - Endothelial dysfunction
what are the disease mechanisms of coronary microvascular dysfunction?
1- microvascular remodeling- luminal narrowing of the intramual arterioles and capillaries- microvascualr obstruction
2- endothelial dysfunction- impared vasodilator response and reduced coronary blood during exercise or stress
3-functional abnormalities of smooth muscle cells that regulate arteriolar tone
consequence of coronary microvascular dysfunction
impact on coronary flow reserve& inc risk of myocardial ischarmia= INOCA (Microvascular angina) OR MINOCA (MI with no obstructive CAD)
What is the progressive process of athersclerosis?
Normal –> Fatty Streak –> Fribrous Plaque –> Occlusive Atherosclerotic Plaque –> Plaque Rupture and Thrombosis –> UA, AMI, Sudden Coronary Death
What are the main medical and modifiable risk factors of coronary atheroma and CHD (7)
- poor diet
- obesity
- -physical inactivity
- cigarette smoking
- high blood cholesterol
- hypertension
- diabetes
