Topic 8 - CardiovascularDisease Flashcards
What is atherosclerosis?
hardening/thickening of artery walls
What are the causes of atherosclerosis?
endothelial damage, platelet adhesion to endothelium, LDL accumulation, oxidation and glycation of LDL, fatty streaks, ulceration, rupture
What is ischemic heart disease?
-atherosclerosis affecting coronary arteries and the narrowing of coronary vessels
What is ischemia?
cell deprivation of blood and oxygen, symptoms = angina, breathlessness
What is myocardial infarction?
complete occlusion of coronary arteries and damage to heart muscle
What is the difference between systemic and pulmonary circulation?
Systemic: heart and body
Pulmonary: heart and lungs
What is the cardiac cycle?
mechanical and electrical events in one beat
What is diastole?
relaxation phase, ventricles untwist, lengthen and unthicken for filling
What is systole?
contraction phase, ventricles twist, shorten and thicken for rapid blood ejection
What are the diastolic events of the cardiac cycle? (mechanical)
- ventricles are relaxed and fill passively
- atrial systole - atria contract to eject blood into ventricles
- isovolumentric ventricular contraction - ventricles contract but valves are closed
What are the systolic events of the cardiac cycle?
- rapid ejection of blood from ventricles (semi-lunar valves open)
- isovolumetric ventricular relaxation - decreased pressure to close semi-lunar valves
What is the entire process of the cardiac cycle?
- ventricles are relaxed and fill passively
- atrial systole - atria contract to eject blood into ventricles
- isovolumentric ventricular contraction - ventricles contract but valves are closed
- rapid ejection of blood from ventricles (semi-lunar valves open)
- isovolumetric ventricular relaxation - decreased pressure to close semi-lunar valves
Define heart rate
number of cardiac cycles per minute
Define stroke volume
vol of blood pumped from ventricles in one heart beat
Define cardiac output
HR x SV, blood pumped out in one min
Define ejection fraction
% end diastolic volume (EDV) pumped in one heart beat
What is preload?
workload imposed on ventricle prior to contraction
What is the Frank-Starling mechanism?
ability of the heart to change force of contraction, therefore SV, in response to changes in venous return.
-the force of contraction of heart is directly proportional to the initial length of muscle fibres
What is afterload?
force required to eject blood from the heart
What does afterload depend on?
- systemic vascular resistance
- ventricular wall tension
What is the difference between positive and negative inotropic agents?
+ increase contractility
- decreased contractility
What is blood pressure?
pressure exerted on arterial walls
What is the formula for blood pressure?
cardiac output x total peripheral resistance
What is systolic BP?
pressure during ventricular contraction
What is diastolic BP?
pressure during ventricular filling
What is the role of ADH in blood pressure?
- causes retention of water by kidney
- vasoconstrictor
- increased blood volume
- alters permeability of DCT
What is the role of the RAAS system in blood pressure?
low Na+ –> renin released by kidneys –> angiotensin I –> angiotensin II by ACE (angiotensin converting enzyme) –> aldosterone released
What is hypertension?
constant elevation of systemic arterial blood pressure, resulting from sustained TPR and increased blood volume
What are the three types of hypertension?
primary/idiopathic - most common, systolic and diastolic hypertension
secondary - caused by underlying disease
isolated systolic/diastolic
What are some risk factors of hypertension?
low K+ in diet, alcohol, diabetes, age, race, family history, gender, high cholesterol, obesity, physical inactivity, smoking, high Na+ intake
What are the consequences of hypertension?
stiffness of arteries, left heart failure, stroke, kidney failure, blindness
What is the use of an ECG?
diagnostic tool that detects electrical disturbances and abnormalities in heart rhythm
What are the phases of the electrical activity of the heart?
depolarisation (Na+ influx)) –> rapid repolarisation (K+ out) –> plataeu (balanced movement) –> repolarisation (overall -ve) –> diastolic depolarisation (resting membrane potential)
What is the P wave?
atrial depolarisation, contraction
What is the QRS complex?
ventricular depolarisation, commencement of ventricular systole, masks atrial repolarisation
What is the T wave?
ventricular repolarisation, -ve membrane potential
What are the layers of blood vessels?
tunica adventitia: CT –> collagen
tunica media: smooth muscle, elastic fibres
tunica intima: direct contact with blood, endothelium
What is the pathogenesis of atherosclerosis?
- intra-aterial fat deposts enter into intima
- it hardens and causes occlusion to blood flow
What is pathophysiology of atherosclerosis?
- injury to tunica media - dysregulated parainflammatory response
- macrophages
- macrophages oxidise to foam cells
- foam cells -> fatty streaks
- plaque formation –> blockage, emobolism
What are some examples of injurious environments for atherosclerosis?
smoking, hypertension, diabetes, increased LDL, decreased HDL, insulin resistance, infection, oxidative stress
What is the progression of atherosclerosis?
injury - inflammation - macrophages - foam cells - fatty streak - fibrous plaque - complicated plaque or embolism
What is coronary artery disease?
any vascular disorder which narrows/occludes coronary arteries
What are some risk factors of coronary artery disease?
hypertension, smoking, diabetes, obesity, sedentary lifestyle, infection
What is the process of coronary artery disease?
decreased myocardial blood supply - ischaemia - acute coronary syndrome - infarction
What is heart failure?
inability of the heart to adequately pump blood to meet metabolic requirements
Systolic heart failure
-inability for heart to pump blood efficiently
Left sided heart failure
blood backed up to lungs
What are the causes of systolic left sided heart failure? left
coronary atherosclerosis: plaque buildup - less blood to heart tissue - damage to myocardium - death or scar tissue
long standing hypertension: harder for LV to pump blood into hypertensive state, hypertrophy of LV (greater demand for oxygen), increased bulk squeezes coronary arteries
dilated cardiomyopathy: chamber grows in size, can work for a little while but muscle becomes weaker and thinner until failure, eccentric hypertrophy
What is diastolic heart failure? Left
concentric hypertrophy, less room for blood, no change in ejection fraction, decreased preload
What are the causes of diastolic heart failure?
- aortic stenosis: narrowing of aortic opening
- restrictive cardiomyopathy - stiffer and less compliant
- RAAS system - increased preload: increased fluid retention - increased contraction strength (Frank-Starling), BUT fluid leaks into lungs and builds up: difficult gas exchange, increased pressure, pulmonary oedema
What is right-sided heart failure?
- often caused by left-sided heart failure
- inability for RV to provide enough blood to supply pulmonary circulation
- caused by L to R cardiac shunt (hole between left and right) –> high to low pressure
What is diastolic right sided failure?
concentric hypertrophy of RV - smaller volume
What is systolic right sided failure?
chronic lung disease, increased pressure in pulmonary vessels
What are the symptoms of right-sided heart failure?
liver failure, pitting oedema in legs/sacrum
What are risk factors for heart failure?
circulating LDL (hyperlipidemia), hypertension, diabetes, insulin resistance, increased sodium intake, smoking, hypertrophic cardiomyopathy
What is an aneurysm?
excessive, localised enlargement of an artery or balloon-like buldge of blood, caused by weakening of arterial walls
Where are aneurysms common?
common in areas of weakness, vulnerability, high pressure
What are the types of aneurysms?
Fusiform: symmetrical
Sacular: hangs off to one side
Extra-vascular haematoma: weakened area, hole in artery
What are the signs and symptoms of an aneurysm?
severe pain, pulsating mass in area of pain, hypotension in ruptured aneurysm
What is a thombosis?
coagulated mass of aggregated platelets, RBC and fibrin that form locally
What is an embolism?
piece of thombus that has broken free inside a vessel and circulates around the body
What is haemostasis?
process involving platelets and factors in response to blood vessel injury in order to decrease blood loss
What is the difference between a primary and secondary haematoma?
1: platelet plug creation
2: reinforcement by fibrin
What does haemostasis involve?
platelets, blood proteins (clotting factors), vasculature
What is the role of platelets?
contribute to regulation of blood flow (vasoconstriction), initiate interactions (platelet plug), initiate clotting cascade (stabilise plug), initiate repair process
How is a platelet activated?
when a vessel is damaged, through: adhesion, activation, degranulation, aggregation
What is a clot?
a meshwork of protein (fibrin) to stabilise a plug and trap other cells
What are the purposes of a clot?
plug damaged vessel, trap microorganisms, framework for healing
What is the process fora clot development?
- release clotting factors from injured tissue and platelets
- formation of thombin
- formation of fibrin
What are the two parts of the coagulation cascade?
- intrinsic (contact activation)
2. extrinsic (tissue factor)
When do the two parts of the coagulation cascade join?
factor X is the common pathway
Intrinsic/contact activation
activated by presence of abnormal/damaged vessel
Extrinsic/tissue factor
tissue factor released by damaged endothelium
