how the CV system fails Flashcards
what is a haemorrhagic stroke?
cerebral blood vessel rupture
what is an ischaemic stroke?
cerebral blood vessel blockage
what causes a blood vessel to burst?
- stresses
- damage
in a cylinder what is the vessel wall tension?
proportional to P x radius
what are the activities of the endothelium?
- blood vessel tone
- fluid filtration
- haemostasis
- white cell recruitment
- angiogenesis
- hormone trafficking
what is an acute myocardial infarction?
a region of heart tissue that is dying or dead
what causes an acute myocardial infarction?
usually due to a blocked coronary artery
what is atherosclerosis?
a disease process that results in the furring of the arteries
what causes atherosclerosis?
hyperlipaemia, immune action of unknown aetiology
what is coronary artery disease?
a disease process resulting in obstruction of the arteries supplying the heart tissue
what are the symptoms of coronary artery disease?
angina or asymptomatic
what is the cause of coronary artery disease?
atherosclerosis
what is plaque rupture?
a fibrous cap of plaque that burst open
what does the sympathetic nervous system do during an acute MI?
releases adrenaline and noradrenaline in response to pain and haemodynamic abnormalities
what does the sympathetic nervous system do during heart failure?
increases heart rate and increases contractility, increases peripheral resistance and increases risk of arrhythmia
what is pulmonary oedema?
fluid accumulation in lungs
what does pulmonary oedema lead to?
impaired gas exchange
what causes pulmonary oedema?
left heart failure
what are the symptoms of pulmonary oedema?
dyspnoea/orthopnoea which leads to hypoxia
what is ascites?
accumulation of fluid in the peritoneal cavity
what is peripheral oedema?
swelling of tissues especially in ankles
what is compensation?
maintaining homeostasis of physiological function despite stressors or malfunctions which happens via endogenous physiological feedback
what is decompensated heart failure?
the failure of the heart to maintain adequate blood circulation, after long-standing vascular disease causing respiratory distress
what causes cardiac remodelling?
injury: MI, hypertension, valve disease, response to increase afterload or preload
what is the result of cardiac remodelling?
hypertrophy or dilation
what are the treatments for cardiac remodelling?
ACE inhibitors or spironolactone
what is eccentric ventricular hypertrophy?
dilation due to volume overload
what is concentric ventricular hypertrophy?
thickening due to pressure overload
what is another name for ADH?
vasopressin
what is aldosterone?
a steroid that causes kidneys to reabsorb more NaCl and therefore more water
where is aldosterone secreted from?
the adrenal cortex
what does angiotensin II do?
- causes vasoconstriction
- increased fluid retention
- increases ADH secretion
- contributes to ventricular hypertrophy and remodelling
what does thiazine do?
blocks reabsorption in the distal convoluted tubule
what does K+ sparing diuretics do?
inhibits aldosterone receptors in cortical collecting duct
what causes left sided heart failure?
the right heart pumps into lungs but the left atrium its too full
what symptoms do you get from left sided heart failure?
respiratory symptoms
what is congestive heart failure?
pulmonary vasculature is congested and in extreme fluid leaks out of blood vessels into lungs
what symptoms do you get with right sided heart failure?
systemic symptoms
what happens with right sided heart failure?
increase in central venous pressure leading to peripheral oedema or ascites
what are symptoms of heart failure?
- fatigue
- peripheral oedema
- dyspnoea
what is a key difference between and MI and heart failure?
MI is anatomical and heart failure is physiological
what unites all forms of heart failure?
fluid retention
what is cardiogenic shock?
critically low perfusion due to low cardiac output leading to insufficient perfusion of tissues especially the heart
how does cardiogenic shock progress?
positive feedback
how do you treat cardiogenic shock?
aggressive intravenous fluid and oxygen and airway maintained
what are treatments of chronic heart failure?
- ACE inhibitors
- diuretics
- beta blockers
what are the 2 methods for low cardiac output?
- increase sympathetic activity
- kidney accumulates fluid
what happens when you increase sympathetic activity?
- the fast response
- increases heart rate, increases heart contractility
- vasoconstriction
what happens when the kidney accumulates fluid?
- the slower response
- decreases glomerular filtrate rate
- increased central venous pressure
- increased venous return and increased preload
what happens with heart failure or infarct?
- normal pressure
- ends with shock
- rare before age of 50
what happens with haemorrhage?
- loss of fluid leads to loss of pressure
- ends with shock
- any age
what are the 4 main ways the body tries to decompensate heart failure?
- the kidney increases plasma volume
- the heart is unable to pump extra fluid
- the capillaries leak fluid into tissues
- the lungs cannot exchange oxygen and carbon dioxide
why does the kidney increase plasma volume?
- to compensate for poor perfusion of renal tissue
- the kidney responds to it as if it a haemorrhage
- this leads to fluid overload
why is the heart unable to pump extra fluid?
- fluid damming leads to increased venous hydrostatic pressures
- increased back pressure further damages heart
- positive feedback loop leads to rapid deterioration
what are the treatments for low output heart failure?
- prevent acute decompensated heart failure
- counteract cardiac remodelling
- minimise symptoms
