Determinants of Cardiac Performance Flashcards
what is happening in diastole?
mitral valve is open
blood flows from left atrium to left ventricle
aortic valve is closed
what is happening in systole?
mitral valve closes
aortic valve opens
blood leaves the left ventricle and goes into aorta
what is a pressure volume loop?
real time change of volume and pressure
when does ventricular filling begin?
mitral valve opening
what happens with pressure and volume during ventricular filling?
volume in the left ventricle increases
pressure increases slightly
when does ventricular filling end?
ventricular contraction after end of diastole
when does isovolumetric contraction begin?
onset of systole
what valve is closed at the beginning of isovolumetric contraction?
mitral valve
when does ejection begin?
when aortic valve opens
what is the pressure volume loop strictly bounded by?
end diastolic pressure volume relationship
end systolic pressure volume relationship
what is compliance inversely related to?
stiffness
what is preload?
the force which fills the heart
the extent of filling of the heart before contraction
wall stress at diastole
when does end systolic pressure volume relationship occur?
maximal contraction
what does the laplace relationship tell us?
force experienced or exerted by each sarcomere
is contractility independent of afterload and preload?
yes
what is contractility determined by?
conditions within the myocyte
what does increased preload lead to?
increased stroke volume
what are the two components of synergy of contraction?
atrioventricular synchrony
inter-ventricular synergy
what does inter-ventricular synergy require?
functional bundle branches (purkinje fibers)
what does an increase in heart rate do to stroke volume?
decreases it
what are the methods to increase cardiac output?
increase heart rate
increase stroke volume
how can you increase stroke volume?
increase preload
decrease afterload
increase contractility
what happens if afterload increases (and no other determinants)?
end systolic volume increases
stroke volume decreases
what is the common theme in compensation?
increase preload
