cardiac mechanics Flashcards
4 determinants of cardiac output
HR
preload (EDV)
contractility (inotropy)
afterload (force overcome to eject blood from heart)
which of the 4 determinants of cardiac output contribute to stroke volume
preload
contractility
afterload
with decreased ventricular compliance
-ventricle state
-systole or diastole
-impact on pressure
-impact on volume
stiff ventricle
systole
increased P
decreased V
equation relating compliance, volume, pressure
C = V / P
with increased ventricular compliance
-ventricle state
-systole or diastole
-impact on pressure
-impact on volume
flexible ventricle
diastole
decreased P
increased V
is compliance linear in end diastolic P & V relationship (EDPVR)
NO
end diastolic P & V relationship (EDPVR)
end systolic P & V relationship (ESPVR)
is compliance linear in end systolic P & V relationship (ESPVR)
YES
what is end systolic P & V relationship (ESPVR) regulated by and what does it represent
regulated by the body
represents inotropic state (contractility) of the ventricle
what does Pressure-Volume loop show
the relationship between pressure & volume at different stages of the cardiac cycle
stroke volume (SV) =
EDV - ESV
P-V loop stage 0
mitral valve opens
ventricle fills
P-V loop stage 1
EDV
mitral valve closes
isovolumetric contraction begins
P-V loop stage 2
isovolumetric contraction
P-V loop stage 3
aortic valve opens
ejection phase begins
P-V loop stage 4
ejection phase
ventricular pressure peaks
(mid-systole)
P-V loop stage 5
aortic valve closes
(peak systole)
isovolumetric relaxation begins
P-V loop stage 6
isovolumetric relaxation
P-V loop stages that are systole
2, 3, 4, 5
P-V loop stages that are diastole
6, 0, 1
what is preload
volume of blood still in the ventricle at the end of diastole (EDV)
increased preload = _____ EDV, _____ SV
increased EDV, increased SV
how does increasing preload (EDV) change the P-V loop?
widens the loop to the right
