Lecture 3: Cardiac Cycle Flashcards
Define systole
Ejection = pump
Define diastole
“Dilation” = fill
What phases of cardiac cycle occur during systole?
IVC
Isovolumetric contraction
VE
Ventricular ejection
What phases of the cardiac cycle occur during diastole?
IVR
Isovolumetric relaxation
VF
Ventricular filling
When does the mitral valve open and close?
Opens = VF
Closes = IVC
When does the aortic valve open and close?
Opens = VE
Closes = IVR
When are both valves closed?
IVC
IVR
When does S1 occur?
Systole
IVC
Mitral valve closed
Aortic valve closed
When does S2 occur?
Diastole
IVR
Aortic valve closed
Mitral valve closed
Define valve event that defines start of each phase of cardiac cycle
Mitral closes = IVC
Aortic opens = VE
Aortic closes = IVR
Mitral opens = VF
What is an equation for stroke volume?
EDV - ESV = SV
End diastolic vol. - end systolic vol.
What are the 3 sub-phases of ventricular filling?
Rapid filling
Slow filling (diastasis)
Atrial systole
When does peak SP occur?
Ventricular ejection
When does end-systolic pressure (ESP) occur?
IVR
When is end diastolic pressure?
IVC
Start of QRS
How do left ventricular pressure (LVP) compare to aortic pressure (AoP) during VE and VF?
Ventricular ejection:
LVP > AoP
(To push blood to flow forward)
Ventricular filling:
LVP < AoP
(To close valve)
Write an equation for mean aortic pressure
Mean AoP = DP + 1/3 (SP - DP)
= DP + 1/3 (PP)
What is pulse pressure?
PP = SP - DP
What is the aortic pressure at aortic valve closure?
AoP @AC = DP + 2/3 (SP - DP)
= DP + 2/3 (PP)
= End systolic pressure (ESP)
What is DP on wiggers?
Diastolic pressure - when aortic valve opens
@ start of VE
What does y descent depict?
Blood rushing into ventricle, resulting in drop of pressure of left atrium
When can S3 and S4 sounds be heard?
Diastole, ventricular filling
Rapid filling = S3
Atrial systole = S4
Describe asynchrony of semilunar valve closure
Aortic valve closure BEFORE pulmonic closure
This is why during INSPIRATION, two S2 sounds can be distinguished
Describe paradoxical splitting of S2 sounds
Pulmonic (P2) precedes aortic (A2) component because the aortic part is occurring late
When is the time interval for mitral valve closure (S1)?
MC occurs when LVP exceeds LAP @ end of ventricular filling
What is the time interval for aortic valve opening?
AO occurs when LVP exceeds AoP at end of IVC
AKA diastolic pressure (DP)
What is the time interval for aortic valve closure (S2)?
AC occurs when LVP falls below AoP at end of ventricular ejection
What is the time interval for mitral valve opening?
MO occurs when LVP falls below LAP at end of IVR
How do you calculate ejection fraction?
ejection fraction (EF) = SV/EDV
Typical value is 2/3
What are the coordinates for MC (S1) on PV loop?
@ lower right:
x = LVEDV Y = LVEDP
What are the coordinates for AO on PV loop?
At upper right:
X = LVEDV Y = DP
What are the coordinates for AC (S2) on PV loop?
@upper left:
X= LVESV Y = LVESP = DP + 2/3 (SP-DP)
What are the coordinates for MO on PV loop?
@ lower left:
X = LVESV Y = peak of v wave
What pressures are measured with a BP cuff?
Aorta
LV
What pressure are measured with right heart catheterization?
RA
RV
Pulmonary artery
Pulmonary capillary wedge
What pressure is measured with jugular venous pressure (JVP)?
RAP
