Lecture 3: Cardiac Cycle

Question 1

Define systole

Answer 1

Ejection = pump

Question 2

Define diastole

Answer 2

“Dilation” = fill

Question 3

What phases of cardiac cycle occur during systole?

Answer 3

IVC
Isovolumetric contraction

VE
Ventricular ejection

Question 4

What phases of the cardiac cycle occur during diastole?

Answer 4

IVR
Isovolumetric relaxation

VF
Ventricular filling

Question 5

When does the mitral valve open and close?

Answer 5

Opens = VF

Closes = IVC

Question 6

When does the aortic valve open and close?

Answer 6

Opens = VE

Closes = IVR

Question 7

When are both valves closed?

Answer 7

IVC

IVR

Question 8

When does S1 occur?

Answer 8

Systole

IVC

Mitral valve closed
Aortic valve closed

Question 9

When does S2 occur?

Answer 9

Diastole

IVR

Aortic valve closed
Mitral valve closed

Question 10

Define valve event that defines start of each phase of cardiac cycle

Answer 10

Mitral closes = IVC

Aortic opens = VE

Aortic closes = IVR

Mitral opens = VF

Question 11

What is an equation for stroke volume?

Answer 11

EDV - ESV = SV

End diastolic vol. - end systolic vol.

Question 12

What are the 3 sub-phases of ventricular filling?

Answer 12

Rapid filling

Slow filling (diastasis)

Atrial systole

Question 13

When does peak SP occur?

Answer 13

Ventricular ejection

Question 14

When does end-systolic pressure (ESP) occur?

Answer 14

IVR

Question 15

When is end diastolic pressure?

Answer 15

IVC

Start of QRS

Question 16

How do left ventricular pressure (LVP) compare to aortic pressure (AoP) during VE and VF?

Answer 16

Ventricular ejection:
LVP > AoP
(To push blood to flow forward)

Ventricular filling:
LVP < AoP
(To close valve)

Question 17

Write an equation for mean aortic pressure

Answer 17

Mean AoP = DP + 1/3 (SP - DP)

= DP + 1/3 (PP)

Question 18

What is pulse pressure?

Answer 18

PP = SP - DP

Question 19

What is the aortic pressure at aortic valve closure?

Answer 19

AoP @AC = DP + 2/3 (SP - DP)
= DP + 2/3 (PP)
= End systolic pressure (ESP)

Question 20

What is DP on wiggers?

Answer 20

Diastolic pressure - when aortic valve opens

@ start of VE

Question 21

What does y descent depict?

Answer 21

Blood rushing into ventricle, resulting in drop of pressure of left atrium

Question 22

When can S3 and S4 sounds be heard?

Answer 22

Diastole, ventricular filling

Rapid filling = S3

Atrial systole = S4

Question 23

Describe asynchrony of semilunar valve closure

Answer 23

Aortic valve closure BEFORE pulmonic closure

This is why during INSPIRATION, two S2 sounds can be distinguished

Question 24

Describe paradoxical splitting of S2 sounds

Answer 24

Pulmonic (P2) precedes aortic (A2) component because the aortic part is occurring late

Question 25

When is the time interval for mitral valve closure (S1)?

Answer 25

MC occurs when LVP exceeds LAP @ end of ventricular filling

Question 26

What is the time interval for aortic valve opening?

Answer 26

AO occurs when LVP exceeds AoP at end of IVC AKA diastolic pressure (DP)

Question 27

What is the time interval for aortic valve closure (S2)?

Answer 27

AC occurs when LVP falls below AoP at end of ventricular ejection

Question 28

What is the time interval for mitral valve opening?

Answer 28

MO occurs when LVP falls below LAP at end of IVR

Question 29

How do you calculate ejection fraction?

Answer 29

``` ejection fraction (EF) = SV/EDV ``` Typical value is 2/3

Question 30

What are the coordinates for MC (S1) on PV loop?

Answer 30

@ lower right: ``` x = LVEDV Y = LVEDP ```

Question 31

What are the coordinates for AO on PV loop?

Answer 31

At upper right: ``` X = LVEDV Y = DP ```

Question 32

What are the coordinates for AC (S2) on PV loop?

Answer 32

@upper left: ``` X= LVESV Y = LVESP = DP + 2/3 (SP-DP) ```

Question 33

What are the coordinates for MO on PV loop?

Answer 33

@ lower left: ``` X = LVESV Y = peak of v wave ```

Question 34

What pressures are measured with a BP cuff?

Answer 34

Aorta LV

Question 35

What pressure are measured with right heart catheterization?

Answer 35

RA RV Pulmonary artery Pulmonary capillary wedge

Question 36

What pressure is measured with jugular venous pressure (JVP)?

Answer 36

RAP