cardiac pressure volume loop Flashcards Preview

physiology IV > cardiac pressure volume loop > Flashcards

Flashcards in cardiac pressure volume loop Deck (32):
1

what is the equation for work done by the ventricle muscle?

work= pressure x volume change

2

what is occurring during isovolumic contraction in the ventricle?

heart is still contracting without changing volume

3

what is occurring during isovolumic relaxation in the ventricle?

heart is relaxing without changing volume

4

what is occurring during the "mitral valve open to mitral valve close" phase in the cardiac cycle?

ventricle is filling with blood
there is an increase in pressure due to increase in passive tension as the ventricle muscle stretches

5

what is the "increase in passive tension" called?

preload

6

what is the end-systolic pressure volume relationship (ESPVR)?

the curve that describes that maximal pressure that can be developed by the ventricle at any given LV volume

7

what is the inverse of compliance?

elastance

8

what is the equation for compliance?

change in volume/change in pressure

9

in describing the ventricle filling, what does a high compliance/low elastance mean

that the ventricle is "easy" to fill

10

what happens to the ESPVR curve as inotropy (contactility) increases?

curve becomes steeper and shifts to the LEFT

11

what happens to the ESPVR curve as inotropy (contactility) decreases?

becomes flatter and shifts to the RIGHT

12

what does a steeper EDPVR slope mean regarding compliance
what is an example of when this could happen?

indicates decreased compliance
ex. in ventricular hypertrophy

13

what does a flatter EDPVR slope mean regarding compliance
what is an example of when this could happen?

indicates increased compliance
ex. dilated cardiomyopathy

14

what does end diastolic pressure volume relationship curve describe?

the passive filling curve for the ventricle (and thus passive properties of the myocardium)

15

after the ventricle reaches is end diastolic volume and the mitral valve closes, what occurs?

muscle begins to actively contract and pressure increases rapidly (isovolumetrically) until the aortic valve opens

16

what is the afterload?

the point when the blood pressure in the ventricle equals or exceeds the blood pressure in the aorta

17

what word does this definition describe?
"volume of blood ejected by the ventricle in a single contraction"

stroke volume

18

in what type of situation is stroke volume sensitive to afterload changes?

in a failing heart, normally SV is NOT greatly influenced by afterload

19

define ejection fraction

fraction of end diastolic volume that is ejected out of the ventricle during each contraction
EF= SV/EDV

20

in a healthy ventricle, what is the usual ejection fraction?

greater than .55

21

low EF is usually indicative of what?

systolic dysfunction

22

if the EF is lower than .2 what is the heart at risk for?

severe heart failure

23

increased enotrophy does what to the EF?

increases it

24

define preload

the EDV at the beginning of systole

25

what is preload and afterload measured in?

preload is in volume
afterload is in pressure mmHg

26

increasing aortic pressure does what to the amount of work that the heart has to do?

increases it

27

increasing stroke volumes will do what to the amount of work that the heart has to do?

increase it because they heart has to move more blood

28

increasing the preload will do what to the tension and stroke volume?

increase it

29

increasing ventricular afterload does what to stroke volume and ejection fraction?

it decreases stroke volume and ejection fraction

30

what does norepi do to:
stroke volume
ejection fraction
contractility

increase SV
can increase EF
increase contractility

31

how does cardiomyopathy and heart failure normally effect CO

decrease it

32

how does infection and sepsis normally affect CO

increase cardiac output