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Flashcards in Heart as a Pump Deck (29)
1

what is cardiac ouptut

volume of blood pump per min (5 L/min at rest)

2

equation for cardiac output

CO = HR x SV

3

what is stroke volume

amount of blood pump per beat

4

what controls heart rate

set by SA node

affected by autonomic NS

5

what affects stroke volume (3 things)

1) preload (venous return)
2) afterload (resistance to flow - aortic pressure)
3) strength of contraction

6

For LV what is preload ~ to?

end diastolic volume

7

factors that affect preload

1) blood volume

2) filling pressure and time (HR)

3) resistance to filling
- RA pressure
- AV stensosis
- ventricular compliance

8

Graph of EDPVR

what does graph mean

incr LV volume, incr LV pressure

9

Graph of EDPVR

what does slope mean

inverse of ventricular compliance

steeper slope = decr compliance b/c harder for ventricle to fill (hypertrophy)

10

how does hypertrophy affect EDPVR?

how does dilation affect EDPVR?

hypertrophy = steep slope = decr compliant

dilation = shallow slope = very compliant

11

for LV what is afterload ~ to?

aortic pressure

12

factors affecting afterload

1) aortic pressure

2) wall stress so wall thickness and radius (T= dP * R / u(thickness))

3) aortic stenosis

13

what is inotropy

contractility - force of contraction independent of fiber length

describes systolic fxn of heart

14

what is the biggest factor affecting inotropy

sympathetic tone

15

what is shown on EDPVR

P-V relationship during filling of heart BEFORE CONTRACTION

16

what does EDPVR slope mean

passive elastic properties of heart

slope = inverse of compliance
steeper = less complaint

17

EDPVR represents the ___ on the left ventricle

PRELOAD

18

what is shown on systolic pressure-volume relationship

P-V relationship at PEAK OF ISOMETRIC CONTRACTION

19

compare slopes of EDPVR vs. systolic PV relationship

Systolic P-V relationship is steeper (pressure incr a lot for small change in volume

20

what properties are included in systolic PV relationship

ACTIVE + PASSIVE

21

how do you create the Starling (ventricular function) curve

subtract SPVR from EDPVR

22

what does starling curve represent?

active tension

23

what are all the possible y axes for Starling curve

ventricular fxn on y-axis = tension, CO, stroke volume

24

what are all the possible x axes for Starling curve

preload on x-axis = length, pressure, or EDV

25

what does frank-starling law of heart describe (3 things)

1) heart ALWAYS ON ASCENDING LIMB OF STARLING CURVE

2) heart responds to incr in EDV with incr in force

3) what goes in heart must come out

26

what does a violation of frank starling law lead to?

HEART FAILURE

27

HOW DOES incr preload affect PV loop?

shift EDV to the right

more EDV, so heart contract with more force to ensure same end systolic volume

--> INCR STROKE VOLUME

28

How does incr afterload affect PV loop?

shift end systolic volume to the right and shift top pressure line up

incr aortic pressure = heart work harder to eject, less time
incr end systolic volume (can't empty)

--> DECR STROKE VOLUME

29

How does incr inotropy affect PV loop?

new Starling curve

shift top line up and shift end systolic volume to the left

peak pressure higher
--> INCR STROKE VOLUME (until return to original)