# Cardiac Physiology - Normal Values and Equations Flashcards

1
Q

How to approximate the mean arterial pressure at a normal heart rate?

A

MAP = diastolic P + 1/3 pulse pressure

2
Q

A

120/80

3
Q

Pulse pressure?

A

Systolic P - Diastolic P

4
Q

What equation relates flow, pressure, and resistance?

A

Q = ΔP/R

5
Q

Equation to calculate cardiac output?

A

CO = HR x SV

6
Q

Normal CO value?

A

5L/min

7
Q

Normal SV for a 170 lb person?

A

70 mL

8
Q

Formula for CI?

A

CI = CO / m^2

9
Q

CI for 170 lb person?

A

CI = 5/1.5 = 3.3 L/min/m^2

10
Q

Formula for SI?

A

SI = SV/ m^2

11
Q

What is the unit of resistance?

A

mmHg/mL/min

12
Q

Normal resistance of the systemic circulation?

A

0.02 PRU

13
Q

1 m3 = x L?

A

1 L

14
Q

1 L = x cm3?

A

1,000 cm3

15
Q

1 L = x mm3?

A

1,000,000 mm3

16
Q

Equation for ejection fraction?

A

Ejection fraction = SV/EDV

17
Q

Equation for end diastolic volume?

A

EDV = SV + ESV

18
Q

% of cardiac output going to the brain? VO2?

A

13%

VO2: = 21%

19
Q

% of cardiac output going to the coronary circulation? VO2?

A

4%

VO2 = 11%

20
Q

% of cardiac output going to the liver and GIT? VO2?

A

24%

VO2 = 23%

21
Q

% of cardiac output going to skeletal muscles? VO2?

A

21%

VO2 = 27%

22
Q

% of cardiac output going to the kidneys? VO2?

A

20%

VO2 = 7%

23
Q

% of cardiac output going to the skin and other organs? VO2?

A

18%

VO2 = 11%

24
Q

What vessels account for most of the resistance of the CV system? What to note?

A
1. Small arteries/arterioles: 47%
2. Capillaries: 27%
3. Large arteries: 19%
4. Veins: 7%

Highest resistance in arterioles though

25
Q

Breakdown % of blood in systemic vs pulmonary circulation?

A

Systemic circulation => 90% of the blood

Pulmonary circulation => 10% of the blood

26
Q

Pulmonary arterial pressure?

A

25/10 mmHg

27
Q

Pulmonary MAP?

A

15 mmHg

28
Q

Where is the largest pulse pressure found in the CV system? What is it?

A

LV: 120

29
Q

Where is the lowest pulse pressure found in the CV system? What is it?

A

RV: 20

30
Q

Normal venous pressure?

A

2-6 mmHg

31
Q

Normal RA pressure?

A

9/4 mmHg (5)

32
Q

Normal LA pressure (wedge)?

A

12/5 mmHg (10)

33
Q

Normal RV end-diastolic pressure?

A

< 6 mmHg

34
Q

Normal LV end-diastolic pressure?

A

4-12 mmHg

35
Q

What is the actual equation to measure CO using the indicator-dilution technique?

A

I/C.T

```I = mass of indicator injected
C = mean dye concentration
T = duration of 1st circulation```
36
Q

What is the Fick principle?

A

Amount of substance added or removed to or from an organ = blood flow x (a-v)

(a-v) = difference in concentration across the organ between arteries and veins

37
Q

How is Fick’s principle used to calculate CO?

A

CO = blood flow across the lungs = amount of oxygen consumed (mL/min) / (a-v)O2

```a = systemic arterial oxygen concentration (sampled from any artery)
v = pulmonary arterial oxygen concentration```
38
Q

How to use the indicator dilution technique when all you have is the curve produced?

A

CO = amount of indicator added / area under first circulation curve

39
Q

Normal RV pressure?

A

25/0 mmHg

40
Q

Normal LV pressure?

A

120/0 mmHg

41
Q

BV for 170 lb patient?

A

5L

42
Q

List the distribution of BV throughout blood vessels.

A
1. Veins: 64%
2. Lungs: 9%
3. Small arteries and arterioles: 8%
4. Large arteries: 7%
5. Heart in diastole: 7%
6. Capillaries: 5%
43
Q

Velocity of blood in aorta?

A

~30 cm/s

44
Q

Velocity of blood in capillaries?

A

~0.1 cm/s

45
Q

Equation to relate velocity, flow, and area of blood in vessels?

A

Flow (Q) = V x A

```V = blood velocity
A = cross-sectional area```
46
Q

Largest vessel in body? A?

A

Aorta

A = 4 cm^2

47
Q

What is Poiseuille’s Law?

A

Flow equation, that expands on the original Q = ΔP/R:

Q = π.(P1 - P2).r^4/(8.η.L)

```r = vessel radius
‎η‎‎ = fluid viscosity
L = length of the vessel```
48
Q

Rearranging Poiseuille’s Law, what is the equation for resistance?

A

R = 8.η.L/π.r^4

49
Q

How does doubling the radius of the vessel affect flow rate?

A

16x

50
Q

Equation to calculate total peripheral resistance?

A

TPR = (aortic P - CVP)/CO

CVP = central venous P

51
Q

Equation to calculate total pulmonary resistance (PVR)?

A

PVR = Pulmonary artery P - LA P/CO

52
Q

Normal PVR?

A

0.002 PRU

53
Q

How can TPR be approximated in a clinical situation?

A

TPR = MAP/CO

54
Q

How to measure total resistance in series circuit?

A

RT = R1 + R2 + R3 + … + Rn

55
Q

What is the pressure gradient Pi-Po equal to in series and parallel circuits?

A

The sum of all the pressure gradients: (Pi-P1)+(P1-P2)+(P2-Po)

56
Q

What is the equation of the total flow of a circuit in parallel?

A

Qtotal = Q1 + Q2 + Q3 + … + Qn

57
Q

How to measure total resistance in parallel circuit?

A

1/RT = 1/R1 + 1/R2 + 1/R3 + … + 1/Rn

58
Q

Equation for Reynold’s number?

A

Re = ρ.D.v/η

```ρ = fluid density
D = vessel diameter
v = mean velocity
η = fluid viscosity```
59
Q

How can Reynold’s number predict flow?

A
• Re<2000 => laminar flow

- Re>2000 => turbulent flow

60
Q

What is the density of blood?

A

1 g/mL

61
Q

Equation for wall tension? What is this called?

A

La Place’s Law:

T = P.r

```P = transmural pressure
62
Q

BP in capillary?

A

35 mmHg

63
Q

How does tripling the radius of the vessel affect flow rate?

A

81x

64
Q

Combined pressure of ejection of RV and LV?

A

125 mmHg

65
Q

Duration of average cardiac cycle?

A

70 beats/min => 0.85 second cardiac cycle => 0.28 systole and 0.58 diastole

66
Q

What is the aortic pressure during the isometric contraction of the LV?

A

80 mmHg

67
Q

What % of ventricular filling does atrial contraction account for AT REST?

A

20-25%

68
Q

What is LV EDV at rest?

A

140 mL

69
Q

Normal ejection fraction at rest?

A

0.5

70
Q

What is the CO during maximal aerobic exercise?

A

25 L/min

71
Q

Max HR?

A

180 bpm

72
Q

What is the SV during maximal aerobic exercise?

A

100-130 mL

73
Q

What diastolic pressure is considered HT?

A

Above 90 mmHg

74
Q

Normal PO2 of arterial blood?

A

95-100 mmHg

75
Q

Normal PCO2 of arterial blood?

A

40 mmHg

76
Q

Normal pH?

A

7.4

77
Q

What is stroke work?

A

SV x systolic pressure

78
Q

How many mL of blood need to be added to the artery for the pressure to go up 40 mmHg?

A

70 mL = SV to go from diastolic to systolic pressure

79
Q

What is CVP at rest?

A

2 mmHg

80
Q

Combined, what fraction of the CO do the liver and the GIT receive?

A

1/3

81
Q

Normal arteriolar transmural pressure?

A

100 mmHg

82
Q

What max % of CO can skeletal muscles get during exercise?

A

80% of 25 L/min CO

83
Q

Normal MAP?

A

95 mmHg

84
Q

Systolic RA and CVP pressure?

A

5 mmHg

85
Q

Systolic RV and PA pressure?

A

25 mmHg

86
Q

Systolic LA and PA occlusion pressure?

A

10 mmHg

87
Q

Systolic LVP?

A

125 mmHg

88
Q

Normal CI?

A

2.6-4.2 L/min/m^2