Cardiovascular Calculations

Question 1

What does LVEF stand for?

Answer 1

Left ventricular ejection fraction

Question 2

LVEF equations

Answer 2

• (EDV-ESV)/EDV x 100
• SV/EDV x 100

Question 3

Normal LVEF

Answer 3

55-60%

Question 4

Normal EDV

Answer 4

110-120 ml

Question 5

Normal ESV

Answer 5

40-50 ml

Question 6

Normal SV

Answer 6

70 ml

Question 7

Cardiac output equations

Answer 7

CO= Arterial pressure/ Total peripheral resistance

CO= SV X HR

Question 8

Normal cardiac output

Answer 8

Men: 5.7 L/ min

Women= 4.9 L/ min

Question 9

Cardiac index

Answer 9

CO per square meter of body surface area

*Normal is 3L/ min/m2 of BSA

Question 10

CO with Fick

Answer 10

CO= [O2 absorbed per minute by lungs (mL/min)]/ [Arteriovenous O2 difference (mL/L of blood)]

• O2 consumption can be measured or assumed to be 125 ml/min/m2
• Arterial venous O2 contents need to be calculated
• Mixed venous O2 content needs to be determined

Question 11

Calculation of arterial and venous O2 contents

Answer 11

Question 12

Systemic cardiac output

Answer 12

Question 13

Determining mixed venous O2 Content

Answer 13

Question 14

What are the advantages and disadvantages to Fick?

Answer 14

Advantages

• Most accurate method if the heart rate or rhythm is irregular such as AFIB
• Most accurate for low flow states

​Disadvantages

• Cannot detect rapid changes in cardiac output
• Requires simultaneous measurements

Question 15

Continuity equation

Answer 15

Q1= Q2

v1xA1= v2 x A2

Question 16

Modified Bernoulli equation

Answer 16

4(V)²

Needed values:

• Peak velocity across the valve for the gradient
• The gradient is used to calculate the valve area
• Stenotic lesions such as aortic stenosis

*Represent maximal instant gradient

Question 17

LVOT Area

Answer 17

(D/2)²

D= Diameter

Question 18

The Bernoulli equation

Answer 18

Question 19

Gorlin’s formula: Aortic valve area

Answer 19

Question 20

Simplified Gorlin for Aortica valve area

Answer 20

AVA= (CO)/ (square root of the peak to peak gradient)

Question 21

Systolic Ejection Period

Answer 21

Question 22

What are the limitations of AVA calculations?

Answer 22

• Limitations in pressure measurement, especially if pulmonary capillary wedge pressure replaces left atrial pressure or if femoral artery pressure replaces aortic pressure
• Valve area itself can be dependent on flow and pressure- “dynamic area?”

Question 23

Arterial ____ is used clinically. Arterial _____ is used in laboratory investigations.

Answer 23

Resistance; impedence

Question 24

Vascular resistance *pulmonary

Answer 24

(Mean pulmonary artery pressure- left atrial pressure)/ Left-sided cardiac output

NOTE: Systemic vascular resistnace is calculated the same way but wth the right atrial presure and mean aortic pressure

Question 25

Units for Vascular resistance

Answer 25

Wood unit: mmHg (1/min)

1 wood unit= 80dynes.s.cm-5

Question 26

Normal pulmonary arterial restistance

Answer 26

67 dynes.s.cm-5

Question 27

Normal total pulmonary resistance

Answer 27

205 dynes.s.cm-5

Question 28

Normal systemic resistance

Answer 28

1,130 dynes.s.cm-5

Question 29

In the absence of a shunt what is the relationship between systemic and pulmonary flow?

Answer 29

Qp=Qs

• In the setting of left to right shunt Qp> Qs
• In the setting of right to left shunt Qs> Qp

Question 30

What do you notice observing oxygen saturation profile in the figure?

Answer 30

• There is an oxygen saturation “step-up” in the right atrium
• This patient has an atrial septal defect

Question 31

What are normal oxygen saturation levels in the compartments of the heart?

Answer 31