The Cardiac Cycle

Question 1

At what point is diastolic pressure measured?

Answer 1

Diastolic pressure is measured in the arteries at the end of the ventricular filling phase. I.e. just before the mitral valve closes

Question 2

When is systolic pressure measured?

Answer 2

Systolic pressure occurs at the height of ventricular contraction when ventricular and aortic pressure are at their highest.

Question 3

What are ICP?

Answer 3

ICP = Isometric Contraction Phase. Between mitral valve closing and aortic valve opening. The ventricle is contracting but no blood is moving in or out so pressure climbs.
Start of Systole

Question 4

What is the IRP?

Answer 4

Isometric Relaxation Phase
Between Aortic Valve closing and Mitral Valve opening again. The ventricle is relaxing but no blood is moving in or out.
Start of Diastole

Question 5

What is the pulse pressure?

Answer 5

The difference between the diastolic and systolic pressures. (~40mmHg at rest)

Question 6

What is mean arterial pressure?

Answer 6

The average arterial pressure throughout a cardiac cycle.

As a rule of thumb its diastolic + 1/3 pulse pressure.

Question 7

On a pressure time graph the atrium has 3 waves a, c & v. What are they?

Answer 7

a - equates to the p wave on an ECG. And the active filling phase of diastole. This is where the atrium contracts to force a little extra blood into the ventricle, hence the brief increase in atrial pressure.
c - During ICP when ventricular pressure climbs causing the mitral valve to briefly balloon back into the atrium causing an atrial pressure increase
v - steady rise in atrial pressure after the c wave as venous blood from lungs fills the atrium. Stops at the end of IRP when the mitral valve opens and blood can flow into the ventricle.

Question 8

What is the End Diastolic Volume?

Answer 8

The max ventricular volume at the end of diastole. (EDV)

Question 9

What is the end systolic volume?

Answer 9

The min ventricular volume at the end of systole. (ESV)

Question 10

What is stroke volume?

Answer 10

The differnece between the EDV & ESV. Essentially how much blood is pumped out in each cycle.

Question 11

What is the ejection fraction?

Answer 11

The Stroke Volume over End diastolic volume. (SV/EDV).

Should be around 2/3 in a healthy heart.

Question 12

How is the ejection phase divided?

Answer 12

Ejection phase is all the time th eaortic valve is open and blood flows out the ventricle into the artery. (most of systole)
The first 3rd is the rapid ejection phase
The last two 3rds are the slow ejection phase.

Question 13

How is the filling phase divided?

Answer 13

All the time the mitral valve is open and blood flows into the ventricle. (Most of diastole)
First 3rd - Rapid filling phase
Second 3rd - Slow filling phase
Third 3rd - Active filling Phase. When the atrium contracts to force the last bit of blood into the ventricle.

Question 14

There are 4 heart sounds during the cardiac cycle that are audible due to turbulence in the blood. What is the 1st?

Answer 14

The sound of the mitral valve and tricuspid valve closing at the start of systole

Question 15

What is the 2nd heart sound?

Answer 15

The sound of aortic & pulmonary valves closing during the IRP

Question 16

What is the 3rd heart sound?

Answer 16

The sound of the rapid filling phase

Question 17

What is the 4th heart sound?

Answer 17

The sound of the active fillin phase

Question 18

How does the cadiac cycle in the right side compare to that in the left side of the heart?

Answer 18

The right side is very similar.

The volumes involved are identical but the pressure is about 1/5 in the right side compared to the left.

Question 19

What happens to the cardiac cycle as the heart rate climbs?

Answer 19

Diastole shortens, i.e. the filling phase

Question 20

Why isnt the output affected as the heart climbs to 150BPM

Answer 20

Because most of the filling occurs in the rapid fillin phase which isnt isnt shortened at this heart rate

Question 21

Why is the output reduced above ~150bpm?

Answer 21

The filling phase shortens so much it cuts into the rapid filling phase and the EDV significantly decreases, therefore so does the SV.

Question 22

What is a phonogram used for?

Answer 22

Detecting heart sounds and any abnormal sounds (murmurs)

Question 23

What would cause a systolic murmer? (between 1st & 2nd heart sounds)

Answer 23

Stenosis of aortic/pulmonary valves

Or Regurgitation through the mitral/Tricuspid valves.

Question 24

What could cause a diastolic murmur?

Answer 24

Stenosis of mitral/tricuspid valves

Or Regurgitation through aortic/pulmonary valves.

Question 25

What could cause a constant murmur?

Answer 25

A septal Defect

Question 26

What is a pressure-volume loop?

Answer 26

A way of graphing the cardiac cycle in a ventricle.

Question 27

What is normal blood pressure at resting HR? (75BPM)

Answer 27

120/80

Question 28

What is the value of resting pulse pressure?

Answer 28

40mmHg

Question 29

What is normal EDV at rest?

Answer 29

~140ml

Question 30

What is normal ESV at rest?

Answer 30

~60ml

Question 31

What is normal stroke volume at rest?

Answer 31

~80ml

Question 32

What should the ejection fraction be in a healthy heart?

Answer 32

2/3

Question 33

Now go back and learn the pressure/volume vs time graph and pressure-volume loop.

Answer 33

JUST DO IT

Question 34

What is the dicrotic notch

Answer 34

A small increase in aortic pressure just after the aortic valve closes.
As aortic pressure exceeds the ventricular pressure theres a slight backflow of blood which causes the aortic valve to close. This results in a slight increase in aortic pressure due to the elastic recoil of the valve.