Cardio Phys: Lecture 3

Question 1

What causes the Aortic Valve to open after isovolumetric contraction?

Answer 1

Pressure within the left ventricle reaches, and exceeds the pressure in the aorta.

Question 2

What does Isovolumetric contraction mean?

Answer 2

Isovolumetric contraction means no change in volume while the myocytes contract and build pressure in the left ventricle. Both the Mitral and Aortic valves are closed, allowing pressure to buildup and exceed aortic pressure. Only then can blood be pumped systemically.

It’s all about the pressure gradients.

Question 3

In systemic vasculature, where is the point of highest pressure? Lowest?

Answer 3

Highest pressure = aorta

Lowest pressure = vena cava. (barely over 0, and the right atrium has 0 mmHg pressure!)

Question 4

Inspiration can cause splitting of which heart sound? what valves are closing at this point? Which is the 1st split noise?

Answer 4

Inspiration can cause splitting of the S2 heart sound –> Aortic/Pulmonic Valve closure.

Pulmonic valve closes AFTER the Aortic due to decreased intrapleural pressure. This causes increased venous return to the right atrium, and a resulting delay in pulmonary valve closure due to increased volume of blood being pumped by the right ventricle.

Question 5

S4 heart sound corresponds with….

Answer 5

LATE DIASTOLE

Atrial systole makes this noise if there is ventricular hypertrophy. Lack of ventricular compliance makes it hard for the atria to pump in the last bit of blood, so they make a noise.

(strain to push it in when it doesn’t want to go)

Question 6

S1 heart sound corresponds with…

Answer 6

AV valve closure (mitral and tricuspid)

Question 7

S2 heart sound corresponds with…

Answer 7

Aortic/Pulmonic valve closures

Question 8

S3 heart sound corresponds with…..

Answer 8

VIBRATION OF BLOOD DURING VENTRICULAR FILLING. (rapid blood flow from atria to ventricle)

(EARLY DIASTOLE)

1. ventricles are stiffer… so as blood rushes into them, there is a buzz.
2. Weak mitral valve –> regurgitation

Question 9

Where can you hear the abnormal heart sounds the best?

Answer 9

PMI–> at the apex (Point of Maximum Intensity)

Question 10

Which heart sound is called Ventricular Gallop?

Answer 10

S3

Question 11

T/F: Systole begins at S1 and ends at S2.

Answer 11

TRUE

Question 12

Compare the intensity and pitches of the abnormal heart sounds (S3 and S4) to the normal ones.

Answer 12

S3 ad S4 are lower pitched and lower intensity than the normal heart sounds.

Question 13

Which heart sound has the highest pitch?

Answer 13

S2 (aortic/pulmonic valve closures…the sound is due to oscillating blood in the big vessels once the valves shut)

Question 14

Define: Preload.

Answer 14

Ventricular pressure at the end of diastole. It is determined by ventricular end diastolic volume. (EDV)

Remember, the larger the preload, the greater the contractility, stroke volume, and ejection fraction.

Question 15

Define Afterload.

Answer 15

Ventricular pressure during contraction. It is equivalent to DASTOLIC (resting) AORTIC PRESSURE.

Remember that in order to open the aortic valve and pump blood systemically, ventricular pressure must overcome the aortic pressure or “after load”. If the afterload is increased, it takes more ventricular pressure to overcome it.

Systemic hypertension can cause this. It makes the heart work harder, ejection fraction and stroke volume decrease because more of the contraction of the heart is spent on overcoming the pressure rather than pumping the blood. When stroke volume decreases, so does End Systolic Volume.

Question 16

Define Contractility (also known as ___________).

Answer 16

Contractility = the strength of ventricular contraction

Independent of preload or after load, but can be affected by them.

Also known as inotropy.

Question 17

What is stroke volume and how do you calculate it?

Answer 17

Stroke Volume is the volume of blood ejected by ventricle during systole

SV = EDV - ESV

Question 18

What is Ejection Fraction and how do you calculate it?

Answer 18

Ejection Fraction is the fraction of end diastolic volume (EDV) ejected by the ventricle during systole.

Ej. Fraction = SV/EDV

(Stroke volume divided by End Diastolic Volume)

Question 19

Define Cardiac Output. How is it calculated?

Answer 19

Cardiac Output =Volume of blood ejected by ventricle in one minute.

CO = HR x SV

It’s a measurement of VOLUME.

Question 20

What is the normal value range for Cardiac Ejection Fraction?

Answer 20

55% - 75%

Question 21

You have an aortic stenosis. Do you have a systolic or a diastolic murmur?

Answer 21

Systolic. You hear the murmur when the blood rushes through the narrowing artery(TURBULENCE)

Question 22

You have an aortic regurgitation. Do you have a systolic or diastolic murmur?

Answer 22

Diastolic, due to turbulent retrograde flow into the relaxed ventricle.

Question 23

You have a mitral valve stenosis. DO you have a systolic or diastolic murmur?

Answer 23

Diastolic, because blood flows from the left atrium to the left ventricle during diastole.

Mitral valve stenosis is associated with increased left atrial pressure, because you need to to push the blood through the narrowing valve. This hard push is heard as a murmur (TURBULENCE)

Question 24

You have mitral regurgitation. Do you have a systolic or diastolic murmur?

Answer 24

Systolic.

There is turbulent back flow of ventricular blood into the atrium during systole. Occurs when the ventricles contract.