Car 7 Cardiac Cycle

Question 1

What does the Pressure-volume loop measure?

Answer 1

The pressure and volume of left ventricle only.

Question 2

What happens to the Pressure-Volume Loop when there is increased afterload (e.g. Hypertension)?

Answer 2

The square shifts to the right and gets taller: there is ^ aortic pressure, \/ Stroke volume (SV), ^ End systolic volume (ESV).

Question 3

What happens to the Pressure-Volume Loop when there is increased contractility?

Answer 3

The square shifts the left, and gets taller: ^ SV, ^ Ejection fraction (EF), \/ End systolic volume (ESV). Afterload and preload stay the same.

Question 4

What happens to the Pressure-Volume Loop when there is increased preload?

Answer 4

Only the systolic volume increases. The rest stay the same.

Question 5

What is happening in the S1 heart sound?

Answer 5

The turbulence of the blood when the mitral valve closes.

Question 6

What is happening in the S2 heart sound?

Answer 6

The turbulence of the blood when the aortic valve closes.

Question 7

What is happening in the S3 heart sound?

Answer 7

Early diastole or sometimes mid diastole. Associated w/ rapid ventricular filling (increased filling pressure) and/or dilated ventricles.

Question 8

What are the causes of S3 heart sound?

Answer 8

Dilated cardiomyopathy. Congestive heart failure. Mitral regurgitation. Left to right shunting (VSD, ASD, PDA). Can be normal in children and pregnant women.

Question 9

What is happening in S4 sound?

Answer 9

Found right before S1 sound, occurs in late diastole. Due to high atrial pressure, often associated w/ ventricular hypertrophy and atrial kick.

Question 10

What are the causes of S4 heart sound?

Answer 10

Hypertrophic cardiomyopathy. Aortic stenosis. Chronic hypertension w/ LVH (left ventri hypertrophy). Post MI.

Question 11

What is happening in the a wave in venous pulse?

Answer 11

A wave: atrial contraction.

Question 12

What is happening in the c wave in venous pulse?

Answer 12

Right ventricular contraction where the tricuspid valve bulging into the atrium.

Question 13

What is happening in the v wave in venous pulse?

Answer 13

Increased atrial pressure due to filling of a closed tricuspid valve.

Question 14

What is happening in the QRS in electrocardiogram?

Answer 14

A-V valve closure.

Question 15

What happens in normal splitting of the S2 heart sound?

Answer 15

The aortic valve closes slightly earlier than pulmonic valve.

Question 16

What are the causes of Wide splitting of S2?

Answer 16

Pulmonic stenosis. Right bundle branch block.

Question 17

What is the cause of fixed splitting of S2?

Answer 17

Atrial septal defect: left atrium is spilling into the right atrium, causing an overload of right ventricle.

Question 18

What are the cause of paradoxical splitting of S2?

Answer 18

Aortic stenosis. Left bundle branch block.

Question 19

When does isovolumetric contraction take place?

Answer 19

During QRS after mitral valve closure and before the aortic valve opens.

Question 20

How does an increase in afterload affect the stroke volume of the heart assuming contractility remains the same?

Answer 20

Decrease the SV (stroke volume).

Question 21

What impact does an increase in contractility have on stroke volume assuming preload and afterload remain constant?

Answer 21

Increase stroke volume (SV).

Question 22

What heart sound is associated w/ dilated congestive heart failure? What heart sound is associated w/ chronic hypertension?

Answer 22

Dilated CHF: S3. Chronic hypertension and stiffened left ventricle: S4.