Lecture 12: Cardiac Cycle

Question 1

Cardiac cycle 2 phases

Answer 1

Process of atrioventricular contraction + relaxation
1. Systole (vent. contract., blood ejection)
2. Diastole (vent. relax., blood filling)

Question 2

Systole phases

Answer 2

1. Isovolumetric ventricular contraction
2. Rapid ventricular ejection
3. Reduced ejection

Question 3

Isovolumetric ventricular contraction

Answer 3

Ventricles develop tension with closed valves; no ejection occurs, ventricular P rises

Question 4

Ventricular ejection

Answer 4

Vent. P > aorta P, pulm. trunk P opens semilunar valves. Stroke volume = volume of blood ejected in systole

Question 5

Diastole phases

Answer 5

1. Isovolumetric ventricular relaxation
2. Rapid ventricular filling
3. Reduced filling
4. Atrial systole

Question 6

Isovolumetric ventricular relaxation

Answer 6

Ventricles relax with all valves closed; no change in blood volume. Vent. P decreases

Question 7

Ventricular filling

Answer 7

Vent. P < atrial P. AV valves open and passive blood filling from atria occurs. 80% filling occurs before atrial contraction right at the end.

Question 8

Heart sounds

Answer 8

Lub = AV valve closure, softer; systole start
Dub = pulmonary/aortic valves closure, louder; diastole start

Question 9

Heart murmurs

Answer 9

Sounds caused by turbulent flow due to heart defects

Question 10

Stenosis

Answer 10

Abnormally narrow valve

Question 11

Insufficiency

Answer 11

Backflow through leaky valve

Question 12

Septal defect

Answer 12

Hole in wall separating the 2 atria or the 2 ventricles

Question 13

Dicrotic notch

Answer 13

Slight bump in aortic pressure when aortic valve closes at end of systole; caused by rebounding of aortic P against the valve.

Question 14

Wiggers diagram

Answer 14

Describes cardiac cycle events for L side of heart; R side flow must match bc 2 pumps in series

Question 15

Stroke volume

Answer 15

SV = EDV - ESV

Question 16

Ejection fraction

Answer 16

EF = SV / EDV (amnt ejected versus filled)

Question 17

Sinus tachycardia

Answer 17

Increase in HR, often in stressful situations

Question 18

Paroxysmal tachycardia

Answer 18

Rapid, abrupt start and stop increased HR

Question 19

Arrythmias

Answer 19

1. Supraventricular rhythms
2. Ventricular rhythms
3. AV blocks

Question 20

Supraventricular rhythms

Answer 20

Brady, tachy, premature atrial contract., atrial flutter, atrial fibrillation. Sinoatrial, atrial, and AV sourced rhythms.

Question 21

Atrial flutter

Answer 21

Very fast but regular atrial contraction

Question 22

Atrial fibrillation

Answer 22

Very fast and irregular atrial contraction; stroke predisposition due to blood pooling in atria.

Question 23

AV blocks

Answer 23

1st: delay in impulse transmission to vent. (P-R > 0.2s)
2nd: Failure of some but not all atrial contractions to be transmitted (occasional missing QRS)
3rd: complete dissociation of AV electrical activity (A/V out of sync)

Question 24

Ventricular rhythms

Answer 24

Ventricular automaticity e.g. wide QRS complex (>0.1s)

Question 25

AV blocks

Answer 25

Diagnosed by P/QRS relation