Session 2- The heart as a pump and valve disease

Question 1

what is systole

Answer 1

contraction and ejection of blood from ventricles

Question 2

what is diastole

Answer 2

relaxation and filling of ventricles

Question 3

pressure in systemic circulation and pulmonary circulation

Answer 3

systemic- high

pulmonary- low

Question 4

how much blood does each ventricle pump each heart beat

Answer 4

70ml which is stroke volume
at a heart rate of 70bpm = 4.9 litres blood per minute

every minute your heart pumps the entirety of your blood

Question 5

how long does a cardiac action potential last

Answer 5

280ms

Question 6

what determins the opening of valves

Answer 6

differential blood pressure

Question 7

how are cusps of valves attatched

Answer 7

cusps of mitrial and tricuspid valves attach to papillary muscles via chordae tendinaeae
they prevent inversion of valves on systole

Question 8

what generates an action potential in the heart

Answer 8

pacemaker cells in the sinoatrial node

Question 9

what is atrial systole

Answer 9

activity spreads over atria

Question 10

how long is the action potential delayed in the atrioventricular node

Answer 10

120ms

Question 11

how does an action potential spread across the heart

Answer 11

activity spreads across atria from SA node
reaches the atrioventricular node and delayed
from av node excitation spreads down septum between ventricles
next spreads through ventricular myocardium from inner to outer surface
ventricle contracts from the apex up forcing blood through outflow valves

Question 12

what changes happen in systole and diastole when the heart beats faster

Answer 12

systole remains constant but diastole reduces

Question 13

what are the 7 phases of the cardiac cycle

Answer 13

atrial contraction
isovolumetric contraction
rapid ejection 
reduced ejection
isovolumetric relaxation
rapid filling
reduced filling

Question 14

how long does diastole last

Answer 14

around 0.55s

Question 15

how does systole last

Answer 15

0.35s

Question 16

what side of the heart is the wiggers diagram plotted for

Answer 16

left

right side would be lower pressure

Question 17

Phase 1

Answer 17

atrial contraction
atrial pressure-atrial pressure rises due to atrial systole. This is called the ‘A wave’

ventricular pressure-atrial contraction accounts for 10% of ventricular filling

electrocardiogram- p wave in ECG

Question 18

what is EDV

Answer 18

end diastolic volume- at the end of phase 1 ventricular volumes are maximal- typically 120ml

Question 19

Phase 2

Answer 19

isovolumetric contraction
same volume as all the valves are closed

mitrial valve closes as intraventricular pressure exceeds atrial pressure

ventricular pressure- rapid rise in ventricular pressure as ventricle contracts
atrial pressure- closing of mitral valve causes the ‘C wave’ in the atrial pressure curve

ventriculr volume- isovolumetric since there is no change in ventricular volume

electrocardiogram- QRS complex in ECG signifies onset of ventricular depolarisation

s1- closure of mitral and tricuspid valve

Question 20

phase 3

Answer 20

rapid ejection
ejection begins when the intraventricular pressure exceeds the pressure within the aorta. This causes the aortic valve to open

ventricular volume- rapid decrease in ventricular volume as blood is ejected into aorta

mitrial/tricuspid- closed
aortic/pulmonary- open

Question 21

phase 4

Answer 21

reduced ejection
repolarisation of ventricle leads to a decline in tension and the rate of ejection begins to fall

electrocardiogram- ventricular repolarisation depicted by T-wave of ECG

mitrial/tricuspid- closed
aortic/pulmonary- open

Question 22

phase 5

Answer 22

isovolumetric relaxation
-when the intraventricular pressure falls below aortic pressure, there is a brief backflow of blood which causes the aortic valve to close

aortic pressure- valve closure causes dip in pressure

although rapid decline in ventricular pressure, volume remains constant since all valves are closed.

closure of aortic and pulmonary valves- S2 dub

Question 23

phase 6

Answer 23

rapid filling
-fall in atrial pressure that occurs after the opening of mitral valve is called Y descent

ventricular volume- when intraventricular pressure falls below atrial pressure, the mitral valve opens and rapid ventricular filling begins

mitral/ tricuspid: open
aortoc/pulmonary: closed

Question 24

phase 7

Answer 24

reduced filling
ventricular volume- rate of filling slows down as ventricle reaches its inherent relaxed volume. Further filling is driven by venous pressure

at rest the ventricles are 90% full by end of phase 7

mitral/ tricuspid valve: open
aortic/pulmonary: closed

Question 25

what is stenosis

Answer 25

valve doesnt open enough

obstruction to blood flow when valve normally open

Question 26

what is regurgitation

Answer 26

valve doesnt open all the way
back leakage

AKA incompetence
insufficiency

Question 27

aortic valve stenosis- causes and complications

Answer 27

causes: - degenerative
- congenital
- chronic rheumatic fever - inflammation- commissural fusion

less blood can get into the valve which leads to increased LV pressure- LV hypertrophy

it also leads to left sided heart failure- which leads to syncope and angina

shear stress leads to microangiopathic haemolytic anaemia

Question 28

what causes aortic valve regurgitation

Answer 28

aortic valve dilation- leaflets pulled apart

valvular damage- endocarditis rheumatic fever

Question 29

what does aortic valve regurgitation lead to

Answer 29

blood flows back into LV during diastole
increased stroke volume 
systolic pressure increases
diastolic pressure decreases 
bounding pulse
LV hypertrophy

Question 30

what causes mitrial valve regurgitation

Answer 30

myxomatous degeneration can weaken tissue leading to prolapse- blood leaking back into left atria

caused by damage to papillary muscle after heart attack
left sided heart failure leads to LV dilation which can stretch valve
rheumatic fever can lead to leaflet fibrosis which disrupts seal formation

this increases preload- LV hypertrophy

Question 31

cause of mitral valve stenosis

Answer 31

caused by rheumatic fever
commissural fusion of valve leaflets
harder for blood to floe LA to LV

Question 32

what does mitral valve stenosis lead to

Answer 32

pulmonary oedema
dyspnea
pulmonary hypertension 
all above lead to...
RV hypertrophy 

LA dilation
atrial fibrillation leads to thrombus formation
oesophagus compression leads to dysphagia