The Cardiac Cycle

Question 1

Define venous return

Answer 1

Blood returning to the heart from the systemic circulation and pulmonary circulation. Passes through the atrioventricular valves under its own pressure

Question 2

Define isovolumetric contraction

Answer 2

Ventricles contract, but the pressure is to yet enough to open the semilunar valves therefore ventricular volume remains constant

Question 3

Define ventricular ejection

Answer 3

Exit of the blood from the heart

Question 4

Define isovolumetric relaxation

Answer 4

Ventricles relax, but pressure is too much to allow the atrioventricular valves to open but not enough to keep the semi lunar valves open. So all the valves are shut and ventricular volume doesn’t change

Question 5

Define ventricular filling

Answer 5

Blood enters the ventricles for the atria

Question 6

What is aortic pressure

Answer 6

A blood pressure measurement

Question 7

Why is there a decline in aortic pressure?

Answer 7

As the blood is leaving the aorta

Question 8

When is aortic pressure at its lowest point?

Answer 8

When the aortic valves close in diastole

Question 9

When does aortic pressure increase?

Answer 9

when the aortic valves open during systole

Question 10

When is aortic pressure at its maximum? During diastole or systole?

Answer 10

Systole

Question 11

What causes the formation of the diacritic notch?

Answer 11

It is caused by the shutting of the aortic valve

Question 12

What is the average aortic pressure = to?

Answer 12

Mean arterial pressure (MAP)

Question 13

What is usually the value of the diastolic pressure?

Answer 13

80mmHg

Question 14

What is usually the value of the systolic pressure?

Answer 14

120mmHg

Question 15

How do you calculate pulse pressure (PP)?

Answer 15

Systolic pressure-Diastolic pressure
SP-DP= PP
E.g. 120-80=40mmHg

Question 16

What does a high pulse pressure indicate

Answer 16

Can indicate hardening of arteries (Reduced elasticity)

Question 17

How do you calculate mean arterial pressure (MAP)?

Answer 17

Diastolic pressure + (Pulse pressure/3)
DP+(PP/3)= MAP
E.g. 80+(40/3)=93.3

Question 18

Why is mean arterial pressure NOT an average of the diastolic and systolic pressure?

Answer 18

Because aortic pressure in a cardiac cycle is closer to the diastolic for more time than the systolic values

Question 19

What is end diastolic volume (EDV)?

Answer 19

Volume of blood in ventricles at the end of diastole

Question 20

What is end systolic volume (ESV)?

Answer 20

Volume of blood in the ventricles at the end of systole

Question 21

How do you calculate stroke volume (SV)?

Answer 21

End diastolic volume - end systolic volume
(EDV-ESV= SV)
E.g. 135-65= 70ml

Question 22

What is the ejection fraction (EF)?

Answer 22

It is the ratio of volume ejected in one beat to volume immediately prior to ejection
Volume ejected :volume before ejection

Question 23

How do you calculate the ejection fraction (EF)?

Answer 23

Stroke volume / end diastolic volume
(SV/EDV= EF)
E.g. 70/135= 0.52
Which is 52%

Question 24

What creates the first heart sound?

Answer 24

First sound occurs at the start of systole when atrioventricular valves close

Question 25

What creates the second heart sound?

Answer 25

Second heart sound occurs at the start of diastole when the semi lunar valves close

Question 26

What actually is a heart sound?

Answer 26

Turbulent rush of blood through valves as they narrow and close

Question 27

What is coronary artery disease?

Answer 27

It is due to the accumulation of atherosclerotic plaque in the coronary arteries The plaque restricts blood flow to the myocardium It can lead to chest pain (angina pectoris) and heart attack

Question 28

Name some of the risk factors associated with coronary artery disease

Answer 28

``` Genetics Diabetes Obesity High blood pressure High blood cholesterol Sedentary lifestyle Smoking ```

Question 29

How do doctors detect coronary artery disease?

Answer 29

Before 1999 injected patients with steptokinase to break up blood clots Now we use primary angioplasty to detect narrowing of coronary arteries. This involves injecting a radio opaque dye into the coronary circulation and detecting narrowing areas with X-ray imaging

Question 30

State the 2 routine procedures used to treat coronary artery disease

Answer 30

1. Percutaneous transluminal coronary angioplasty (PTCA) | 2. Coronary artery bypass graft (CABG)

Question 31

Describe what a percutaneous transluminal coronary angioplasty entails (PTCA)

Answer 31

A balloon catheter with an uninflected balloon is threaded into the obstructed are in the artery The balloon is then inflated, it stretches out the arterial walls and squashes any atherosclerosis plaque After lumen is widened, balloon is deflated and catheter is withdrawn

Question 32

What are the problems associated with percutaneous transluminal coronary angioplasty (PTCA)?

Answer 32

Balloon inflation induces ischaemia (Restriction of blood supply to tissues) in heart Damage to the vessel may lead to closure of artery again in 3-6 months. To solve this problem a Stent is introduces to stop the arteries narrowing again

Question 33

What word describes the renarrowing of arteries?

Answer 33

Restenosing

Question 34

Describe what a coronary artery bypass graft (CABG) entails

Answer 34

Normally the saphenous vein from the legs is used (sometimes LIMA is used) It is routine to have between 2-4 grafts to bypass a blocked artery

Question 35

What are the problems associated with a coronary artery bypass graft (CABG)?

Answer 35

Involves open heart surgery Involves stopping the heart Grafts can restenose

Question 36

Define acyanotic

Answer 36

Blood to systemic circulation has normal levels of oxygen carried

Question 37

Deine cyanotic

Answer 37

Blood to systemic circulation has reduced level of oxygen carriage, hence darker blood colour and visible cyanosis

Question 38

What is a septal defect?

Answer 38

Allows blood to flow directly left to right

Question 39

Give an example of a septal defect?

Answer 39

Ventricular septal defect

Question 40

What causes ventricular septal defect?

Answer 40

It is caused by incomplete development of the septum. Causes oxygenated and deoxygenated blood to mix Occurs in 1:500 births

Question 41

Name some congenital heart diseases

Answer 41

Ventricular septal defect Coarctation of the aorta Patent ductus arteriosus Tetraology of fallot

Question 42

What is coarctation of the aorta?

Answer 42

Narrowing of the aorta Which reduces blood flow Results in the left ventricle to pump harder So higher blood pressure

Question 43

What does the ductus arteriosus do?

Answer 43

Allows for oxygen expanse to occur in utero

Question 44

What is patent ductus arteriosus?

Answer 44

When the blood vessel between the pulmonary trunk and aorta (the ductus arteriosus) remains open after birth. This results in blood destined for the aorta flowing instead to the pulmonary trunk as it has a lower blood pressure. This increases the trunk blood pressure and overworks the ventricles

Question 45

What is Tetralogy of fallot?

Answer 45

``` It is a combination of 4 defects: ventral septal defect "over riding" aorta Stenosed pulmonary valve Enlarged right ventricle ``` Results on very little blood reaching the pulmonary circulation leading to cyanosis

Question 46

What is another name for the teratology of fallot and how common is it?

Answer 46

"Blue Baby" | Occurs in 1:2000 births

Question 47

What is an "over riding" aorta?

Answer 47

When the aorta takes output from both ventricles

Question 48

What is the plaque that causes coronary arteries disease called?

Answer 48

atherosclerotic plaque