The Cardiac Cycle

Question 1

What does the cardiac cycle comprise of

Answer 1

• Pump cycle
• Opening and closing of valves
• Changes in aortic, ventricular and atrial pressure
• Changes in ventricular volume

Question 2

What stages can the cardiac cycle be split into

Answer 2

• Mid-to-late diastole
• Systole
• Early diastole

Question 3

Describe aortic pressure

Answer 3

• Used for blood pressure monitoring
• Minimum - diastolic
• Highest - systolic
• Dicrotic notch caused by shutting of aortic valve

Question 4

Whats the definition of stroke volume

Answer 4

The volume of blood pumped by the LV in one contraction

Question 5

Whats the definition of ventricular diastole

Answer 5

The phase of the heartbeat when ventricles fill with blood

Question 6

Whats the definition of ventricular systole

Answer 6

The phase of the heartbeat when ventricles contract

Question 7

Whats the definition of mean arterial pressure

Answer 7

The average aortic pressure during one cardiac cycle

Question 8

Whats the definition of end diastolic volume

Answer 8

The volume of blood in a ventricle at the end of diastole

Question 9

Whats the definition of isovolumetric contraction

Answer 9

When ventricles contract, but there’s not enough pressure to open semilunar valves, ventricular volume remains constant

Question 10

Whats the definition of isovolumetric relaxation

Answer 10

when ventricles relax, but there’s too much pressure to open atrioventricular valves or keep semilunar valves open, all valves shut, no change in ventricular volume

Question 11

What are the heart sounds

Answer 11

1. First sound occurs at start of systole when the AV valves close
2. Second sound occurs at start of diastole when the SL valves close

Question 12

Describe coronary heart disease

Answer 12

• Caused by accumulation of atherosclerotic plaques in coronary arteries
• Plaques restrict blood flow to the myocardium - leads to chest pain
• Blockade of blood flow causes a heart attack

Question 13

How is a PTCA carried out

Answer 13

• Balloon inflation induces ischaemia in the heart
• Damage to vessel may lead to reclosure in 3-6 months
• Restenosis prevented by introducing stents
• Acute treatment for myocardial infarction

Question 14

Describe the coronary artery bypass graft

Answer 14

• Risk of complication
• Involves stopping the heart
• Grafts can still restenose

Question 15

What are the 2 categories of congenital heart disease

Answer 15

• Acyanotic
• Cyanotic

Question 16

Describe an acyanotic heart disease

Answer 16

• Blood to systemic circuit has normal level of oxygen carried
• Narrowing of the aorta
• Patent ductus arteriosus - Persistent opening between 2 main blood vessels leaving the heart, so blood re-enters heart and puts pressure on ventricles leading to hypertorphic cardiomyopathy

Question 17

Describe a cyanotic heart disease

Answer 17

• Blood to systemic circuit has reduced oxygen carriage
• Very little blood reaches pulmonary circulation
• Ventricular septal defect – blood flows directly from left to right ventricle - caused by incomplete development of septum