Cardiac cycle

Question 1

List the sequence of the cardiac cycle

Answer 1

Atrial systole
Isovolumic contraction
Rapid ejection
Reduced ejection
Isovolumic relaxation
Rapid filling
Reduced filling

Question 2

Describe systole and diastole

Answer 2

Systole- when the heart contracts and ejects blood into the pulmonary trunk and aorta (isovolumic contraction, rapid and reduced ejection)
Diastole- The rest of the cardiac cycle

Question 3

Describe the atrial contraction- when in occurs in relation to the ECG and what wave it is on atrial line.

Answer 3

It occurs just after the start of the P wave. Represented by the A wave

Question 4

When does isovolumic contraction occur in relation to the ECG and what heart sound is heard here and what causes the sound

Answer 4

Peak of R wave

The first heart sound. Is the inlet valves closing

Question 5

What valves open during the rapid ejection phase and what happens to atrial pressure

Answer 5

The outlet (aortic and pulmonary semilunar valves)
Atrial pressure instead of slowly rising due to atrial filling against closed bicuspid and tricupid valves, dips as when the ventricles contract they pull down on the atria increasing their size

Question 6

Describe reduced ejection aortic pressure, atrial pressure, ventricular pressure, end systolic volume

Answer 6

As the run off from the aorta to the periphery exceeds ventricular output aortic pressure drops. Atrial pressure starts rising with the filing from the veins and ventricles relaxing pulling less on atria. The outlet valves stay open despite the arteries having slightly greater pressures due to the forward momentum of the flow. ESV is around 60mLs

Question 7

Describe isovolumic relaxation. Valves, heart sounds and what the incisura is on the aortic pressure curve

Answer 7

Outlet valves close producing second heart sound. Incisura is where there aortic valve closes and there is a a small back flow. Atrial pressure rises

Question 8

Describe rapid filling

Answer 8

Atrial pressure rises above ventricular pressure and the inlet (bicuspid and tricuspid) valves open there is a rapid increase in ventricular volume

Question 9

Describe reduced filling

Answer 9

Equalized pressures, slow rise in ventricular volume and atrial and ventricular pressures.

Question 10

Describe the 1st heart sound (what, when, frequency)

Answer 10

• Atrioventricular valve closure
• Onset of ventricular systole.
• Low frequency

Question 11

Describe the 2nd heart sound

Answer 11

• Closure of the outlet, semilunar, valves
• At beginning of isovolumic relaxation
• Higher frequency

Question 12

Describe the 3rd heart sound

Answer 12

• Early diastole
• Rapid entry of blood into ventricle causing wall vibrations
• During rapid filling

Question 13

Describe a means of obtaining right atrial pressure

Answer 13

Thread a catheter from jugular vein- SVC- R atrium-Rventricle- Pulmonary artery. The pressure recorded during balloon inflation is similar to left atrial pressure because the occluded vessel and its distal branches that eventually form the pulmonary veins act as a long catheter that measures the blood pressures within the pulmonary veins and left atrium.

Question 14

Describe the Ficks Method

Answer 14

A means of obtaining CO through using the conservation of mass principle.

Question 15

Describe thermodilution

Answer 15

An indicator dilution technique.
Indicator is cold saline
Measure downstream temperature change instead of dye concentration. Changes in temperature in pulmonary artery then used to calculate CO