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LSS 1 > Cardiovascular Systems 3 - Cardiovascular Mechanics 2 > Flashcards

Cardiovascular Systems 3 - Cardiovascular Mechanics 2 Flashcards

1
Q

What are the two main phases of the heart, and what proportion of the heart beat do they take up?

A
  • Diastole is the relaxation of the ventricle, which is split into 4 distinct phases
  • Systole is the contraction of the ventricle, which is split into 3 phases.
  • Diastole is 2/3 of the heartbeat, and systole is 1/3.
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2
Q

List the 3 phases of systole.

A
  • Isovolumetric contraction
  • Rapid ejection
  • Slow ejection
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3
Q

List the 4 phases of diastole.

A
  • Isovolumetric relaxation
  • Rapid passive filling
  • Slow passive filling
  • Atrial systole
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4
Q

How can the stroke volume be calculated?

A

End diastolic volume - end systolic volume

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5
Q

How can the ejection fraction be calculated?

A

Stoke volume / end diastolic volume x 100

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6
Q

Describe the process of atrial systole.

A
  • The P wave on an ECG signifies the start of the heartbeat
  • The ventricles are already filling slowly via movement of blood down its pressure gradient. To finish vetricular filling, there is contraction of the atria
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7
Q

When is the 4th heart sound heard?

A

When there is arterial stenosis, resulting in a greatly thickened ventricular wall.

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8
Q

Describe the process that occurs in isovolumetric contraction.

A
  • This is where the ventricle is contracting and pressure is increasing but there is no change in volume, as the pressure must be high enough to open the aortic valve/pulmonary valve.
  • Accompanied by the QRS complex - signifying ventricular depolarisation.
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9
Q

What causes the first heart sound (lub)?

A

The AV valve closing due to increasing ventricular pressure.

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10
Q

What happens during rapid ejection?

A
  • The aortic and pulmonary valves open at this stage

- He volume in the ventricles decreases

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11
Q

What happens during reduced ejection?

A
  • End of systole
  • There is a reduced pressure gradient, so the pulmonary and aortic valves start to close. Blood leaving the ventricle slows. Finally, the valves fully close.
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12
Q

What happens during isovolumetric relaxation?

A
  • All valves are shut

- There is no change in ventricular volume, but the pressure decreases. Atrial pressure increases as blood flows in.

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13
Q

What does the T wave signify?

A

Ventricular depolarisation

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14
Q

What causes the second heart sound?

A

Closing of the semilunar valves

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15
Q

What happens in rapid passive filling?

A
  • The pressure in the atria overcomes that in the ventricle, so the AV node opens.
  • Blood flows into the ventricles
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16
Q

What causes the third heart sound?

A
  • Usually abnormal - turbulent ventricular filling

- Due to hypertension or mitral incompetence

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17
Q

What is another name for reduced passive filling?

A

Diastasis

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18
Q

What occurs in reduced passive filling?

A
  • The ventricle fills slowly without contraction of the atria.
  • This is the longest phase.
19
Q

How similar are the pressures in the left and right heart?

A
  • Pressures in the right heart are lower
  • Patterns of pressure changes are different
  • Right ventricle ejects the same volume of blood as the left.
20
Q

What is the pressure in the systemic circuit?

A

120/80mmHg

21
Q

What is the pressure in the pulmonary circuit?

A

25/5mmHg

22
Q

What is the axis on a pressure volume loop?

A

Volume (x) and pressure (y)

23
Q

What is the point A on a pressure volume loop?

A
  • Mitral valve closes

- End diastolic volume, meaning it represents the preload

24
Q

What is the point B on a pressure volume loop?

A
  • Aortic valve opens

- Diastolic blood pressure

25
Q

What is point C on a pressure volume loop?

A
  • End systolic volume

- Aortic valve closes (lub)

26
Q

What is point D on a pressure volume loop?

A
  • Mitral valve opens
27
Q

What is the line A to B on a pressure volume loop?

A

Isovolumetric contraction

28
Q

What is the line B to C on a pressure volume loop?

A

Ejection

29
Q

What is the line D to C on a pressure volume loop?

A

Isovolmetric relaxation

30
Q

What is the line D to A on a pressure volume loop?

A

FIlling

31
Q

Where is the end diastolic PV line on a pressure volume loop and what does it denote?

A
  • Passes from A to D and beyond

- The end diastolic PV line denotes elastance (preload)

32
Q

Where is the end systolic PV line on a pressure volume loop?

A
  • Passes through C

- Denotes contractility

33
Q

Where is the afterload line on a pressure volume loop?

A

From C through the highest ventricular volume on the x axis.

34
Q

Which section of the PV loop is longest?

A

D to A

35
Q

How is ejection fraction calculated from a PV loop?

A

(volA - volD)/volA

36
Q

How is mean arterial pressure calculated from a PV loop?

A

PressureB + 1/3(PressureC-PressureB)

37
Q

How is pulse pressure calculated on a PV loop?

A

Pressure C - Pressure B

38
Q

How is cardiac output measured on a PV loop?

A

(VolA - VolB) x Heart Rate (67)

39
Q

How can you calculate stroke volume?

A

Volume A to B - Volume C to D

40
Q

How do increases in preload affect the pressure volume loop?

A
  • Increase in stroke volume

- Line A B moves to the right (increased volume)

41
Q

Hoe do increases in afterload affect the pressure volume loop?

A
  • Decreased stroke volume, but an increased pressure
  • Line C D moves to the right (increased volume)
  • Line D A moves upwards (increased pressure)
42
Q

What factors affect stroke volume?

A
  • Preload
  • Afterload
  • Contractility
43
Q

What is contractility?

A
  • The capability of the heart to contract

- Measured by ejection fraction

44
Q

What is the dicrotic notch?

A

A small rise in aortic pressure when the aortic valve closes

LSS 1 (35 decks)

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