Lecture 7

Question 1

Define stroke and kinetic work

Answer 1

Stroke work:

• Contracting and pumping blood into aorta (and pulmonary artery)
• Area represented by pressure volume loop

Kinetic Work:
-Accelerating the blood through the valves into aorta (and pulmonary arteries)

Question 2

Calculate stroke work

Answer 2

Mean arterial Pressure x Stroke volume

(MAP= 1/3(SBP-DBP)+DBP)

MAP = (2xDBP)+SBP/3

Question 3

How is preload changed in the body?

Answer 3

-Altering end diastolic volume (Direct relationship w preload)

(Venoconstriction/venodilation or altering blood volume –> Alters VR –> Alters EDV)

(Vasoconstriction = direct = increase VR = Inc EDV, vasodilation = inverse = decrease VR = dec EDV)

Question 4

How is afterload changed in the body?

Answer 4

-Altering aortic pressure of changing total peripheral resistance

Question 5

How is contractility changed in the body?

Answer 5

-Altering sympathetic activity, or by giving drugs which alter inotropic state

Question 6

Whats the relationship between preload and stroke volume?

Answer 6

Direct Relationship

Increasing preload increasing stroke volume

Question 7

What’s the relationship between contractility and stroke volume?

Answer 7

Direct Relationship

Increasing contractility increasing stroke volume

Question 8

What’s the relationship between afterload and stroke volume

Answer 8

Inverse Relationship

Increasing afterload decreases stroke volume

(Heart can usually compensate for this)

Question 9

What effects does exercise have on pressure volume loop?

Answer 9

1) Increases sympathetic activity
- Increases venomotor tone –> increases venous return –> Increases end diastolic volume–> increases preload –> increases stroke volume

2) Increases sympathetic activity –> Increases contractility –> Increases stroke volume

Question 10

When should you hear sound in a normal heart?

Answer 10

When valves are closing

Never when valves are opening

Question 11

What does the “Lub” sound come from

Answer 11

S1: Closure of A-V valves (Mitral and tricuspid)

-Bottom right corner of Pressure volume loop

Question 12

What does the “Dub” sound come from

Answer 12

S2: Closure of semilunar valves (Aortic and pulmonary)

-Top left corner of the pressure volume loop

Question 13

Splitting of S2 heart sound

Answer 13

-Aortic closes before the pulmonary valve during inspiration

Physiological = normal - inspiration

Pathological = Conduction defects

Question 14

S1 Splitting

Answer 14

Pathological

-Occurs in conduction defects on one side of the heart

Question 15

S3 Pathological heart sounds

Answer 15

-Rush of blood into ventricles from atria can create a sound

Question 16

S4 Pathological heart sounds

Answer 16

-Stiff ventricles can make a sound

Question 17

What’s a Heart murmur and how does it happen

Answer 17

• Abnormal sounds heard during Auscultation
• Caused by faulty valves –> turbulent flow = noise

1) Stenosis
- Opened valve is narrowed
- Higher pressures needed to push blood through

2) Incompetence
- Closed valve is leaky –> Regurgitation

Question 18

What causes a systolic murmur

Answer 18

1) Aortic stenosis

2) Mitral incompetence

Question 19

What causes a diastolic murmur

Answer 19

1) Mitral stenosis

2) Aortic incompetence

Question 20

Describe aortic stenosis and it effects

Answer 20

• Systolic murmur
• Difficult to eject blood through aortic valve (Narrow high resistance valve)
• Decrease stroke volume
• Increase end-systolic volume

Buzzword: “Crescendo Descendo”

Question 21

Describe Mitral Incompetence and its effects

Answer 21

• Systolic murmur
• Ventricular systole causes blood to regurgitate back into Left atrium in murmur that extends throughout systole
• Increase stroke volume
• Decrease end-systolic volume
• Increase end-diastolic volume

Question 22

Describe Aortic incompetence and its effects

Answer 22

• Diastolic murmur
• Aortic valves fail to close properly left ventricle pressure rises as blood regurgitates from aorta into left ventricle
• Increase stroke volume
• Increase end-diastolic volume

Question 23

Describe Mitral stenosis and its effects

Answer 23

• Diastolic murmur
• Turbulent flow across mitral/tricuspid valve
• LA pressure is elevated
• Decrease stroke volume
• Decrease end-diastolic volume

Buzzword: “Open snap”