Heart Pump - Nordgren

Question 1

How do you calculate the Arterial Pulse Pressure?

(hint: Wigger’s Diagram)

Answer 1

PP = Systolic pressure – Diastolic pressure

Question 2

How do you calculate the Stroke Volume from the Wigger’s Diagram?

Answer 2

SV = End-Diastolic volume – End-Systolic volume

Question 3

What is the S1 heart sound due to?

Answer 3

closure of AV valves

(Lub)

Question 4

What is the S2 heart sound due to?

Answer 4

closure of aortic & pulmonic valves

(Dub)

Question 5

When does the physiological splitting of the S2 heart sound occur?

Answer 5

• Pulmonic valve closes slightly after aortic valve
  
  • Inspiration causes increase in this gap
    
    • changes intrathoracic pressure and pulmonary vascular resistance lead to prolonged right ventricular ejection

Question 6

What does the presence of the S3 heart sound indicate in an adult?

Answer 6

left ventricular failure

Question 7

What does the presence of the S4 heart sound indicate in an adult?

Answer 7

ventricular diastolic stiffness

Question 8

How do you calculate the Ejection Fraction from the PV loop?

Answer 8

Stroke Volume ÷ Peak Volume

(e.g. SV: 125-50=75 —> EF: 75/125=60%)

Question 9

Increased Preload has what effect on stroke volume?

Answer 9

• Increase initial muscle fiber length
• Increase amount of shortening
• Increased end-diastolic volume
• Increased stroke volume

Question 10

Increased afterload has what effect on Stroke Volume?

Answer 10

• Larger total load on muscle
• Less amount of shortening possible
• Decrease Stroke volume
  
  • decreased cardiac output

Question 11

What two clinical conditions demonstrate the problem with increased afterload?

Answer 11

• Hypertension
• Aortic valve obstruction

Question 12

What effect does norepinephrine have on the contractility of cardiac muscle cells?

Answer 12

• NE –> increased contractility
  
  • more shortening potential

Question 13

What effect does norepinephrine have on the Stroke Volume?

Answer 13

• NE –> more shortening potential –>
• Increased contractility –>
• Decreased end-systolic volume
• Increases Stroke Volume

Question 14

What effect does altered sympathetic neural activity have on the cardiac inotropic state?

Answer 14

• Norepinephrine = positive inotrope
  
  • increased cardiac contractility
  • altered Ca²⁺ current –> additional Ca²⁺ release from sarcoplasmic reticulum
  • allows additional binding to troponin –> exposure of even more myosin heads.

Question 15

What are the major distinct phases of the cardiac cycle as delineated by valve opening and closure?

Answer 15

• Mitral Valve opens:
  
  • after T wave
  • after S2 (Dub)
  • when the left ventricular pressure falls below atrial pressure
• Mitral Valve closes:
  
  • S wave
  • during S1 (Lub)
• Aortic Valve opens:
  
  • ST segment
  • after S1 (Lub)
• Aortic Valve closes:
  
  • end of T wave
  • during S2 (Dub)

Question 16

What is Starling’s Law of the Heart?

Answer 16

The heart pumps what it receives!

(If cardiac filling increases during diastole, the volume ejected during systole also increases.)

Question 17

What factors influence myocardial oxygen consumption?

Answer 17

• HR
  
  • more O₂ is needed to contract rapidly than to do it slowly.
• Cardiac preload
  
  • at a larger radius more tension is needed
  • more pressure work takes more energy
  • Laplace’s Law: T= P x r
• Cardiac afterload
  
  • systemic arterial pressure
• Cardiac contractility