L4.1 Valve dysfunction

Question 1

Valve features

Answer 1

• Passive, works through pressure gradient
• Ensure undirectional flow
• Closure → creates heart sounds

Question 2

Heart sounds

Answer 2

• 1st: tri/bicuspid closing (start systole)
• 2nd: semi-lunar closing (start diastole)

Question 3

Isovolumetric relax/contract

Answer 3

• Isovolumetric relaxation: same vol, both valve closed, pressure in V ↓
• Isovolumetric contraction: same vol, both valve closed, pressure in V ↑

Question 4

Valve lesions: Stenosis

Answer 4

• Restricted opening of valve
  
  • ↑resistance → restricted flow
  • ↑pressure gradient
    
    • ↑PRESSURE in upstream chamber

Question 5

Valve lesions: incompetence

Answer 5

• Imperfect closure of valve
• ↓fwd flow & ↑bkwd flow of blood (REGURGITATION)
• ↑VOLUME in upstream chamber

Question 6

What is turbulence?

Answer 6

• Valve lesions causes turbulence
  
  • From high blood velocity
    
    • Results in murmurs

Question 7

Turbulence with normal valves?

Answer 7

• From ↑CO relative to body size
• e.g.:
  
  • Children (growing → ↑CO)
  • Fever (↑CO to skin to lose heat)
  • Anemia (↑CO → pump more blood for same O2 dose)

Question 8

Relationship b/w exercise & valve dysfunction

Answer 8

• ↑demands of exercise exacerbate hemodynamic diifficulties of valve dysfunction

Question 9

Rate of valve lesion onsets

Answer 9

May be v. quick or takes years

Question 10

Consequence of heart attacks on valve lesions

Answer 10

• Papilary muscles lack O2 → die → chordae tendinae detaches → valve broken

Question 11

Aortic regurgitation

Answer 11

• Blood falls back into LV during diastole
• LV vol overload
• Eccentric cardiac hypertrophy
• ↑PP (more blood delivered in systole to compensate)
• Ejection fraction normal (↑ in SV & EDV)

Question 12

Mitral regurgitation

Answer 12

• LV contraction results in blood entering aorta & LA during systole
• LV vol overload (need to pump blood into aorta & LA)
• LA ↑vol during systole (blood from LV)
• LA & LV enlargement
  
  • Enlargement of LA may compress oesophagus → troubles swallowing
• Ejection fraction normal (↑ in SV & EDV)

Question 13

Mitral stenosis

Answer 13

• ↑LA pressure (by ↑vol → hypertrophy of LA)