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MRCP PACES Cardiology > Valve Replacement > Flashcards

Valve Replacement Flashcards

1
Q

What are the examination findings/signs of mechanical valve replacement?

A
  1. Midline sternotomy scar in all valve replacement
    - Look for concomittant CABG harvest scars
    - Look for left lateral thoracotomy scar - previous mitral valvotomy
    - Complex scars -> Tetralogy of Fallot
  2. Apex beat - deviated vs not deviated
  3. Metallic and distinct heart sound: S1 or S2
    - Ball and cage: whoosing sound and double metallic click (closing > opening)
    - Disc: metallic click without murmur
    (Careful of double metallic valve replacement - confused with SE valve)
  4. Valve thrombosis or flow murmur?
    - All AVR will produce ESM (which may also signify AVR stenosis/thrombosis)
    - SE MVR will produce MDM at apex loudest on expiration in left lateral position (which also signify MVR stenosis /thrombosis)
    (Always comment in PACES TRO valve thrombosis)
  5. Any untreated murmurs or new onset valve failure
    - Loss of crisp click in metallic valve
    - New murmurs (regurgitation): PSM for MVR leak; EDM for AVR leak
    - Change in character or intensity of existing sound
    - Low volume, slow rising pulse - stenotic AVR or normal in Starr-Edwards valve
    - Large volume or collapsing pulse - malfunctioning AVR with AR
  6. Signs of overwarfarinisation
  7. Signs of anaemia - blood loss, haemolysis, endocarditis
  8. +/- pulmonary hypertension if longstanding prior to surgery (mitral lesion > aortic lesion)
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2
Q

How to determine what was the original vavular lesion prior to valve replacement?

A
  1. Which valve is replaced? mitral vs aortic
    - S1 metallic -> mitral valve replacement
    - S2 metallic -> aortic valve replacement

(S1 is closure of mitral/tricuspid, S2 is closure of aortic/pulmonary)

  1. Apex beat deviation
    - Deviated: MR (S1 metallic) ; AR (S2 metallic)
    - Not deviated: MS (S1 metallic) ; mild AS (S2 metallic) - severe AS with LVH will deviate
  • Careful about double metallic valve replacement
Clues in the event of double audible click (Starr Edwards) :
- Left lateral thoracotomy scar - previous mitral valvotomy -> MVR
- Pulmonary hypertension and right heart failure more common in MV disease
- Starr Edwards mitral valve - S1 closing click, **S2 native valve + opening click**
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3
Q

How would you investigate valve dysfunction?

A
  1. History and examination
  2. TTE - often difficult
  3. TEE - MV prosthesis
  4. Cinefluoroscopy
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4
Q

What are the criterias for valve replacement in aortic regurgitation?

A

Symptomatic: severe aortic regurgitation with angina or dyspnoea
Asymptomatic: mod/severe aortic regurgitation undergoing other cardiac surgery, left ventricular dysfunction, dilated left ventricle

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5
Q

What are the indications for aortic valve replacement?

A
  1. Aortic stenosis
    - Severe symptomatic (gradient > 50mmHg)
    - Mod-severe asymptomatic: concomittant CABG, LVSD > 40mmHg, abnormal BP response, VT, valve area <0.6cm2
  2. Aortic regurgitation
    - Severe symptomatic: angina, dyspnoea
    - Mod-severe asymptomatic: concomittant CABG, EF < 50%, LVESD > 55mm
  3. Infective endocarditis not responding to medical therapy
  4. Enlarging aortic root diameter irrespective of degree of aortic regurgitation
  5. Sinus of valsalva aneurysm rupture
  6. Aortic dissection causing aortic regurgitation
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6
Q

Which patients should receive bioprosthetic valves?

A

Anticoagulation is contraindicated
Life expectancy shorter than expected life span of the prosthesis
Patient age >70 (degeneration is slower)

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7
Q

What are the complications of prosthetic valves? (Metallic and tissue)

A
  1. Thromboembolism (5%)
    - < 5mm for IV heparin, > 5mm for fibronolysis or valve replacement
  2. Complications of anticoagulation
    - Overanticoagulation -> BGIT, anaemia, ICB
  3. Valve dysfunction
    - Leaking, dehiscence, fracture
    - Stiffening or calcification and stenosis (bioprosthetic)
    - Perforation and regurgitation (bioprosthetic)
    (Valve strut failure in Bjork Shiley valve - high mortality)
  4. Infective endocarditis
  5. Haemolytic anaemia (mechanical valve) and jaundice
  6. AV conduction defect (in aortic lesion)
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8
Q

What are the advantages and disadvantages of mechanical valves?

A

Advantages:
- Longer life span of valve compared to biological valve
- Lowere rate of re-operation

Disadvantages:
- Life long anticoagulation (INR 2.5 - 3.5)

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9
Q

What are the indications for mitral valve replacement?

A
  1. Mitral stenosis
    - Pulmonary congestion and pulmonary hypertension
    - Haemoptysis
    - Recurrent thromboembolism despite anticoagulation
  2. Mitral regurgitation
    - LV dysfunction
    - EF < 60% even if asymptomatic
    - LVESD > 45mm even if asymptomatic
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10
Q

What are the indications for anticoagulation in mitral valve disease?

A

Valvular atrial fibrillation (mitral stenosis)

Previous embolic disease

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11
Q

What are the types of mechanical heart valves?

A
  1. Ball and cage (Starr Edwards)
    - Ball valve hitting cage in systole/diastole with whooshing sound of blood. double metallic click
  2. Single tilting disc (Bjork-Shiley) - low incidence of haemolysis
  3. Double tilting disc (St Judes)
    - Metallic click of valve shutting, no murmur
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12
Q

Which patients should receive mechanical valve?

A
  1. Young age - longer lifespan of mechanical valve
    (However homografts are still 1st choice of replacement)
  2. Already on long term anticoagulation
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13
Q

What are the types of bioprosthetic heart valves?
What are the advantages and disadvantages?

A
  1. Xenograft (porcine or bovine)
  2. Homograft (cadaveric)

Advantages
- No need lifelong anticoagulation (3 months only) unless AF -> safer in elderly, pregnancy
- Homografts are more resistant to infection (useful in replacing infected valves)

Disadvantages
- Less durable (mitral 7 years, aortic 10 years)
- High rate of re-operation
- Prone to calcification

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14
Q

What are the causes of anaemia in valve replacement?

A
  1. Overanticoagulation
  2. Haemolytic anaemia
  3. Infective endocarditis
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15
Q

When to suspect clinically that valve has malfunctioned?

A
  1. New murmur
  2. Change in characteristic or intensity of pre-existing murmur/audible sound
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16
Q

Are MRI safe for mechanical heart valves?
Which mechanical heart valve is unsafe?

A

Yes
Except pre-6000 Starr Edwards prosthesis (1960-1964)

17
Q

Describe this valve sound

A

Ball and cage aortic valve replacement
- Ejection rattle in systole (opening position)
- Loud metallic S2 in diastole, ball closes back into place

(For ball and cage mitral valve replacement - the S1 closure is loud, with rattle in S2 rattle during ventricular diastole/filling)

MRCP PACES Cardiology (21 decks)

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