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Week 11: Prosthetic Valve Complications > Prosthetic Valve Complications > Flashcards

Prosthetic Valve Complications Flashcards

1
Q

Definition of prosthesis-patient mismatch (PPM)?

A
  1. PPM presents when EOA of prosthesis being implanted is less than that of normal human valve
  2. PrV is too small in relation to body size
  3. Leads to abnormally high transvalvular pressure gradients
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2
Q

IEOA (cm2/m2) reference values for AVR?

A
  • Mild or not clinically significant PPM: IEOA > 0.85
  • Moderate PPM: IEOA 0.85 - 0.66
  • Severe PPM: IEOA ≤ 0.65
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3
Q

IEOA (cm2/m2) reference values for MVR?

A
  • Mild or not clinically significant PPM: IEOA > 1.2
  • Moderate PPM: IEOA 1.2 - 1.0
  • Severe PPM: IEOA ≤ 0.9
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4
Q

IEOA (cm2/m2) reference values for TVR?

A
  • Mild or not clinically significant PPM: -
  • Moderate PPM: -
  • Severe PPM: IEOA ≤ 0.9
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5
Q

Why is the identification of PPM important?

A
  • Risk of mortality increases with severity of PPM
  • PPM is also associated with:
    1. Suboptimal haemodynamic status
    2. Reduced exercise tolerance
    3. More adverse cardiac events
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6
Q

PPM vs PrV Stenosis: Gradients

A
  • Gradients elevated in both PPM and stenosis
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7
Q

PPM vs PrV Stenosis: IEOA

A
  • IEOA reduced in both PPM and stenosis
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8
Q

DPI/DVI in PPM?

A

Normal

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9
Q

PPM vs PrV Stenosis: Baseline Study

A
  • PPM: no change from baseline study

- Stenosis: increasing gradients as stenosis worsens

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10
Q

PPM vs PrV Stenosis: Leaflet/disc Motion

A
  • PPM: normal

- Stenosis: abnormal leaflet/disc motion

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11
Q

Cause of bioprosthetic valve stenosis?

A
  • Caused by leaflet thickening and degeneration (secondary to fibrocalcific changes); reduced mobility of leaflets
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12
Q

Causes of machanical valve stenosis?

A
  1. Thombus and/or pannus formation (most common cause of obstruction)
  2. Faulty design
  3. Acute dehiscence
  4. Swelling of poppet (ball-cage valves)
  5. Residual chordal tissue obstruction of mechanical disc motion (such as MVR with chordal preservation)
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13
Q

What is the role of echo in PrV stenosis?

A
  1. Identify aetiology of stenosis/obstruction
  2. Determine the pressure gradients
  3. Calculate the effective orifice area (EOA)
  4. Assess chamber dimensions and ventricular function
  5. Estimate RVSP (especially for MVR stenosis)
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14
Q

How to identify mechanical MVR obstruction?

A
  • Mechanical disc opening but lateral disc stuck closed throughout cardiac cycle
  • Lateral disc vs medial disc reverberation artifact - can see lateral artifact not moving unlike medial
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15
Q

What is the aim of MVR with chordal preservation?

A

Performed with the aim to:

  1. Preserve LV geometry and function
  2. Reduce operative mortality
  3. Improve early and long-term survival
  4. Reduce risk of ventricular rupture
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16
Q

How can MVR with chordal preservation cause obstruction?

A

Resected chordal tissue can become entangled between discs/struts of the valve causing PrV obstruction

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17
Q

How can MVR cause LVOTOB?

A

If struts of PrV are angled towards LVOT, can cause LVOTOB

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18
Q

CFI Doppler evidence of obstruction?

A

Turbulent flow across the valve

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19
Q

Spectral Doppler evidence of obstruction?

A
  1. Elevated transprosthetic gradients
  2. Decreased EOA
  3. Decreased DPI (AVR)
  4. Increased DVI (MVR, TVR)
  5. Prolongation of p1/2t (MVR, TVR)
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20
Q

Formula for DPI in AVR?

A

DPI = LVOT VTI / AV VTI

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21
Q

Indications of severe AVR obstruction/stenosis?

A
  1. DPI < 0.25
  2. AVR signal round; peaks mid-systole
  3. AVR AT > 100ms
  4. AT ÷ LVOT ET = greater than 0.37
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22
Q

Formula for DVI in MVR?

A

DVI = MV VTI / LVOT VTI

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23
Q

Limitation of MVR DVI?

A

DVI can also be elevated when significant prosthetic mitral regurgitation

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24
Q

Indications of likely (95%) MVR obstruction?

A
  1. Peak E ≥ 1.9m/s
  2. DVI ≥ 2.2
  3. P1/2t ≥ 130ms
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25
Q

Indications of TVR obstruction/stenosis?

A
  1. Peak E > 1.7m/s
  2. mPG ≥ 6mmHg
  3. p1/2t ≥ 230ms
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26
Q

Limitations elevated gradients in TVR obstruction/stenosis?

A

Elevated gradients may also occur:

  1. In high flow conditions/high output states
  2. Prosthetic valve regurgitation (regurgitation increases SV across valve)
  3. PPM
  4. Rapid pressure recovery (RPR)
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27
Q

What is rapid pressure recovery (RPR)?

A
  • The recovery of pressure which occurs downstream from a narrowing
  • As flow passes through narrowed orifice, velocity at narrowest point (vena contracta) increases and the pressure at this point drops
  • Once flow has passed through the narrowed orifice, the pressure gradually ‘recovers’ so that the pressure increases towards its original value
28
Q

Effect of rapid pressure recovery (RPR) in mechanical valves?

A
  • May be encountered in small sized bileaflet mechanical valves where velocity through smaller central orifice is higher than those at larger, lateral orifices
  • Therefore, velocities measured through central orifice leads to overestimation of pressure gradients and underestimation of EOA
  • Can also occur in ball-cage valves
  • If aorta is small in dimension, RPR within aorta immediately distal to PrV may also occur
  • RPR not usually problematic in most mechanical valves, and definitely not in bioprosthetic valves
29
Q

What causes transvalvular regurgitation in biological valves?

A

Leaflet degeneration causes regurgitation

30
Q

What causes transvalvular regurgitation in mechanical valves?

A

Thrombosis/pannus causing incomplete closure of discs = regurgitation

31
Q

What are the causes of paravalvular regurgitation?

A
  1. Dehiscence
  2. Vegetations
  3. Fibrosis
  4. Calcification
    - Associations with the valve bed
32
Q

Possible mechanisms for AR in TAVI?

A
  1. Incomplete prosthesis apposition to native annulus due to ridges of calcium
  2. Implantation of valve too shallow
  3. Implantation of valve too deep
  4. Implantation of prosthesis too small for valve annulus
33
Q

What is transvalvular regurgitation?

A

Regurgitation that occurs within the sewing ring

34
Q

What is paravalvular regurgitation?

A

Regurgitation that arises outside the sewing ring => between sewing ring and valve annulus

35
Q

What is the role of echo in PrV regurgitation?

A
  1. Identify aetiology of regurg. (show abnormality eg. ring rocking or other abnormal motion to suggest valve is loosening and may be regurgitant)
  2. Determine site of regurg. (valvular versus paravalvular)
  3. Differentiate normal from pathological regurg.
  4. Assess regurg. severity
  5. Assess chamber dimensions and ventricular function
  6. Estimate RVSP (esp. for MVR regurg.)
36
Q

Mild grading for paravalvular AR?

A

< 10% of circumference (PSAX) or < ‘6 mins’ of ‘clock face’

37
Q

Moderate grading for paravalvular AR?

A

10-20% of circumference (PSAX) or ‘6-12 mins’ of clock face

38
Q

Severe grading for paravalvular AR?

A

> 20% of circumference (PSAX) or > ‘12 mins’ of clock face

39
Q

What are the clues to identifying MVR regurgitation?

A
  1. Strong MR CW signal
  2. Increased transmitral flow velocities and mPG (in the absence of PrV stenosis, PPM or high output states)
  3. Increased DVI > 2.2
  4. Increased RVSP
40
Q

Echo limitations in detecting MR in MVR?

A

Assessment of regurgitation via TTE especially difficult due to imaging artefacts distal to MVR which obscure LA so MR jet is difficult to image

41
Q

Indications of Significant MVR Regurgitation (83%)?

A
  1. Peak E velocity ≥ 1.9m/s
  2. DVI ≥ 2.2
  3. P1/2t < 130ms
42
Q

P1/2t in MVR regurgitation vs MVR obstruction?

A

P1/2t < 130ms suggests regurgitation whilst p1/2t ≥130 suggests MVR obstruction

43
Q

Qualitative CFI parameters used to grade AVR regurgitation?

A
  1. Jet height ratio
  2. Jet area ratio
  3. Vena contracta width
44
Q

Qualitative CFI parameters used to grade MVR regurgitation?

A
  1. Jet height ratio
  2. Vena contracta width
  3. Flow convergence radius
45
Q

Qualitative CFI parameters used to grade TVR regurgitation?

A
  1. Jet height ratio
  2. Vena contracta width
  3. Flow convergence radius
46
Q

Qualitative CFI parameters used to grade PVR regurgitation?

47
Q

Qualitative spectral Doppler parameters used to grade AVR regurgitation?

A
  1. Intensity of AR CW jet
  2. AR p1/2t
  3. Diastolic flow reversal (desc. & abdo. aorta)
48
Q

Qualitative spectral Doppler parameters used to grade MVR regurgitation?

A
  1. Pulmonary venous PW
  2. Intensity of MR CW jet
  3. MR jet contour
49
Q

Qualitative spectral Doppler parameters used to grade TVR regurgitation?

A
  1. Hepatic venous PW
  2. Intensity of TR CW jet
  3. TR jet contour
50
Q

Qualitative spectral Doppler parameters used to grade PVR regurgitation?

A
  1. Diastolic flow reversal (branch PA)
  2. Intensity of PR CW jet
  3. Deceleration of PR
51
Q

Quantitative parameters used to grade AVR regurgitation?

A
  1. Regurgitant volume

2. Regurgitant fraction

52
Q

Quantitative parameters used to grade MVR regurgitation?

A
  1. Regurgitant volume
  2. Regurgitant fraction
  3. Effective regurgitant orifice area
53
Q

What is thrombus in PrV?

A
  1. Formation of blood clot around/over PrV
  2. Interferes with valve function; stuck closed = obstruction, stuck open = regurgitation
  3. More common in mechanical valves (and inadequate anti-thromboembolitic therapy)
54
Q

What is pannus in PrV?

A
  1. In-growth fibrous tissue over sewing ring (response to healing, develops over years)
  2. More common in mechanical valves
  3. Interferes with valve function:
    => significant obstruction = may interfere with occluder/leaflet motion, narrowing PrV resulting in significant obstruction
    => secondary thrombus can occur
55
Q

Thrombus vs Pannus: Clinical parameters

A

Thrombus:

  1. Time from surgery to valve malfunction shorter (~2 months)
  2. Symptom duration shorter (<1 month)
  3. Inadequate anticoagulation

Pannus:

  1. Time from surgery to valve malfunction longer (~6 months)
  2. Symptom duration longer (~10 months)
  3. Adequate anticoagulation
56
Q

Thrombus vs Pannus: Echo parameters

A 
Thombus:
1. Larger
2. Soft tissue appearance
3. Mobile
4. Extension beyond PrV ring to adjacent cardiac structures
5. More common in MVR than AVR
Pannus:
1. Smaller
2. Echo dense appearance
3. Firmly fixed
4. Annular location (along valvular plane)
5. More common in AVR than MVR
57
Q

Why is distinction of thrombus from pannus essential?

A
  • Thrombolytic therapy for thrombus

- Re-operation (if significant obstruction) for pannus

58
Q

What is dehiscence?

A
  • “Rocking” of valve with angle of excursion far beyond normal
  • Caused by partial separation of sewing ring from annulus
59
Q

What can cause dehiscence?

A
  • “Unraveling” of sutures

- Pulling away of PrV from native annulus secondary to IE

60
Q

What can dehiscence result in?

A
  1. Significant obstruction

2. Paravalvular regurgitation

61
Q

How can prosthetic valve endocarditis (PVE) lead to regurgitation?

A
  1. Infection of prosthetic leaflets or native annulus
  2. Further complicated by leaflet perforation and valve bed abnormalities (eg. abscesses, dehiscence and paravalvular regurgitation, fistula or pseudoaneurysms)
62
Q

TTE vs TOE in PVE?

A
  • TOE more sensitive than TTE in detection of IE
  • TTE often inadequate in detection of PVE, especially in detection of complications of IE => vegetations can be masked by artifact
63
Q

What is the echo appearance of IE?

A
  1. Hypermobile and independently mobile mass
  2. Intermittent or persistent impairment to valve closure/opening (due to vegetation)
  3. Varying degrees of stenosis and/or regurgitation
    Note: consideration of clinical information required i.e. febrile illness etc. = IE
64
Q

What is haematoma?

A
  • Complication of cardiac surgery
  • Pericardial haematoma can form around RA in region where venous cannula was inserted
  • Heterogenous appearance characteristic of clotting blood
65
Q

RA haematoma

A

Large heterogenous mass encroaching on right heart - consistent with large haematoma around RA

66
Q

How does Haematoma Occur Post AVR?

A
  • Small leak from suture line can result in accumulation of blood around aortic root which clots over time
  • Appearance can be initially mistaken for aortic root abscess
  • Aortic haematoma usually resolves over 3-6 months

Week 11: Prosthetic Valve Complications (1 decks)

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