Prosthetic Valves Flashcards
Prosthetic Valve Classification
Bioprosthetic
•stented: valve tissue (porcine/pericardial), frame (struts), sewing ring
•stentless: allow valves 1-2x larger, increased EOA, decreased gradient, less leaflet stress, more complicated surgery
•transcatheter
Mechanical
•bileaflet: predominant valve (St. Jude, Carbomedics/Soren, ATS/Medtronic)
•single leaflet: rare (Med-Hall off market, Bjork-Shiley recalled, Omniscience)
•ball-cage: rare (Starr-Edwards)
Composite root valves
Homografts
Echo assessment of prosthetic valves
Step 1: 2D exam
What type of valve is it?
•porcine valve — commissural supports are wider
•pericardial valve — leaflets at inner border of struts
•Sorin — leaflets draped around the commissural supports
Valve well seated and leaflets moving appropriately?
•TG views helpful if acoustic shadowing
•ME MC view —> can see 2 leaflets then is anti-anatomic [allows blood to move the leaflets more symmetrically and subvalvular apparatus less likely to interfere with motion]
•not uncommon for one leaflet to stick with low flows off CPB but shouldn’t occur when fully off — subvalvular interference or valve dysfunction
Any extraneous masses present?
Step 2: CFD
- Wide enough sector to see outside sewing ring
- Omniplane 0 - 180º
- If confused : freeze + slow motion replay
Does the antegrade flow look normal?
•limited turbulence
•symmetrical flow with most valves
Are the normal washing jets present?
•closure backflow (prosthetic valves close slower than native valves): short duration and more significant with higher HRs but not substantial
•leakage backflow (built into the valve to minimize thrombus formation = washing jets): after valve closes, low velocity, uniform color, low signal strength with CWD
Bioprosthetic regurgitation
•should be minimal (especially porcine)
•pericardial valve from C-E designed to have small gap in middle to decrease leaflet trauma
•trace - mild central regurgitation commonly seen
Mechanical valve regurgitation sites — dependent on valve type and imaging plane
Any intravalvular pathological regurgitation? •deeply penetrating jets •high velocity •non-homogeneous jets •PISA in the proximal chamber •anything outside the sewing ring
Is there a paraprosthetic leak?
•small, low velocity paravalvular leaks typically resolve after protamine
•map the leak…
Step 3: Hemodynamics
•velocity — peak
•gradients — peak, mean, DVI
•area calculation — EOA, EOAI
Step 4: Rule out collateral damage •non-operative valve damage •coronary obstruction •LV or RV dysfunction •VSD •LVOTO •LV rupture
Prosthetic AV assessment — indicators of significant stenosis
*Peak velocity > 4 m/s
*Mean gradient > 35 mmHg
*DVI < 0.25 [normal = 0.35 - 0.5]
*EOA < 0.8 cm^2
EOAI < 0.75 cm^2/m^2
Contour of jet rounded and symmetrical
AT > 100 ms
Prosthetic MV assessment — indicators of significant stenosis
*Peak velocity ≥ 2.5 m/s
*Mean gradient > 10 mmHg
VTI pmv / VTI lvo > 2.5
EOA < 1 cm^2
*PHT > 200 ms
Prosthetic TV assessment — indicators of significant stenosis
Peak velocity > 1.7 m/s
Mean gradient ≥ 6 mmHg
PHT ≥ 230 ms
EOA and VTI prtv / VTI lvo — no data
Clinical prosthetic valve exam post - bypass
ME LAX view
- Sewing ring well-seated
- Leaflets demonstrate normal excursion
- Normal valvular leak present
- No significant pathological valvular or paravalvular leak (0 - 180º)
- Hemodynamics (gradients, velocities, EOA, etc.)
- Rule out collateral damage
10 General principles for prosthetic valve cases
- Know the prosthetic valves used in your hospital (2D and washing jet pattern)
- Record baseline (pre-bypass) loops of all cardiac structures
- Listen to / watch surgeons during CPB
- Begin post-op assessment before separation from CPB
- Use ME LAX view during de-airing
- Become an expert at obtaining TG views
- Use zoom and slow motion replay
- Get a second opinion if any question
- Have a copy of the HDs reference
- Use the same exam sequence every time
Prosthetic valve complications
Regurgitation ->valvular: •Valve structural defect •Surgical complication •Bioprosthetic leaflet failure •Mechanical leaflet malfunction •Endocarditis ->paravalvular: •Calcium •Surgical •Disrupted suture •Endocarditis / abscess
Stenosis (decreased EOA) ->mechanical: •inadequate leaflet opening (thrombus, retained chordae, structural defect) •pannus formation ->bioprosthetic: •calcium •thrombus •pannus
Masses on valve
•endocarditis
•thrombus
•pannus
TEE characteristics of IE
- mobile mass
- similar gray scale to myocardium
- on upstream surface of valve
- tendency to prolapse into upstream chamber
Differential for high gradient after AVR
- Bad measurement
•over-tracing
•contamination my MR - Bad math
•If flow in LVOT is high (V1^2) then use the modified Bernoulli equation NOT the simplified that the machine uses - Bad physics
•turbulent flow —> thermal loss
•laminar flow —> pressure recovery (small ascending aorta [<3cm], Bentall, mechanical AV)
** # 1 - 3 are NOT at the valve level **
4. Bad choices •patient-prosthesis mismatch ... measured EOA = Expected EOA? ... yes —> EOA < 0.86 cm^2/m^2 = moderate ... yes —> EOA < 0.65 cm^2/m^2 = severe
- Bad valve
•thrombosis
•pannus
•technical mishap ( most likely in fresh valve )
Increased suspicion for valve obstruction: •low LVOT velocity •DVI < 0.25 •calculated EOA < predicted EOA •parabolic profile (AT > 100ms)
