1. Universitätsherzzentrum
Thüringen
Klinik für Herz- und Thoraxchirurgie
Hemodynamic Comparison between Two
Supraannular Biological Aortic Prosthesis. The
Importance of Sizing Strategies.
Mahmud Diab , Gloria Faerber, Jack Peter,
Wolfgang Bothe, Susan Lemke, Martin Breuer,
Torsten Doenst
Department of Cardiothoracic Surgery, University of Jena, Jena, Germany
2. Background I Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
• Aortic Valve Replacement (AVR) is a common cardiac
procedure with approximately 200 000 implantations
each year worldwide.
• There is a dramatic shift toward use of bioprosthetic
valves.
• Today, according to the STS Database, 80% of
patients receive biological valves.
3. Background II Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
• Despite evolutionary improvement in prosthetic heart
valve design, hemodynamic performance of
prostheses does not yet match that of native valves.
• Significant residual gradients may prevent
regression of LV hypertrophy and are postulated to
influence long-term survival after AVR; a
phenomenon having been described as patient-
prosthesis mismatch.
4. Stented Tissue Valves are „Hemodynamically Challenged“ Universitätsherzzentrum
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Passable for blood stream
Space needed for implantation
5. Mitroflow: Taking on the Challenge… Universitätsherzzentrum
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Passable for blood stream
Space needed for implantation
6. Improved Hemodynamics by Design Universitätsherzzentrum
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Internal orifice area Internal orifice area
Site of Stitches in Sewing Ring
Pericard on the inside Pericard on the outside
7. Porcine Bioprostheses Universitätsherzzentrum
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• The Epic is a stented bioprosthesis made
from porcine aortic cusps.
8. SJM Epic and Epic Supra Universitätsherzzentrum
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9. In vitro comparison Universitätsherzzentrum
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Mitroflow Peri-in Supra Porc-intact Epic Supra
Supra
10. Hemodynamic Expectations Universitätsherzzentrum
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The Mitroflow should be hemodynamically superior to
the Epic Supra,
11. Hemodynamic Expectations Universitätsherzzentrum
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The Mitroflow should be hemodynamically superior to
the Epic Supra,
i.e., Mitroflow should have lower postoperative
pressure gradients and therefore larger effective
orifice areas (EOA)
12. How are „Hemodynamics“ assessed? Universitätsherzzentrum
Thüringen
Klinik für Herz- und Thoraxchirurgie
• Pressure gradient : modified Bernoulli equation:
ΔP= 4 V2
• Effective orifice area (EOA) from continuity equation:
EOA = (Alvot × VTIlvot) / VTItransvalvular
13. Effect of anatomy on EOA Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
Effective
Orifice Area
Geometric
Orifice Area
Large aortic root Small aortic root
14. Hemodynamic Assessment Summary Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
• EOA reflects hemodynamic relevance for the patient.
• EOA is influenced by patient anatomy (LVOTA)
• EOA cannot be used to compare different prostheses.
15. Valves and Sizers – Labeled „23“ Universitätsherzzentrum
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Doenst et al. JTCVS 2011
16. Valves Comparison by Outer Diameter Universitätsherzzentrum
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Internal orifice area
Internal orifice area
28 mm
29 mm
SJM Epic Supra 23 Mitroflow 25
17. Valve Size Selection based on Manufacturer
Suggested Sizing Strategy
Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
18. Valve Comparison by Selected Size Universitätsherzzentrum
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Epic Supra 23 Sorin Mitroflow 21
23mm 17.3mm
23
29
19. Hypothesis Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
The hemodynamic design advantage of the Mitroflow
is lost due to a defensive sizing strategy
compared to the Epic Supra.
20. Patients and Methods Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
• Between Januar 2007 and November 2011, we performed 1067
Aortic valve replacements.
• We retrospectively reviewed discharge echos (performed by the
same examiner) from all patients having received a Mitroflow
(n=161) or an Epic Supra (n=92) aortic prosthesis as the only
valve procedure.
• The decision to implant the given prosthesis was made by the
operating surgeon.
• All patients received supraannular valve placement.
21. Demographic Data Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
Mitroflow Epic Supra
(n=161) (n=92)
Age 74 ± 9.75 74.30 ± 8.36
Female 60% 40%
EF 60.1% ± 13.33 59.4 ± 13.53
AS
moderate 8% 8.7%
severe 64% 45.7%
22. Size Distribution of Implanted Valves Universitätsherzzentrum
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Mitroflow Epic Supra
23. Pressure gradients by size label for Mitroflow Universitätsherzzentrum
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24. Pressure gradients by size label for Epic Supra Universitätsherzzentrum
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25. Valve comparison by Size Label 21 Universitätsherzzentrum
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P <0.05 P <0.05
26. Valve comparison by Size Label 23 Universitätsherzzentrum
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P <0.05 P <0.05
27. Valve Size Selection based on Manufacturer
Suggested Sizing Strategy
Universitätsherzzentrum
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28. Comparison by Selected Size Universitätsherzzentrum
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n.s n.s
29. Conclusions Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
• The hemodynamic design advantage of the Mitroflow
is lost due to a “defensive” sizing strategy.
• The results underscore the importance of sizing
strategy and surgical technique and supports the
provision and the intensive use of replica sizers with
the new generation valves.
31. The Surgeon as Patient Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
• 27 cardiac surgeons in the US needed
aortic valve replacement.
• Question: How many times did they choose
a tissue valve?
32. Determinants of Pressure Gradient Universitätsherzzentrum
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• Valve opening area
o
• Subvalvular dimension
(outflow tract)
• Supravalvular dimension
• Angle LV outflow tract/aorta
34. Controversy about PPM Universitätsherzzentrum
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Klinik für Herz- und Thoraxchirurgie
PPM Relevant PPM Not Relevant
Pibarot et al 2001 Moon et al 2006
Rao et al 2000 Ryomoto et al 2008
Ennker et al 2005 Florath et al 2008
Borger et al 2005 Mascherbauer et al 2008
Lopez et al 2008 Nozohoor et al 2008
Kohsaka et al 2008 Sakamoto et al 2007
Pibarot et al 2007 Kapetanakis et al 2008
Moon et al. 2009* Rinas et al 2007
Mohthy et al. 2009* Moon et al. 2009*
Mohthy et al. 2009*
Jamieson et al. 2010
Geometric expressions of prosthesis size include internal orifice area and external diameter. It would seem logical that the valve with the greatest internal opening area in relation to ist outer diameter should allow the best hemodynamic performmance. The problem is neither of these 2 parameters is reflected by the label size provided by the manufacturer.
The FlexFit stent reduces leaflet stress The outflow edge of the Epic valveis covered with a pericardial shield, providing a tissue-to-tissue interface to help prevent the riskof abrasion. Three separate porcine leafletsare matched to optimize leafletcoaptation and reduce stress
Alvot is the area of the LVOT just before the valve, VTI lvot is the velocity-time integral of pulsed doppler velocity at the LVOT level, VTI transvalvular is calculated from continuous wave doppler velocity through teh prosthesis. Caveats: Varies from moment to moment with patient activity, cardiac output and blood pressure. Varies with the anatomy of the LVOT and aortic root. pitfalls in its calculation. failure to incorporate the effects of pressure recovery.
This fig is an illustration of the influence of different anatomy on the relationship between GOA (green) and EOA (red) by echocardiography. A, if a tissue valve leaves a rest stenosis, the vena contracta moves distally to the GOA. As a consequence, the EOA will be smaller than the GOA. B, ideal placement of the same tissue valve in a smaller annulus would place the vena contracta at the site of the GOA , and EOA would then equal GOA.
Despite this controversy i think most of the audience wuold agree with me that this notion ..Bigger valves are better seems logical.
Another factor that makes comparison of different biological valves difficult is discripancies between external diameters of valves with the same label size as well as diameter difference in their sizers.
Geometric expressions of prosthesis size include internal orifice area and external diameter. It would seem logical that the valve with the greatest internal opening area in relation to ist outer diameter should allow the best hemodynamic performmance. The problem is neither of these 2 parameters is reflected by the label size provided by the manufacturer.
The outer diameter of a label size 23 Perimount is 31 mm, while that of a same label size Mitroflow is 26 mm This may be explained by the design advantage of the Mitroflow
