The Mechanical Bioprosthesis: Does Valve Motion Predict Thrombogenicity ? Lawrence Scotten1 David Walker1 Peter Harbott2 Jurgen de Hart3 Robert Perrault4 Damien Coisne4 Ernie Lane2 Didier Lapeyre2 ViVitro Systems Inc., Victoria, Canada Lapeyre-Triflo Industries LLC, Atlanta, USA Technische Universiteit Eindhoven, the Netherlands Aerodynamics Institute, CNRS, Poitiers, France

Valve design and motion are major determinants of flow structure Background: Valve design and motion are major determinants of flow structure Un-natural flow structure can cause trauma to blood cell membranes KEY discovery recently reported that traumatized blood cell membranes release glycoprotein tissue-factor which initiates blood coagulation.

may not need anti-coagulation Background: *Prior study of valve motion: (aortic & mitral) 4 Biological vs. 6 Mechanical Open more rapidly Close more gently Exhibit NO rebound Unaffected by gravity Stable cycle to cycle behavior *Conclusion: Newer mechanical valve designs that mimic biological valve motion may not need anti-coagulation CONCLUSION: -A new valve testing technique has been demonstrated which eases the analysis of valve motion -and shows that valves demonstrate unique kinematics -Compared to Mechanical valves -BIOLOGICAL VALVES Open more rapidly Close more gently Exhibit NO rebound Unaffected by gravity Have stable cycle to cycle behavior *New laboratory technique measures projected dynamic area of prosthetic heart valves. J Heart Valve Dis 2004;13:120-33

All valves were size 25 mm TAD Aortic Valves Tested: Methods New three leaflet mechanical valve Lapeyre -Triflo All valves were size 25 mm TAD Widely used clinical valves Carpentier-Edwards PerimountTM St. Jude Medical RegentTM

Laboratory technique reveals valve motion Test conditions: Laboratory technique reveals valve motion Leonardo A.D. 2005 Area Detection System Methods Light sensor (Response to 1 MHz) TEST CONDITIONS: Aortic position Rate 70 BPM Cardiac output 5 L/min Systemic pressures 120/80 mmHg 10 consecutive cycles recorded Light source

Valve motion was revealed by open area Methods Valve motion was revealed by open area

Methods

Low thrombogenicity with tissue valve motion Results Carpentier-Edwards PerimountTM Low thrombogenicity with tissue valve motion VALVE MOTION (Area) FLOW cm2 OPEN PHASE: Valve motion responds well to slowly decreasing flow ml/s 3 600 OPEN RAPID opening MAX. NOTE: Valve reaches maximum opening… GENTLE closing 32 ms AHEAD of flow max. OPENING: Valve opens rapidly providing no obstacle to the accelerating flow CLOSING: Valve motion responds quickly to decreasing flow FINAL CLOSURE: Low leaflet closing velocity, small regurgitation, no rebound > ¾ closed at zero flow 24% OPEN CLOSED CLOSED DIASTOLE SYSTOLE DIASTOLE 0.1 s -300

Valve Motion and Fluid Flow Results Valve Motion and Fluid Flow Abrupt, erratic and delayed closing Results in: 4. Greater occluder/housing impact and rebound at closure 5. Potential HITS and cavitation Rebound 1. Valve 89% OPEN at zero flow SLOW opening causes opening stenosis MOTION FLOW 2. Late closure (in diastole) SYSTOLE 3. Greater closing regurgitation 0.1 s

Valve Motion and Fluid Flow Results Valve Motion and Fluid Flow GENTLE closing (like bioprosthesis) 3. Infrequent small rebound 4. No indication for cavitation or HITS 2. End of systole closure and small closing reflux (like bioprosthesis) RAPID opening (like bioprosthesis) 1. Valve > ½ closed at zero flow MOTION FLOW SYSTOLE 0.1 s

Does valve motion predict thrombogenicity? Results MOTION FLOW SYSTOLE 0.1 s

Opening Time x Displaced opening fluid volume Results OPENING index O Opening Time x Displaced opening fluid volume END Opening OPENING MOTION VALVE FLOW BEGIN Opening OPENING FLUID VOLUME Opening time Beginning of Systole

Motion closure ratemax x Backflow fluid volume Results CLOSING index C Motion closure ratemax x Backflow fluid volume CLOSING MOTION MOTION CLOSURE RATEmax END OF CLOSURE VALVE FLOW BACKFLOW FLUID VOLUME End of Systole

Results 1.0 0.9 OPENING index O Opening Time x Displaced opening fluid volume 4.7 10.2 1.1 CLOSING index C Motion closure ratemax x Backflow fluid volume 2.0 14.9 1.0+1.0 4.7+10.2 0.9+1.1 OPENING + CLOSING index T BLOOD TRAUMA INDEX S 7.5 1.0 T Tce

Proposed blood trauma index Results Proposed blood trauma index S Valve opening and closing data is normalized to the tissue valve performance.

“The Mechanical Bioprosthesis” Conclusions: Bioprosthetic valve motion may have referentiality to benign, non-thrombogenic flow structure Lapeyre-Triflo tri-leaflet mechanical valve motion is similar to that of bioprosthetic valves and very different from that of current mechanical valves Lapeyre-Triflo tri-leaflet mechanical valve may require little or no anticoagulant therapy, and may represent “The Mechanical Bioprosthesis”