`Medtronic, Inc., Medtronic Vascular, Inc.,
`& Medtronic Corevalve, LLC
`v. Troy R. Norred, M.D.
`Case IPR2014-00395
`
`
`
`‘
`
`H
`the forces which are exerted from the ventricular rnyocardiurn (Cardiovascular
`Research,22,7,l988)(Journal of Biomechanics33(6):653-658, 2()0()June). In a similar fzislriomas the aortic}
`root this structure allow the valvular apparatur to open with the least amount of strain.
`The coronary arteries arise within or above the(%nus of 'v\;‘tlsalva. The blood flow of the heart
`occurs mostly when the ventricle relaxes. At this time 116 cusps of the aortic valve are closed and as
`mentioned the diastolic forces of the blood against the valve are dispersed along the valve and adjacent
`sinus. The opening or ostia of the coronary arteries when located near the apex and middle of the sinuses
`allows for the most laminar flow characteristics. This in turn promotes the greatesilamount of flow with the
`least amount of resistance. In disease states,where these relationships are lost, it has been proposed that
`this could lead to increase stress at the coronary ostia.
`(The Aortic Valve CRC press).
`These integral relatiorrslriphiot only pertain to the gross anatomy of the valvular apparatus, but
`also“/fire rnicroanatorny-~ahewsthe~integral+iature+af4lrese»struetrtres.J The amount of elastin is in a higher
`concentration as shown by staining methods (American Journal of Pathology 445 (7): 193 .1). This allows a
`greater amount of dilatation of the structures in this area. Further, scanning electron micrographs have
`shown the unique arrangement of collagen in the valves which permit the unique reversal of curvature
`which is vital in the function of the valve (figure 6)( Anatomic Embryology 172(61): 1985). The fibers are
`unusually small and arranged in sheets with unique distances between each strand. In theory,this would
`give a greater amount of tensile strength while allowing continued flexibility. As always, nature l1as
`selected the most efficient machinery, and we have only to discover the reasons why.
`
`11.
`
`Aortic Valve Dynamics and Physics
`
`The aortic valve is better understood in a dynamic state given it is not a static structure. To frilly
`understand this structure it is integral to understand the opening and closing of the valve, the motion of the
`various parts, the design of the valve in vitro and the hydrodynamics of the valve. The valve’s ultimate
`function is to allow lluid transfer from the ventricle to the systemic circulation.
`In order to do this
`efficiently it minimizes shear stress, resistance to flow, and tensile forces.
`The opening and closing of the aortic valve depends upon differential pressures, flow velocity
`3 my M,
`characteristicsand as mentioned earlier. he uni ue anatomic relationshi between the valves and the st.../“r«:w~«“’*4§3g
`.
`x
`/®iTrusesef»@a
`Va. One of the most comprehensive stridyeeireorripassed a model developed by Bellhouse
`et al.
`In this model,
`the flow of fluid through the aortic valve was studied by injecting dye within the [low
`of fluid.
`Some of the pertinent observations found within this model were as follows: 1) The valve opens
`rapidly, and as the leaflets move into the sinuses, vortices form between the leaflet and the sinus walls; 2)
`The flow enters the sinus at the sinus ridge, curls back along the sinus wall and leaflet and then back into
`the main stream; 3) During the end of systole the vorticeal motion created during contraction forces the
`valves back toward a closed position. These observations are important to show that absolute pressure
`differences created between the aorta and ventricle are not the source of initial closure of the aortic valves.
`In fact,
`it would be detrirninal to valve stress if these forces dictated closure of the aortic valve.
`For
`example, if two objects area greater distance apart and a set amount of force is applied to each, the greater
`distance would produce greater velocity and the momentum at impact would be greater. Therefore, if the
`lea llets are closed or near closure as contraction is coming to an end then the force used for coaptation
`would be less. Less force per cycle equates to greater longevity of the valve.
`In conclusion, the CllSpS and
`the relationship of closure for prosthetic valves must incorporate passive closure during systole which
`would logically lengthen the lifespan of any such device.
`To expand these concepts, the theory of laminar llow and how the native aortic valve
`accomplishes this must be developed. A laminar flow is predicted by a Reynolds number which
`incorporates the laws as described by Pouiselle and Bernoulli.
`In general, the lower the
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`NORRED EXHIBIT 2240 - Page 2
`NORRED EXHIBIT 2240 - Page 2