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On-X heart valve Overview
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Every aspect of the
On-X valve plays a role in maximizing benefits for the
recipient. The scope of innovations in the design reflects
the MCRI's commitment to perfection in creating
the On-X Prosthetic Heart Valve.
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ON-X Carbon
The purity and finish of On-X carbon
coatings assures the greatest biocompatibility
for the On-X valve design. The human body does
not react against its pure carbon surfaces. Advanced
processing technology yields highly polished and
contoured features in the critical pivot area,
which minimizes opportunities for clots to form
or adhere.
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 SJM Valve Pivot (silicon alloyed carbon) |
On-X
Valve Pivot (pure On-X carbon) |
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Natural Length
The unique
aspect ratio of On-X valves is a crucial element
of the comprehensive On-X valve design strategy
for maximizing benefits to the patient. Its length-to-diameter
ratio approaches that of a native valve.
 Somewhat counter-intuitively,
its greater length (or height) actually reduces
turbulence and increases flow. It also allows
for reduced leaflet excursion to reduce backflow
losses, provides leaflet protection and protects
the valve opening from tissue encroachment.
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| Inlet Flare
 On-X valve is the first prosthetic heart
valve to successfully incorporate a flared inlet,
the well-known fluid dynamic principle for producing
smooth, organized flow with reduced turbulence.
The flare produces an increased volume of flow,
comparable to that of a larger orifice.
Because the
inlet flare extends through the annulus, it is
not compromised by encroaching annular tissue
and thus maintains the favorable annular shape
for a lifetime of consistently optimal flow.
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Stasis-Free Pivots
Pivots are a potential site of clot formation
because of possible stasis (flow stagnation).
The On-X design provides increased washing throughout
the pivot to eliminate areas of potential flow
stagnation.
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.gif) Traditional Valve |
On-X
Valve |
Optimal
pivot cleansing is accomplished by introducing flow
paths between the leaflet and the pivot wall. The
backflow channels are carefully designed to avoid
hemolysis. Backflow over smooth, blended contours
is key to the low thrombosis rate of the On-X valve.
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Full Opening
Leaflets
On-X valve
leaflets are free to follow the flow. Other valves
must stop short of the fully open position to
ensure that they will close reliably with backflow,
which can increase obstruction and turbulence
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With the On-X
valve's patented "actuated pivot design",
closure is assured even when leaflets are open
to the full 90? Leaflet freedom reduces turbulence
and its accompanying effects such as pressure
loss and blood damage.
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On-X design allows leaflets to fully open
on every cycle. As flow reverses, the leaflets
engage a “closing ramp?which slightly rotates
the leaflets enabling closure.
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Soft Closure
The On-X valve
has patented two-point "soft landing" leaflets
to reduce blood stress in three ways.
- The two
points are closer to the pivots so that the
closing impact velocity is reduced by 40%.
- The two-point
landing distributes the closing impulse so that
the impact is glancing rather than direct.
- This "soft
landing" minimizes the potential for cavitation
that can damage blood.
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Soft Landing also
minimizes
the potential for noise. |
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Leaflet
Guards
The leaflet guards on the On-X
valve extend the orifice to form an effective
barrier, which protects the leaflet motion from
impingement by tissue. This is particularly important
in the mitral position when chordae tendinae are
preserved. The On-X valve is the only valve with
leaflet guards that offer this degree of protection.
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| Leaflet Guards protect against impingement. |
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