Holding: Patent prosecution history estoppel may narrow the scope of an unamended claim when a substantively related claim is amended or cancelled, even if the related claim is not dependent on the unamended claim.
Colibri owns US Patent No. 8,900,294, which claims a method of providing an installer of an artificial heart valve with a repeat opportunity to install the heart valve in the correct position. The replacement valve is partially deployed from the delivery apparatus, but recaptured by the delivery apparatus before full deployment if the valve needs to be repositioned.
The method claimed in the ‘294 Patent employs a device including a catheter that carries a stent on which the replacement valve is sutured. The catheter also includes a pusher member for advancing the stent and a removable sheath that surrounds the stent and the valve. When the catheter is within the desired position within the artery, an operator uses the pusher member to push the stent out of a distal end of the sheath. The stent partially expands as it is pushed out of the sheath, but if the positioning seems incorrect, the stent may be returned to its original position in the sheath to be repositioned where desired.
Claim 1 of the ‘294 Patent recites that the stent and the attached valve are partially deployed by “pushing out the pusher member from the moveable sheath to expose the distal portion of the replacement heart valve device” (emphasis added). The application that became the ‘294 Patent also included a similar independent method claim, claim 39, that recited that the stent and the attached valve are partially deployed by “retracting the moveable sheath to expose a portion of the replacement heart valve device” (emphasis added). However, this claim was cancelled during prosecution as lacking written description in the specification.
The accused Medtronic device is a recapturable replacement valve and stent that deploys the stent by retracting the moveable sheath. Colibri brought suit against Medtronic alleging infringement of the ‘294 Patent under the doctrine of equivalents. Medtronic argued that patent prosecution history estoppel prevented infringement by the doctrine of equivalents, based on the claim cancelled during prosecution of the ‘294 Patent. However, the district court found that patent prosecution history estoppel did not apply because the cancelled claim 39 was an independent claim separate and distinct from the allowed claim 1. The district court also construed Colibri’s doctrine of equivalents argument to require not just retraction as recited in the cancelled claim 39, but a combination of pushing and retracting. At trial, a jury found infringement of the ‘294 Patent and awarded damages to Colibri. Medtronic’s motion for judgment as a matter of law (JMOL) on noninfringement was denied.
On appeal, the Federal Circuit held that the district court erred in finding that patent prosecution history estoppel did not apply to the ‘294 Patent. Patent prosecution history estoppel applies when narrowing amendments are made during prosecution of a patent application. The doctrine of equivalents cannot be used to recapture claim scope that was surrendered by the narrowing amendments. In some claims, a narrowing amendment may not just affect the scope of a single claim, but may inform the scope of other claims of the patent. As an example, cancelling a claim that includes similar terminology as another closely related claim may indicate that the scope of the related claim is narrowed.
In this case, a person of ordinary skill in the art would have realized that Colibri’s claim 39 would have required both retracting the removable sheath and applying some type of pushing force on the stent to allow the stent to be removed from the sheath. The partial deployment step recited in claim 1 of the ‘294 Patent is substantially similar to the deployment step that was recited in the cancelled claim 39. The only difference is that claim 1 achieves partial deployment by pushing the stent, while claim 39 recited partial deployment by retracting the sheath. Therefore, the cancellation of claim 39 indicates that deployment of the stent by retraction of the sheath, even when a pushing force is also applied on the stent, cannot be covered by the doctrine of equivalents.
The district court erred in its analysis by reasoning that claim 1 and the cancelled claim 39 were not sufficiently related since they were two separate independent claims. However, to find patent prosecution history estoppel, there is no requirement for a cancelled claim to be dependent on the claim to which estoppel is applied. Patent prosecution history estoppel requires an analysis of the substantive relationship between claims. Cancelling a claim that is substantively related to another claim may affect the scope of the claim that is retained. Estoppel is not limited only to cases in which the asserted claim was amended, but instead looks at the effect of an amendment on the claims of the patent as a whole.
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