The High Cost of Canceling: How Prosecution History Estoppel Killed a Heart Valve Infringement Claim

The Federal Circuit has overturned a $125 million patent judgment against Medtronic's CoreValve unit for allegedly infringing a Colibri Heart Valve LLC patent.

The court found that Colibri's arguments and amendments barred Colibri’s assertion of infringement under the doctrine of equivalents during the prosecution of its patent application.

The case is Colibri Heart Valve LLC v. Medtronic CoreValve, LLC.

Artificial heart valves are used to replace diseased or otherwise defective heart valves.

As the Federal Circuit explained,

Blood flows through valves in the heart from areas of relatively high pressure to areas of relatively low pressure. … Each valve includes “leaflets” (sometimes called “cusps”) spanning the passageway through which blood flows, with the opening and closing of the leaflets allowing blood to flow only in the proper direction through the circulatory system.

The ’294 patent describes a replacement heart valve formed by folding biologically compatible material to form a tubular portion and a leaflet portion.

As the court explained,

U.S. Patent No. 8,900,294, owned by Colibri Heart Valve LLC, claims a method, for use in trying to implant an artificial heart valve to replace a defective valve, that furnishes a do-over opportunity to the installer to get the positioning right. In the claimed method, the replacement valve is only partially deployed from the delivery apparatus, but recaptured within the delivery apparatus before full deployment if it looks like the positioning will be off.

if the positioning seems incorrect, the valve can be recovered and returned to its original position within a catheter, with the stent re-squeezed, and then re-deployed once the catheter’s overall location is adjusted.

Initially, the ’294 patent included two independent claims reciting the opportunity-for-do-over method of partial deployment:

• one claimed pushing out the valve from an outer sheath of the delivery apparatus, and
• one claimed retracting the outer sheath to expose the valve.

During prosecution, the examiner rejected the latter claim for lack of written description under 35 U.S.C. § 112, which states:

The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.

Colibri then cancelled the latter claim, and the patent issued with an independent claim reciting partial deployment by pushing, and no claims expressly reciting partial deployment by retracting.

Medtronic sells replacement heart valves, which include a self-expanding metal stent and a replacement heart valve with three leaflets sutured to a cylindrical “inner skirt.” Its products can be “recaptured” during implantation, if necessary.

Colibri sued Medtronic, alleging that Medtronic was inducing surgeons to perform Colibri’s claimed method with Medtronic’s own products.

In the district court, Medtronic argued that the accused's use of its product involved partial deployment by retracting, not pushing.

At trial, Colibri dropped its claim of literal infringement, relying only on the doctrine of equivalents to establish infringement by the accused direct infringers using the accused method with Medtronic’s products.

As Cornell Law School explains,

The doctrine of equivalents is a means by which a holder of a patent may raise a claim of infringement even though each and every element of the patented invention is not identically present in the allegedly infringing product. The purpose of the doctrine is to prevent an infringer from stealing the benefit of a patented invention by changing only minor or insubstantial details of the claimed invention while retaining the same functionality. The essential inquiry in determining equivalency is whether the accused product or process contains elements identical or equivalent to each claimed element of the patented invention.

At trial, the parties disputed the construction of the term “pushing out the pusher member from the movable sheath.”

Colibri proposed that the phrase meant a “pushing force is applied to the pushing member in a direction outwards from the movable sheath.”

Medtronic, on the other hand, proposed the phrase meant “pressing against the pusher member with a force that moves the pusher member out of the movable sheath.”

A special master recommended that the district court adopt Medtronic’s proposed construction, reasoning that the claimed “pushing out” limitation is not just a matter of the force’s direction but “requires movement of the pusher member such that the replacement heart valve moves outward from the sheath to at least some degree.”

The district court adopted the recommended claim construction.

The special master also recommended that the court reject Medtronic’s prosecution-history-estoppel argument. Again, the court agreed.

At trial, Colibri argued that, under the doctrine of equivalents, Medtronic’s partial-deployment method (applying a force to hold the stent in place while retracting the movable sheath) is equivalent to the claimed partial-deployment method (applying a force to push the stent out of the movable sheath).

The jury, besides rejecting Medtronic’s challenge to the validity of the patent, found that Medtronic had induced infringement and awarded more than $106 million in damages to Colibri.

The Federal Circuit concluded that

prosecution history estoppel, based on Colibri’s cancelling of a claim to “retraction” for partial deployment of the replacement valve and Colibri’s own recognition of the close linkage of the subject matter of the cancelled and retained claims, bars application of the doctrine of equivalents.

The court agreed with Medtronic that Colibri’s cancellation of its claim 39 in favor of pursuing limitations that already appeared in retained claim 34 (issued claim 1) was a narrowing amendment giving rise to prosecution history estoppel.

Said the court:

Narrowing is a prerequisite to prosecution history estoppel: “If the amendment was not narrowing, then prosecution history estoppel does not apply.”

However, said the court,

the required narrowing is not a purely formal matter of altering a single claim’s terms; it can exist, and we conclude here does exist, as a substantive matter based on cancelling a closely related claim involving such intertwined terminology that cancelling one claim necessarily communicated that the scope of the other claim had narrowed.

The court concluded that Medtronic was entitled to judgment as a matter of law of noninfringement of the ’294 patent.