Medtronic Corevalve Llc v Edwards Lifesciences AG & Anor

Patent claims are construed by asking what the skilled person would have understood the patentee to mean, read in context. Purposive construction may allow a geometric term to lack mathematical precision, but it does not permit the court to remove a claim limitation because it appears purposeless. A term such as cylindrical retains its ordinary meaning unless the patent provides sufficient teaching for a special meaning. Ambiguous figures or cryptic passages cannot, without more, establish that a stent described as cylindrical may vary in diameter along its length. An accused unitary device is assessed as understood by the skilled person and cannot be divided artificially into infringing and non-infringing parts.

Edwards appealed from the decision of Peter Prescott QC in the Patents Court, reported at [2009] EWHC 6 (Pat). The judge held that Edwards’ patent was valid but that CoreValve’s heart-valve device did not infringe it. CoreValve brought a contingent cross-appeal on validity, to be considered only if infringement were established.

The dispute concerned whether the terms cylindrical surface and cylindrical support means in claim 1 could cover a stent with a variable diameter adapted to the implantation site. Edwards also argued that the accused stent should be treated as having separate parts. The Court of Appeal bifurcated the appeals and determined infringement first.

1. Disposition. The Court of Appeal dismissed Edwards’ appeal. It concluded that the CoreValve product did not infringe claim 1. The contingent cross-appeal on validity therefore did not arise, and the parties agreed the consequential order.
2. Applicable construction. The court adopted the principle that the question is what the person skilled in the art would have understood the patentee to mean by the language of the claim, citing Kirin-Amgen [2004] UKHL 46 at [35]. The relevant skilled reader knew that catheter-implanted stents were cylindrical in the ordinary sense, with a uniform circular cross-section at right angles to the axis. The claim was directed to the device as manufactured, and to a device capable of catheter introduction without opening the thoracic cavity.
3. Meaning of cylindrical. Edwards’ proposed construction, under which cylindrical meant only a generally circular cross-section sufficient to mirror the implantation site, was rejected. The patent’s teaching was simply the mounting of a valve on a known cylindrical stent. It did not disclose reshaping the stent according to the anatomy of the implantation site. The figures and the passage referring to a taller stent and several rings did not provide sufficient teaching for a variable-diameter construction.
4. Purposive construction does not permit a claim integer to be treated as struck out merely because it appears not to affect the inventive concept, following STEP v Emson [1993] RPC 513 at 523. Although a geometric term may sometimes lack mathematical precision, as illustrated by Catnic [1982] RPC 183, that did not justify removing the word cylindrical from the claim.
5. The accused device was a unitary article, not a two-part stent whose lower portion could alone satisfy the claim. In any event, its commissural points were mounted above the waist on a surface with an approximately 30-degree flare, not on a cylindrical surface. There was therefore no infringement.

• Court of Appeal (Civil Division): In [2010] EWCA Civ 704, Edwards’ appeal against the finding of non-infringement was dismissed. The contingent validity cross-appeal was not reached.
• High Court, Patents Court: In [2009] EWHC 6 (Pat), Peter Prescott QC held the patent valid but found that CoreValve’s product did not infringe.