IP Law Daily, PATENT—Fed. Cir.: Non-infringement judgment vacated due to improper claim construction, (Feb 11, 2026)

By Linda O’Brien, J.D., LL.M.

Statements by a medical device manufacturer during inter partes review were not “clear and unmistakable” to invoke the doctrine of prosecution disclaimer.

A district court erred in narrowing the claim scope by misapplying the doctrine of prosecution disclaimer in entering a judgment of non-infringement with respect to five of six patents owned by a medical device manufacturer, the U.S. Court of Appeals for the Federal Circuit has ruled in a nonprecedential disposition. However, there was no genuine dispute of material fact that precluded summary judgment regarding one of those patents. Thus, the grant of summary judgment to the medical device manufacturer was affirmed-in-part, vacated-in-part, and remanded (Abiomed Inc. v. Maquet Cardiovascular LLC, No. 24-1062 (Fed. Cir. Feb. 9, 2026)).

Maquet Cardiovascular LLC, a manufacturer of medical equipment, owns six patents directed to intravascular blood pumps, which are used for acute support during cardio-pulmonary operations, for short-term support while awaiting recovery of the heart from surgery, and as a bridge to keep a patient alive while awaiting a heart transplant. In May 2016, medical device technology company Abiomed, Inc. filed an action seeking a declaratory judgment that its Impella intravascular blood pumps did not infringe Maquet’s patents and that Maquet’s patents were invalid. Maquet filed a counterclaim against Abiomed for patent infringement. The scope of the case was narrowed to claims 16 and 17 of Maquet’s Patent No. 7,022,100 (“the ’100 patent”). Abiomed filed a motion for summary judgment of non-infringement. In September 2021, the district court granted summary judgment in favor of Abiomed regarding the ’100 patent. In September 2023, the district court entered a final judgment that Abiomed did not infringe any claims of Maquet’s U.S. Patent Nos. 7,022,100; 8,888,728; 9,327,068; 9,545,468; 9,561,314; and 9,597,437. Maquet appealed the decision.

Claim construction. The district court erred in narrowing the claim scope by misapplying the doctrine of prosecution disclaimer, the court found. Although the district court correctly determined that no part of the claims, written description or prosecution history supported restricting the claim phrase “elongate lumen associated with the cannula,” it erred by restricting the terms based on statements by Maquet in related inter partes review proceedings. To invoke the doctrine of prosecution disclaimer, statements made by a patent owner during inter partes review must be “both clear and unmistakable.” Maquet’s statements regarding Abiomed’s characterization of prior art references were “far too slender to support the judicial narrowing of a clear claim term.”

The district court also erred by importing a negative limitation into the “purge fluid” terms by holding that the purge fluid “does not go through the rotor bearings and into the bloodstream.” The claim language did not restrict what path the purge fluid may take and the specification did not support that the purge fluid could not “go through the rotor bearings and into the bloodstream.” Maquet’s statements during inter partes review did not clearly and unmistakably disclaim passing purge fluid through rotor beatings and into the blood stream. Thus, the district court final judgment with respect to the ’728, ’068, ’468, ’314, and ’437 patents was vacated and remanded, the court determined.

No genuine dispute of material fact. However, Maquet failed to show a genuine dispute of material fact that precluded summary judgment regarding the ’100 patent. The district court correctly construed “guide mechanism” as a means-plus-function term and correctly identified corresponding structures disclosed in the specification. To infringe a means-plus-function limitation, the “accused structure must either be the same as the disclosed structure” to perform the identical function and be otherwise insubstantially different with respect to the structure. It was undisputed that the Impella devices perform an identical function to the “guide mechanism” of the patent. The testimony of Maquet’s expert never identified the alleged structural differences between the Impella and the disclosed structure, was conclusory, and was insufficient to defeat summary judgment. Therefore, the district court did not err in determining Abiomed’s Impella devices did not infringe claims 16 and 17 of the ’100 patent because no reasonable jury could have found that Impella devices contain a “guide mechanism,” the court concluded.

The Case is No. 24-1062.

Judge: Cunningham, T.

Attorneys: Keith Hummel (Cravath, Swaine & Moore LLP) for Abiomed Inc. Kirk T. Bradley (Alston & Bird LLP) for Maquet Cardiovascular LLC.

Companies: Abiomed Inc.; Maquet Cardiovascular LLC

Cases: Patent FedCirNews GCNNews