Federal Circuit Vacates Non-Infringement Judgment Over Improper Claim Construction

In Maquet Cardiovascular LLC v. Abiomed Inc., No. 2023-2045 (Fed. Cir. Mar. 21, 2025), the Federal Circuit vacated a judgment of non-infringement regarding Maquet’s U.S. Patent No. 10,238,783, ruling that the district court improperly narrowed the claim scope by misapplying prosecution disclaimer.

Marquet asserted that Abiomed infringed certain claims of the ’783 patent directed to a system for deploying a blood pump to a desired location in a patient’s circulatory system. At issue on appeal were the district court’s claim construction rulings related to three terms in the ’783 patent. The district court accepted Abiomed’s arguments that prosecution history from prior applications required reading negative limitations into the claims—namely, that the claimed “guide mechanism comprising a lumen” does not encompass a lumen that is distal to a cannula or that passes through the pump’s rotor blades.

The Federal Circuit disagreed, finding the district court overextended the doctrine of prosecution disclaimer. First, the Court held that the claims in the ’783 patent were not sufficiently similar to those in its parent patent to justify importing limitations from its prosecution. Second, although the ’783 patent and another prior application shared nearly identical “guide wire” language, Maquet had not clearly disavowed claim scope during the earlier prosecution. The Court reasoned that Maquet’s silence or vague statements during PTO proceedings and IPRs did not amount to the “clear and unmistakable” disavowal required.

Because the judgment was based entirely on these constructions, the court vacated and remanded for further proceedings.