Maquet Cardiovascular LLC v. Abiomed Inc.

Authored by: Jeremy J. Gustrowsky

In a recent decision, the Federal Circuit vacated a lower court’s ruling in the patent dispute between Maquet Cardiovascular LLC and Abiomed Inc., providing important guidance on how prosecution history can—and cannot—be used to limit the scope of patent claims. The case involved two patents: U.S. Patent No. 10,238,783 and U.S. Patent No. 9,789,238, both related to intravascular blood pump systems used in medical procedures.

The heart of the dispute was how certain terms in the ‘783 patent should be interpreted, specifically around the design and placement of a “guide mechanism comprising a lumen” and the path of a “guide wire.” The district court had ruled in favor of Abiomed, adopting a narrow interpretation based on statements and amendments made during the prosecution of related, but not identical, patents. This narrow interpretation led to a judgment of non-infringement in Abiomed’s favor.

On appeal, the Federal Circuit found that the district court went too far in importing limitations from the prosecution history of a related patent into the claims of the ‘783 patent. The appellate court emphasized that prosecution disclaimer—a doctrine that can limit the scope of a patent based on statements made during the patent’s prosecution—only applies when there is a “clear and unmistakable” disavowal of claim scope, and only when the claims in question are sufficiently similar. In this case, the court determined that the relevant claims were not similar enough, and that Maquet had not clearly disavowed the broader claim scope.

As a result, the Federal Circuit vacated the judgment of non-infringement for the ‘783 patent and sent the case back to the district court for further proceedings, while leaving the judgment on the ‘238 patent untouched. This decision serves as a reminder that prosecution history must be used carefully and only when it truly reflects a clear and specific limitation on claim scope.