IP Law Daily, PATENT—D. Mass.: Motion for summary judgment denied in part in medical device dispute, (Apr 20, 2026)

By Carolin Dennis, B.Sc., LL.B., LL.M.

A medical device technology company adequately alleged the affirmative defense of prosecution laches.

A federal district court in Massachusetts denied a medical device patent owner’s motion for summary judgment on its competitor’s affirmative defense of prosecution laches as to claim 24 of the U.S. Patent No. 10,238,783 due to a genuine dispute of material fact as to the laches defense. However, the district court granted the motion for summary judgment as to claims 1-3 because the company, Abiomed, did not proffer any evidence to support a defense of prosecution laches as to claims 1-3 (Maquet Cardiovascular LLC v. Abiomed Inc., No. 1:17-cv-12311-FDS (D. Mass. Apr. 15, 2026)).

Background. Maquet Cardiovascular, LLC (Maquet), a developer of cardiovascular medical devices, was the owner of U.S. Patent No. 10,238,783 (the ’783 patent), which claimed an intravascular blood pump system that included a “pigtail-shaped distal tip.” Maquet sued Abiomed, Inc., Abiomed R&D, Inc., and Abiomed Europe GmbH (collectively, Abiomed) for infringing the ’783 patent. Abiomed counterclaimed for declaratory judgment of noninfringement. Maquet moved for summary judgment as to the affirmative defense of prosecution laches with respect to claim 24, which among other things claims a “pigtail shaped distal tip.” It also seeks summary judgment as to that defense for claims 1-3, which do not claim such a tip.

Prosecution laches. Prosecution laches is an equitable affirmative defense. To succeed, the party asserting a laches defense must establish two elements: (1) the patentee’s delay in prosecution must be unreasonable and inexcusable under the totality of circumstances and (2) the accused infringer must have suffered prejudice attributable to the delay.

Unreasonable delay. According to Abiomed, Maquet’s delay in the prosecution of a claim involving a “pigtail shaped distal tip” from 2001 to 2016 was unreasonable and inexcusable under the totality of the circumstances. Maquet contended that it publicly disclosed the “pigtail shaped distal tip” when it filed the PCT/US00/2415 (PCT Application) in September 2000 and when it was published in March 2001. That application, incorporated by reference the Steerable Cannula Application, which was filed in 1999, and which included a reference to a pigtail tip. In 2016, Maquet amended its continuation application to claim such a tip. It contended that the filing of a continuation application is permitted by statute, and the fact that it did so in 2016 to include a claim that recited a pigtail does not preclude it from claiming priority to the filing of the PCT Application.

The court noted that the PCT Application was published with no direct mention of a pigtail. While it incorporated by reference the U.S. Patent Application No. 09/280,988 or the Steerable Cannula Application’s “guidability features,” it was ambiguous as to what those guidability features were and whether it was incorporating the entire Steerable Cannula Application. Indeed, it referred specifically to two “guidability features”—“side lumens” and “deformable materials”—without mentioning pigtail tips. The Steerable Cannula Application was then abandoned. After the PCT Application, four more continuing applications were filed over the course of more than 15 years, not one of which mentioned a pigtail. Maquet only amended the pending application to claim the pigtail after litigation had begun against Abiomed. And if Maquet was actually aware that Abiomed was investing in a device with a pigtail during the period between 2001 and 2016, that fact must be given weight when considering the issue of whether the delay was unreasonable.

By regulation, an unpublished, abandoned application that was identified in a U.S. patent is available to the public—but only by written request to the USPTO and payment of a $15 fee. Abiomed’s expert claimed that the requirement to file a written request and pay a fee, combined with the indication provided by the Steerable Cannula Application’s abandoned status that it would describe only the background of the invention and the state of the art, would deter any party conducting a due diligence review of patents and published applications from viewing the ’988 application. He also asserted that his review of the file history produced by the USPTO suggested that no member of the public had requested the Steerable Cannula Application before August 2016. A reasonable factfinder could therefore conclude that Maquet did not, in fact, reasonably disclose the pigtail tip in 2001.

Accordingly, viewing the facts in the light most favorable to Abiomed because the issue of unreasonable delay arises in the context of summary judgment, the court found that there is a genuine issue of material fact as to whether Maquet’s delay in prosecuting the pigtail claims was “unreasonable and inexcusable.”

Prejudice. The court noted that there is no dispute that Abiomed “invested in, worked on, or used the claimed technology during the period” between 2001 and 2016. However, proof that Abiomed was unfairly prejudiced requires, among other things, a showing that it made those investments without being aware of Maquet’s claim to the invention and that its lack of knowledge was reasonable.

There is a disputed issue of fact as to whether a reasonable diligence review would have uncovered the abandoned Steerable Cannula Application. However, there are factors that may favor Maquet. In 2007, Dr. Aboul-Hosn, the first named inventor on the Steerable Cannula and PCT Applications, went to work for Abiomed as a consultant. That is circumstantial evidence that Abiomed knew, or reasonably could have known, about the pigtail no later than 2007, although it is apparently undisputed that Abiomed began investing in the pigtail in 2003. In addition, Dr. Thorsten Siess, the Chief Technology Officer of Abiomed, saw the PCT Application when it was published in 2000, but did not request or obtain a copy of the Steerable Cannula Application.

The court determined that under these circumstances, there is genuine question of material fact as to whether Abiomed was unfairly prejudiced by the delayed prosecution of the pigtail claim. Therefore, the court denied summary judgment as to the affirmative defense of prosecution laches as to claim 24. However, the court concluded that Abiomed did not proffer any evidence to support a defense of prosecution laches as to claims 1-3 and granted the motion for summary judgment as to claims 1-3.

The Case is No. 1:17-cv-12311-FDS.

Judge: Saylor, F.

Attorneys: Andrew J. Ligotti (Alston & Bird, LLP) for Maquet Cardiovascular LLC. Andrei Harasymiak (Cravath, Swaine & Moore LLP) for Abiomed Inc.

Companies: Maquet Cardiovascular LLC; Abiomed Inc.

Cases: Patent MassachusettsNews USPTO