IP Law Daily, PATENT—D. Mass.: Abiomed’s summary judgment motions denied in intravascular blood pump developer’s infringement lawsuit, (Apr 10, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

The court found factual disputes on equivalence and deemed the invalidity motion moot after the plaintiff withdrew asserted claim 2, which had been challenged for lack of written description.

A federal district court in Massachusetts has denied Abiomed’s motions for summary judgment in a patent infringement dispute involving intravascular blood pump technology, concluding that genuine issues of material fact precluded judgment on infringement under the doctrine of equivalents and that the invalidity motion was moot after the asserted claim was withdrawn. The court held that competing expert testimony created triable disputes regarding whether accused pressure-sensing technologies were equivalent to the claimed “fluid column” limitation, and emphasized that such determinations are generally reserved for the factfinder (Maquet Cardiovascular LLC v. Abiomed, Inc., No. 1:17-cv-12311-FDS (D. Mass. Apr. 8, 2026)).

Maquet Cardiovascular LLC, a developer of cardiovascular medical devices, brought the action against Abiomed, Inc. and associated entities, which manufacture competing intravascular blood pump systems. The dispute marked the second litigation between the parties concerning similar product lines, reflecting an ongoing commercial and technological rivalry in the field of cardiac assist devices.

The asserted patent was U.S. Patent No. 10,238,783 (the ’783 patent), which relates to intravascular blood pumps equipped with pressure detection mechanisms. The claims at issue, particularly claims 3 and 24, required a “blood pressure detection mechanism comprising a fluid column” or a “pressure sensing element … comprising a fluid column extending through the catheter.”

Maquet filed suit alleging that Abiomed’s Impella devices infringed the ’783 patent. Abiomed responded with counterclaims seeking declaratory judgments of noninfringement and moved for summary judgment on two grounds: first, that claim 2 was invalid for lack of written description; and second, that its products did not infringe under the doctrine of equivalents. However, after Maquet withdrew its reliance on claim 2, the court terminated the invalidity motion as moot. The remaining motion centered on whether Abiomed’s devices—which used differential and optical pressure sensors rather than fluid-column sensors—could nonetheless infringe under the doctrine of equivalents.

Doctrine of equivalents. The court began by outlining the governing legal framework for the doctrine of equivalents, citing Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997), which permits a finding of infringement where an accused product contains elements equivalent to those claimed in a patent. The court also relied on Deere & Co. v. Bush Hog, LLC, 703 F.3d 1349 (Fed. Cir. 2012) for the “function-way-result” test, under which equivalence depends on whether the accused element performs substantially the same function, in substantially the same way, to achieve substantially the same result.

Applying this framework, the court emphasized that equivalence is ordinarily a question of fact for the jury. Because Maquet presented expert testimony asserting that Abiomed’s differential and optical sensors operated in substantially the same way as the claimed fluid-column mechanism, the court found that a reasonable factfinder could conclude equivalence. This alone was sufficient to defeat summary judgment.

Vitiation. Abiomed argued that Maquet’s theory improperly “vitiated” the fluid-column limitation by effectively expanding it to cover any pressure-sensing mechanism. The court agreed in principle that a patentee cannot broaden a claim to encompass all possible alternatives, citing Tronzo v. Biomet, Inc., 156 F.3d 1154 (Fed. Cir. 1998).

However, the court found that Maquet had not advanced such an overbroad theory. Instead, it identified specific alternative technologies—differential and optical sensors—and provided detailed expert analysis comparing their operation to the claimed fluid-column system. Accordingly, the court held that the vitiation doctrine did not bar Maquet’s claims at the summary judgment stage.

Function-way-result analysis. The court gave particular weight to Maquet’s expert testimony, which explained that both the accused and claimed systems detected blood pressure near the pump by transmitting pressure-induced deflections through the catheter to a sensor. Although the technologies relied on different physical phenomena—hydraulic pressure in the claimed invention versus electrical or optical signals in the accused devices—the expert opined that these differences were insubstantial.

Abiomed, by contrast, argued that the differences were fundamental and represented a “difference in kind,” citing Freedman Seating Co. v. American Seating Co., 420 F.3d 1350 (Fed. Cir. 2005). The court acknowledged that this argument was plausible but held that it raised factual disputes rather than resolving them. At the summary judgment stage, the court was required to credit the nonmovant’s evidence and draw reasonable inferences in its favor.

Ensnarement and prior art. Abiomed also contended that Maquet’s equivalence theory improperly ensnared the prior art, another limitation on the doctrine of equivalents. The court rejected this argument for similar reasons, noting that factual disputes existed regarding the scope of the prior art and the extent to which Maquet’s theory overlapped with it. These issues, too, were deemed appropriate for trial.

Thus, the court ultimately denied Abiomed’s motion for summary judgment of no infringement under the doctrine of equivalents and terminated its invalidity motion as moot.

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

Judge: Saylor, F.

Attorneys: Andrew J. Ligotti (Alston & Bird, LLP) for Maquet Cardiovascular LLC. C. Sebastian Zonte (White & Case LLP) for Abiomed Inc.

Companies: Maquet Cardiovascular LLC; Abiomed Inc.

Cases: Patent MassachusettsNews GCNNews