Abiomed Inc. v. Maquet Cardiovascular LLC

NOTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
ABIOMED INC.,
Plaintiff/Counterclaim Defendant-Appellee
v.
MAQUET CARDIOVASCULAR LLC,
Defendant/Counterclaim Plaintiff-Appellant
v.
ABIOMED EUROPE GMBH, ABIOMED R&D, INC.,
Counterclaim Defendants-Appellees
______________________
2024-1062
______________________
Appeal from the United States District Court for the
District of Massachusetts in No. 1:16-cv-10914-FDS, Judge
F. Dennis Saylor, IV.
______________________
Decided: February 9, 2026
______________________
KEITH HUMMEL, Cravath, Swaine & Moore LLP, New
York, NY, argued for appellees. Also represented by
SHARONMOYEE GOSWAMI, ANDREI HARASYMIAK, LAUREN
MOSKOWITZ.
Case: 24-1062 Document: 49 Page: 1 Filed: 02/09/2026

-- 1 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 2
KIRK T. BRADLEY, Alston & Bird LLP, Charlotte, NC,
argued for appellant. Also represented by NICHOLAS
CHRISTOPHER MARAIS; CHRISTOPHER L. MCARDLE, WADE G.
PERRIN, New York, NY.
______________________
Before HUGHES, CUNNINGHAM, and STARK, Circuit Judges.
CUNNINGHAM, Circuit Judge.
Maquet Cardiovascular LLC (“Maquet”) appeals from
a final judgment of the United States District Court for the
District of Massachusetts, ordering that Abiomed Inc., Abi-
omed Europe GmbH, and Abiomed R&D, Inc. (collectively,
“Abiomed”) have not infringed any claim of U.S. Patent
Nos. 7,022,100; 8,888,728; 9,327,068; 9,545,468; 9,561,314;
and 9,597,437 (collectively, the “Asserted Patents”).
J.A. 1–2. For the reasons discussed below, we affirm-in-
part, vacate-in-part, and remand.
I. BACKGROUND
Maquet is the owner of the Asserted Patents, which
claim various intravascular blood pump systems and meth-
ods for providing heart support using intravascular blood
pump systems. See, e.g., ’100 patent col. 20 ll. 20–28; ’437
patent col. 33 l. 42 to col. 34 l. 31; Abiomed, Inc. v. Maquet
Cardiovascular LLC, 329 F. Supp. 3d 1, 8 (D. Mass. 2018)
(“Claim Construction Order”).1
1 “The specifications of the ’100, ’728, and ’068 pa-
tents are identical, and the specifications of the ’468, ’314,
and ’437 patents are different only in that they explicitly
incorporate as Appendices A and B certain material that
was incorporated by reference in the other three patents—
namely, two patent applications, also owned by Maquet,
U.S. Patent App. Nos. 09/280,988 and 09/280,970.” Claim
Case: 24-1062 Document: 49 Page: 2 Filed: 02/09/2026

-- 2 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 3
The Asserted Patents disclose three “broad aspect[s] of
the present invention,” each defined by a specific type of
“guide mechanism:” (1) “an ‘over-the-wire’ type guide
mechanism;” (2) “a ‘side-rigger’ or ‘rapid exchange’ type
guide mechanism;” and (3) “a ‘guide catheter’ type guide
mechanism.” ’100 patent col. 2 l. 56 to col. 3 l. 41; Claim
Construction Order at 10–11.
Three claim limitations are at issue in this ap-
peal: (1) “an elongate lumen associated with the cannula;”
(2) “purge fluid;” and (3) “guide mechanism.” Appellant’s
Br. 26–32; Claim Construction Order at 14–17. The “elon-
gate lumen” limitation is found in claims 1 and 22 of the
’468 patent, claim 27 of the ’314 patent, and claims 1 and
28 of the ’437 patent. See ’468 patent; ’314 patent; ’437
patent; see also Claim Construction Order at 28. The
“purge fluid” limitation is found in claim 1 of the ’728 pa-
tent, claim 1 of the ’068 patent, claims 1 and 22 of the ’468
patent, claims 1, 20, and 27 of the ’314 patent, and claims
1 and 28 of the ’437 patent. See ’728 patent; ’068 patent;
’468 patent; ’314 patent; ’437 patent; see also Claim Con-
struction Order at 45. The “guide mechanism” limitation
is found in claim 16 of the ’100 patent. See ’100 patent;
Claim Construction Order at 22. Claim 1 of the ’468 patent
recites:
1. An intravascular blood pump system,
comprising:
An intravascular blood pump adapted to be
guided to a predetermined location within
the circulatory system of a patient by a
guide wire and configured to provide left-
heart support, the intravascular blood
pump comprising a rotor having a rotor
Construction Order at 10. For this reason, we generally
cite to the specification of the ’100 patent.
Case: 24-1062 Document: 49 Page: 3 Filed: 02/09/2026

-- 3 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 4
hub tapering in the distal direction, at least
one blade extending radially outward from
the rotor hub,
a catheter coupled to a proximal end of the
intravascular blood pump, a purge lumen
extending through the catheter and opera-
tively arranged to deliver purge fluid to-
wards the intravascular blood pump;
A cannula coupled to a distal end of the in-
travascular blood pump, one or more first
ports and one or more second ports estab-
lishing fluid communication between a lu-
men of the cannula and an exterior region
of the cannula, wherein at least one first
port is located in proximity to the rotor and
at least one second port is spaced apart
from and located distal to the at least one
first port, the cannula is configured such
that when the intravascular blood pump is
positioned in the patient to provide left-
heart support the distal end of the cannula
and the at least one second port are posi-
tioned inside the patient’s heart and the
proximal end of the cannula and the at
least one first port are positioned in the pa-
tient’s aorta, the intravascular blood pump
is configured to draw blood from the pa-
tient’s heart into the at least one second
port through the cannula lumen and out
the at least one first port to provide left-
heart support while the cannula is posi-
tioned across an aortic valve of the patient;
an elongate lumen associated with the can-
nula and sized to slidably receive the guide
wire and dimensioned such that the guide
wire passes slidably and coaxially through
Case: 24-1062 Document: 49 Page: 4 Filed: 02/09/2026

-- 4 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 5
the elongate lumen, the elongate lumen is
sized smaller cross sectionally than the
cannula lumen, both the elongate lumen
and the cannula lumen not extending
through the rotor hub, the intravascular
blood pump system configured for the guide
wire to extend proximally away from the
intravascular blood pump, the guide wire
not passing through the rotor hub or the
catheter, and the guide wire extending out
of the intravascular blood pump system in
a distal direction through the elongate lu-
men;
a pressure sensing element configured to
sense pressure proximate the intravascu-
lar blood pump;
a housing connected to a proximal end of
the catheter; and first and second conduits
each connected to the housing, at least one
of the first conduit and second conduit in
fluid communication with the purge lu-
men.
’468 patent col. 33 l. 58 to col. 34 l. 42 (emphases added).
Claim 16 of the ’100 patent recites:
16. An intravascular blood pump system
comprising:
an intravascular blood pump having a can-
nula coupled thereto,
a guide mechanism adapted to guide said
intravascular blood pump and cannula to a
predetermined location within the circula-
tory system of a patient, and
a blood pressure detection mechanism to
detect the pressure of the blood proximate
Case: 24-1062 Document: 49 Page: 5 Filed: 02/09/2026

-- 5 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 6
at least one of the intravascular blood
pump and cannula.
’100 patent col. 20 ll. 20–28 (emphasis added).
On May 19, 2016, Abiomed filed a suit seeking a declar-
atory judgment that its Impella devices do not infringe the
claims of the Asserted Patents and that the claims of the
Asserted Patents are invalid. Abiomed, Inc. v. Maquet Car-
diovascular LLC, 566 F. Supp. 3d 59, 65 (D. Mass. 2021)
(“Summary Judgment Order”); J.A. 158. Maquet filed a
counterclaim seeking a declaratory judgment of infringe-
ment and damages. Summary Judgment Order at 65.
On September 7, 2018, the district court construed dis-
puted claim terms after holding a Markman hearing.
Claim Construction Order at 8. The district court con-
strued “an elongate lumen associated with the cannula” in
the ’468, ’314, and ’437 patents to mean “a permanent elon-
gate lumen formed along the side of the cannula.” Claim
Construction Order at 30. In addition, in relevant part, the
district court construed the “purge fluid” limitations of the
’728, ’068, ’468, ’314, and ’437 patents to require that “the
purge fluid does not go through the rotor bearings and into
the bloodstream.” Claim Construction Order at 47. The
district court also construed the “guide mechanism” limita-
tion in the ’100 patent as a means-plus-function term.
Claim Construction Order at 36–38.
Maquet moved for reconsideration and/or clarification
regarding the district court’s construction of the “purge
fluid” limitations. J.A. 79, 176. The district court denied
Maquet’s motion for reconsideration and/or clarification.
J.A. 88, 180. Maquet subsequently limited its asserted
claims to claims 16 and 17 of the ’100 patent. Summary
Judgment Order at 65; J.A. 3497.
Abiomed moved for summary judgment of non-in-
fringement of the ’100 patent, arguing that the Impella de-
vices “are not literally infringing, nor equivalent under
Case: 24-1062 Document: 49 Page: 6 Filed: 02/09/2026

-- 6 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 7
35 U.S.C. § 112 ¶ 6 or the doctrine of equivalents.” Sum-
mary Judgment Order at 65; J.A. 1572–1607. On Septem-
ber 30, 2021, the district court granted summary judgment
of non-infringement of claims 16 and 17 of the ’100 patent.
Summary Judgment Order at 65. On September 1, 2023,
the district court entered final judgment. J.A. 1–2.
This appeal followed. We have jurisdiction under
28 U.S.C. § 1295(a)(1).
II. STANDARD OF REVIEW
“Regarding questions of claim construction, including
whether claim language invokes 35 U.S.C. § 112, para. 6,
the district court’s determinations based on evidence in-
trinsic to the patent as well as its ultimate interpretations
of the patent claims are legal questions that we review de
novo.” Williamson v. Citrix Online, LLC, 792 F.3d 1339,
1346 (Fed. Cir. 2015) (en banc in relevant part).
“In reviewing the grant of a motion for summary judg-
ment we apply the law of the regional circuit in which the
district court sits, here, the First Circuit.” AntennaSys,
Inc. v. AQYR Techs., Inc., 976 F.3d 1374, 1377 (Fed. Cir.
2020). “The First Circuit reviews a grant of summary judg-
ment de novo.” Id.; see also Santiago-Diaz v. Rivera-Ri-
vera, 793 F.3d 195, 199 (1st Cir. 2015). Summary
judgment is appropriate when the moving party demon-
strates that “there is no genuine dispute as to any material
fact and the movant is entitled to judgment as a matter of
law.” Fed. R. Civ. P. 56(a). We view the evidence in the
light most favorable to the nonmovant and draw all reason-
able inferences in that party’s favor. Santiago-Diaz,
793 F.3d at 199; Pineda v. Toomey, 533 F.3d 50, 53
(1st Cir. 2008).
III. DISCUSSION
Maquet presents four arguments on appeal. First, Ma-
quet argues that the district court erred by restricting the
claim phrase “elongate lumen associated with the cannula”
Case: 24-1062 Document: 49 Page: 7 Filed: 02/09/2026

-- 7 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 8
to only elongate lumens “formed along the side of” the can-
nula. See Appellant’s Br. 33–45. Second, Maquet argues
that the district court erred by importing a negative limi-
tation into the “purge fluid” terms. See id. at 46–55. Third,
Maquet argues that the district court erred in construing
“guide mechanism” as a means-plus-function term. See id.
at 55–62. Fourth, Maquet argues that the district court
erred in granting summary judgment of noninfringement
because even under the district court’s construction of
“guide mechanism,” there were genuine disputes of mate-
rial fact precluding summary judgment. See id. at 62–68.
We address each argument in turn.
A.
We first address whether the district court erred by
limiting the claim phrase “an elongate lumen associated
with the cannula” to only elongate lumens “formed along
the side of” the cannula.2 Maquet argues that although the
district court correctly determined that no part of the
claims, written description, or prosecution history supports
restricting the claim phrase, Appellant’s Br. 35–38, the dis-
trict court erred by restricting the claim phrase based on
statements by Maquet in related inter partes review pro-
ceedings. Id. at 38–45. Abiomed responds that based on
the claims, specification, and the prosecution history, the
district court correctly construed the “elongate lumen”
terms. Appellees’ Br. 23–39. We agree with Maquet.
“Claim terms are generally given their plain and ordi-
nary meaning, which is the meaning one of ordinary skill
in the art would ascribe to a term when read in the context
of the claim, specification, and prosecution history.”
2 Maquet does not dispute the district court’s con-
struction to the extent that the elongate lumen is “perma-
nent.” Appellant’s Br. 39; see also Claim Construction
Order at 30.
Case: 24-1062 Document: 49 Page: 8 Filed: 02/09/2026

-- 8 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 9
Kyocera Senco Indus. Tools Inc. v. ITC, 22 F.4th 1369, 1378
(Fed. Cir. 2022) (citing Phillips v. AWH Corp., 415 F.3d
1303, 1313–14 (Fed. Cir. 2005) (en banc)). “There are only
two exceptions to this general rule: 1) when a patentee
sets out a definition and acts as his own lexicographer, or
2) when the patentee disavows the full scope of a claim
term either in the specification or during prosecution.” Id.
(quoting Thorner v. Sony Computer Ent. Am. LLC,
669 F.3d 1362, 1365 (Fed. Cir. 2012)).
As always, “[w]e start with the claim language.”
Straight Path IP Grp., Inc. v. Sipnet EU S.R.O., 806 F.3d
1356, 1360 (Fed. Cir. 2015). The claim language does not
support limiting “an elongate lumen associated with the
cannula” to only elongate lumens “formed along the side of”
the cannula. Claim Construction Order at 30. The claims
only specify two restrictions on the lumen: it must
(1) “elongate” and (2) be “associated with the cannula.”
See, e.g., ’468 patent col. 33 l. 58 to col. 34 l. 42, col. 35 l. 63
to col. 36 l. 59; ’314 patent col 36 l. 55 to col. 38 l. 18; ’437
patent col. 33 l. 42 to col. 34 l. 30, col. 36 l. 13 to col. 37 l. 18.
Thus, the claims do not specify whether the elongate lumen
is “formed along the side of” the cannula.
Turning to the specification, the embodiments that
Abiomed points to do not limit the scope of “an elongate
lumen associated with the cannula” to only elongate lu-
mens “formed along the side of” the cannula. Abiomed ar-
gues that because the “elongate lumen” is part of the “guide
mechanism,” a skilled artisan would examine the “side-rig-
ger” aspect of the guide mechanism to understand the re-
lation between the elongate lumen and the cannula in the
“elongate lumen” claims. Appellees’ Br. 27–29. The prob-
lem for Abiomed is that the side-rigger configuration is one
of several ways for a lumen to be associated with a cannula.
See, e.g., ’468 patent col. 3 ll. 4–59; id. col. 15 l. 67 to col. 16
l. 4 (“[T]he cannula . . . may be equipped with dedicated lu-
mens to receive various guide mechanisms (such as guide
wires, balloon catheters, selectively deformable elements
Case: 24-1062 Document: 49 Page: 9 Filed: 02/09/2026

-- 9 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 10
such as Nitonol, etc).”). The embodiments Abiomed points
to are exemplary only and do not limit the scope of “an elon-
gate lumen associated with the cannula” to only elongate
lumens “formed along the side of” the cannula.
The district court recognized this but nonetheless de-
termined that Maquet “disclaimed certain interpretations”
in related inter partes review proceedings, requiring “a nar-
rower construction.” Claim Construction Order at 29. In
those IPR proceedings, Maquet distinguished its “elongate
lumen” claims from a prior art source, Jegaden,3 by argu-
ing that “Jegaden provides a separate device—a catheter
with a guide wire—to guide an unmodified device into a
patient. If anything, this [statement] teaches away from
[Abiomed’s] proposed modification as Jegaden teaches us-
ing a separate catheter instead of modifying the cannula to
accommodate a side lumen,” as described in another prior
art reference. J.A. 1305–06. The district court concluded
that “[b]y saying that the ‘elongate lumen’ claims are not
satisfied unless the cannula is modified to accommodate a
side lumen, Maquet has clearly and unmistakably (1) asso-
ciated the ‘elongate lumen’ claims with the side-rigger de-
sign and (2) explained that, in its view, the cannula itself
must be modified to support the side lumen.” Claim Con-
struction Order at 29.
The district court erred in holding that prosecution dis-
claimer applied to the “elongate lumen” claims. Although
statements made by a patent owner during inter partes re-
view can be relied on to support a finding of prosecution
disclaimer, Aylus Networks, Inc. v. Apple Inc., 856 F.3d
1353, 1360 (Fed. Cir. 2017), “to invoke the doctrine of pros-
ecution disclaimer, any such statements must ‘be both
3 O. Jegaden, Clinical Results of Hemopump Sup-
port in Surgical Cases, in Temporary Cardiac Assist with
an Axial Pump System 61 (W. Flameng ed., 1991),
J.A. 1426–30 (“Jegaden”).
Case: 24-1062 Document: 49 Page: 10 Filed: 02/09/2026

-- 10 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 11
clear and unmistakable.’” Id. at 1361 (quoting Omega
Eng’g, Inc. v. Raytek Corp., 334 F.3d 1314, 1326 (Fed. Cir.
2003)); see also Maquet Cardiovascular LLC v. Abiomed
Inc., 131 F.4th 1330, 1342–43 (Fed. Cir. 2025). Maquet’s
argument that Jegaden discloses using a separate catheter,
which allegedly teaches away from modifying a cannula to
accommodate a side lumen, does not rise to the requisite
level of being “‘words or expressions of manifest exclusion
or restriction’ in the intrinsic record.” Unwired Planet,
LLC v. Apple Inc., 829 F.3d 1353, 1358 (Fed. Cir. 2016)
(quoting Teleflex, Inc. v. Ficosa N. Am. Corp., 299 F.3d
1313, 1327 (Fed. Cir. 2002)). Instead, a skilled artisan
could read Maquet’s statement as refuting Abiomed’s char-
acterizations of Jegaden and another prior art reference.
Since Maquet’s statements are “far too slender [ ] reed[s] to
support the judicial narrowing of a clear claim term,” N.
Telecom Ltd. v. Samsung Elecs. Co., 215 F.3d 1281, 1294
(Fed. Cir. 2000), the district court erred in limiting “an
elongate lumen associated with the cannula” to mean “a
permanent elongate lumen formed along the side of the
cannula.” Claim Construction Order at 30.
B.
Next, Maquet argues that the district court 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.” Appellant’s
Br. 46 (quoting Claim Construction Order at 46–47) (em-
phasis omitted); see id. at 46–55. In response, Abiomed ar-
gues that the district court correctly construed the “purge
fluid” terms because Maquet “clearly and unequivocally
distinguish[ed] Aboul-Hosn4 and disparage[d] a pump con-
figuration in which purge fluid is discharged into the
4 WO 99/02204 (filed October 14, 1997; published
January 21, 1999), J.A. 862–933 (“Aboul-Hosn”).
Case: 24-1062 Document: 49 Page: 11 Filed: 02/09/2026

-- 11 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 12
bloodstream.” Appellees’ Br. 39; see id. at 39–50. We agree
with Maquet.
Starting with the claim language, the representative
claim recites a lumen “operatively arranged to deliver
purge fluid to the intravascular blood pump.” ’728 patent
col. 18 ll. 36–59.5 The claim language does not restrict
what path the purge fluid may take, and therefore it does
not preclude the purge fluid from going through the rotor
bearings and into the bloodstream.
Nor does the specification support that the purge fluid
cannot go through the rotor bearings and into the blood-
stream. In fact, the specification directly supports that the
purge fluid can pass through ball bearing assemblies and
into the blood stream. ’728 patent col. 10 ll. 19–24 (“[T]he
purge fluid flows distally around the cable adapter 60,
through the ball bearing assemblies 50, 52, and onward
past the radial seal 64. This egress of purge fluid past the
radial seal 64 can be controlled to effectively thwart the in-
gress of blood past the radial seal 64, which might other-
wise cause clotting and/or pump damage.”); id. col. 15
ll. 51–64.
Although the language from the claims and specifica-
tion indicate that the purge fluid is not precluded from go-
ing through the rotor bearings and into the bloodstream,
the district court nonetheless determined that “Maquet
clearly and unmistakably disparaged one-way systems in
which the purge fluid runs both (1) through bearing assem-
blies and (2) into the blood stream” based on statements
Maquet made during inter partes review of the ’728 patent.
Claim Construction Order at 46. In that IPR, Maquet
5 “Because the claim construction dispute centers on
the prosecution history for the ’728 patent, Maquet cites
the claims and specification of the ’728 patent as repre-
sentative.” Appellant’s Br. 46 n.4.
Case: 24-1062 Document: 49 Page: 12 Filed: 02/09/2026

-- 12 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 13
argued, in response to Abiomed’s argument regarding Fig-
ure 10 of Aboul-Hosn, that a person of ordinary skill in the
art “would recognize that injecting floating particles from
bearings into a patient’s blood stream is a bad idea.”
J.A. 1230.
However, Maquet’s statements during related inter
partes review proceedings do not clearly and unmistakably
disclaim passing purge fluid through rotor bearings and
into the blood stream. Maquet’s argument appears to be
specific to addressing why Abiomed misread Figure 10 of
Aboul-Hosn. See J.A. 1228–30 (section titled “Petitioners
Misread the Disclosure in Aboul-Hosn”). These statements
do not amount to an instance “[w]here an applicant argues
that a claim possesses a feature that the prior art does not
possess in order to overcome a prior art rejection,”
Seachange Int’l, Inc. v. C-COR, Inc., 413 F.3d 1361,
1372–73 (Fed. Cir. 2005); see also Andersen Corp. v. Fiber
Composites, LLC, 474 F.3d 1361, 1374 (Fed. Cir. 2007) (col-
lecting cases), because it is unclear from Maquet’s state-
ment whether it is contending that the Asserted Patents do
not teaching running purge fluid through bearings, or
merely through bearings with gaps. See J.A. 1230. In fact,
the district court was “not entirely sure what to make of
this statement,” since “[i]t directly contradicts statements
in the specification that clearly contemplate passing purge
fluid through ball bearing assemblies and into the blood-
stream.” Claim Construction Order at 45. Because it is
unclear whether Maquet’s argument was specific to Aboul-
Hosn, the district court erred in finding “clear and unmis-
takable” disclaimer.
Accordingly, we vacate the district court’s final judg-
ment with respect to the ’728, ’068, ’468, ’314, and ’437 pa-
tents and remand for proceedings consistent with this
opinion.
Case: 24-1062 Document: 49 Page: 13 Filed: 02/09/2026

-- 13 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 14
C.
Maquet also argues that the district court erred in con-
struing “guide mechanism” as a means-plus-function term,
and the term should be given its plain and ordinary mean-
ing. Appellant’s Br. 55–60. In addition, Maquet argues
that even if “guide mechanism” were a means-plus-func-
tion term, the district court erred by failing to include cer-
tain structures disclosed in the specification. Id. at 60–62.
In response, Abiomed argues that “guide mechanism” is a
means-plus-function term, Appellees’ Br. 50–58, and the
district court correctly identified the corresponding struc-
tures. Id. at 58–65. We agree with Abiomed.
i.
We begin by addressing whether “guide mechanism” is
a means-plus-function term. To determine whether
35 U.S.C. § 112 ¶ 6 applies, the essential inquiry is
“whether the words of the claim are understood by persons
of ordinary skill in the art to have a sufficiently definite
meaning as the name for structure.” Williamson, 792 F.3d
at 1348. We traditionally look to whether the claim uses
the word “means;” if so, there is a rebuttable presumption
that § 112 ¶ 6 applies. Id. The converse is also true: “[T]he
failure to use the word ‘means’ also creates a rebuttable
presumption—this time that § 112, para. 6 does not apply.”
Id. If “a claim term lacks the word ‘means,’ the presump-
tion can be overcome and § 112, para. 6 will apply if the
challenger demonstrates that the claim term fails to ‘re-
cite[ ] sufficiently definite structure’ or else recites ‘func-
tion without reciting sufficient structure for performing
that function.’” Id. (quoting Watts v. XL Sys., Inc., 232 F.3d
877, 880 (Fed. Cir. 2000)). “Intrinsic evidence, such as the
claims themselves and the prosecution history, can be in-
formative in determining whether the disputed claim lan-
guage recites sufficiently definite structure or was
intended to invoke § 112 ¶ 6.” Dyfan, LLC v. Target Corp.,
Case: 24-1062 Document: 49 Page: 14 Filed: 02/09/2026

-- 14 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 15
28 F.4th 1360, 1365–66 (Fed. Cir. 2022).6 As the claimed
“guide mechanism” does not use the word “means,” we
begin our analysis with the presumption that the claim
does not invoke § 112 ¶ 6.
The district court did not err, however, in determining
that “guide mechanism” invokes § 112 ¶ 6 because the term
does not recite sufficiently definite structure. A skilled ar-
tisan would not understand the claimed “guide mecha-
nism” to have “a sufficiently definite meaning as the name
for a structure.” Williamson, 792 F.3d at 1348. “Guide
mechanism” alone does not constitute structure. “Mecha-
nism” is a nonce term that is “tantamount to using the
word ‘means,’” id. at 1350, and “guide” is just a functional
modifier. Media Rts. Techs., Inc. v. Cap. One Fin. Corp.,
800 F.3d 1366, 1373 (Fed. Cir. 2015) (“We have never found
that the term ‘mechanism’”—without more—connotes an
identifiable structure; certainly, merely adding the modi-
fier “[guide]” to that term would not do so either.”). Fur-
thermore, the “surrounding claim language” neither
describes structural detail about the “guide mechanism,”
nor specifies how the “guide mechanism” interacts with an
intravascular blood pump and cannula. See, e.g., Kyocera,
22 F.4th at 1380. Rather, claim 16 is expressed solely in
functional terms—that is, the guide mechanism has the
function of “guid[ing] said intravascular blood pump and
6 Maquet argues that “Abiomed supplied no evi-
dence—no expert declaration, for example—that the term
‘guide mechanism’ fails to connote structure.” Appellant’s
Br. 57. However, “none of our cases mandate that a party
seeking to overcome the presumption against application
of § 112, para. 6 can only do so by presenting extrinsic evi-
dence that one of ordinary skill would fail to understand
that a term connotes a definite structure.” Diebold Nix-
dorf, Inc. v. ITC, 899 F.3d 1291, 1299 (Fed. Cir. 2018).
Case: 24-1062 Document: 49 Page: 15 Filed: 02/09/2026

-- 15 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 16
cannula to a predetermined location within the circulatory
system of a patient.” ’100 patent col. 20 ll. 20–28.
Moreover, “[n]othing in the written description pro-
vides a clear and unambiguous definition” of the claim
term “guide mechanism.” Kyocera, 22 F.4th at 1380–81.
Although the specification describes use of a “guide mech-
anism” in the prior art, the specification provides no evi-
dence that “guide mechanism” had a definite meaning
before the alleged invention. See, e.g., ’100 patent col. 2
ll. 19–55. “That the specification discloses a structure cor-
responding to an asserted means-plus-function claim term
does not necessarily mean that the claim term is under-
stood by persons of ordinary skill in the art to connote a
specific structure or a class of structures.” MTD Prods. Inc.
v. Iancu, 933 F.3d 1336, 1344 (Fed. Cir. 2019). Therefore,
the district court did not err in determining that “guide
mechanism” invokes § 112 ¶ 6.
ii.
Because the term “guide mechanism” is a means-plus-
function term, “we next determine whether the specifica-
tion discloses sufficient structure that corresponds to the
claimed function.” Williamson, 792 F.3d at 1351. This de-
termination is a two-step process. Id. We “must first iden-
tify the claimed function,” and then “determine what
structure, if any, disclosed in the specification corresponds
to the claimed function.” Id.
The district court construed “guide mechanism” as hav-
ing the function of “guid[ing] said intravascular blood
pump and cannula to a predetermined location within the
circulatory system of a patient” with the following struc-
tures: “(a) a guide wire passing slideably through a central
lumen extending through a drive cable assembly, blood
pump, and cannula; (b) a guide wire passing slideably
through a lumen extending through a guide carriage inte-
grally formed along at least a portion of the cannula side-
wall; or (c) a conduit assembly, including guide catheter, a
Case: 24-1062 Document: 49 Page: 16 Filed: 02/09/2026

-- 16 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 17
rotor shroud, and a cannula, which is capable of docking to
a separate pump assembly.” Claim Construction Order
at 36–38. Maquet argues that the district court “erred by
excluding two other corresponding structures disclosed in
the specification:” (1) a “rapid exchange” guide mechanism
and (2) a guide mechanism that “includes a guide carriage
124.” Appellant’s Br. 60–62. We disagree.
The district court did not exclude a “rapid-exchange”
guide mechanism, as the specification repeatedly and con-
sistently equates a “side rigger” and “rapid-exchange” type
guide mechanism. See, e.g., ’100 patent col. 3 ll. 6–7; id.
col. 12 ll. 13, 31–32. The specification explains that “the
‘rapid [ ] exchange’ or ‘side-rigger’ guide mechanism 122 in-
cludes a guide carriage 124 formed along at least a portion
of the cannula 14, and a suitable guide element (such as
guide wire 22) dimensioned to pass slidably through a lu-
men (not shown) extending through the guide carriage
124.” ’100 patent col. 12 ll. 14–19. Even though one of the
’100 patent’s inventors testified that a “rapid exchange”
guide mechanism does not require a “side rigger,” Appel-
lant’s Br. 61 n.7 (citing J.A. 1567–68 at 281:22–283:11),
this extrinsic evidence is insufficient to add a correspond-
ing structure. See Vitronics Corp. v. Conceptronic, Inc.,
90 F.3d 1576, 1584 (Fed. Cir. 1996) (concluding that extrin-
sic evidence may not “contradict the import of other parts
of the specification.”).
Furthermore, contrary to Maquet’s argument, the dis-
trict court did not exclude the guide mechanism that “in-
cludes a guide carriage 124.” Maquet relies on one
sentence of the specification: “guide mechanism 122 in-
cludes a guide carriage 124 formed along at least a portion
of the cannula 14, and a suitable guide element (such as
guide wire 22) dimensioned to pass slidably through a lu-
men (not shown) extending through the guide carriage
[124].” Appellant’s Br. 61 (quoting ’100 patent col. 12
ll. 15–19). But “guide carriage 124” is the same guide car-
riage already required by structure (b). Therefore, the
Case: 24-1062 Document: 49 Page: 17 Filed: 02/09/2026

-- 17 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 18
district court did not err in identifying the corresponding
structures.
D.
Maquet argues that even accepting the district court’s
allegedly incorrect construction of “guide mechanism,”
summary judgment should have been denied because there
are genuine disputes of material fact. Id. at 62–68. Abio-
med responds that the district court correctly granted sum-
mary judgment of non-infringement of claims 16 and 17 of
the ’100 patent and that there were no genuine disputes of
material fact precluding summary judgment. Id. at 66–77.
We agree with Abiomed.
To literally infringe a means-plus-function limitation,
“the accused structure must either be the same as the dis-
closed structure or be a section 112, paragraph 6 ‘equiva-
lent,’ i.e., (1) perform the identical function and (2) be
otherwise insubstantially different with respect to struc-
ture.” Kemco Sales, Inc. v. Control Papers Co., 208 F.3d
1352, 1364 (Fed. Cir. 2000). “It is undisputed that the ac-
cused [Impella] devices perform an identical function to the
‘guide mechanism’ of the patent.” Summary Judgment Or-
der at 85. The only disputes are whether Abiomed’s Im-
pella contains an inlet cage which is part of the cannula,
and, if so, whether the Impella’s pigtail is integrally formed
along at least a portion of the cannula sidewall. Summary
Judgment Order at 85.
For purposes of deciding Abiomed’s summary judg-
ment motion, the district court viewed this fact “in the light
most favorable to Maquet” and accepted Maquet’s conten-
tion, assuming that “the term ‘cannula’ includes the inlet
cage.” Summary Judgment Order at 85. This approach by
the district court is further supported by the fact that in
denying Maquet’s motion for reconsideration of summary
judgment, the district court explained that its “ruling was
not premised on the notion that the threaded nub is dis-
tinct from the cannula” and “assumed that the cannula
Case: 24-1062 Document: 49 Page: 18 Filed: 02/09/2026

-- 18 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 19
consists of the inlet cage and that the threaded nub is at-
tached to the inlet cage and, therefore, the cannula.”
J.A. 132. Thus, the record is clear that the district court
accepted Maquet’s contention that the threaded nub is part
of the inlet cage, and, therefore, is part of the cannula.
The district court did not err in determining that the
Impella’s pigtail is not “formed along” the cannula side-
wall. Specifically, the parties dispute whether the struc-
ture of the Impella products meets structure (b) of the
district court’s claim construction. Maquet contends that
“a jury could reasonably find that the Impella’s pigtail
guide carriage is ‘integrally formed along at least a portion
of the cannula sidewall.’” Appellant’s Br. 63–64. However,
as the district court determined, “the pigtail is not attached
to any portion of the cannula sidewalls. Rather, it is at-
tached to the threaded nub, which is attached to a flat sur-
face, which is attached to the inlet cage at the distal end of
the cannula[:]”
Summary Judgment Order at 87; Appellant’s Br. 23 (anno-
tating J.A. 2872).
Case: 24-1062 Document: 49 Page: 19 Filed: 02/09/2026

-- 19 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 20
Appellant’s Br. 24 (annotating J.A. 2770). Because “[t]he
cannula sidewalls lie entirely below (proximal) to that
plane; the pigtail and threaded nub lie entirely above (dis-
tal) to it,” “there is never any point in the structure where
the pigtail or nub are ‘along’ even a ‘portion’ of the cannula
sidewall.” Summary Judgment Order at 87. Therefore, the
district court did not reversibly err in determining that the
Impella pigtail is not “formed along at least a portion of the
cannula sidewall.” Summary Judgment Order at 86–88;
Claim Construction Order at 36.
Maquet also argues that “[t]he district court further
erred in finding no genuine dispute over the Impella prod-
uct’s infringement as a structural equivalent under § 112
¶ 6 or as an equivalent under a traditional doctrine of
equivalents framework.” Appellant’s Br. 65; see id. at 65–
68. However, the expert testimony that Maquet points to
does not create a genuine dispute of material fact for the
jury to resolve. Maquet’s expert never identified the al-
leged structural differences between the Impella and struc-
ture (b) or explained why any differences are
“insubstantial.” J.A. 2775; see generally J.A. 2774–78.
Conclusory opinions like those of Maquet’s expert are in-
sufficient to defeat summary judgment. See Traxcell
Techs., LLC v. Sprint Commc’ns Co., 15 F.4th 1121, 1129
(Fed. Cir. 2021) (determining that “Traxcell [did not] pro-
vide enough evidence for a reasonable jury to conclude that
the accused structure performs the claimed function in
‘substantially the same way’ as the disclosed structure”).
Thus, Maquet fails to show a genuine dispute of material
fact precluding summary judgment.
In sum, the district court did not err in determining
that the Impella devices do not infringe claims 16 and 17
of the ’100 patent because no reasonable jury could have
found that Abiomed’s Impella devices contain a “guide
mechanism” under structure (b).
Case: 24-1062 Document: 49 Page: 20 Filed: 02/09/2026

-- 20 of 21 --

ABIOMED INC. v. MAQUET CARDIOVASCULAR LLC 21
IV. CONCLUSION
For the reasons above, we affirm-in-part, vacate-in-
part, and remand for proceedings consistent with this opin-
ion.
AFFIRMED-IN-PART, VACATED-IN-PART, AND
REMANDED
COSTS
No costs.
Case: 24-1062 Document: 49 Page: 21 Filed: 02/09/2026

-- 21 of 21 --