In a significant decision issued on July 14, 2025, the Federal Circuit in Shockwave Medical, Inc. v. Cardiovascular Systems, Inc., Nos. 2023-1864, 2023-1940, affirmed the Patent Trial and Appeal Board’s finding that most of the claims of U.S. Patent No. 8,956,371 were unpatentable as obvious—but reversed the Board’s lone finding of non-obviousness, holding that claim 5 too was unpatentable. This decision is notable for its continued development of the law concerning the permissible use of applicant admitted prior art (AAPA) in inter partes review (IPR) proceedings and its clarification of what constitutes a “basis” under 35 U.S.C. § 311(b).
Charles Gideon Korrell observes that this ruling confirms the Federal Circuit’s firm adherence to limiting the scope of IPR grounds to prior art patents and printed publications while still allowing general knowledge—including that evidenced by AAPA—to play a critical role in obviousness analysis.
Background of the Patent and Proceedings
Shockwave Medical owns the ’371 patent, which covers an “angioplasty catheter” that uses electrohydraulic lithotripsy (EHL) to treat calcified plaque in blood vessels—a novel application of a technology more traditionally used to break up kidney stones. The invention incorporates electrodes within a balloon catheter, which, when activated, produce shockwaves that break apart hardened deposits without excessive balloon pressure.
Cardiovascular Systems, Inc. (CSI) challenged all 17 claims of the ’371 patent in an IPR proceeding. The Patent Trial and Appeal Board found that claims 1–4 and 6–17 were obvious over the prior art but that claim 5 was not. Shockwave appealed the adverse ruling on claims 1–4 and 6–17, while CSI cross-appealed the Board’s non-obviousness finding on claim 5.
Federal Circuit’s Holding on the Direct Appeal (Claims 1–4 and 6–17)
The Federal Circuit, in an opinion authored by Judge Dyk and joined by Judges Lourie and Cunningham, rejected Shockwave’s arguments and affirmed the Board’s invalidation of these claims.
1. Use of AAPA Does Not Violate § 311(b)
Shockwave argued that CSI improperly relied on AAPA to form the “basis” for its obviousness grounds, violating 35 U.S.C. § 311(b), which limits IPR challenges to “prior art consisting of patents or printed publications.” The court rejected this argument, emphasizing that:
“[A]lthough the prior art that can be considered in [IPRs] is limited to patents and printed publications, it does not follow that we ignore the skilled artisan’s knowledge when determining whether it would have been obvious to modify the prior art.” (Citing Koninklijke Philips N.V. v. Google LLC, 948 F.3d 1330 (Fed. Cir. 2020)).
The court distinguished its prior holdings in Qualcomm I (24 F.4th 1367 (Fed. Cir. 2022)) and Qualcomm II (134 F.4th 1355 (Fed. Cir. 2025)), noting that CSI never labeled the AAPA as a “basis” in its petition. The use of AAPA here merely provided background knowledge, consistent with permissible uses recognized in Randall Mfg. v. Rea, 733 F.3d 1355 (Fed. Cir. 2013).
Charles Gideon Korrell notes that this distinction between AAPA as a reference and as a “basis” helps clarify a murky area in IPR practice. Petitioners may use AAPA to demonstrate a skilled artisan’s background knowledge, but must be cautious not to identify it as a foundational reference for an obviousness ground.
2. Claim Construction of “Angioplasty Balloon”
Shockwave sought to limit the construction of “angioplasty balloon” to require that it displace plaque into the vessel wall, but the court sided with CSI’s broader construction as “an inflatable sac…to widen narrowed or obstructed blood vessels.” The specification itself undermined Shockwave’s construction, explicitly stating that the balloon need not be snug to the vessel wall.
3. Obviousness Over Levy and Background Knowledge
Substantial evidence supported the Board’s findings:
- It was obvious to use Levy’s shockwave technique with known over-the-wire angioplasty catheters.
- Levy disclosed shockwave generation in vascular applications.
- The commercial success and secondary considerations proffered by Shockwave lacked sufficient linkage to the claimed invention and were unpersuasive.
Reversal on CSI’s Cross-Appeal: Claim 5 Is Also Obvious
Claim 5 requires that the “pair of electrodes [be] disposed adjacent to and outside of the guide wire lumen.” The Board had found that this configuration was not disclosed in CSI’s references. However, the Federal Circuit reversed that determination, finding the Board had failed to consider the combination of references as a whole.
The key reference was Uchiyama, which taught placement of electrodes in a balloon for lithotripsy but did not show them outside the guidewire lumen. CSI’s expert testified that relocating the electrodes outside the lumen would be a routine design modification offering better lateral plaque coverage—something well within the grasp of a skilled artisan.
The court emphasized that:
“The standard for obviousness requires consideration of the prior art combination taken as a whole.” (Citing In re Mouttet, 686 F.3d 1322, 1331 (Fed. Cir. 2012)).
CSI’s expert also relied on KSR International Co. v. Teleflex Inc., 550 U.S. 398 (2007), and Uber Technologies, Inc. v. X One, Inc., 957 F.3d 1334 (Fed. Cir. 2020), to argue that the placement of electrodes was among a finite number of predictable options.
Because Shockwave failed to rebut this with contrary evidence, the Federal Circuit found the Board’s ruling unsupported by substantial evidence and reversed outright.
Charles Gideon Korrell observes that this aspect of the decision serves as a reminder that design choices considered “routine” in the context of the art may justify an obviousness finding—especially when unchallenged by countervailing expert testimony.
Standing on Appeal
The Federal Circuit also addressed—and rejected—Shockwave’s challenge to CSI’s standing to cross-appeal. The court found that CSI had sufficiently concrete plans to commercialize a competing IVL product and was at risk of being sued under claim 5, especially in light of Shockwave’s public statements claiming broad coverage and intent to assert that claim.
This mirrors prior rulings like Adidas AG v. Nike, Inc., 963 F.3d 1355 (Fed. Cir. 2020), and General Electric Co. v. Raytheon Techs. Corp., 983 F.3d 1334 (Fed. Cir. 2020).
Conclusion
In sum, the Federal Circuit:
- Affirmed the Board’s finding that claims 1–4 and 6–17 are unpatentable,
- Reversed the Board’s finding that claim 5 is patentable, and
- Held that CSI had Article III standing to pursue its cross-appeal.
The opinion reinforces key principles of IPR law, especially:
- Proper use of AAPA as background knowledge (not a “basis”),
- Permissibility of using general knowledge to fill in gaps in prior art,
- The importance of considering combined references in obviousness analysis.
Charles Gideon Korrell believes this decision is a helpful roadmap for petitioners navigating the narrow permissible uses of AAPA in IPRs. It also serves as a cautionary tale for patentees relying heavily on secondary considerations or overly narrow claim constructions without robust evidentiary support.