• Federal Circuit Invalidates Patent For Angioplasty Catheter Based On Applicant Admitted Prior Art

  07/22/2025

  The Federal Circuit recently issued a precedential decision in Shockwave Med., Inc. v. Cardiovascular Sys., Inc. (CSI), affirming-in-part and reversing-in-part the Patent Trial and Appeal Board’s (PTAB) decision, and ultimately invalidated the patent at issue.  The patent, Shockwave’s U.S. Patent No. 8,956,371, relates to an angioplasty catheter for treating atherosclerosis with intravascular lithotripsy (IVL).  This system combines a standard over-the-wire balloon catheter with electrodes and a pulse generator.  When the device is activated, the electrodes create plasma arcs inside the fluid-filled balloon, which in turn generate shockwaves.  These shockwaves are designed to break up hardened plaque in blood vessels without putting excessive pressure on the artery walls.

  CSI challenged all seventeen claims of the ‘371 patent through an inter partes review (IPR), arguing that the claims were obvious in view of prior art, including a European patent called Levy and other references.  The PTAB ultimately found that all except claim 5 were unpatentable as obvious. Both companies appealed the decision to the Federal Circuit.

  One of the issues raised by Shockwave on appeal was the use of “applicant admitted prior art” (AAPA) to invalidate claims 1-4 and 6-17.  Shockwave argued that CSI and the Board improperly relied on AAPA as a basis for the IPR in violation of 35 U.S.C. § 311(b)’s limitation that only patents or printed publications can be relied upon in IPRs.  The Federal Circuit clarified and reaffirmed its previous holding that, while AAPA cannot serve as the basis of a ground in an IPR petition, it can be used as evidence of the background knowledge of an ordinarily skill artisan, which can be used to fill in a missing claim limitation.  Because the CSI properly relied on general background knowledge, as evidenced by AAPA, to supply missing claim limitations, the IPR petition did not violate § 311(b).

  The Federal Circuit also rejected the Shockwave’s argument that the PTAB erred in its claim construction.  The Court found that Shockwave’s construction was not supported by the language of the claims or specification.  Shockwave also challenged the factual findings by the Board, which the Federal Circuit rejected as well.

  With respect to claim 5, which the PTAB determined was valid, the Federal Circuit found that CSI had standing to appeal the PTAB decision given the advanced stage of development of CSI’s own IVL device—especially in view of Shockwave’s public statements that it viewed any IVL device as practicing the elements of claim 5 and that it would aggressively assert claim 5.   

  With respect to the merits of the patentability of claim 5, CSI argued on cross-appeal, and the Court agreed, that the PTAB erred by failing to properly consider the combined teachings of the prior art. Instead, the PTAB had predicated its conclusion on the finding that a single reference, Uchiyama, alone did not disclose the claimed electrode position.  The Federal Circuit found that there were a limited number of well-known design choices in the prior art, and that it would have been a matter of routine design choice to substitute one for the other.  Consequently, the Court reversed the PTAB’s determination of patentability for claim 5 and affirmed its determination of unpatentability for the remaining claims.

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• Shockwave Med., Inc. v. Cardiovascular Sys., Inc.