The U.S. Court of Appeals for the Federal Circuit has invalidated all claims of Shockwave Medical's patent covering an innovative angioplasty catheter system that combines traditional balloon catheter technology with intravascular lithotripsy (IVL) to treat atherosclerosis. The precedential decision in Shockwave Medical, Inc. v. Cardiovascular Systems, Inc. (CSI) resolves a complex patent dispute while establishing important guidelines for the use of applicant admitted prior art in patent invalidity proceedings.
Technology and Patent Claims
Shockwave's U.S. Patent No. 8,956,371, titled "Shockwave Balloon Catheter System," describes an angioplasty catheter that applies lithotripsy technology to break up calcified plaque deposits in blood vessels. The system combines a standard over-the-wire balloon catheter with electrodes and a pulse generator. When activated, the electrodes create plasma arcs inside the fluid-filled balloon, generating shockwaves designed to break up hardened plaque without putting excessive pressure on artery walls.
The technology represents an adaptation of lithotripsy, a well-established technique traditionally used to break up kidney stones with high-intensity sonic waves, for cardiovascular applications in treating calcified plaque deposits.
Patent Challenge and PTAB Proceedings
CSI challenged all seventeen claims of the patent through 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 Patent Trial and Appeal Board (PTAB) initially found that all claims except claim 5 were unpatentable as obvious. The surviving claim 5 included the additional limitation that electrodes are disposed adjacent to and outside of the guide wire lumen.
Both companies appealed the PTAB decision to the Federal Circuit, with Shockwave challenging the invalidation of claims 1-4 and 6-17, while CSI cross-appealed the validity finding for claim 5.
Applicant Admitted Prior Art Ruling
A central issue in the appeal concerned the proper use of applicant admitted prior art (AAPA) in IPR proceedings. 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 serve as the basis for invalidity grounds in IPR proceedings.
The Federal Circuit clarified its precedent, explaining that "what matters is the grounds raised in the petition, and CSI's petition never phrased the AAPA in terms of constituting a basis for its obviousness arguments." The court distinguished this case from its recent Qualcomm decisions, noting that CSI only used Shockwave's AAPA to demonstrate what the patent itself acknowledged: that the claimed over-the-wire angioplasty balloon catheter was well-known technology.
The court reaffirmed 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 skilled artisan to fill in missing claim limitations. Because CSI properly relied on general background knowledge, as evidenced by AAPA, to supply missing claim limitations, the IPR petition did not violate statutory requirements.
Claim Construction and Obviousness Analysis
The Federal Circuit rejected Shockwave's arguments regarding claim construction, finding that Shockwave's proposed narrower construction of "angioplasty balloon" was not supported by the patent's language or specification. The court noted that the patent's specification expressly disavowed any requirement that the balloon must exert pressure on artery walls to break plaque.
The court also found that the Board properly outlined reasons why an ordinarily skilled artisan would combine the Levy reference with the AAPA's angioplasty catheter, including the ability to increase the treatments Levy could perform. The Federal Circuit determined that Levy's specification disclosed the use of shockwaves in blood vessels and was not limited to cleaning tooth canals.
Cross-Appeal and Final Invalidation
Regarding CSI's cross-appeal challenging the validity of claim 5, the Federal Circuit found that CSI had Article III standing based on public statements made by Shockwave's President indicating that claim 5 would be asserted against competitors in the intravascular lithotripsy market. The court noted that CSI was close to initiating clinical trials of an IVL product and had reached the design freeze phase at the time of the cross-appeal.
The Federal Circuit faulted the PTAB for considering a Japanese patent application (Uchiyama) in isolation rather than in combination with the teachings of Levy and AAPA. The court found that the Board improperly discounted CSI's argument that placing Uchiyama's electrodes outside of the lumen would have been a routine design choice among the limited number of well-known design options available to skilled artisans.
Industry Impact
The decision eliminates patent protection for Shockwave's foundational IVL technology, potentially opening the market to additional competition. At the time of the proceedings, CSI was developing its own IVL device and had advanced to clinical trial preparation stages, suggesting the competitive landscape in intravascular lithotripsy may evolve following this ruling.
The precedential nature of the decision also provides important guidance for future IPR proceedings regarding the proper use of applicant admitted prior art, clarifying the boundaries between impermissible reliance on AAPA as a basis for invalidity grounds versus acceptable use as evidence of background knowledge.
