Received wisdom is that inter partes review proceedings are limited to prior art as defined by patents and printed publications. But in recently decided Shockwave Medical, Inc. v. Cardiovascular Systems, Inc., another prior art species, applicant-admitted prior art (AAPA), played a strong role in helping the Petitioner satisfy the burden of showing that the challenged claims were obvious.
The case arose as an inter partes review challenging all claims of U.S. Patent No. 8,956,371, directed to devices for treating atherosclerosis through intravascular lithotripsy ("IVL") (thus giving the Court the opportunity to explain several polysyllabic medical terms). Atherosclerosis (being the easier or at least more commonly known term) the opinion reminds is a common condition characterized by the buildup of fatty deposits in blood vessels that calcifies with age and restricts blood flow. Conventional treatment includes balloon angioplasty wherein atherosclerotic plaques are compressed onto blood vessel walls and blood flow thereby increased. Specifically the opinion notes that "[a] typical balloon catheter is the over-the-wire balloon catheter, which consists of a hollow carrier (called a lumen), which is inserted over a wire to guide the balloon catheter to the correct position." Lithotripsy is a technique usually used to treat kidney stones by using high intensity sonic waves to break up the stones so they can pass through the ureters and urethra. This technique uses plasma produced in two ways: one using an electrical discharge (termed "electrohydraulic lithotripsy") and the other by laser. The invention uses electrohydraulic lithotripsy to break up calcified atherosclerotic plaque to treat atherosclerosis. The claimed device uses a conventional over-the-wire angioplasty balloon catheter and adds electrodes and a pulse generator.
Claim 1 is set forth as being exemplary:
1. An angioplasty catheter comprising:
an elongated carrier sized to fit within a blood vessel,
said carrier having a guide wire lumen extending there through;
an angioplasty balloon located near a distal end of the carrier with a distal end of the balloon being sealed to the carrier near the distal end of the carrier and with a proximal end of the balloon defining an annular channel arranged to receive a fluid therein that inflates the balloon; and
an arc generator including a pair of electrodes,
said electrodes being positioned within and in non-touching relation to the balloon,
said arc generator generating a high voltage pulse sufficient to create a plasma arc between the electrodes resulting in a mechanical shock wave within the balloon that is conducted through the fluid and through the balloon and wherein the balloon is arranged to remain intact during the formation of the shockwave.
Dependent Claim 2 recites that the pair of electrodes includes a pair of metallic electrodes, and dependent claim 5 recites:
5. The catheter of claim 2, wherein the pair of electrodes is disposed adjacent to and outside of the guide wire lumen.
In its IPR petition, Cardiovascular Systems (CSI) asserted as its primary reference supporting its obviousness allegations European Patent Application Publication No. EP 0571306 A1 to Levy, which discloses using laser-generated pulses to break up atherosclerotic plaque in blood vessels. CSI's argument was that it would have been obvious to modify "well-known" angiogenic catheters to produce plasma pulses as disclosed by Levy, basing their "well-known" argument on it being "applicant admitted prior art (AAPA)" by Shockwave (such as "typical prior art over-the-wire angioplasty balloon catheters[s] . . . [that] are usually non-compliant with a fixed maximum dimension when expanded with a fluid such as saline"). The Patent Trial and Appeal Board issued its Final Written Decision that claims 1-4 and 6-17 were obvious but failed to invalidate claim 5 on obviousness grounds. In its Decision, the Board held that AAPA qualified to support CSI's obviousness assertions. Less than one month thereafter the Patent and Trademark Office ("PTO") issued a binding guidance that AAPA was not prior art under Section 311(b) of the statute, and the Board reconsidered, arriving at the same legal conclusion of obviousness but characterizing AAPA as merely being "evidence of the background knowledge in the art." This appeal followed.
The Federal Circuit affirmed Shockwave's appeal and reversed the Board's decision on claim 5 in Cardiovascular System's cross-appeal, in an opinion by Judge Dyk joined by Judges Lourie and Cunningham. After dismissing (in a footnote) CSI's contention that Shockwave's appeal of the Board's decision to consider AAPA to be applicable to the obviousness question under Section 311(b) was precluded by Section 314(d), the panel on the merits rejected Shockwave's contention that considering AAPA was error. According to the Federal Circuit, while Section 311(b) specifies patents or printed publications as the source of prior art used to render a decision regarding a petitioner's validity challenge, "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, 1337 (Fed. Cir. 2020). The reason: obviousness "requires an assessment of the . . . 'background knowledge possessed by a person having ordinary skill in the art'" under Dow Jones & Co. v. Ablaise Ltd., 606 F.3d 1338, 1349 (Fed. Cir. 2010) (quoting KSR Int'l Co. v. Teleflex, Inc., 550 U.S. 398, 401 (2007)). The Court in Qualcomm Incorporated v. Apple Inc., 24 F.4th 1367 (Fed. Cir. 2022) ("Qualcomm I"), and Qualcomm Incorporated v. Apple Inc., 134 F.4th 1355 (Fed. Cir. 2025) ("Qualcomm II") had determined that AAPA was properly considered in making obviousness determinations. These cases held that while AAPA can be used to support the substantive question of invalidity it cannot be used as the basis for the IPR petition (but it can be used in combination with permissible patents or printed publications).
In this case, CSI did not use AAPA as the express basis for its obviousness challenge, but "only to show, as the '371 patent itself acknowledged, that the over-the-wire angioplasty balloon catheter was well known in the prior art and that this general background knowledge satisfied the '371 patent's claim limitations relating to an over-the-wire configuration."
The Court also rejected Shockwave's argument that the Board used the term "basis" in referring to the asserted AAPA, on the grounds that while their precedent held Petitioner to a standard where AAPA was not used as the basis for an IPR petition, this restriction did not apply to the Board's characterizations regarding AAPA.
Shockwave also argued unsuccessfully regarding claim construction, wherein the Board rejected their interpretation of "angioplasty balloon" to mean "a balloon that displaces the plaque into the vessel wall to expand the lumen of the vessel" in favor of CSI's construction of "an inflatable sac that is configured to be inserted into a blood vessel for use in a medical procedure to widen narrowed or obstructed blood vessels." The significance of this choice (according to Shockwave) is that it misconstrued the meaning of the term "angioplasty." The panel rejected Shockwave's challenge on this issue because "[n]othing in the language of the claims or specification supports requiring that an angioplasty balloon press plaque into the vessel wall" (indeed the specification asserted that "pressing" or "fitting snugly" into the vessel wall" was not "a requirement"). Nor was the panel convinced that the prosecution history supported Shockwave's construction.
Shockwave's last challenge to the Board's decision was directed towards three of the Board's fact findings. First, that the skilled artisan would have been motivated to adapt Levy's shockwave system to an over-the-wire balloon catheter. Second, that Levy discloses producing shockwaves in the first place. And third, that secondary considerations did not rebut CSI's prima facie obviousness showing.
The panel held that substantial evidence supported all three of the Board's factual determinations. First, the Court found that contrary to Shockwave's argument the Board asserted two reasons why an ordinarily skilled artisan would have combined conventional balloon angioplasty with Levy's shockwave technology: "(1) "to assist a physician to navigate the catheter to reach the area for treatment" and (2) "to increase the types of treatments Levy could perform." This evidence was supported (according to the opinion) by CSI's expert witness testimony. Nor did the panel credit Shockwave's contention that there was insufficient evidence that Levy's technology could produce shockwaves in blood vessels (to the extent that the Levy EP reference incorporated an earlier Levy patent by reference, relating to cleaning tooth canals with laser radiation pulses that disclosed "this same technique 'can also be employed in the medical field for cleaning vessels, such as blood vessels'") (there being additional undiscussed prior art references supporting the use of shockwaves as disclosed by Levy). Regarding evidence of secondary considerations, the Board rejected as insufficiently persuasive Shockwave's expert's testimony supporting a presumption of a nexus related to non-obviousness (the totality of what the opinion calls Shockwave's "purported objective indicia" was "largely weak" being based on "potential efficacy" or "potential commercial success").
Turning to CSI's cross-appeal on the Board's determination that claim 5 had not been shown to be obvious, the opinion first rejected Shockwave's contentions that CSI lacked standing to appeal. Recognizing that a party needs to establish Article III standing to appeal (but not to bring an IPR, under Incyte Corp. v. Sun Pharm. Indus., Inc., 136 F.4th 1096, 1099 (Fed. Cir. 2025), the panel turned to CSI's assertions (required under Gen. Elec. Co. v. Raytheon Techs. Corp., 983 F.3d 1334, 1341 (Fed. Cir. 2020)) that in the absence of current infringing activity it must have "concrete plans for future activity that creates a substantial risk of future infringement." CSI relied on its development of an IVL device and Shockwave's CEO's statement that the company intended to "aggressively assert" claim 5 of the '371 patent to be sufficient to establish Article III standing.
Regarding the merits, CSI argued that the Board failed to consider the prior art as a whole, and the Federal Circuit agreed. Specifically, CSI asserted a Japanese patent application to Uchiyama and expert testimony concerning the combination to support CSI's obviousness contentions. The panel found that the Board erred in not combining the Uchiyama disclosure with Levy's modification of a conventional over-the-wire catheter balloon. As a result, the Board "improperly discount[ed] CSI's argument in its petition that modifying Uchiyama to place the electrodes outside the lumen would have been a routine design choice" according to the opinion. This was contrary to the rubrics in KSR v. Teleflex that "[w]hen there is a design need or market pressure to solve a problem and there are a finite number of identified, predictable solutions, a person of ordinary skill has good reason to pursue the known options within his or her technical grasp" and accordingly was error by the Board. In view of the factual situation that Shockwave had not adduced evidence on the record, contrary to the Board's erroneous nonobvious determination the panel reversed the decision rather than vacating and remanding.
This result immediately suggests that, while patent applicants are required under the duty of candor (37 C.F.R. § 1.56), the key word in the dispositive phrase in the court's opinion is admitted prior art. There is little admission involved in citing a patent or printed publication that antedates the earlier priority date asserted (or accorded) to an application (other than any dispute arising from whether the reference was publicly available). But there are many opportunities to characterize (to the applicant's detriment) the status of knowledge in the prior art; for example, when facing a Section 112(a) challenge on enablement or written description grounds. Here Shockwave's specification provided the needed AAPA. Patent law has often been characterized as being replete with "traps for the unwary" and the outcome of this case reinforces the need for prudence in how prior knowledge is considered (or admitted) by applicants before they become patentees.
Shockwave Medical, Inc. v. Cardiovascular Systems, Inc. (Fed. Cir. 2025)
Panel: Circuit Judges Lourie, Dyk, and Cunningham
Opinion by Circuit Judge Dyk
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