Bardy Diagnostics Inc v. iRhythm Tech Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:

  • Plaintiff: Bardy Diagnostics, Inc. (Delaware)
  • Defendant: iRhythm Technologies, Inc. (Delaware)
  • Plaintiff's Counsel: Potter Anderson & Corroon LLP

• Case Identification: 1:24-cv-01355, D. Del., 06/11/2025

• Venue Allegations: Venue is asserted in the District of Delaware on the basis that Defendant iRhythm Technologies, Inc. is a Delaware-incorporated corporation and therefore resides in the district.

• Core Dispute: Plaintiff alleges that Defendant's Zio line of wearable heart monitors infringes four patents related to the design and functionality of electrocardiography (ECG) patches.

• Technical Context: The technology involves wearable, adhesive patches for long-term ambulatory cardiac monitoring, a field aimed at improving patient comfort and diagnostic accuracy for sporadic heart rhythm abnormalities over traditional monitoring methods.

• Key Procedural History: This is a Second Amended Complaint. Plaintiff alleges Defendant was on notice of U.S. Patent No. 12,161,473 and U.S. Patent No. 12,171,562 upon the filing of the original and first amended complaints, respectively. Plaintiff further alleges Defendant was notified of U.S. Patent No. 12,285,261 and U.S. Patent No. 12,310,735 via letters sent from counsel. These allegations form the basis for claims of willful infringement.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 12,161,473 - Electrocardiography Patch

The Invention Explained

• Problem Addressed: The patent's background describes the difficulty of effective long-term ECG monitoring (e.g., beyond 24-48 hours) Compl. Ex. 1, '473 Patent, col. 2:25-33 It notes that conventional ambulatory monitors like Holter monitors are cumbersome, and existing patch-style devices may cause skin irritation, have limited wear-time, and struggle to record high-quality atrial signals (P-waves) due to suboptimal placement on the body '473 Patent, col. 2:34-61
• The Patented Solution: The patent proposes a wearable monitor comprising two main components: a flexible, extended-wear electrode patch and a removable, reusable monitor recorder '473 Patent, col. 3:9-12 The patch is described as having a narrow, "hourglass"-like shape designed to fit comfortably along the patient's sternal midline, a location that improves the ability to sense atrial P-waves '473 Patent, col. 3:12-25 '473 Patent, FIG. 4 This design allows the patient to replace the adhesive patch while reusing the monitor, facilitating continuous monitoring over many weeks '473 Patent, col. 9:55-10:14
• Technical Importance: This two-part, anatomically-conformed design aimed to improve patient compliance and the diagnostic quality of long-term ambulatory ECGs by increasing comfort and enhancing the capture of atrial signals critical for arrhythmia diagnosis '473 Patent, col. 6:17-30

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claims 2-3, 6, 8, 10, 13, 15, 16, and 19 Compl. ¶54
• Independent Claim 1 of the '473 Patent includes these essential elements:
  • A wearable electrocardiography monitoring device comprising a flexible backing with a strip having a first face, a second face, first and second end sections, and a mid-section that is narrower than the end sections.
  • A flexible circuit mounted to the second face of the strip.
  • First and second electrocardiographic electrodes configured to sense ECG signals, conductively exposed on the first face at the first and second end sections, respectively, and coupled to the flexible circuit.
  • The first electrode includes an inline resistor.
  • A battery vertically aligned with a sealed housing.
  • The sealed housing includes rounded edges on its top surface, is coupled to the flexible backing, and includes a processor that processes the sensed ECG signals.
  • A wireless transceiver that draws power from the battery.
• The complaint reserves the right to assert additional claims Compl. ¶54

U.S. Patent No. 12,171,562 - Electrocardiogramy Patch

The Invention Explained

• Problem Addressed: Similar to the '473 Patent, the '562 Patent addresses the clinical and practical challenges of long-term ECG monitoring, such as patient discomfort with traditional devices, skin irritation from adhesives, and the difficulty of capturing sporadic cardiac events, which are often missed during short-term recordings '562 Patent, col. 2:36-61
• The Patented Solution: The patent describes a similar two-component wearable monitor with a flexible, sternum-mounted patch and a reusable recorder '562 Patent, col. 4:4-10 A key feature distinguished in this patent's claims is the inclusion of a "button configured to be pressed to mark an event" '562 Patent, claim 8 This allows the patient to actively correlate subjective symptoms (like dizziness or palpitations) with the concurrently recorded ECG data, a critical function for diagnosis '562 Patent, col. 11:64-12:5
• Technical Importance: The integration of a patient-activated event marker into a comfortable, long-wear patch was intended to improve the clinical utility of ambulatory monitoring by directly linking a patient's symptoms to their cardiac rhythm at that specific moment '562 Patent, col. 7:1-6

Key Claims at a Glance

• The complaint asserts independent claims 8 and 15 and dependent claims 9-14 and 16-30 Compl. ¶63
• Independent Claim 8 of the '562 Patent includes these essential elements:
  • A wearable electrocardiography monitoring device comprising a flexible backing with a strip having first and second end sections, and a mid-section narrower than the ends and having parallel edges.
  • A flexible circuit mounted to the strip's second face.
  • First and second electrocardiographic electrodes coupled to the circuit and configured to sense ECG signals.
  • The first electrode includes an inline resistor.
  • A battery.
  • A wireless transceiver that draws power from the battery.
  • A sealed housing with rounded edges, coupled to the backing, and including a processor.
• The complaint reserves the right to assert additional claims Compl. ¶63

U.S. Patent No. 12,285,261 - Moisture-Resistant Electrocardiography Monitor

• Patent Identification: U.S. Patent No. 12,285,261, issued April 29, 2025 (the "'261 Patent") Compl. ¶35
• Technology Synopsis: This patent details a moisture-resistant design for a wearable ECG monitor. The invention centers on a "moisture-resistant seal" and a "seal coupling" that protect the electrical interface between the removable monitor housing and the disposable electrode patch, ensuring functionality during long-term wear that includes activities such as showering '261 Patent, abstract '261 Patent, col. 6:2-20
• Asserted Claims: The complaint asserts at least claim 1 Compl. ¶72
• Accused Features: The complaint alleges that the Zio Monitor's design, which is intended for continuous, long-term wear, infringes the claims related to moisture resistance Compl. ¶72 Compl. Ex. 18

U.S. Patent No. 12,310,735 - Extended Wear Ambulatory Electrocardiography Monitor

• Patent Identification: U.S. Patent No. 12,310,735, issued May 27, 2025 (the "'735 Patent") Compl. ¶37
• Technology Synopsis: This patent describes the physical and electronic architecture of an extended-wear ECG monitor. Key elements include a non-conductive receptacle for housing a battery, a sealed housing for the electronics, and a patient feedback button, with a focus on the specific arrangement of these components to create a functional, long-wear device '735 Patent, abstract '735 Patent, col. 11:15-12:1
• Asserted Claims: The complaint asserts at least claim 1 Compl. ¶81
• Accused Features: The complaint targets the overall construction of the Zio Monitor, including its battery housing, sealed electronics, and patient-operable button, as infringing the claimed configuration Compl. ¶81 Compl. Ex. 19

III. The Accused Instrumentality

Product Identification

• The primary accused product is the "Next-Generation Zio Monitor," also referred to as the "Zio Monitor" Compl. ¶14 Compl. ¶45 The complaint also references the Zio XT and Zio AT monitors Compl. ¶41

Functionality and Market Context

• The Zio Monitor is a wearable, prescription-only ECG patch that adheres to a patient's chest to continuously record cardiac data for up to 14 days Compl. ¶47 Compl. ¶48 It is described as being "23% thinner, 62% lighter, and 72% smaller" than previous iRhythm products Compl. ¶45 The device includes two electrodes to acquire ECG data and a button for the patient to press when a symptom is felt, which marks the event in the data record Compl. ¶47 Compl. p. 10 The complaint includes a diagram from the Zio monitor's instructions for use that labels the electrodes, adhesive wings, indicator light, and patient-activated button Compl. p. 10 After the wear period, the patient mails the device to an iRhythm data processing center for analysis and report generation Compl. ¶48
• The complaint positions iRhythm and Bardy as direct competitors in the cardiac monitoring field Compl. ¶11 The complaint also presents a market analysis chart indicating that the U.S. Ambulatory Cardiac Monitoring Devices market is substantial and growing Compl. p. 3

IV. Analysis of Infringement Allegations

The complaint references non-limiting claim chart exhibits for each asserted patent Compl. ¶54 Compl. ¶63 Compl. ¶72 Compl. ¶81 The analysis below summarizes the allegations for the lead patents.

'473 Patent Infringement Allegations

Identified Points of Contention

• Scope Questions: The infringement analysis may focus on whether the Zio Monitor's physical shape meets the specific geometric limitations of the claims, such as the "narrower" mid-section and "rounded edges on a top surface." A key question will be how broadly these dimensional and descriptive terms are construed.
• Technical Questions: A significant point of contention could be the "inline resistor" limitation. The complaint alleges iRhythm's technology involves "integrat[ing] [the resistors] into the ECG tracings themselves" Compl. ¶45 The court may need to determine if this specific method of integrating resistive material into a circuit trace is technically equivalent to the "inline resistor" described in the patent, which could be interpreted as a discrete component. The meaning of "vertically aligned" with respect to the battery and housing will also require factual and technical analysis of the accused device's construction.

'562 Patent Infringement Allegations

Identified Points of Contention

• Scope Questions: As with the '473 Patent, disputes may arise over the specific geometric language, such as whether the mid-section's edges are "parallel" in the manner claimed.
• Technical Questions: The analysis of the "inline resistor" limitation, as discussed for the '473 Patent, will be equally applicable here and likely a central technical question for the court.

V. Key Claim Terms for Construction

The Term: "inline resistor" ('473 Patent, claim 1; ['562 Patent, claim 8](https://ex:cit:11))

• Context and Importance: This term is critical because the complaint alleges the Zio Monitor has a unique design that integrates resistors "into the ECG tracings themselves" Compl. ¶45, rather than using a discrete component on a circuit board. Practitioners may focus on this term because Defendant iRhythm could argue its integrated design is a distinct, non-infringing alternative to a conventional "inline resistor."
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification describes a "protection circuit 72, which is an inline resistor that protects the patient from excessive leakage current" '473 Patent, col. 13:59-62 This functional description, without structural limitation, may support a broader definition covering any resistive element placed in the electrical path for patient protection.
  • Evidence for a Narrower Interpretation: Figure 10 of the patents depicts the "Protection (72)" as a discrete schematic symbol for a resistor placed along a circuit trace. A defendant may argue this embodiment limits the term to a distinct component, rather than a resistive property integrated into the trace material itself.

The Term: "vertically aligned" ('473 Patent, claim 1)

• Context and Importance: The infringement of claim 1 of the '473 Patent depends on the spatial relationship between the battery and the sealed housing. The definition of this geometric term will determine whether the physical layout of the Zio Monitor meets the claim limitation.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The term is not explicitly defined, which may support giving it a plain and ordinary meaning, such as the centers of the battery and housing sharing a common vertical axis when viewed in a particular orientation.
  • Evidence for a Narrower Interpretation: The specification provides a functional purpose: "the locating of the battery 71 physically on the electrode patch 15 lowers the center of gravity of the overall wearable monitor 12 and thereby helps to minimize shear forces" '473 Patent, col. 13:8-12 A party could argue that "vertically aligned" should be construed in light of this stated objective, potentially narrowing its scope to an alignment that demonstrably achieves this functional outcome.

VI. Other Allegations

Indirect Infringement

• The complaint does not contain specific counts for indirect infringement under 35 U.S.C. § 271(b) or (c). The infringement allegations focus on direct infringement under § 271(a) Compl. ¶54 Compl. ¶63 Compl. ¶72 Compl. ¶81

Willful Infringement

• The complaint alleges willful infringement for all four asserted patents. For the '473 and '562 Patents, willfulness is based on iRhythm's alleged continued infringement after gaining knowledge of the patents through the filing of the original and first amended complaints, respectively Compl. ¶56 Compl. ¶65 Compl. ¶58 Compl. ¶67 For the '261 and '735 Patents, willfulness is based on alleged knowledge from a pre-suit letter sent by Plaintiff's counsel on May 28, 2025, followed by continued infringing activities Compl. ¶74 Compl. ¶83 Compl. ¶76 Compl. ¶85

VII. Analyst's Conclusion: Key Questions for the Case

• A core issue will be one of technical and definitional scope: Does iRhythm's method of integrating resistive material "into the ECG tracings themselves" fall within the scope of the claim term "inline resistor"? The case may turn on whether this term is limited to a discrete component, as depicted in patent figures, or broadly covers any resistive element serving the same protective function in the circuit.
• A second key question will be one of structural equivalence: Do the specific geometric and spatial arrangements claimed in the patents, such as the "hourglass" shape, "parallel" edges of the mid-section, and the "vertically aligned" battery and housing, read on the physical construction of the accused Zio Monitor? This will likely require detailed claim construction and factual analysis of the accused device's design.
• A central issue for damages will be willfulness: Did iRhythm's continued manufacture and sale of the Zio Monitor after receiving notice of the asserted patents-first through prior complaints and later through counsel letters-constitute egregious conduct sufficient to warrant a finding of willful infringement and potential enhancement of damages?