United States Patent 7,881,777: Claims, Scope, Expiration, and Patent Landscape for Fluorescence Imaging of Cardiovascular Bypass Grafts

U.S. Patent No. 7,881,777 protects an intraoperative near-infrared fluorescence imaging system and method for evaluating blood flow through a cardiovascular bypass graft and connected vasculature. Its core limitations are indocyanine-green-compatible fluorescence, image acquisition at 15 or more angiographic frames per second, imaging while the heart is beating, and analysis of sequential images showing dye movement through the graft.

The patent is directed to an imaging device and surgical imaging method, not to indocyanine green itself. Its commercial relevance is therefore concentrated in intraoperative fluorescence angiography systems used in coronary artery bypass grafting and related vascular procedures.

What technology does U.S. Patent 7,881,777 protect?

The patent covers a coordinated system comprising:

A near-infrared illumination source.
A camera that captures fluorescence from dye moving through a bypass graft.
Acquisition at a minimum of 15 images per second.
Imaging during a beating-heart surgical procedure.
A fluorescent dye with an absorption peak between 800 and 850 nanometers.
A display that converts captured images into viewable angiographic images.

Claim 1 is the principal device claim. Claim 14 is the principal method claim. Claims 2 through 13 and 15 through 25 add implementation details involving indocyanine green, camera speed, laser illumination, optical geometry, filters, adjustable optics, pulsed illumination, magnification, distance sensing, and a defined illumination field. [1]

The patent’s practical focus is dynamic fluorescence angiography. The claimed system is intended to show how quickly and extensively fluorescent dye travels through a graft and its connected vasculature, rather than merely producing a static image.

How are the claims organized?

Claim group	Claim type	Main subject matter	Key limitations
1	Independent device	Intraoperative imaging device	Bypass graft, beating heart, fluorescence, 15+ images/sec, 800-850 nm absorption
2	Dependent device	High-speed ICG imaging	At least 30 images/sec; indocyanine green
3	Dependent device	Camera-light geometry	Optical-axis angle below 85 degrees
4-8	Dependent device	Laser illumination	Diverging optics, 20-70 degree geometry, adjustable optics, filters, pulsing
9-13	Dependent device	Imaging and spatial controls	Emission filter, magnification, linked illumination, distance sensor, 7.5 cm x 7.5 cm field
14	Independent method	Intraoperative graft-flow evaluation	Injection, illumination, imaging at 15+ images/sec, flow assessment
15-25	Dependent method	Method implementations	30+ frames/sec, ICG, laser, geometry, filters, magnification, 7.5 cm x 7.5 cm field

The independent claims establish the commercial center of gravity. The dependent claims provide narrower positions that may be relevant in infringement analysis if a competing system avoids one or more limitations of the independent claims.

What are the essential limitations of claim 1?

Claim 1 requires more than a general fluorescence camera. A potentially infringing device must satisfy each material limitation:

A cardiovascular bypass graft and connected vasculature

The claimed imaging target is a cardiovascular bypass graft and the vasculature connected to it. A system used only for general tissue perfusion, lymphatic mapping, plastic surgery, or nonvascular anatomy would not naturally satisfy this limitation without additional facts concerning its intended configuration and use.

A moving fluorescent dye in blood

The dye must be contained in blood moving through the graft and connected vasculature. Static fluorescence or tissue fluorescence is outside the central claim concept.

Near-infrared spectral range

Claim 1 specifies a dye having a peak absorption between 800 and 850 nm. Claim 14 is narrower in one respect because it requires both peak absorption and peak emission in that range.

Indocyanine green is the principal commercial dye implicated by the dependent claims. ICG has near-infrared absorption and emission characteristics that make it suitable for blood-flow visualization using specialized cameras and illumination sources.

At least 15 angiographic images per second

The frame-rate limitation is significant. A conventional still-image fluorescence system or a low-frame-rate system may avoid the claim if it cannot capture at least 15 angiographic images per second in the claimed operating configuration.

Claim 2 and claim 15 raise the threshold to at least 30 images per second and require ICG.

Imaging while the heart is beating

The claims expressly identify imaging during a surgical procedure while the subject’s heart is beating. This limitation links the invention to off-pump coronary artery bypass procedures and other dynamic cardiac or vascular operations.

An optimal image and images leading and trailing it

Claim 1 requires captured images that include an optimal image of dye initially moving through the graft and connected vasculature, together with images leading and trailing that image. This language supports a time-sequenced assessment of dye progression. It may also create claim-construction issues concerning the meaning of “optimal image,” particularly whether the term identifies a specific image-selection process or simply the best image in a captured sequence.

The corresponding method claim, claim 14, does not expressly include the “optimal image” and leading/trailing-image limitation. That difference makes claim 14 potentially broader in temporal-image requirements, although it has its own limitations concerning dye absorption and emission.

What do the dependent claims add?

High-speed ICG imaging

Claims 2 and 15 require at least 30 images per second and specify indocyanine green. These claims are commercially important because many intraoperative fluorescence systems use ICG and high-speed digital cameras.

A system operating at 15 to 29 frames per second may fall within claim 1 or claim 14 while avoiding the narrower 30-frame claims, assuming all other limitations are met.

Camera and illumination geometry

Claims 3 and 16 require an angle of less than 85 degrees between the camera’s optical axis and the illumination beam. Claims 5 and 18 narrow the range to 20 to 70 degrees when a laser is used.

These geometric limitations may be useful in prosecution history and infringement analysis because they define a physical relationship between system components. A competing system using coaxial illumination, a different beam path, or a geometry outside the claimed range may have a noninfringement position for the dependent claims.

Laser and diverging optics

Claims 4 and 17 require a laser associated with optics that diverge the beam to cover the graft and connected vasculature. Claims 6 and 19 cover adjustable optics that vary the illuminated field.

Systems using broad-area LEDs rather than lasers may avoid these limitations, although they could remain within the broader independent claims if the illumination source and other limitations are satisfied.

Optical filtering

Claims 7, 9, 20, and 22 cover bandpass filters. The claims address both excitation control, by limiting the illumination wavelength, and emission control, by preventing the camera from capturing unwanted radiation.

These limitations are conventional in fluorescence imaging, but their combination with the graft-flow and acquisition-rate requirements creates a narrower system position.

Magnification and linked field illumination

Claims 10, 11, 23, and 24 cover camera lens magnification and coordination between camera field of view and laser illumination. A system in which changing magnification automatically adjusts the illumination field may implicate these claims.

Distance sensing and defined illumination area

Claim 12 requires a distance sensor that provides the distance from the camera or laser to the graft. Claims 13 and 25 specify a 7.5 cm by 7.5 cm illumination area.

These are narrow hardware limitations. They are unlikely to apply to every fluorescence angiography system, but they may be relevant to systems using fixed surgical working distances or standardized illumination fields.

What is the scope of independent method claim 14?

Claim 14 requires:

Injection of fluorescent dye into the subject’s blood.
A dye with peak absorption and emission between 800 and 850 nm.
Illumination of the bypass graft and connected vasculature.
Capture of emitted fluorescence as an angiographic image.
A camera acquisition rate of at least 15 images per second.
Evaluation of the images to assess blood flow.

The claim is directed to the clinical workflow rather than the hardware architecture. It could therefore be relevant where a hospital performs the claimed sequence using a third-party imaging platform.

The method claim does not require the laser, specific camera-light angle, display, magnification, distance sensor, or 7.5 cm x 7.5 cm field. Those features appear only in dependent claims. A method can potentially fall within claim 14 even if the system uses a nonlaser source, provided the remaining claim elements are satisfied.

What patents protect commercial systems related to this technology?

The relevant landscape has several overlapping patent categories:

Patent category	Protected subject matter	Relevance to U.S. 7,881,777
Fluorescence angiography systems	Camera, excitation source, filters, display, image processing	Directly overlapping technical field
ICG imaging	Near-infrared imaging using indocyanine green	Overlaps claims 2 and 15
Cardiac bypass assessment	Graft patency and intraoperative coronary-flow evaluation	Directly overlaps intended use
Image acquisition and processing	Frame-rate control, time-series analysis, perfusion quantification	May overlap the dynamic-imaging concept
Surgical imaging platforms	Integrated camera, light source, scopes, displays	May create system-level freedom-to-operate issues
ICG formulations and administration	Dye composition, dosing, injection protocols	Separate from the device claims
Manufacturing and optical assemblies	Laser modules, filters, sensor integration, sterilizable components	Potentially relevant to supplier and component risk

The strongest overlap is expected from patents that claim near-infrared fluorescence imaging of vascular flow, rather than patents that merely claim generic surgical cameras or ICG administration.

A complete freedom-to-operate review should separate:

Patent claims directed to the imaging platform.
Claims directed to coronary bypass graft evaluation.
Claims directed to ICG use or dosing.
Claims directed to optical hardware.
Claims directed to quantitative perfusion or time-series analysis.
Claims directed to sterile drapes, endoscopes, and operating-room integration.

Which companies are commercially relevant?

Stryker and Novadaq

Novadaq developed the SPY fluorescence imaging platform, which was used for intraoperative imaging with ICG. Stryker acquired Novadaq in 2017 and integrated SPY fluorescence imaging into its surgical product portfolio. [2]

SPY-related products are the most obvious commercial reference point for the patent because the claims align with intraoperative near-infrared fluorescence imaging of blood flow and tissue perfusion.

Medtronic

Medtronic has marketed surgical and cardiac technologies relevant to bypass procedures and intraoperative graft assessment. Its potential exposure would depend on the specific imaging system, acquisition rate, optical architecture, and use protocol.

Karl Storz, Olympus, and other surgical imaging suppliers

Major surgical imaging companies have developed near-infrared and fluorescence-capable platforms. Product-level analysis must examine whether the system is configured for ICG, whether it captures at least 15 angiographic images per second, and whether the intended use includes bypass-graft flow evaluation.

Fluoptics and other fluorescence-imaging companies

Fluorescence-imaging suppliers may have relevant patent families covering camera systems, surgical illumination, image processing, and ICG-based visualization. Their claims may overlap technically without reaching the specific combination required by claims 1 or 14.

What is the Orange Book status of U.S. Patent 7,881,777?

U.S. Patent 7,881,777 is a device and surgical-method patent, not a patent claiming an approved drug product. It would not ordinarily be listed in the FDA Orange Book for indocyanine green because the patent claims do not cover the active ingredient as a drug product, a drug formulation, or a drug method of use in the conventional Orange Book sense. FDA Orange Book listings are tied to approved drug applications and qualifying patents submitted by the NDA holder. [3]

The patent therefore does not create a conventional Orange Book Paragraph IV pathway. A generic-drug applicant would not typically address this patent through an Orange Book certification unless the patent were properly listed against an applicable approved drug product.

When does the patent lose exclusivity?

U.S. utility patents generally expire 20 years after the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, and other statutory adjustments. [4]

The relevant expiration analysis for U.S. 7,881,777 requires review of:

The earliest effective nonprovisional application in the priority chain.
Any continuation or divisional relationship.
Patent-term adjustment shown on the issued patent.
Any terminal disclaimer.
Maintenance-fee status.
Whether the patent has expired, been disclaimed, or lapsed for nonpayment.

Because this patent was issued in 2011, its remaining life is governed primarily by the earlier priority and filing dates, not by the issue date. A commercial assessment should use the USPTO Patent Center record and the issued patent’s term-adjustment data rather than calculate expiration from the grant date. [1, 5]

The patent is not a biologic patent and has no biosimilar exclusivity implications. It also does not provide regulatory exclusivity for ICG.

Are Paragraph IV challenges or generic-launch risks relevant?

Paragraph IV risk

Paragraph IV litigation is primarily relevant to patents listed in the Orange Book against an approved drug application. U.S. 7,881,777 is not naturally positioned as an Orange Book drug patent because it claims an imaging device and surgical method.

The more realistic challenge scenarios are:

Patent litigation against an imaging-system manufacturer.
A declaratory-judgment action concerning device sales or clinical use.
An infringement claim based on hospital use of the claimed method.
Contractual indemnification disputes between hospitals and equipment suppliers.

Generic launch risk

A generic ICG product could launch without practicing the claimed device architecture. Conversely, a competing imaging platform could potentially avoid drug-related patents while still raising risk under this patent if it is used for the claimed bypass-graft imaging workflow.

The patent creates product and use risk, not conventional generic-drug launch risk.

What patent litigation affects the patent?

No litigation outcome should be inferred solely from the grant or commercial association of the patent. A proper litigation review would include PACER, district-court dockets, the Patent Trial and Appeal Board, and USPTO maintenance records.

The key litigation questions are:

Issue	Relevance
Infringement	Whether an accused platform satisfies every limitation of an asserted claim
Claim construction	Meaning of “optimal image,” “configured to capture,” “moving,” and “evaluating”
Validity	Prior art concerning ICG angiography, high-speed cameras, laser illumination, and bypass-graft assessment
Written description	Support for the specific frame rates, geometry, filters, and field dimensions
Enablement	Whether the specification enables the full breadth of the claimed systems and methods
Obviousness	Combination of known ICG imaging, surgical cameras, laser optics, and high-speed acquisition
Damages	Device sales, reasonable royalty, hospital use, and supplier indemnification

The “optimal image” limitation may be particularly important in claim construction. If interpreted as requiring a defined image-selection algorithm, it could narrow claim 1. If interpreted as a descriptive reference to the best image in a sequence, it may impose a less demanding limitation.

How strong is the patent estate?

The patent has a focused but technically dense claim set.

Strengths

It targets a specific clinical use with clear commercial relevance.
It combines fluorescence imaging with dynamic blood-flow assessment.
The 15-frame-per-second limitation distinguishes the claims from static fluorescence imaging.
The dependent claims cover practical system details, including filters, laser optics, magnification, and illumination control.
The method claims may reach clinical use even when system architecture differs.

Weaknesses and design-around opportunities

The claims depend on specific bypass-graft and vascular-use facts.
The 15-frame-per-second threshold can be tested and potentially avoided.
The dependent claims contain narrow geometric and dimensional limitations.
A system using a different fluorescent agent may avoid ICG-specific claims.
A nonlaser illumination architecture may avoid laser-dependent claims.
The “optimal image” language in claim 1 may create construction and proof issues.
The patent’s remaining enforceable term may be limited by its priority chain and statutory expiration.

What generic launch and competitive scenarios are most plausible?

Scenario	Patent exposure
Generic ICG drug launch	Low direct exposure under this patent
General surgical fluorescence camera	Low to moderate, depending on configuration
ICG-capable camera used for bypass grafts	Moderate to high if 15+ frames/sec and other limitations are met
Static fluorescence imaging system	Lower exposure to claims requiring dynamic acquisition
Laser-based high-speed graft imaging	Higher exposure, especially to dependent claims
LED-based system	May avoid laser-dependent claims, but not necessarily claims 1 or 14
Hospital use of a covered workflow	Method-claim exposure may remain
Quantitative perfusion platform	Potential additional exposure under separate image-processing patents

Key Takeaways

U.S. Patent 7,881,777 covers dynamic near-infrared fluorescence imaging of blood flow through cardiovascular bypass grafts.
Claims 1 and 14 are the primary enforcement positions.
The key technical thresholds are 15 or more images per second and a fluorescent dye operating in the 800-850 nm range.
Claims 2 and 15 narrow the technology to at least 30 frames per second with indocyanine green.
Dependent claims cover laser illumination, beam divergence, camera-light geometry, filters, magnification, distance sensing, and a 7.5 cm x 7.5 cm illumination field.
The patent is a device and method patent, not an Orange Book drug patent.
Paragraph IV certification and biosimilar exclusivity are generally not the relevant risk frameworks.
The principal commercial exposure is for ICG-enabled intraoperative imaging platforms used in coronary bypass or related vascular procedures.
Patent-term analysis must use the priority chain, patent-term adjustment, terminal-disclaimer data, and maintenance-fee record.
The strongest design-around paths involve acquisition rate, imaging target, illumination architecture, optical geometry, fluorescent agent, and clinical workflow.

FAQs

Does U.S. Patent 7,881,777 cover indocyanine green itself?

No. The patent claims imaging devices and methods that can use ICG. It does not claim ICG as a chemical compound or establish drug exclusivity for ICG.

Can a hospital infringe the patent by using an ICG fluorescence camera?

Potentially, if the hospital performs the claimed method, including imaging blood flow through a cardiovascular bypass graft at the required frame rate and using a dye within the claimed spectral range.

Does a system operating below 15 frames per second avoid the patent?

It may avoid the independent claims that expressly require at least 15 images per second, assuming no separate claim or patent applies. Product specifications and actual operating modes would control the analysis.

Are LED-based fluorescence systems outside the patent?

Not necessarily. The independent claims require an illumination source but do not require a laser. LED systems may avoid laser-dependent claims while remaining potentially relevant to claims 1 or 14.

Does the patent cover fluorescence imaging for plastic or reconstructive surgery?

The asserted claims are directed to blood moving through a cardiovascular bypass graft and connected vasculature. Use in other surgical fields would not automatically satisfy that limitation.

References

United States Patent and Trademark Office. (2011). U.S. Patent No. 7,881,777, Fluorescence imaging system and method.
Stryker Corporation. (2017). Stryker completes acquisition of Novadaq Technologies Inc.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
United States Code. (2023). 35 U.S.C. § 154: Contents and term of patent; provisional rights.
United States Patent and Trademark Office. (2024). Patent Center: Patent term adjustment and patent maintenance records.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	375749	⤷ Start Trial
Austria	506005	⤷ Start Trial
Australia	6767500	⤷ Start Trial
Australia	782257	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 7,881,777