Intra-operative Fluorescence Imaging

Intra-operative vascular angiography uses the fluorescence properties of indocyanine green (IC-Green™) dye and a 806 nm laser diode as a monochromatic light source.  The IC-Green rapidly binds to plasma proteins when injected intravenously confining the dye to the intravascular compartment.  IC-Green fluoresces when illuminated at 806 nm with a laser beam and emits light of a longer wavelength at 830 nm.  This fluorescence is captured on a charged couple device (CCD) video camera.

SPY Intra-operative Imaging System

The SPY® Intra-operative Imaging System enables the surgeon and or team to view, record, replay, print, and archive high quality, real-time images of the coronary arteries and bypass grafts.   The SPY Imaging System features:

The SPY Imaging Device

Automatic Focus Camera: Enables the surgeon to acquire image sequences of the heart

Laser Light Source: Excites the IC-Green imaging agent causing fluorescence

Automatic Distance/Focus Sensor: Ensures the camera remains in constant focus

Articulating Arm Mount: Allows the camera head to be positioned easily over the patient without contaminating the sterile field

Touch Screen Monitor on Swivel Mount: Optimizes device positioning for operator and surgeon. Enables quick entry of patient and procedural information

Convenient Intra-operative Angiographic Film Review: Enables the importing and viewing of X-ray angiographic films, and the review of pre-operative, intra-operative and post-operative angiograms

The SPY Paq The components of the SPY Paq™ are used in combination with the SPY Intra-operative Imaging Device Each SPY Paq contains 6 vials of IC-Green™ imaging agent and aqueous solvent, and 6 custom Novadrape® sterile drapes

The SPY Imaging Procedure

The SPY System captures emitted fluorescent light at 30 frames per second.  The laser, with an output of 2.0 W, illuminates an area of 56 cm² of the heart.  Due to the low power density of the applied laser energy, no safety gear or protective clothing is required. A sterile drape is placed over the articulating arm during the procedure.  The arm is placed above the area of interest and the correct positioning is indicated by means of an automatic distance sensor, ensuring the camera is at the correct focal length.  After injection of IC-Green, activation of the laser and image acquisition to the computer are initiated by means of a single command to the computer.  Real-time images are displayed on the computer screen as the IC-Green passes through the field of view.  Images may be saved to the computer for easy review, copying and printing.²

Indocyanine Green

Indocyanine Green (IC-Green) is a water soluble tricarbocyanine dye with a peak spectral absorption at 800 to 810 nm when dissolved in blood.  After injection, it is rapidly bound to plasma proteins, thus remaining within the vasculature. IC-Green is excreted by the liver being secreted unchanged into the bile.  IC-Green has been used extensively to determine cardiac output, to measure liver function and for ophthalmic angiography.  Adverse reactions to the clinical use are rare.²  The incidence of allergic reaction is approximately 1:40,000 and has been reported especially in patients allergic to iodine.  The risk is strongly dose-dependent, being greatest with doses in excess of 0.5 mg/kg wt.¹  Refer to the indications for use for IC-Green indications and contraindications.

References

1. Semin Thorac Cardiovasc Surg. 2004; 16:266-71
2. Chest 2004; 125:418-24