Utility of Intraoperative Fluorescence Angiography in Congenital Heart Disease

INTRODUCTION:
Achieving successful repair in congenital heart disease requires attention to details. Careful evaluation of anastomotic site patency, re-implanted coronary arteries, location of epicardial coronaries and myocardial perfusion may be needed to ensure safe conduct of the operation and excellent results. We have used the technique of IOFA using indocyanine green (ICG) as an integral part of several of our repair techniques.

METHOD:
ICG has a short half-life but long history of safe use. It generates fluorescence of 800-850 nm wavelength when is exposed to 760-780 nm wavelength of near infrared rays. It has been widely used in other subspecialties, most commonly for sentinel lymph node biopsy in breast, stomach, as well as colon cancer and in liver tumor resection, etc.

The technique requires the following: (1) SPY-PHI machine which is commercially available (Novadaq Technologies Inc., Toronto, Canada), (2) Hand-held infra-red probe, (3) Video-processor/illuminator (VPI), and (4) the monitoring screen. Three modes are available: (1) Overlay mode: the fluorescence image (green) is displayed over a white light image, (2) SPY CSF mode: a white light image is displayed in greyscale with fluorescence overlaid in a color scale, and (3) SPY mode: is a fluorescence image displayed in a greyscale, and this is the mode we have used. A sterile sleeve is used to allow probe use in the operative field, and image recording starts prior to administration of ICG due to its short half-life.

ICG is administered in incremental doses, maximum dose in children is 2mg/kg.

APPLICATIONS:
We have used the technique in a variety of lesions and a variety of indications. The examples provided in the video include (1) assessment of the patency of a modified Blalock-Taussig shunt in a neonate with double outlet right ventricle, pulmonary atresia and atrioventricular discordance, (2) visualization of right ventricular-dependent coronary circulation in a neonate with pulmonary atresia and intact septum, (3) assessment of myocardial perfusion after stage I Norwood palliation in a neonate with aortic and mitral atresia, (4) determination of the location of epicardial coronary arteries prior to a ventriculotomy in a child who required reoperation for a right ventricular-to-pulmonary artery conduit placement, and (5) a recent use in localization of thoracic duct in a neonate who had persistent chylothorax after arch repair.

CONCLUSIONS:
ICG-IOFA is a useful and safe technique that should be part of the cardiac surgeon armamentarium. It has the advantages of safety, speed, and the ability to be performed intraoperatively. This may increase safety in the operating room and help minimize invasive testing postoperatively

References

1. Feins EN, Si MS, Baird CW, Emani SM. Intraoperative Coronary Artery Imaging for Planning. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2020;23:11-16
2. Kogon B, Fernandez J, Kanter K, Kirshbom P, Vincent B, Maher K, Guzetta N. The role of intraoperative indocyanine green fluorescence angiography in pediatric cardiac surgery. Ann Thorac Surg. 2009 Aug;88(2):632-6
3. Kuroyanagi S, Asai T, Suzuki T. Intraoperative fluorescence imaging after transit-time flow measurement during coronary artery bypass grafting. Innovations (Phila). 2012 Nov-Dec;7(6):435-40

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