Warren Grundfest, MD
Professor, Department of Bioengineering, UCLA

Authors: Grundfest W¹, Val-Mejias J⁴, Monnet E⁵, Knight BP⁵, Nazarian S², Berger RD², Ferguson TB⁶, Amundson D³, Hanlin J³, and Blankenship L³

1 – UCLA, Los Angeles, CA
2 – Johns Hopkins, Baltimore, MD
3 – CardioOptics, Boulder, CO
4 – Galichia Heart Hospital, Wichita, KS
5 – University of Chicago, IL
6 – East Carolina University, Greenville NC
7 – Colorado State University, Fort Collins, CO

Real-time imaging through blood is theoretically feasible using infrared imaging technologies. Using Mie optical scattering theory and experimentation we determined that infrared light in the range of 1550-1650nm would permit imaging through blood. We designed and built a catheter-based, infrared optical imaging system using an Indium-Gallium-Arsenide 320x256 pixel focal plane array. Subtraction of background noise, removal of the fiberoptic pixel pattern, and image enhancement are accomplished using standard digital signal processing techniques. Frame rates of 15 frames per second are used, and stop-frame imaging helps to identify intracardiac structures. These IR angioscopes were tested in 35 canine and 40 porcine models. Imaging through human blood was considered based on results of animal experimentation. After obtaining FDA approval in-vivo applications were examined in human clinical trials. In the first 50 patients studied intracardiac images revealed the ability to identify the coronary sinus, the eustacian ridge, the fossa ovalis, the tricuspid valve, and other intracardiac and vascular structures. In some patients tissue detail was resolved to 100 microns, but useful images could not be obtained in some patients. Additional technical improvements will be required for routine clinical use. Early experience shows that IR endoscopy can be used to define intracardiac and vascular anatomy and guide interventional procedures.