Real-time intraoperative visualization of myocardial circulation using augmented reality temperature display
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For direct visualization of myocardial ischemia during cardiac surgery, we tested the feasibility of presenting infrared (IR) tissue temperature maps in situ during surgery. A new augmented reality (AR) system, consisting of an IR camera and an integrated projector having identical optical axes, was used, with a high resolution IR camera as control. The hearts of five pigs were exposed and an elastic band placed around the middle of the left anterior descending coronary artery to induce ischemia. A proximally placed ultrasound Doppler probe confirmed reduction of flow. Two periods of complete ischemia and reperfusion were studied in each heart. There was a significant decrease in IR-measured temperature distal to the occlusion, with subsequent return to baseline temperatures after reperfusion (baseline 36.9 ± 0.60 (mean ± SD) versus ischemia 34.1 ± 1.66 versus reperfusion 37.4 ± 0.48; p < 0.001), with no differences occurring in the non-occluded area. The AR presentation was clear and dynamic without delay, visualizing the temperature changes produced by manipulation of the coronary blood flow, and showed concentrically arranged penumbra zones during ischemia. Surface myocardial temperature changes could be assessed quantitatively and visualized in situ during ischemia and subsequent reperfusion. This method shows potential as a rapid and simple way of following myocardial perfusion during cardiac surgery. The dynamics in the penumbra zone could potentially be used for visualizing the effect of therapy on intraoperative ischemia during cardiac surgery.
KeywordsAugmented reality Mixed reality Myocardium Ischemia Infrared thermometry Visualization
The national Swedish Visualization Program of the Knowledge Foundation, Vinnova, the Swedish Foundation for Strategic Research, the Vårdal Foundation and the Invest in Sweden Agency (Grant No. 2007/0173).
Conflict of interest
Stefan Sjökvist, Torbjörn Gustafsson, Per Carleberg and Magnus Uppsäll are employees, founders and co-owners of Thermirage AB, who invented the concept and produced the technical equipment.
Video of the surgical exposure of the heart. An elastic vessel loop is placed around the middle of the left descending coronary artery. Note the falling temperature in the area supplied by the LAD seen in the lower part of the video picture. Dark color indicates the decreased temperatures. At the release of the vessel loop round the LAD the temperature returns to the baseline. The ultrasound probe for flow measurements in the LAD is intermittently inserted by the surgeon Supplementary material 1 (MPG 22036 kb)
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