Estimation of coronary blood flow by cardiac thermography in open chest conditions

We developed a thermographical method for quantitative estimation of coronary flow, analyzing the dynamic response of the epicardial temperature to cold saline injection into the aortic root. In eight dogs, the heart was exposed and imaged by a thermographic camera. LAD flow was measured by a transit time flowmeter. End diastolic images were recorded for 20-30 sec after aortic root injection of 20 cc of cold saline. Several LAD flow rates were achieved by one minute occlusion of the LAD, obtaining a reactive hyperemic response. A temperature response curve was obtained by averaging over an edge detected arterial segment for each frame. Several indices were calculated for each curve and correlated with coronary flow, one of which was a parameter of a heat transfer model, that was successfully fitted to the curve. In conclusion, we developed a method for quantitative estimation of coronary blood flow by thermography, which can provide important information regarding coronary blood flow during open chest procedures