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

This work is based on the hypothesis that coronary blood flow could be estimated from the dynamics of thermographic images during cold saline injection into the aortic root. The heart was exposed in five dogs, and imaged by an Agema thermographic camera. Coronary flow was measured by a transit-time flowmeter. Images were acquired 30 s after aortic root injection of 20 ml of cold saline. Several flow levels were achieved in each dog by obtaining a reactive hyperemic response to transient coronary occlusions. A temperature washout 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. The authors also tried the approach of model fitting, and consequently a model based on heat transfer theory was implemented.