A new thermal sensor for surface-based measurement of local myocardial perfusion

The transient response of a new thermal sensor for continuous surface-based measurement of local tissue blood flow was evaluated in the beating dog heart. The sensor is 2.5 mm square, tests on the heart, and responds to flow changes only within a region of tissue 3-4 mm below its location on the epicardial surface. Initial studies demonstrate excellent sensitivity, good frequency response with a time constant of the order of 10-11 s, and an ability to continuously monitor changes in local myocardial blood flow during a variety of well-understood interventions, including coronary artery occlusion, reactive hyperemia, and intravenous administration of nitroglycerin and dipyridamole.