Since 1970 Dr. Hartley has been involved in the design, development, and application of ultrasonic instrumentation for cardiovascular measurements in man and in animal models of human diseases. His group designed the first high frequency (20 MHz) pulsed Doppler velocimeter and catheters to measure coronary blood flow velocity and reserve in man (1973), the first multichannel pulsed Doppler system and implantable probes to measure regional blood flow in chronically instrumented animals (1976), and the first tissue Doppler to measure ventricular wall thickening (myocardial strain) in animals (1981) and in man (1987). Since 1992, he has been developing and using similar methods noninvasively to measure blood flow velocity and arterial wall motion in mice with unprecedented precision (100 nm) and temporal resolution (100 us). His group recently showed that left main coronary flow reserve, measured noninvasively in mice, is reduced by many types of heart disease and loading and is a sensitive index of global cardiac function. The ultrasonic technology developed by Dr. Hartley's laboratory has been incorporated into many clinical and research systems.