Abstract: A device for sensing blood flow in a human aorta and a method for its use. The device includes two arrays, each array including one or more ultrasonic transducers for transmitting and/or receiving ultrasonic pulses. By appropriate weighting and phasing of the two ultrasonic arrays, a wide beam for insonifying the entire aorta, and a narrow beam for insonifying only a portion of the interior of the aorta, are produced. In addition, signals from the arrays can be processed to produce a signal indicating the direction to move the device so that the wide beam insonifies the entire aorta and the narrow beam insonifies only an interior portion of the aorta. The direction-finding array can be made from sensors arranged in a north-south-east-west pattern or as four sectors of an annulus.