Ultrasonic transesophageal measurement of hemodynamic parameters in humans.

A noninvasive method has been developed to monitor centerline blood velocity waveforms and vessel diameter in the descending aorta and pulmonary artery of conscious humans. An esophageal endoscope fitted with miniature ultrasound transducers is swallowed and positioned in the esophagus near vessels of interest. The transducers are connected to ultrasound Doppler velocimeters and echotrack instrumentation to obtain the pertinent hemodynamic parameters. This paper describes the design and fabrication of the esophageal ultrasound transducers and the techniques involved in human applications. In addition, blood velocity and wall motion measurements obtained in conscious men at rest and during exercise are described.