Millar formed the Texas-based company in 1969 to develop state-of-the-art catheter-tip technology for measuring physiological parameters in research and clinical applications.
He served as visiting professor in the Department of Molecular Physiology and Biophysics at Baylor College of Medicine from 1976 to 1995.
McDonald's Blood Flow in Arteries: Theoretical, Experimental and Clinical Principles, Sixth Edition by Nichols, O'Rourke and Vlachopoulos lists numerous cases in which Millar catheters have yielded information about the human circulatory system that was not available by any other technology.
Measuring pressure at the source delivers a high-fidelity signal without the disadvantages of fluid-filled catheters.
Michael F. O'Rourke[2] credits Millar with the development of an applanation tonometer with the accuracy to record pulse pressure wave fluctuations when the surface of an artery is flattened.