ESTIMATION OF ARTERIAL MECHANICAL-PROPERTIES FROM AORTIC AND TONOMETRIC ARTERIAL-PRESSURE WAVE-FORMS

Although arterial mechanical properties have been evaluated using arte rial input impedance, the relative difficulty in accurate flow measure ment made the value of impedance somewhat limited. To develop an alter native method to evaluate arterial mechanical properties, we analyzed the aortic pressure (AoP)-radial arterial pressure (RAP) relationship because of relative ease in obtaining peripheral pressure waveform by tonometry. In 8 patients we simultaneously recorded aortic root and ra dial arterial pressure waveforms. We calculated the transfer function from AoP to RAP. We then fitted the transfer function to a model of a lossless uniform elastic tube terminated with a modified Windkessel mo del. The fact that the model transfer function predicted AoP from RAP waveform with considerable accuracy indicated that the model represent ed the arterial mechanical properties well. We conclude that we can es timate the arterial mechanical properties by the pressure-pressure tra nsfer function analysis.