In vivo application of the generalised radial-aorta and carotid-aorta pressure transfer function

Recently, generalised pressure transfer functions (TFF) have been proposed to estimate central aorta pressure and pulse pressure (PP_ao) from non-invasive carotid (TFF_c-a) and radial (TFF_r-a) pressure recordings. In this study, we investigate whether (i) both TFF yield the same PP_ao; (ii) PP_ao is significantly different from PP_car; (iii) differences are significant for the estimation of total arterial compliance using the Pulse Pressure Method (PPM). Therefore, ECG, radial and carotid artery pressure (Millar tonometer) and aortic flow (Doppler) were measured in 9 controls (34+/-5 yr.) and 14 patients (62+/-12 yr.). In both patients and controls, TFF_c-a gave significantly lower estimates (10%) for PP_ao than TFF_r-a. In controls, we found no difference between PP_CAR and PP_ao computed using TFF_r-a; in patients, there was no difference between PP_car and PP_ao computed with TFF_c-a. The observed differences in computed PP were reflected in the compliance estimates using PPM. Although small, the discrepancy between PP_ao predicted by TFF_r-a and TFF_c-a illustrates the need for more individualised transfer functions. Meanwhile, the carotid pulse pressure is probably the overall best estimate for PP_ao.