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/sub ao/) from non-invasive carotid (TFF/sub c-a/) and radial (TFF/sub r-a/) pressure recordings. In this study, the authors investigate whether (i) both TFF yield the same PP/sub ao/; (ii) PP/sub ao/ is significantly different from PP/sub 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/sub c-a/ gave significantly lower estimates (10%) for PP/sub ao/ than TFF/sub r-a/. In controls, the authors found no difference between PP/sub CAR/ and PP/sub ao/ computed using TFF/sub r-a/; in patients, there was no difference between PP/sub car/ and PP/sub ao/ computed with TFF/sub c-a/. The observed differences in computed PP were reflected in the compliance estimates using PPM. Although small, the discrepancy between PP/sub ao/ predicted by TFF/sub r-a/ and TFF/sub c-a/ illustrates the need for more individualised transfer functions. Meanwhile, the carotid pulse pressure is probably the overall best estimate for PP/sub ao/.