Estimation of central aortic systolic pressure using late systolic inflection of radial artery pulse and its application to vasodilator therapy

Background: Central blood pressure (BP) is a useful predictor of cardiovascular risk. Recently, a fully automated device that measures central SBP (cSBP) from radial late SBP (rSBP2) has been developed. Method: We measured cSBP using this device, compared it with aortic SBP (aSBP) measured with a high-fidelity pressure sensor, and evaluated the accuracy of cSBP before and after vasodilator administration. The data of 66 patients (mean age, 63.4 +/- 9.7 years; 49 men) who underwent cardiac catheterization were analyzed. The radial artery pulse waveform and brachial BP were measured sequentially and used to calculate cSBP. Brachial SBP and DBP were used for radial SBP (rSBP) and radial DBP to calculate the absolute value of rSBP2. The radial pulse waveform was recorded by an applanation tonometer (HEM-9000AI; Omron Healthcare Co. Ltd). A high-fidelity pressure sensor was placed in the ascending aorta, and aSBP was measured simultaneously by an invasive method. Results: Significant positive correlations between directly measured aortic late SBP and cSBP or rSBP were observed (r=0.93, 0.88, respectively). Changes in aSBP before and after vasodilator administration showed a trend toward higher correlation with changes in cSBP than with changes in rSBP (r=0.84, 0.78, respectively). The slope of the linear regression line of aSBP with cSBP (slope: 0.94) was closer to unity than with rSBP (0.66). Conclusion: Noninvasive cSBP calculated with rSBP2 accorded well with aSBP measured by the invasive method. Vasodilator medication and four of five diseases did not affect this relation.