Noninvasive assessment of baroreflex sensitivity in post-MI patients by an open loop parametric model of RR-systolic pressure interactions

摘要

Noninvasive evaluation of baroreflex sensitivity is considered an important goal for diagnosis and prognosis in post-MI patients. Methodological approach and physiological measure conditions may be the main causes for the differences found with respect to the standard Phenylephrine test. In this study, three linear parametric models, describing variability and mutual interactions of RR interval and systolic arterial pressure (SAP), were compared in relation to their ability to quantify baroreflex gain, using the Phenylephrine test index (Phe/sub BRS/) as reference. By monovariate autoregressive (AR) model, bivariate AR model and open loop ARXAR model, specific gain indexes (/spl alpha//sub AR/, /spl alpha//sub 2AR/, /spl alpha//sub ARXAR/) were calculated. Variance and regression analysis selected /spl alpha//sub ARXAR/ first in correlation with Phe/sub BRS/ demonstrating that a better agreement is achieved using the ARXAR model, specifically designed to describe the causal influences of SAP on the RR interval.