Polar Coordinate Description of Blood Pressure Measurements and Implications for Sex-Specific and Personalized Analysis.

Vascular properties and their associated impact on cardiovascular risk factors are often evaluated by metrics such as pulse pressure (PP) and the augmentation index (AIx). All derived metrics are essentially based on the combination of blood pressure recordings. These clinically used metrics typically concern a difference (as in PP) or a ratio (as in AIx). A polar coordinate description reveals the companion (C) of the traditional metric. The aim of this study is to evaluate the impact of PPC and AIxC by analyzing both patient data and a detailed data set on healthy children derived from the literature.Companions are calculated using the Pythagorean theorem, and show that PPC is related to mean arterial pressure, thus complementing the biomarker PP. Also, inflection pressure is tied to systolic pressure, implying a possible simplification of obtaining the numerical value of AIx. Outcomes for adults and children are comparable. We conclude that derived metrics such as PP and AIx are incomplete. The associated companion metrics PPC and AIxC can easily be calculated. They add clinically relevant information without the need to perform additional measurements. Combination of traditional and the newly described companion metrics permits more precise characterization of individual patients.