Novel theory and potential applications of central diastolic pressure decay time constant

Central aortic diastolic pressure decay time constant ( $$ ) is according to the two-element Windkessel model equal to the product of total peripheral resistance ( $$ ) times total arterial compliance ( $$ ). As such, it is related to arterial stiffness, which has considerable pathophysiological relevance in the assessment of vascular health. This study aimed to investigate the relationship of the constant $$ with the product $$ , given by heart period ( $$ ) times the ratio of mean blood pressure (MBP) to central pulse pressure ( $$ ). The relationship was derived by performing linear fitting on an in silico population of n₁ = 3818 virtual subjects, and was subsequently evaluated on in vivo data (n₂ = 2263) from the large Asklepios study. The resulted expression was found to be $$ with $$ (R² = 0.9). The evaluation of the equation on the in vivo human data reported high agreement between the estimated and reference $$ values, with a correlation coefficient equal to 0.94 and a normalized RMSE equal to 5.5%. Moreover, the analysis provided evidence that the coefficient $$ is age- and gender-independent. The proposed formula provides novel theoretical insights in the relationship between $$ and central blood pressure features. In addition, it may allow for the evaluation of $$ without the need for acquiring the entire central blood pressure wave, especially when an approximation of the $$ is feasible. This study adds to the current literature by contributing to the accessibility of an additional biomarker, such as the central diastolic pressure decay time constant, for the improved assessment of vascular ageing.