10.6 VARIATION OF THE ASYMPTOTIC DIASTOLIC PRESSURE WITH DIFFERENT FITTING TECHNIQUES IN HEALTHY HUMANS

• Main Authors: Nicola Pomella, Christina Kolyva, Ernst Rietzschel, Patrick Segers, Ashraf W. Khir, Madalina Negoita
• Format: Article
• Language: English
• Published: Atlantis Press 2016-11-01
• Series: Artery Research
• Online Access: https://www.atlantis-press.com/article/125930447/view

Background: Reservoir-wave model assumes the measured pressure (Pm) consists of two additive components: reservoir (Pr) and excess pressure (Pex)1–2. Calculation of Pr requires fitting the diastolic decay of Pm for calculating parameters P∞ (asymptotical value) and b (time constant)1. However, there is no consensus over the value of these parameters1–3–4. Although many investigators use free-fitting, different degrees of freedom (dof) could be used1–2–5. The aim of this study was to examine the effect of varying fitting method on P∞ ,b and calculate the peaks of Pr and Pex. Methods: Pressure data from common carotid artery of 505 middle-aged healthy subjects were selected from the Asklepios dataset. Free-fitting methods with 3 dof (dicrotic notch not fixed) and 2 dof (dicrotic notch fixed) were used to obtain P∞ , b and calculate Pr and Pex. Results: Mean value of P∞ change significantly between 3 dof and 2 dof (58 vs. 50 mmHg p<0.01) as well as b (2.3 vs. 1.9 s−1 p<0.01). Pr- and Pex- peaks didn’t significantly change (Pr= 105 mmHg for 3 dof and 2 dof p>0.05 Pex = 30 mmHg and 31 mmHg for 3 dof and 2 dof, respectively p>0.05). Conclusions: P∞ and b values are method-dependent with a large variation between methods. P∞ values in our study are higher than previously reported in literature, and variation in P∞ and b values don’t affect Pr- and Pex- peaks. Given the variability in the combination of P∞ ,b in different subjects, the use of free-fitting is more appropriate.