Data on sex differences in various cardiovascular time series characteristics are conflicting. While some studies suggest that heart rate variability (HRV), heart rate asymmetry (HRA), blood pressure variability (BPV) and spontaneous baroreflex sensitivity (BRS) differ between men and women, other studies contradict this. Of the studies reporting gender differences, some have shown that women generally have higher HRV than men, while others have reported the opposite. Even less is known about sex differences in BPV, blood pressure asymmetry (BPA), complexity and microstructure of cardiovascular time series, and baroreflex function. Many studies have analysed limited numbers of people over a wide age range, sometimes with an imbalance between men and women. The studies have been conducted under different conditions, such as at rest or under different physiological challenges, or in specific populations (e.g. athletes). Thus, despite decades of research on HRV, BPV and the baroreflex, sex differences remain unclear.
The HYPOL database contains a balanced group of healthy men and women of the same ethnicity and within a similar age range. All participants underwent resting recordings in the supine position to eliminate the effects of physical activity. The data set includes exported values of RR intervals, systolic, diastolic and mean blood pressure values, and inter-beat intervals. No pharmacological or non-pharmacological interventions were administered during the recordings.
References to quote when using the database
 Guzik P, Krauze T, Wykrętowicz A, Piskorski J. Healthy Young POLes – HYPOL database with synchronised beat-to-beat heart rate and blood pressure signals: HYPOL – Cardiovascular Time Series Database. Journal of Medical Science. 2023 Nov. 13:e941. doi.org/10.20883/medical.e941, https://jms.ump.edu.pl/index.php/JMS/article/view/941
The challenge aims to study sex differences in the temporal structure, main features, complexity, and linear and nonlinear interrelationships of beat-to-beat variability of heart period and blood pressure series.
The participants in the challenge must report sex differences in any cardiovascular markers derived from heart period and blood pressure series and their dynamic interactions using various methods applied in the cardiovascular time series analysis or for baroreflex function.
More details on the HY database are provided here:
Guzik P, Krauze T, Wykrętowicz A, Piskorski J. Healthy Young POLes – HYPOL database with synchronised beat-to-beat heart rate and blood pressure signals: HYPOL – Cardiovascular Time Series Database. Journal of Medical Science. 2023 Nov. 13:e941. doi.org/10.20883/medical.e941, https://jms.ump.edu.pl/index.php/JMS/article/view/941
Study population and materials
We carefully selected baseline clinical characteristics and beat-to-beat data from several cardiovascular time series from seven projects conducted in our laboratory at the Department of Cardiology-Intensive Therapy, Poznan University of Medical Sciences, Poznan, Poland. All projects were approved by the local bioethics committee with the following decision numbers and issue dates:
The HYPOL database is available at the https://hypol.ump.edu.pl/
These files contain seven columns with the following labels and data:
and synchronised beat-to-beat values of:
2. HYPOL clinical characteristics.xls, it is a single Excel file with baseline clinical characteristics and file names of each individual. The columns in this file are as follows:
Non-invasive continuous finger blood pressure and ECG recording
All participants rested in the supine position during signal acquisition. Three channels of a bipolar chest lead ECG were recorded by an A/D converter, either Porti 5 with a sampling frequency of 1600 Hz or Porti 17 with a sampling frequency of 2048 Hz. Both devices were manufactured by TMSI (Oldenzaal, The Netherlands).
A non-invasive beat-to-beat finger arterial blood pressure signal was simultaneously recorded using a volume-clamp photoplethysmographic method and transferred to the A/D converter. The finger arterial pressure waveforms were recorded using either the Portapres 2 or the Finapres Nova, both from FMS (Amsterdam, The Netherlands). Signals were recorded for at least 15 minutes, depending on the protocol and project. For the HYPOL database, we have selected signals up to 45 minutes.
Signal processing and export of cardiovascular time series
Preliminary automated analysis of the recordings was performed using the libRASCH/RASCHlab software from the libRASCH project (v. 0.6.1; http://www.librasch.org, Munich, Germany) . It was followed by a visual inspection of all beats and manual correction if necessary. ECG-derived RR intervals for each cardiac cycle with appropriate beat type annotation (normal = 0, ventricular = 1, supraventricular = 2, technical artefact = 3) and photoplethysmography-derived finger SBP, DBP, MBP and interbeat intervals were retrieved from stored recordings. These values form the HYPOL database and can be used to calculate HRV, HRA, BPV, BPA, baroreflex function and other analyses of cardiovascular time series.