Cardio-respiratory phase synchronization has been studied in healthy subjects for several years, but little is known about how cardiovascular impairments affect this subtle phenomenon. In this paper we study data from 874 post-infarction patients, where heartbeat intervals and respiration were recorded approximately one week after the index myocardial infarction event. Calculating the intensity of the first Fourier mode of the cyclic relative phase differences we find that cardio-respiratory phase synchronization is decreased in patients with increased mortality risk or age. However, our analysis also indicates that data from 30 minutes recordings is insufficient to achieve a reliable statistics for predicting mortality risk based on phase synchronization. Therefore, we further develop techniques for extracting respiratory information from ECG recordings to be able to use long-term Holter recordings of post-infarction patients in future studies. We compare breathing-phase reconstructions based on the amplitude of the R peaks in the ECG or beat-tobeat time intervals with real respiratory phases. We find that the reconstruction works better for R peak amplitudes in most patients. We optimize the respiration-reconstruction algorithm and show that it works well for a large group of the patients in our database.
|Title of host publication
|Proceedings of the 6th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO) 2010
|Published - 2010