Wavelet transform coherence estimates in cardiovascular analysis: Error analysis and feasibility study

Wavelet transform coherence (WTC) can provide insight into the transient linear order of the regulatory mechanisms, via the computation of time-frequency maps of the time-variant coherence. This paper presents a framework for applying WTC for quantitative analysis of coherence in cardiovascular variability research. Computer simulations were performed to estimate the accuracy of the WTC estimates and a method for determining the coherence threshold for specific frequency band was developed and evaluated. Finally, we demonstrated, in two representative situations, the dynamic behavior of RSA through the analysis of the WTC between HR and respiration signals. This emphasizes that continuous wavelet transform (CWT) and its application to WTC is a useful tool for dynamic analysis of cardiovascular variability.