This thesis describes the development of new methods to infer the nature of nervous control of the human heart using recordings of its electrical behaviour. Malfunctions of this control system are a leading cause of death, and can be triggered by a diverse range of influences including basic physiological factors and one’s emotional state. However, the mechanisms of failure remain poorly understood, partly due to a lack of relevant human data. The principal purpose of the work described in this thesis is to improve the availability of such data. A literature review was conducted, covering the current understanding of electrical activity in the heart and its control by the nervous system, as well as the techniques available to observe that behaviour. A variety of novel techniques were developed and implemented experimentally to demonstrate their utility. Specialised methods for the filtering and subsequent spectral analysis of electrocardiograph (ECG) signals were used to expose differences between psychologically distinct groups in terms of their response to emotional stimuli. Algorithms were developed to automatically process unipolar electrogram recordings with minimal human intervention, enabling the analysis of heterogeneous electrophysiological dynamics, which requires datasets of a size that would otherwise make in-depth analyses intractable. New indices were developed for measuring the timing of localised electrical activation and recovery from unipolar electrograms, in order to overcome the fact that conventional indices are not well suited to dynamic analyses. Experiments using these tools demonstrated that respiration induces heart-rate independent modulation of the ventricles’ electrophysiological behaviour via the autonomic nervous system. By improving the accessibility of human in situ data, the developed tools enable new research methodologies to study interactions between the heart and the nervous system, which may ultimately contribute to the development of new treatments to prevent thousands of deaths in the UK alone each year
