4.1 Introduction

The availability of open-source computational models and simulators can greatly facilitate the advancement of cardiovascular research by complementing clinical studies. ^[1] Such models provide the researcher with the means of formulating hypotheses that may be subsequently tested through investigations of both simulated biomedical signals and real-world signals obtained from clinical studies. There is a two-way relationship between the development of these models and the exploration of biomedical databases obtained from clinical studies. First, researchers can construct and evaluate their models using the biomedical signals. Access to these databases facilitates the estimation of important cardiovascular parameters and the comparison of different models. Second, the ability to simulate realistic signals using these models can be used to assess novel biomedical signal processing techniques. In addition, these models can be used to formulate new experimental hypotheses.

The ECG signal describes the electrical activity in the heart and each heartbeat traces the familiar morphology labeled by the P, Q, R, S, and T peaks and troughs. Since the R peak is typically associated with the largest deflection away from the baseline, this peak is generally taken as a marker for each heartbeat as it is the easiest to locate. As was pointed out in Chapter 3, the correct fiducial point for each heartbeat is the onset of the P wave. However, this point is both difficult to define and locate and the Q-R interval is often sufficiently short and of low variability that the...