The book comprises of two main sections.The first section encompasses the development of the algorithm for the detection of different heart waves such as Q wave, Tmax and the Tend to measure the intervals such as QT, QTc, RT, QTmax and RTmax respectively. The second section deals with the analysis of different variabilities including HRV, QT, QTc, RT, QTmax and RTmax. The algorithm was validated on ten patients of five minute data segment of paced breathing at 6 breaths per minute and 12 breaths per minute respectively. The algorithm for the detection of Q wave, Tmax and Tend produced an overall success of 99.16% according to automatic verification of accuracy detection and 96.4% based on manual inspection. In this study, the duration of the QT interval was in the range of 450 to 500 milliseconds, which indicated normal duration of repolarization. The variability plots indicated the similarity between HR variability and QT corrected variability.