  Over the years researchers have studied the evolution of Electrocardiogram
(ECG) and the complex classification of cardiovascular diseases. This review
focuses on the evolution of the ECG, and covers the most recent signal
processing schemes with milestones over last 150 years in a systematic manner.
Development phases of ECG, ECG leads, portable ECG monitors, Signal Processing
Schemes and the Complex Transformations are discussed. It also provides
recommendations for the inclusion of certain important points based on the
review.
