Introduction to ECG
Understanding format and important signals of the ECG wave are the good start to analyze and simulate ECG data
An electrocardiogram(ECG) is used to measure the electrical activity over time throughout the heart during each cardiac cycle.
The contraction and relaxation can be measured by different components or waves, that represent the electrical activity in specific regions of the heart. The ECG cycle includes P waves, P-R segment and interval, QRS complex, S-T segment and interval, Q-T interval, T wave.
The P wave corresponds
to atrial depolarization.
P Wave – represents the movement of an electrical wave originating at the sinoatrial (SA) node and resulting in the depolarization of the left and right atria.
P-R Segment – the pause in electrical activity caused by a delay in conduction of the electrical current at the atrioventricular (AV) node to allow blood to flow from the atria to the ventricles before ventricular contraction occurs.
P-R Interval – the time between the beginning of atrial depolarization and the beginning of ventricular depolarization. A change in P-R interval is often an indicator of the activity of the parasympathetic nervous system on the heart.
The QRS complex corresponds
QRS Complex – represents the electrical activity from the beginning of the Q wave to the end of the S wave and the complete depolarization of the ventricles, leading to ventricular contraction and ejection of blood into the aorta and pulmonary arteries
S-T Segment – the pause in electrical activity after the complete depolarization of the ventricles to allow blood to flow out of the ventricles before ventricular relaxation begins and the heart fills for the next contraction.
S-T Interval – the time between the end of ventricular depolarization (S wave) and the end of repolarization (T wave end).
Q-T Interval – the time between the beginning of the ventricular depolarization (Q wave) and the end of repolarization (T wave end).
T Wave – represents the repolarization of the ventricles.
As the first task of the project, we tried to find a simple and flexible way to generate signals that could be similar to those of human ECG with different patterns. Fourier series were selected for representing ECG signals, as any periodic functions which satisfy Dirichlet's condition can be expressed as a series of scaled magnitudes of sin and cos terms of frequencies which occur as a multiple of fundamental frequency.ECG signal is periodic with fundamental frequency determined by the heat beat Each significant feature of ECG signal can be represented by shifted and scaled versions of waveforms.
“ECG simulation using MATLAB” by karthik raviprakash from Anna University, India.
Using his concept to we tried to write a function to simulate ECG using R