ECG
The study of electrical activity of the heart is termed as Electrocardiogram and the instrument use to measure the electrical activity is termed as Electrocardiograph Waveform of human heart P wave Due to atrial contraction Amplitude : 0.25mv Duration :0.12-0.22 s QRS wave Due to relaxation of atria and contraction of ventricles Amplitude : 1.60 mv Duration :0.07-0.1 s T wave Due to ventricular relaxation Amplitude:0.1-0.5mv Duration : 0.05-0.15s U wave Slow relaxation of intraventricular system Amplitude : less than 0.1mv Duration. : 0.2 s ECG LEAD SYSTEM Electrodes are