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 used to pickup the electrical potential from the heart.There are many types of electrodes are used to pickup signal from the body .Here surface electrode is used .

         Types of  lead systems

                      1.Unipolar

                      2.Bipolar