The Cardiovascular System, The normal Electrocardiogram, ECG
Remember the waves precede the contraction. The PR interval has a normal value of 0.16 seconds and is the delay between the atrial contraction and the beginning of the ventricular contraction. The QT interval has a normal value of 0.35 seconds - the time of ventricular contraction. The heart rate can be determined by the reciprocal of the time interval between each heart beat. During depolarisation process, the average electrical current flows from the base of the heart toward the apex. ECG leads - there are three bipolar limb leads. Lead I: negative lead is connected to the Right arm and the positive terminal is connected to the left arm. Lead II: the negative terminal of the ECG is connected to the right arm and the positive terminal is connected to the left leg. Lead III: the negative terminal is connected to the left arm and the positive terminal is connected to the left leg. Einthoven's Law states that the electrical potential of any limb lead equals the sum of the ...