ECG

A ECG is way to measue electrical signal in the heart. This measurement produces a PQRST graph. The P wave represents atrial depolarization by the SA node. The signal is then delayed, and atrial depolarization is complete before the QRS complex. At the QRS complex ventricle depolarization begins at the apex and atrial repolarization occurs. Following this, the ventricle depolarization completes. At the T wave, ventrical repolarization occurs. Then at the plataeu ventrical repolarization is completed. The electrical signal is important because it leads to contraction which in turn create pressure that moves blood. Therefore, depolarization of the SA node is important to keep a normal heart rate. If there was a problem with spontaneous depolarization of the SA node, the AV node would control the heart rate. This would cause a lower heart rate.