Question

1. Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart. 2. The number of QRS complexes that occur in a given time period can seldom correlate with heart beat rate of an individual. Regarding 1 and 2 :

Answer 1

1.At every beat, the heart is depolarized to trigger its contraction. This electrical activity is transmitted throughout the body and can be picked up on the skin. This is the principle behind the ECG. An ECG machine records this activity via electrodes on the skin and displays it graphically. An ECG involves attaching 10 electrical cables to the body: one to each limb and six across the chest.

2.A combination of the Q wave, R wave and S wave, the “QRS complex” represents ventricular depolarization. This term can be confusing, as not all ECG leads contain all three of these waves; yet a “QRS complex” is said to be present regardless.