ABSTRACT
The heart has four chambers, the right and left atria and the right and left ventricles. Inside the right atrium, there is an area of specialised heart tissue called the sinus node or sino-atrial node. This node produces an electrical impulse that travels down through the right atrium to another area of specialised tissue called the atrioventricular node. The electrocardiograph (ECG) is a graphic recording of electrical processes that make the heart muscle contract. The ECG detects the electrical current flowing through the heart, and depending on the size and state of the heart muscle, it will produce deflections on the ECG monitor. Various types of heart disease that affect the heart muscle or interfere with the rate or rhythm may be detected on an ECG. Atrial fibrillation occurs when the sinus node fires erratic impulses, causing the atria to ‘fibrillate’ or quiver when they beat very rapidly and irregularly.
