What is an ECG?

ECG stands for “electrocardiography” and refers to measurement of the electrical activity of the heart. The heartbeat, i.e. the rhythmic contraction of the heart muscle, is triggered by the so-called sinus node in the middle of the heart. From this node electrical impulses spread through branching conduction pathways to all areas of the heart. This heart action is recorded in the ECG in the form of a graph – the ECG “reading”. This gives the doctor important information on the condition of the heart, since in many heart problems the electrical excitation of the heart is altered.

To take an ECG reading several ECG leads are stuck on to the patient’s skin and are then connected to the ECG device, which records the heart activity. The ECG is generally the first and the most rapid means of cardiological diagnosis; every ambulance carries a portable ECG device.

Exertional ECG

In some diseases of the heart, in particular coronary artery disease, changes in the ECG are seen only during physical exertion. For this reason the exertional ECG, also known as ergometry, is one of the most frequent methods of diagnosing a disruption of the blood supply to the heart. For this examination the patient pedals on a bicycle ergometer and the resistance is increased in steps. The patient’s heart rate, blood pressure and ECG are recorded continuously. If there are signs of reduced blood supply to the heart, the indication for a heart catheter examination is usually given.

Long-Term ECG and Loop Recorder

Constant heart rhythm disturbances can be diagnosed on the basis of a resting ECG. However, if the disturbance occurs only occasionally, long-term ECG reading is necessary. An ECG device, which the patient wears on a belt, takes ECG readings over a period of 24 to 72 hours. The ECG leads are stuck to the skin.

When there are rhythm disturbances that are not recorded during long-term readings, use of a loop recorder is sometimes necessary. There are two types: the external, portable recorder and the implantable recorder. The external loop recorder is carried on a belt and the ECG is recorded by means of leads attached to the skin. The recording is started by the patient pressing a button as soon as rhythm disturbances are perceived. The implantable loop recorder, on the other hand, is placed inside the chest, below the heart. It can record the heart rhythm for up to 3 years. Once the diagnostic procedure has been completed or when the batteries run out, the device can be removed in a small, uncomplicated procedure.