Electrocardiogram (ECG)

An electrocardiogram examination records electrical activity of the heart. The electrocardiogram (ECG) is a simple test that allows the doctors to look at certain aspects of how the heart is working and it often takes just a few minutes to perform usually while the patient is resting.

Prior to the test the patient is connected to the ECG machine via a series of small metal contacts (electrodes) that are attached to the skin at various points on the chest, arms and legs.

In the healthy heart an electrical signal begins at a certain point in the heart and travels along special nerves in the heart muscle causing the heart to contract in a co-ordinated way. In an ECG test, these electrical impulses are recorded and usually shown on a piece of paper. This enables the conduction of the heartbeat through the heart to be recorded and any problems with the heart's rhythm to be picked up.

When the electrodes detect the electrical activity of the heart, they send a signal to the recording device, which then causes a pen on the ECG machine to deflect up and down with each heartbeat, producing an ECG tracing on a piece of graph paper that unwinds as the test is being conducted. In PH this pattern of electrical flow often differs slightly from that of the healthy heart in specific ways.

The electrocardiogram may show signs of “right ventricular hypertrophy” (thickening) or “right ventricular strain” (meaning that the right side of the heart is working harder than normal), common findings in PH.