Pacemakers are devices which give tiny electrical signals to the heart when the heart’s own pacemaker is not functioning well. The natural pacemaker of the heart is known as sinus node, located in the right upper part of the heart.
Pacemakers may also be used when the natural pacemaker signals are not conducted well to the lower chambers in a condition called complete heart block. This is an electrical block and not a block in the blood vessels of the heart with which most people are more familiar.
Being an electronic device, which functions on an in build battery, pacemaker function can be interfered by strong electrical and magnetic signals in the vicinity. This is known as electromagnetic interference of pacemakers.
Moreover, modern pacemakers communicate with the equipment used for programming them using radio waves. This communication can also be interfered with by strong electromagnetic fields.
The pacemaker has built in circuitry and a metallic shielding to reduce such interference. Still if the electromagnetic field is very strong, interference with function or communication can still occur.
In the earlier era, the most likely causes were electrical equipments and devices like speakers which have magnets within which used to be important.
But now, probably the most common electromagnetic equipment which we use is a mobile phone. While using a mobile phone, keep it as far away from pacemaker site as possible, at least 15 cm, typically in the opposite ear. If pacemaker is below the left collar bone, use the mobile phone in the right ear.
Of course, a person with a pacemaker should keep away from mobile towers as the signal strength there is very much higher than that from a phone. But this is not usually a problem as the towers are usually located high up.
Other important electromagnetic devices are metal detectors at airports and theft detectors at malls. An identity card will be needed at airports to avoid metal detectors.
In the hospital, there are several devices which use electromagnetic waves like surgical cautery, defibrillators, radiation therapy, dental instruments, nerve and muscle stimulators, which need special precautions.
Most important equipment to be thought of in the hospital is an MRI scanner. With older generation pacemakers, MRI was prohibited. But with newer MRI conditional pacemakers, MRI scan if urgently needed, can be done with special precautions.