Pacemakers: How do they work?

Pacemakers help to regulate your heart rate. Without a pacemaker, you would feel dizzy, tired and breathless when your heart is beating too slowly or erratically.

Although transient irregular heart rhythms or arrhythmias are harmless, some arrhythmias such as heart block and sick sinus syndrome can lead to such abnormally slow heart rates. As a consequence, the heart cannot pump enough blood to meet the needs of the body. This is where a pacemaker could help.

“A pacemaker prevents excessive slowing of heart rate, prevents recurrent fainting spells and gives the patient a new lease of life,” says Adjunct Associate Professor Ching Chi Keong, Senior Consultant, Department of Cardiology and Director, Electrophysiology and Pacing, National Heart Centre Singapore (NHCS), a member of the SingHealth group.

Pacemaker implants: Why do you need one?

The heart’s natural pacemaker (known as sinus node) controls the heart rate through electrical impulses it sends to the heart muscle.

When the sinus node slows down too much, the heart may not contract at a suitable rate and hence become unable to pump sufficient oxygenated blood to supply the body. As a result, one can feel faint, dizzy, breathless or extremely tired.

People with congenital heart disease, who had a heart attack or are taking certain heart medicines such as beta-blockers may also need a pacemaker to control irregular heart rates.

What is a pacemaker?

A pacemaker is a small battery-operated device that monitors your heartbeat and sends electrical impulses to the heart when it is beating too slowly.

The pacemaker comprises a pulse generator and one or two pacing leads. Leads are wires with sensors connected to the pulse generator on one end and to the heart chamber on the other end. The pacemaker can be programmed based on your heart’s pacing needs.

The pacemaker’s battery lasts seven to nine years. Replacing it is a simple procedure.

Types of pacemakers:

  • A single-chamber pacemaker uses only one pacing lead to carry electrical impulses from the pulse generator to either the heart’s right ventricle or right atrium.
  • A dual-chamber pacemaker has two pacing leads – one is placed in the right ventricle and the other in the right atrium.

How is a pacemaker implantation done?

Pacemaker implantation is done under local anaesthesia. The cardiologist will make a small incision below the collarbone and create a pocket to house the pacemaker. The pacing leads are then threaded through a vein behind the collar bone to the heart chamber(s) with the help of X-ray images.

The procedure takes about one hour and patients are usually discharged after a day after the implantation.

Precautions after a pacemaker implantation

It is safe to use common household electrical appliances, including microwave ovens, televisions and radios. But beware of possible electrical interferences from magnetic and large power-generating equipment.

Some tips for pacemaker users:

  • Mobile phones should be kept at least 15 cm away from the pacemaker to prevent possible interference.
  • Inform your doctor or dentist before undergoing any medical procedure that utilises medical or electronic devices.
  • Always carry your pacemaker identification card when travelling overseas as your pacemaker may trigger metal detectors. Otherwise, brief exposure to scanning equipment in airports is unlikely to interfere with your pacemaker’s function.
  • Anti-theft systems are also unlikely to interfere with your pacemaker if you move through them at a normal pace.
  • Check with your doctor if your work requires you to stay near power-generating equipment such as large generators, welding equipment and industrial motors.

Ref: R14