Pacing the heart
Pacemakers are devices that help regulate heart rhythm.
MY friend’s father recently fainted at the airport when he was coming home from Europe. They rushed him to the hospital. After many investigations, they finally diagnosed that he had a heart problem and would need a pacemaker. What is a pacemaker?
A pacemaker is a small medical device that is placed in your chest or abdomen to control abnormal heart rhythms, if you are diagnosed with that condition. The pacemaker will then generate electrical impulses to regulate your heart to beat at its normal rate and rhythm.
Abnormal heart rhythms are called arrhythmias.
Tell me more about arrhythmias.
In a nutshell, arrhythmias are heartbeats with abnormal rates or rhythms. An abnormal rate means that either your heart rate is too fast (tachycardia) or too slow (bradycardia).
In order to understand more about arrhythmias, we have to understand the structure of our heart. It is divided into four chambers – two atria and two ventricles. A structure called the sinus node sits in our right atrium and generates the first impulse that spreads throughout the entire conduction system of our heart.
The result is the contraction of our heart chambers to transport blood through our lungs and entire body. This is the essence of life itself.
Basically, any part of the heart can give rise to an arrhythmia if the conduction system is not working properly. Think of it as an electric grid that is giving off sparks!
What are the types of arrythmias?
There are many types of abnormal rhythms:
> Premature or extra heartbeats: this is the most common type. Usually, they don’t cause problems and can be left alone. Smoking and drinking coffee can cause them, but they may also be indicative of an underlying heart disease.
> Supraventricvular arrythmias: this means abnormal heart rhythms that originate from the atrium (supra = above). Some examples are atrial flutter and atrial fibrillation. As a result, your atria cannot pump blood effectively into your ventricles, and you may feel tired and dizzy because not enough blood is going into your brain. You may faint or have shortness of breath.
Sometimes, your atria may be beating at over 300 beats per minute!
> Ventricular arrhythmias: these originate from your ventricles and can be quite dangerous. Some examples are ventricular tachycardia and ventricular fibrillation.
Ventricular fibrillation is the most dangerous of them all and may cause death. This is the one that will require a defibrillator to your chest (where paddles are put on the patient’s chest and an electric shock is delivered to jump-start the heart).
Arrhythmias can be caused by any sort of heart disorder, such as coronary heart disease or anything that causes damage to the heart muscle. It may also be caused by things external to your heart, such as certain drugs (especially certain older high blood pressure medications) and chemical substances.
So what does a pacemaker do?
Pacemakers generate low-energy electric impulses. They can speed up or slow down an abnormal heart rate. If your atria are fluttering or fibrillating, pacemakers can make sure that at least your ventricles will contract normally by bypassing the weird signals generated from your atrium.
They can also coordinate the electrical signals between your atria and ventricles and between your two ventricles.
Pacemakers give you a good record of your heart’s activity. Some pacemakers also monitor your temperature, breathing rate and other factors, and adjust your heart rate accordingly to your daily activities, such as during exercise or rest.
Once I have a pacemaker, will I have to wear it forever?
Some pacemakers are temporary while others are permanent. Temporary pacemakers are used for arrhythmias that are temporary, such as a slow heart beat after a heart attack or heart surgery. They can also be used until a permanent pacemaker is put in place.
Permanent pacemakers are usually for patients with long-term bradycardia or heart block, where the fibres in your conduction system have been damaged.
Of course, if any arrhythmia is significantly interfering with your life and causing frequent fainting spells and such, the doctor will most probably recommend that you have a pacemaker.
Will wearing a pacemaker significantly disrupt my lifestyle?
You will have to avoid electrical devices or places that have strong magnetic fields. Cellphones, ipods, microwave ovens, high-tension wires and metal detectors may interfere with pacemakers. The manufacturer will have a list of what you can or cannot do and which equipment you must avoid.
Pacemaker batteries last between five and 15 years and should be replaced before they die out on you. Your doctor will monitor when they will need to be replaced.
Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health advice, computers and entertainment. For further information, e-mail starhealth@thestar.com.my.