Palpitations are an unusual awareness of our heart beating. There are of course times when it is normal for us to be aware of our heart beating-when we have had a sudden shock, are stressed or excited, or have just been exercising.
The heart is formed of 8 billion interconnected electrically excitable cells. It is not surprising that sometimes a group of cells in one part of the heart will fire prematurely. These simple premature beats are not serious themselves and can be felt as a missed beat or a “thud”. They can be a sign of underlying heart disease but usually are not.
This rhythm is becoming increasingly common as it occurs in people as they age. By the time we are 90 years old almost 1 in 3 people will be in atrial fibrillation. In atrial fibrillation the electrical activity in the atria is chaotic and the normal clock mechanism, the sinus node, can no longer work. It has two consequences –
- The heart speeds up and is irregular. This is because the disorganised electrical activity in the atria sends a much faster and irregular sequence of beats to the atrioventricular node-the junction box between the top chambers (atria) and bottom chambers (ventricles) of the heart. The fast heartbeats can be felt as palpitations, but as the heart is going too fast, it can gradually fail to cause shortness of breath. So most patients need medication to slow the heart rate.
- There is a risk of strokes in most people with atrial fibrillation. This is because the atria are not contracting in an organised way but are simply shimmering. Consequently, the blood flow in the atria and especially the left atrial appendage is very slow and clots can form. If these clots travel into the main pumping chamber of the heart, it will eject them into the circulation and the clots usually lodge in one of the brain arteries, causing a stroke. The strokes caused by atrial fibrillation tend to be very disabling, as the clots are relatively big compared to the size of the arteries supplying the brain. So most patients with atrial fibrillation have anticoagulants (blood thinners) to lessen the risk of a stroke.
Both DC cardioversion and ablation can restore a normal rhythm (Please see section on procedures).
Other Causes of Palpitations
Palpitations with a fast regular rhythm may come from either the top of the heart or the bottom of the heart. Usually, they originate in the top of the heart and are often best cured with ablation (please see section on procedures) although medication can help.
For all types of palpitations, the initial test is to connect the patient to an ambulatory ECG recording to get an electrical recording of the heart during the patient’s palpitations (please see section on tests).