Our hearts beat approximately 100,000 times every day of our lives, yet most of us are completely unaware of this life-giving energy. Sometimes, however, we can become aware of the heart beat. People frequently find this sensation very difficult to describe, but often use the word ‘palpitations’. The vast majority of palpitations are simply an awareness of a normal heart beat or of mild and unconcerning variations, but, rarely, the heart goes into an abnormal rhythm, which may require treatment.
It is helpful to understand some basic aspects of how the heart rhythm works to explain some of the different types of palpitation. The heart is made up of millions of individual cells. Each cell has an alternating electrical charge and, left to its own devices, would contract regularly at its own rate. However, because all cells are joined together, if one cell contracts, then the electrical signal will spread to all the neighbouring cells, resulting in a wave of contraction spreading through the whole heart. The heart beat is normally initiated in the sinus node, in the top right hand side of the heart, and sets a regular ‘sinus rhythm’, which is usually between 60 and 90 beats per minute.
Many different factors will affect the heart rate. Relaxation and high levels of fitness may drop the heart rate below 60 beats per minute, which is usually not a cause for concern. Exercise, stress, anxiety and fear will increase the heart rate. If the heart rate is above 100 beats per minute it is termed a ‘tachycardia’, and, as long as the normal pattern of electrical conduction continues, this is ‘sinus tachycardia’, which is normal. Many people who experience palpitations are simply aware of normal sinus tachycardia, and the anxiety caused by these symptoms may make them worse. Once sinus tachycardia is confirmed no treatment is usually required and reassurance.
One of the commonest causes of palpitations is 'ectopics'. Ectopic beats are normal, and happen to us all, and they become more frequent as we get older. There is a huge variation in the frequency of ectopic beats. Some people may have only a handful in a day. Others may have many thousands. Most people are blissfully unaware of them, but, once you become aware of them, they can be very intrusive and worrying. The more you worry and think about them, the more you will be aware of them, and anxiety may actually make them happen more frequently. Treatment is very rarely required, and reassurance and an understanding of what they are is often all that is required to allow the awareness of ectopic beats to fade away over a period of time.
As noted above, a normal heart beat is initiated from the sinus node. An ectopic beat is simply one which was started by a cell other than the sinus node. Thus the flow of electricity and contraction through the heart occurs in just the same way as with a normal heart beat, it just starts from a different place, and thus travels in a different direction, and so appears different on an ECG.
The reason for the symptoms is that the ectopic beat starts earlier than the expected sinus beat. After the ectopic beat there is usually a pause, while the normal heart beat is resumed. Because the ectopic beat is early, the heart has not had time to fill up properly, so the ectopic beat often produces a weaker pulse than usual. However, because of the extra pause before the next beat, the heart has longer to fill, so produces a more forceful beat. Some people feel the weak early beat, some people feel a pause or ‘missed beat’, some experience a forceful beat or a ‘thump’, and some people feel both. Sometimes people experience runs of multiple extra beats or thumps in a row. Occasionally this can be associated with momentary lightheadedness. In the absence of any other symptoms these palpitations are normal, do not pose any risk, are not a cause for concern, and do not require investigation.