Your heart sees to it that blood is circulated around your body. At rest, the heart does so at 60 to 100 beats a minute. If you are exerting yourself, this causes your heart rate to go up in order to cater for the greater need for oxygen. When your heart is beating too fast, too slow or irregularly, this is referred to as a heart rhythm disorder.
Our heart is driven by an electrical impulse that is produced in the right atrium, in the so-called sinus node. This sinus node – also referred to as the heart’s pacemaker – is what regulates your heart rate. Whereas your heart rate may vary, it is best if your heart rhythm remains regular all day long.
Roughly speaking, heart rhythm disorders can be broken down into three groups:
- heart rate too high (tachycardia)
- heart rate too low (bradycardia)
- irregular heart rate
While some of these heart rhythm disorders are innocent and do little more than cause some minor discomfort, others are life-threatening.
What are the symptoms of heart rhythm disorders?
Heart rhythm disorders can present themselves through a wide range of different symptoms, including palpitations, dizzy spells, persistent fatigue or tightness of the chest. By the same token however, heart rhythm disorders can go unnoticed for a long time, getting picked up by sheer fluke as part of a routine examination.
Heart rate too high (tachycardia)
You may have felt your heart pulsating on occasion as though it was about to pop out of your chest right there and then. In a lot of cases, there is a perfectly normal explanation. You’ve just been doing some exercise, you’re getting stressed out about something or you’ve just finished your tenth cup of coffee. In those situations, that pulsating feeling you are getting is short-lived. It soon passes without any need for you to get worked up about it. Only, in the latter case, it may be an idea to cut down on your coffee intake.
Ever wondered what your maximum heart rate is?
As a general rule, you can estimate that maximum rate going by the following formula: 220 – age.1 So if you’re aged 55, you’d better make sure your heart rate doesn’t go above 165 beats per minute (220 – 55) very often.
If your heart rhythm at rest is more than 110 beats per minute, you are suffering from tachycardia. In extreme cases, this means your heart is beating that fast it is no longer capable of efficiently pumping oxygenated blood around your body.
Different types of tachycardia
The condition of tachycardia can be broken down further:
- according to the regularity of your heart rate
- according to the location where the rhythm disorder originates
If your heart rate exceeds 110 beats per minute this is referred to as sinus tachycardia. This is not considered as a real heart rhythm disorder, but more as a normal body response to physical exertion, anxiety or fever. Sinus tachycardia starts and recedes gradually, with your heart rhythm remaining regular throughout.
However, there is also something known as IST (Inappropriate Sinus Tachycardia). This is quite a rare heart rhythm disorder whereby the heart rate consistently exceeds 110 beats per minute. This condition is mainly seen in young women.2
Like sinus tachycardia, in the case of atrial tachycardia your heart rate goes up to more than 110 beats per minute. Only, in this case, this is not a gradual but a very sudden event, whereby your heart rate suddenly skyrockets before plummeting again shortly afterwards.
Atrial tachycardia is caused by fast electrical excitations inside the atria of your heart. Atrial tachycardia may last just a few seconds but it can just as easily go on for a couple of hours. It is chiefly seen among younger members of the population. And even though this heart rhythm disorder is not life-threatening, atrial tachycardia may cause complaints that impact on our everyday activities.
In the case of ventricular tachycardia, you experience an abnormally fast rhythm of more than 120 beats per minute, originating in one of the heart’s chambers (a.k.a ventricles). If this goes on for too long, ventricular tachycardia can be life-threatening.
Because of the fast contraction of the heart’s chambers, there is not enough time for the heart to fill the chambers with blood. As a result, the blood is not properly circulated, which may cause oxygen deficiency, which in turn leads to dizziness and loss of consciousness.
If ventricular tachycardia is not promptly treated, this may result in ventricular fibrillation (see below). It is usually seen in persons with pre-existing heart disease.
In case of an atrial flutter hundreds of minor electrical impulses excite the atria. Only half of these are conducted onwards via the AV node or atrioventricular node (which is the electrical connection between the atria and the ventricles) to the chambers, which in turn results in an average heart rate of 140 to 150 beats per minute. To all intents and purposes, it looks very much like atrial fibrillation (see below).
Heart rate too low (bradycardia)
If you’re an athlete who runs a marathon before breakfast every Saturday, your heart rate at rest will be very low. However, you do need to be careful as endurance sports too come with their own risks. If you prefer to start your weekend a little more relaxed with a nice cup of coffee and your newspaper but you also happen to have a heart rate of less than 40 bpm, you may well have bradycardia.
In serious cases of bradycardia, your heart ends up beating so slowly that it struggles to pump oxygenated blood around your body. This causes serious health issues, as your organs need oxygen to function properly.
Causes of bradycardia
Even though bradycardia may sometimes present itself without a clear cause, this does not hold true for most cases. Some of the most common causes of bradycardia include:3
- Malfunctioning sinus node
- Problems with the conduction system of your heart preventing the electrical impulses from being properly transmitted
- Problems with your metabolism (e.g. underactive thyroid)
- Damage to the heart after heart disease or a heart attack
- Medication that slows down the heart rate
Irregular heart rate
Alongside heart rhythm disorders to do with an unduly fast or slow heart rate, there is also a third group where an irregular heart rate is the common denominator.
Atrial fibrillation (AF) is a heart rhythm disorder characterised by an irregular and often rapid heart rate. In the case of AF, the electrical system of the heart has gone haywire. Normally, it is the sinus node that fires off electrical impulses at a regular pace. In AF patients, these electrical impulses also occur at different places inside the heart, which produces a chaotic jumble of electrical impulses.
Because of this chaotic electrical activity, the atria fail to vigorously contract but vibrate (or fibrillate) up to 400 times per minute. Only part of these impulses are transmitted to the ventricles, which means your heart rate can go up to 150-200 (irregular) beats per minute at rest.
Ventricular fibrillation is a very serious heart rhythm disorder that causes cardiac arrest. Same as with atrial fibrillation, we see a lot of abnormal electrical impulses, which cause the ventricles to start vibrating instead of pumping blood around the body. As a direct result, the blood no longer reaches the vital organs.
One major difference with AF is that ventricular fibrillation does not just end of itself. Ventricular fibrillation results in loss of consciousness in a matter of seconds. If no resuscitation is undertaken, this leads to death.
How do you identify a heart rhythm disorder?
A lot of people are not even aware they have a heart rhythm disorder because they do not have any symptoms. In the case of atrial fibrillation for instance, this percentage is in the region of 40%.4
If you prefer to have some certainty, there is the medically certified FibriCheck app. Monitoring your heart rhythm and heart rate for as little as a minute at a time just two or three times a day using your smartphone and/or smartwatch (Fitbit and Samsung Galaxy Watch), not only sees you putting your own mind at rest, you are also collecting a lot of useful data which are immediately actionable by your doctor.
You can check your heart rhythm and your heart rate at any time of day, 24/7. What if the app does detect abnormal cardiac activity? Within 48 hours, you get a personal review (*) of the measurement results by our medical experts.
(*) Personal reviews by our medical experts are included in our free 24-hour trial and our Premium plan.
- Dr. Sanjay Gupta. York Cardiology. Consulted on https://www.youtube.com/watch?v=88fUnRO44m4.
- Cedars Sinai. Inappropriate Sinus Tachycardia. Consulted on https://www.cedars-sinai.org/health-library/diseases-and-conditions/i/inappropriate-sinus-tachycardia.html/
- American Heart Association. Bradycardia: Slow Heart Rate. Consulted on https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/bradycardia–slow-heart-rate
- Xiong Q. et al. Asymptomatic versus symptomatic atrial fibrillation: A systematic review of age/gender differences and cardiovascular outcomes, 2015, doi: 10.1016/j.ijcard.2015.05.011.