The electrical signal travels across the upper chambers of the heart (the atria), passes into the electrical bridge between the upper and lower chambers (the atrioventricular node) and then on into the lower chambers (ventricles). This passage of electricity throughout the heart muscle culminates in a coordinated contraction of the heart muscle, which results in an effective pumping action. A normal heart contracts over 100,000 times a day at a heart rate usually less than 100 beats per minute. Heart rate changes due to physical activity, diet, age and medication are normal.
An arrhythmia is the medical term for any type of heart rhythm problem, there are many and they can be quite varied in terms of symptoms and effects. These problems can be benign (not so serious but may still require treatment), or in some cases serious or even life-threatening.
Heart rhythm problems can be caused by extra beats (ectopics), a sustained increased heart rate (tachycardia) and also a slow heart rate (bradycardia). The terms ‘tachy’ and ‘brady’ are derived from Greek words meaning ‘swift’ and ‘slow’. So a heart rhythm problem with a fast heart rate may be known as a tachyarrhythmia, while a slow heart rate is called a bradyarrhythmia.
An abnormally fast heart rhythm, or tachycardia, can prove dangerous as it can interfere with the heart’s ability to pump properly. Over a period of time a heart’s function may deteriorate, with either frequent ectopic beats or an abnormal heart rhythm. This is a condition known as tachycardia cardiomyopathy (TCM).
There are a number of different rhythm conditions that can cause a sustained tachycardia; here are some common ones: