Each heart has its own normal rhythm brought about by the flow of electrical impulses from the hearts natural pacemaker (sinus node). The electrical signal travels across the upper chambers (atria) passes into the electrical bridge between the upper and lower chambers (atrioventricular node) and passes into the lower chambers (ventricles). This passage of electricity throughout the heart muscle culminates in a coordinated contraction of the heart muscle resulting in an effective pumping action. A normal heart contracts over 100,000 times a day at a heart rate usually less than 100 beats a 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, of which there are many and varied. These problems can be benign (not so serious but may still require treatment) and in some cases serious, even life threatening. They can be caused by extra beats (ectopics), a sustained increased heart rate (tachycardia) and also a slow heart rate (bradycardia). Therefore a heart rhythm problem with a fast heart rate may be known as a tachyarrhythmia and a slow heart rate a bradyarrhythmia.
An abnormally fast heart rhythm, or tachycardia can prove dangerous as it can interfere with the hearts ability to pump properly. Over a period of time a hearts function may deteriorate with either frequent ectopic beats or an abnormal heart rhythm. A condition known as tachycardia cardiomyopathy (TCM).
There a number of different rhythm conditions that can cause a sustained tachycardia, some are listed below .
Atrial fibrillation (AF or AFib)
Supraventricular tachycardia (SVT)
Ventricular tachycardia (VT)
For more information read this article from the Irish Medical Times – authored by Dr Lyne