What are arrhythmias?
An arrhythmia is an abnormal rate and/or rhythm of the heartbeat. There are various types, and some are more serious than others. Some are intermittent and 'come and go', others are permanent unless treated.
The main types of arrhythmia include the following.
Supraventricular tachycardia (SVT)
In this arrhythmia the heartbeat is not controlled by the SA node (the normal timer of the heart). Another part of the heart overrides this timer with faster regular impulses. The source or 'trigger' of the impulse in an SVT is somewhere above ('supra') the ventricles. But, the impulse then spreads to the ventricles. The heart then contacts (beats) faster than normal, usually between 140 and 240 beats a minute. The heartbeat is regular. An episode of SVT may last just a few minutes, but can last several hours (sometimes even longer).
The time between episodes of SVT can vary greatly. In some cases, short bursts of SVT occur several times a day. At the other extreme, an episode of SVT may occur just once or twice a year. In most cases it is somewhere in between, and an episode ('paroxysm') of SVT occurs now and again.
Atrial fibrillation
In atrial fibrillation (AF) many random electrical impulses 'fire off' from different parts of the atria. The atria then 'fibrillate'. That means they only partially contract - but very rapidly (up to 400 beats per minute). Only some of these impulses pass through to the ventricles in a haphazard way. So, the ventricles contract between 160-180 beats a minute, but in an irregular way with varying force. If you feel your pulse you may count up to 180 beats per minute, the force of each beat can vary, and it feels erratic.
Once AF develops it is usually permanent. But, in some cases, episodes of AF come and go (paroxysmal AF). AF is common in older people, but it also affects some younger people. (See separate leaflet called 'Atrial Fibrillation' for more details.)
Ventricular tachycardia
This is an uncommon arrhythmia. In this condition the ventricles beat faster than normal (between 120 and 200 beats a minute). The rate in the atria is normal. So, there is a trigger of electrical impulses somewhere in the ventricles which overrides the normal impulses coming down from the atria.
Jean taylor, 12 months [Offensive? Unsuitable? Report this comment.]
Having always done plenty of exercise. I would like more advice on wether to continue all the walking swimming etc as normal?? Does it shorten your life?