Causes
There are two basic ways you can develop arrhythmias:
- Problems with initiating the electrical signal - either the sinus node fires abnormally, or there is a competing impulse elsewhere in the heart
- Problems with the conduction of the electrical impulse - connections from the atria to ventricles are hindered; this is often termed a heart block.
People with heart disease are particularly likely to develop arrhythmias, since damage to the heart can stop the beat signal from reaching the ventricles, or cause certain areas of the heart fire abnormally. High blood pressure and an overactive thyroid gland also increase the chances of arrhythmias. Alcohol can cause atrial arrhythmias as well. There are also inherited and congenital (present since birth) types of arrhythmia, often resulting in a weak or late signal getting to the ventricles. The ventricles can emit their own signal, but often at fewer than 40 beats a minute instead of the usual 60 to 100 with the sinus node.