Types and Causes of Arrhythmias
There are several types of arrhythmias that can be divided into different categories. The categories are classified depending upon in which part of the heart the arrhythmia originates. Among these categories are tachycardias and bradycardias.
Tachycardia is where the heart beats very quickly – more that 100 beats per minute.
Bradycardia is where the heart beats very slowly – less than 60 beats per minute.
The categories of arrhythmias are:
- Supraventricular Arrhythmias
- Ventricular Arrhythmias
- Bradycardia Arrhythmias
Supraventricular Arrhythmias
These arrhythmias start in either the atria or the AV node and are tachycardias. They include atrial fibrillation (AF), atrial flutter, and paroxysmal supraventricular tachycardia (PSVT), and premature atrial contractions (PACs).
Atrial Fibrillation (AF)
AF is when the atria contract very quickly yet irregularly. It can last for minutes or weeks, or it can become a chronic conditions. AF can lead to stroke and heart failure. Of the serious arrhythmias, it is the most common.
Causes
AF can be caused by cardiovascular diseases such as high blood pressure, heart failure, congenital heart disease, and cardiomyopathy.
Atrial Flutter
Atrial flutter is similar to AF because the atria contract very quickly. However, in atrial flutter, the contractions are regular beats, as opposed to the irregular ones in AF. Atrial flutter can also lead to stroke or heart failure.
Causes
Atrial flutter can occur spontaneously, but it most often occurs in people with cardiovascular disease.
Paroxysmal Supraventricular Tachycardia (PVST)
PVST is a sudden start and stop of very fast heart beating. It normally occurs in younger people and can happen during exercise. It is not often dangerous.
Causes
PVST is caused by a complication of the electrical connection that is between the atria and the ventricles (electrical signals that normally move from the atria to the ventricle go back into the atria, which causes more heartbeats).
Premature Atrial Contractions (PACs)
PACs are just extra beats that occur in the atria. They are a very common type of arrhythmia, but they are most often not dangerous.
Causes
Although PACs can occur from heart disease, it is uncommon. They normally arise from natural causes or from too much stress, caffeine, nicotine, or exercise.
Ventricular Arrhythmias
These arrhythmias start in the ventricles and include ventricular fibrillation (VF), ventricular tachycardia (VT), and premature ventricular contractions (PVCs).
Ventricular Fibrillation (VF)
VF is when the ventricles do not contract normally. Instead, they shake and do not pump blood out of the heart. If this happens for more than a few seconds, blood will stop circulating, and death will occur very shortly thereafter.
Causes
VF occurs most often in individuals with cardiovascular disease, as well as those with electrolyte disorders and others who have overdosed on cardiotoxic drugs. VF can also occur without any apparent cause.
Ventricular Tachycardia (VT)
VT consists of very fast, regular heartbeats in the ventricles. If this lasts longer than a few seconds, it can be dangerous because it can lead to VF.
Causes
VT can be caused by problems with the electrical circuitry in the ventricle (due to damaged VT muscle or scar tissue from a previous heart attack). It may occasionally occur in a normal heart. All patients with this type of rhythm disorder should be evaluated by a doctor with expertise in rhythms (a cardiologist of preferable a cardiac electrophysiologist) because it is potentially life-threatening.
Premature Ventricular Contractions (PVCs)
PVCs are extra beats that occur in the ventricles. They are a very common type of arrhythmia, but they are most often not dangerous.
Causes
Although PVCs can occur from heart disease, it is uncommon. They normally arise from natural causes or from too much stress, caffeine, nicotine, or exercise.
Brachycardia Arrhythmias
These are arrhythmias in which the heart is beating too slowly (less than 60 beats per minute). Athletes tend to have slower heart rates. These slower heart rates are not dangerous. In the case of individuals with bradycardia, if their heart rate becomes too slow, not enough blood will circulate, and they may lose consciousness.
Causes
Bradycardia arrhythmias can be caused by coronary artery disease, anything harming the electrical system of the heart (including age), beta-blocker medicines, and a disproportion of chemicals in the blood.