Arrhythmia: A Patient Guide

Certain medications and substances can also cause an irregular heartbeat, including caffeine, tobacco, alcohol, cold and cough supressing medications, appetite suppressants, cocaine, psychotropic drugs (used to treat certain mental illnesses), antiarrhythmics, and beta blockers. Stress may also trigger an arrhythmia. Some of these arrhythmias can be dangerous, while others are not. Frequently, there is no obvious cause to an arrhythmia.

Types of arrhythmia

Doctors diagnose arrhythmias based on two factors: where it occurs in the heart – the atria or ventricles – and the effect it has on the heart's rhythm.

Atrial arrhythmias:

• Sinus tachycardia: The heart rate is increased because of fast conduction speed from the sinus node.
• Sick sinus syndrome: The heart rate is decreased because of improper signals from the sinus node. Occasionally the heart rate fluctuates between a rapid and slow heart rate (if this occurs, the condition is referred to as tachycardia-bradycardia syndrome).
• Atrial flutter: Electrical signals originate in the atria and are fired quickly, usually resulting in a regular and fast heart rate.
• Atrial fibrillation: The atria fire rapid and sporadic signals to the ventricles resulting in an irregular heartbeat.
• Sinus arrhythmia: The heart rate changes consistently with breathing.
• Premature supraventricular or atrial contractions (PACs): The atria generate an early heartbeat preceding the next regular heartbeat.
• Supraventricular tachycardia (SVT): The heart rate is increased after a succession of continual beats in the atria.
• Paroxysmal atrial tachycardia (PAT): Periodic and frequently unpredicatable intervals of rapid heartbeats initiated by atrial-generated impulses.
• Wolff-Parkinson-White syndrome: Electrical signals arrive to the ventricles via an "accessory pathway" from the atria (e.g., the signal bypasses the atrioventricular node), creating a potentially dangerous situation whereby the heart rate can become excessively rapid.

Ventricular arrhythmias:

Ventricular arrhythmias are usually more serious than atrial arrhythmias and include the following: