When an arrhythmia is serious and not well-tolerated, there may not be enough blood flow from the heart to vital organs, such as the brain or kidneys or to the heart itself.

In such cases, treatment is urgent and may include electrical "shock" (defibrillation or cardioversion), the implantation of a temporary pacemaker to interrupt the arrhythmia by fast pacing (overdrive supression), or the administration of intravenous medications.

For long-term treatment of arrhythmias, daily medications may be necessary. These include antiarrhythmic medications, medications to speed up or slow down the heart rate, and others.

Over the past decade, life-threatening arrhythmias have been increasingly treated with an implantable cardioverter-defibrillator (ICD). As soon as an arrhythmia begins, the ICD can detect it and send an automatic electrical shock to terminate it, or it can activate a pacemaker function to overdrive the arrhythmia.

Some patients may be better candidates to have a procedure called radiofrequency catheter ablation. Radiofrequency catheter ablation can cure many paroxysmal supraventricular arrhythmias as well as some ventricular arrhythmias. This is performed at the time of EPS.

The outcome is dependent on several factors:

1. The kind of arrhythmia -- whether it is an atrial arrhythmia (originating from the atrium) or a more dangerous arrhythmia such as ventricular tachycardia or ventricular fibrillation, which are potentially fatal.
2. The ejection fraction of the heart, or the overall pumping ability of the heart. In other words, the percentage of blood that the heart pumps from the ventricles to the body with each beat.
3. A person's differing response to the same arrhythmia.

Unfortunately, certain arrhythmias can sometimes cause sudden death.

• Ischemia (the arteries supplying the heart itself are not getting enough blood), which may cause angina (chest pain)
• Heart attack
• Heart failure
• Stroke
• Sudden death

Call your health care provider if you develop symptoms indicating a possible arrhythmia.

Call your health care provider if an arrhythmia has been diagnosed and symptoms worsen or do not improve with treatment.