Paroxysmal supraventricular tachycardia, or PSVT, is an abnormal, fast heartbeat that occurs suddenly. It is triggered in the atria, or upper chambers, of the heart.

What is going on in the body?

The heart has a built-in electrical system. Special pacemaker cells in the heart generate electrical impulses. These cells send electrical current down pathways in the heart muscle. When this occurs at the proper time, a normal heart rhythm is produced. When the electrical current starts in the wrong place or goes in the wrong direction at the wrong time, an abnormal heart rhythm, or arrhythmia, results. PSVT occurs when electrical current flows in a circle instead of a line. The result is a rapid heart rate, generally 160 to 180 beats per minute.

What are the causes and risks of the condition?

A faulty electrical pathway in the heart causes PSVT. It may be triggered by physical or psychological stress. The risks from PSVT are minimal for otherwise healthy people. Most people require very little, if any, medical intervention. PSVT may cause symptoms in older people with weak hearts or coronary artery disease. In some people, PSVT can cause congestive heart failure or a heart attack. Some people have regular episodes of PVST due to an abnormal development of the electrical pathways present at birth. An example of this is a condition called Wolff-Parkinson-White syndrome.