Paroxysmal supraventricular tachycardia (PSVT) is an abnormally fast heart beat, that begins and ends suddenly. While the normal resting heart rate is approximately 60-100 beats per minute, a PVST attack may cause a heart rate as fast as 160-280 beats per minute. People with PVST have attacks of tachycardia that can last anywhere from a few minutes to several hours. The abnormal heart rate originates in heart tissue other than the ventricles or lower chambers of the heart

Although PVST is not usually life-threatening, it can cause symptoms including palpitations or feeling of heart racing, light-headedness, chest discomfort, and rarely loss of consciousness. Frequent and prolonged episodes, if not treated, can cause weakening of the heart muscle. This can result in an inability of the heart to pump effectively. This may limit a person’s physical activity. If you suspect you have this condition, contact your doctor to discuss diagnosis and treatment options.

Anatomy of the Heart
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In a normal heart, electrical impulses from the heart’s natural pacemaker, the sinoatrial or SA-node, prompt the heart to pump blood throughout the body. PVST is the result of a “short circuit” in the electrical system of the heart. Normally there is only one electrical pathway between the upper chambers of the heart (the atria) and the bottom chambers (the ventricles). This connection is called the atrioventricular or AV-node. In some cases, the AV-node has two pathways which can conduct impulses, a slow pathway and a fast pathway. This creates a situation in which a feedback loop can occur called re-entry. Other patients have an abnormal, additional connection between the atria and ventricles called an accessory pathway leading to PSVT. Still others have an irritable group of cells in the atria that drives the tachycardia.