Supraventricular Tachycardia (SVT, PSVT) Symptoms, Causes, and Treatments
What is Supraventricular Tachycardia (SVT, PSVT Definitions)?
Supraventricular tachycardia is a rapid heart rate (tachycardia, or a heart rate above 100 beats per minute) that is caused by electrical impulses that originate above the heart's ventricles. Many doctors and other health care professional include all of the many tachycardias that involve the atrioventricular node (AV node) under this classification, but others do not.
Supraventricular tachycardia does not include those tachycardia rhythms that originate from the ventricles (ventricular tachycardias) such as ventricular tachycardia or ventricular fibrillation.
Supraventricular tachycardia is also called paroxysmal supraventricular tachycardia and abbreviated either SVT or PSVT.
How does the heart's normal electrical activity work?
- The heart consists of four chambers; two upper chambers called atria and two lower chambers called ventricles.
- The atria receive blood from blood vessels and, with coordinated electrical impulses from the sinoatrial (SA) node, contract to push blood into the ventricles.
- The ventricles then contract to push the blood out of the heart into the blood vessels of the lungs and to the rest of the body.
- The heart usually beats 60-90 times a minute. A heart rate faster than 100 beats per minute is considered tachycardia.
- Specialized heart cells coordinate the contractions by means of electrical signals.
- These specialized cells consist of the SA or sinus node in the right atrium, the AV node and the bundle of His (atrioventricular bundle) in the wall between the right and left ventricles.
- The SA node, the natural pacemaker of the heart, starts the electrical signals and transmits them to the AV node.
- The AV node then activates the bundle of His and its branches, resulting in contraction of the ventricles.
- The atria contract to fill the ventricles with blood; then the ventricles contract in quick sequence to move the blood into the lungs and the rest of the body. Each sequence of atrial then ventricular contraction is one normal heartbeat.
- SA node and AV node and the path of the electrical impulse into the ventricles through the bundle and to the right and left ventricle nerve bundles (RB and LB) to complete a heartbeat.
- Nerve impulses, oxygen demand, the level of hormones in the blood, and other factors influence the rate of heart contraction at any given time. A problem in any of these areas can cause abnormal heart rhythm (arrhythmia or dysrhythmia).
Picture of the Heart's Normal Electrical Activity
Who Gets This Heart Condition?
Supraventricular tachycardia can be found in healthy young children, in adolescents, and in some people with underlying heart disease
. Most people who experience it live a normal life without restrictions.
Medically Reviewed by a Doctor on 9/11/2017
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