Tachycardia

Types

Tachycardias may be supraventricular or ventricular.

Normal heart rhythm and supraventricular tachycardia comparison

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Supraventricular Tachycardias (SVTs)

These rapid heartbeats originate in the heart's upper chambers (the atria) and interfere with the efficient flow of blood into the ventricles. Paroxysmal supraventricular tachycardia (PSVT), an occasional or intermittent rapid heart rate, may occur with any SVTs.

The most common SVTs are:

• Atrial fibrillation — In atrial fibrillation, the electrical signals in the upper chambers of the heart are disorganized and fail to flow rhythmically through the heart muscle.
• Atrial flutter — Atrial flutter is an abnormal conduction path within an upper chamber of the heart that causes too many heartbeat signals.
• Atrioventricular nodal re-entrant tachycardia (AVNRT) — In AV nodal re-entrant tachycardia, an extra connection exists in or near the AV node, which causes a fast heart rhythm.
• Atrioventricular tachycardia (AVRT) — An extra electrical pathway in the heart that can result in a rapid heart rhythm. Wolff-Parkinson-White syndrome is a specific type of AVRT.
• Sinus tachycardia — The sinus node (the heart's natural pacemaker) sends electrical signals at a rate greater than 100 beats per minute. Depending on the setting, this rate may be inappropriately high.

Ventricular Tachycardias

These fast heart rhythms begin in the heart's lower chambers (ventricles). A ventricular tachycardia is usually a medical emergency. Although some ventricular tachycardias can effectively pump blood and maintain blood pressure, prolonged episodes can lead to ventricular fibrillation, a quivering of the heart that leads to cardiac arrest (heart attack) and death if not treated immediately.

These abnormalities often occur in people with structural heart problems, such as:

• A scar from a previous heart attack
• Rare inherited heart defects
• Other causes