Paroxysmal Supraventricular Tachycardia

Key facts

• PSVT is a heart rhythm disorder in which episodes of very fast heartbeat, typically 150 to 250 beats per minute, start and stop abruptly.
• Most episodes last seconds to minutes, though some persist for hours; PSVT is rarely life-threatening but can cause dizziness, breathlessness, or brief fainting.
• Vagal manoeuvres such as the Valsalva technique can stop occasional episodes; recurrent or prolonged episodes are managed with antiarrhythmic medicine such as flecainide.
• Seek medical attention if an episode lasts more than 30 minutes, causes chest pain, or makes you feel faint.

What happens during an episode

PSVT occurs when an abnormal electrical circuit above the ventricles fires repeatedly, overriding the heart's normal pacemaker. The heart rate during an episode typically runs between 150 and 250 beats per minute. Most episodes last seconds to minutes, though some persist for hours. PSVT itself is rarely life-threatening, but the sudden pounding sensation in the chest or throat can be alarming and may cause dizziness, breathlessness, or brief fainting. Common triggers include caffeine, alcohol, physical exertion, stress, or stimulant medicines, though episodes can start for no obvious reason.

How PSVT is managed

For occasional or infrequent episodes, vagal manoeuvres such as the Valsalva technique (bearing down as if straining) can slow or stop an attack. For recurrent or prolonged episodes, antiarrhythmic medicines that work on the heart's conduction pathways are used. Flecainide is one such medicine: it acts on sodium channels to dampen the abnormal impulses that drive the fast rhythm. Ongoing management often sits within the broader care of heart and blood pressure conditions, and a cardiologist may also discuss procedures that can permanently interrupt the abnormal circuit for people with frequent episodes.

Reducing triggers

Cutting back on caffeine and alcohol, managing stress, and avoiding stimulant medicines where possible can reduce how often episodes occur. Keeping a record of what preceded an episode helps identify personal triggers over time.

When to see a doctor

If an episode lasts more than 30 minutes, causes chest pain, or leaves you feeling faint, seek medical attention promptly. Anyone having frequent episodes, or episodes that are becoming more intense, should also arrange a cardiology review to discuss longer-term treatment options.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.