Supraventricular Tachycardia (SVT) is a relatively common heart rhythm problem where the heart suddenly starts beating very fast, often between 150 and 250 beats per minute. Unlike normal exercise-related increases in heart rate, SVT episodes occur due to an electrical disturbance in the heart’s upper chambers (the atria) or the atrioventricular (AV) node.
SVT is generally not life-threatening in otherwise healthy individuals, but frequent or prolonged episodes can significantly impact quality of life and sometimes cause complications. For patients with underlying heart disease, SVT can pose additional risks.
The hallmark of diagnosis is a sudden, rapid heartbeat that starts and stops abruptly. Episodes can last seconds, minutes, or even hours.
Palpitations – awareness of rapid or pounding heartbeats.
Dizziness or lightheadedness – due to reduced blood flow to the brain.
Shortness of breath – especially during prolonged episodes.
Chest discomfort or pressure – sometimes mistaken for angina.
Fatigue or weakness – after an episode.
Anxiety or a sense of impending doom – common during fast heart rhythms.
Fainting (syncope) – rare but possible if blood pressure drops suddenly.
Sweating or trembling – related to adrenaline release.
Exercise intolerance – inability to sustain activity due to rhythm disturbance.
You should seek urgent medical attention if:
You experience chest pain, fainting, or severe shortness of breath during an SVT episode.
Your heart rate stays above 150 bpm for more than 20–30 minutes without slowing down.
You have a history of structural heart disease and experience sudden palpitations.
You are pregnant and experience frequent or prolonged SVT episodes.
You should book a routine cardiology appointment if:
You have recurring episodes of fast heartbeat.
Palpitations interfere with work, exercise, or daily life.
You are unsure whether your symptoms are due to SVT or another heart condition.
Diagnosing SVT requires capturing the abnormal rhythm while it happens.
A standard ECG records the heart’s electrical activity.
If done during an episode, it usually confirms SVT.
Portable devices worn for 24 hours to weeks.
Capture heart rhythm during daily activities.
A small device implanted under the skin for long-term rhythm monitoring.
Useful for patients with infrequent but severe symptoms.
A specialised test performed by cardiologists.
Involves inserting thin wires into the heart via veins to map electrical signals.
Often used when catheter ablation is being considered.
Treatment depends on symptom severity, frequency of episodes, and underlying heart health.
These are physical techniques that stimulate the vagus nerve to slow heart rate:
Valsalva manoeuvre – holding breath and straining.
Coughing forcefully.
Splashing face with cold water or applying a cold pack.
Carotid sinus massage (only performed by trained professionals).
Beta-blockers (e.g., metoprolol, propranolol).
Calcium channel blockers (e.g., verapamil, diltiazem).
Antiarrhythmic drugs (e.g., flecainide, propafenone, amiodarone – used selectively).
Adenosine (IV in hospital) – often stops acute SVT within seconds.
Identify triggers – caffeine, alcohol, stress, dehydration, lack of sleep, or certain medications can provoke episodes.
Regular exercise – light to moderate activity improves cardiovascular health, though intense exertion may need caution.
Stress management – yoga, mindfulness, or breathing techniques can help.
Medication adherence – take prescribed medicines consistently.
Medical alert bracelet – useful for patients with recurrent or severe SVT.
Pregnancy and SVT – many women notice more frequent episodes; specialist advice is essential.
While SVT is usually not life-threatening, it can disrupt daily life. Practical strategies include:
Identify triggers – caffeine, alcohol, stress, dehydration, lack of sleep, or certain medications can provoke episodes.
Regular exercise – light to moderate activity improves cardiovascular health, though intense exertion may need caution.
Stress management – yoga, mindfulness, or breathing techniques can help.
Medication adherence – take prescribed medicines consistently.
Medical alert bracelet – useful for patients with recurrent or severe SVT.
Pregnancy and SVT – many women notice more frequent episodes; specialist advice is essential.
Benign in most cases – people with structurally normal hearts usually live a normal lifespan.
Recurrence is common – even after successful treatment, episodes may return.
Catheter ablation offers cure – many patients are free from SVT after the procedure.
Complications are rare – but include fainting, heart failure (if sustained SVT is untreated), or in very rare cases, sudden cardiac arrest in high-risk groups.
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