Supraventricular Tachycardia Types Explained: AVNRT, AVRT, Atrial Tachycardia & More

When your heart suddenly rockets, you’ve likely experienced supraventricular tachycardia. Supraventricular Tachycardia is a fast heart rhythm that starts above the ventricles, usually between 150 and 250 beats per minute. It’s not a disease itself but a symptom of abnormal electrical pathways in the heart. Understanding the different sub‑types helps you recognize triggers, know what to expect from a doctor, and choose the right treatment.

Key Takeaways

• SVT covers several distinct rhythm disorders, each with its own trigger and treatment.
• AVNRT and AVRT are the two most common types, accounting for about 80% of episodes.
• Diagnosis relies on an electrocardiogram (ECG) and sometimes an electrophysiology study.
• Acute management can be as simple as a Valsalva maneuver, while chronic control may involve medication or catheter ablation.
• Lifestyle tweaks-stress control, caffeine reduction, adequate sleep-can cut down episodes for many patients.

What Is Supraventricular Tachycardia?

SVT is a blanket term for any rapid heartbeat that originates in the atria or the atrioventricular (AV) node, rather than the ventricles. The heart’s normal pace sits between 60 and 100 beats per minute. When an SVT episode kicks in, the rate jumps, often making you feel light‑headed, palpitations, chest discomfort, or shortness of breath.

Clinically, SVT is classified by the pathway that creates the fast rhythm. Understanding those pathways is key to proper treatment.

Main Types of SVT

Below are the six most commonly encountered SVT sub‑types. They differ in where the electrical circuit loops and how they respond to maneuvers or medication.

1. Atrioventricular Nodal Re‑entry Tachycardia (AVNRT)

AVNRT is the heavyweight champion of SVT, responsible for roughly 60% of cases. It uses two pathways within the AV node-a fast pathway that conducts quickly but recovers slowly, and a slow pathway that conducts slowly but recovers fast. When a premature heartbeat hits, the fast lane pauses while the slow lane keeps going, creating a re‑entry loop.

Typical ECG shows a narrow QRS complex and a short RP interval. Vagal maneuvers like the Valsalva often terminate the episode.

2. Atrioventricular Re‑entry Tachycardia (AVRT)

AVRT relies on an accessory pathway that bypasses the AV node. The most famous form is linked to Wolff‑Parkinson‑White Syndrome (WPW). In WPW, an extra bundle (the Bundle of Kent) lets impulses travel from the atria to the ventricles instantly, and then back up the AV node, forming a circuit.

ECG shows a short PR interval and a delta wave-those slurred up‑strokes on the QRS.

3. Atrial Tachycardia (AT)

Atrial Tachycardia originates from a single ectopic focus in the atria, not from the AV node. It’s less common but can be persistent. The heart rate often sits around 150‑200 bpm, and the ECG reveals P‑waves that look abnormal or occur earlier than expected.

4. Multifocal Atrial Tachycardia (MAT)

MAT features at least three different P‑wave morphologies, indicating several ectopic atrial foci firing. It’s usually seen in older patients with lung disease or electrolyte imbalances.

5. Orthodromic AVRT (Typical WPW)

When the impulse travels down the normal AV node and returns via the accessory pathway, the circuit is called orthodromic AVRT. The QRS stays narrow, making it look like AVNRT, but the presence of a delta wave on a baseline ECG clues you in.

6. Antidromic AVRT (Rare WPW Variant)

In antidromic AVRT, the impulse goes down the accessory pathway and back up through the AV node, producing a wide QRS complex that can mimic ventricular tachycardia.

How Doctors Diagnose SVT

Diagnosis starts with a careful history: onset, triggers, duration, associated symptoms. Physical exam may reveal a rapid pulse that can be felt at the wrist.

Key tools include:

• Electrocardiogram (ECG): Captures the rhythm, QRS width, PR interval, and any delta waves.
• Holter monitor or event recorder: Records heart rhythm over 24‑48hours or longer, catching intermittent episodes.
• Electrophysiology (EP) study: An invasive test where catheters map electrical pathways, pinpointing the exact SVT type.

Blood tests may be ordered to rule out thyroid disease, electrolyte disturbances, or drug effects that could provoke SVT.

Management and Treatment Options

Therapy follows a stepped approach-first try simple maneuvers, then medication, and finally procedural options if episodes are frequent or dangerous.

Acute Termination

• Vagal maneuvers: Valsalva, carotid sinus massage (only by a professional), or a cold‑water facial immersion.
• Rapid‑acting adenosine: A short IV push that briefly blocks AV node conduction, stopping AVNRT and orthodromic AVRT.

Long‑Term Control

• Beta‑blockers (e.g., metoprolol) - slow AV node conduction.
• Calcium‑channel blockers (e.g., diltiazem) - similar effect, useful if asthma limits beta‑blockers.
• Anti‑arrhythmic drugs such as flecainide or propafenone - especially for WPW patients without structural heart disease.

Catheter Ablation

Catheter ablation is a minimally invasive procedure that destroys the tissue responsible for the re‑entry circuit. For AVNRT, success rates exceed 95% with a low complication risk. WPW ablation targets the accessory pathway and can cure the condition permanently.

Recovery is quick-most patients return to normal activities within a week.

When to Seek Emergency Care

• Chest pain, fainting, or severe shortness of breath.
• SVT lasting longer than 24hours.
• History of heart disease or a known WPW pattern.

Living With SVT: Tips and Lifestyle

Even without medication, many people keep episodes at bay by tweaking daily habits.

• Limit caffeine and energy drinks-these can lower the threshold for triggers.
• Stay hydrated; dehydration can provoke arrhythmias.
• Practice stress‑reduction techniques-deep breathing, yoga, or meditation.
• Maintain a regular sleep schedule; sleep deprivation raises sympathetic tone.
• Track episodes with a smartwatch or app to identify personal triggers.

Regular follow‑ups with a cardiologist or electrophysiologist ensure that any change in pattern is evaluated promptly.

Comparison of Common SVT Types

Frequently Asked Questions