Narrow Complex Tachycardia

Narrow complex tachycardia is an abnormal and fast heart rhythm (arrhythmia). When you have it, your heart beats faster than 100 beats per minute (tachycardia). It’s called narrow complex because the lower chambers of your heart beat in the normal way. This normal contraction produces a “narrow” QRS on an electrocardiogram (EKG/ECG). That’s the "narrow complex" part of the name.

These kinds of arrhythmias can be benign and short-lived, leading to minor palpitations or fluttering heart sensations. They can also be serious, causing chest pain and shortness of breath. Some can lead to a heart attack, stroke or cardiac arrest. Treatments range from physical maneuvers or medications to procedures you have in a hospital.

Types of this condition

Most types of narrow complex tachycardia are supraventricular tachycardias (SVTs). This means that the top chambers of your heart, called the atria, generally cause these.

Types of narrow complex tachycardia include:

• Atrial fibrillation (AFib): SVT with a fast, chaotic rhythm
• Atrial flutter: SVT with a fast but consistent pattern and signals going around in circles in the atria
• Atrial tachycardia: SVT with a fast rhythm affecting one or more places in your heart
• Sinus tachycardia: Fast heart rate due to natural causes
• Atrioventricular nodal reentrant tachycardia (AVNRT): SVT with heartbeat signals going around in circles within the AV node
• Premature atrial complexes: Extra heartbeats that sometimes can cause SVT

Symptoms of narrow complex tachycardia

Symptoms may include:

• Chest pain
• Heart palpitations
• Tiredness
• Lightheadedness
• Dizziness
• Shortness of breath
• Fainting

Narrow complex tachycardia causes

A problem with the electrical activity in your heart causes this condition. There could be an issue with when heartbeat signals happen or where they go. These problems may include:

• Electrical signal reenters a circular path in your heart, like your AV node (part of your conduction system) or atria (upper heart chambers)
• Heart cells fire when they should still be recharging
• Pacemaker cells are too active, or a signal comes from an unusual place

Risk factors

Risk factors or “triggers” can range from a lack of sleep or fluids to heart conditions.

Other triggers include:

• Heart disease
• Heart muscle issues (cardiomyopathy)
• Heart failure
• Heart valve problems
• High blood pressure
• Diabetes
• Electrolyte imbalance
• Beverages with alcohol
• Caffeine
• Stress

Complications of this condition

Narrow complex tachycardia may lead to:

• Blood clots (which can cause a stroke or heart attack)
• Cardiomyopathy
• Heart failure
• Cardiac arrest

How doctors diagnose this condition

If you have narrow complex tachycardia, the rhythm strip from an electrocardiogram (EKG/ECG) shows that signals reach your lower heart chambers in less than 120 milliseconds. Healthcare providers call this a “narrow complex.” It’s normal compared to a wide complex, where the signal takes longer. A wide complex typically starts in the lower part of your heart. Your provider may also refer to this narrow or wide complex as the “QRS complex” on your EKG.

To find the specific kind of tachycardia, your provider may also use devices that monitor your heart’s electrical activity. These may include:

• Holter monitor
• Ambulatory monitor
• Implantable loop recorder
• Telemetry monitor

How is it treated?

Some of these rhythm types, like premature complexes, don’t need treatment. For other types of narrow complex tachycardia, treatment may include:

• Vagal maneuvers: Physical actions like coughing may slow electrical impulses.
• Medicines: Examples include beta-blockers, calcium channel blockers or adenosine.
• Cardioversion: A device or medicine gets your heart back into a normal rhythm.
• Catheter ablation: This makes scars to block certain electrical impulses.

When should I see my healthcare provider?

Contact your provider if you feel lightheaded or dizzy or have heart palpitations. You should also let them know if your symptoms change or get worse. Call your local emergency number if you have chest pain or severe shortness of breath, or you feel faint.

What can I expect if I have this condition?

With treatment, many people with narrow complex tachycardia have a good outlook. For many people, treatments like catheter ablation work well and may even cure them. But for others, the tachycardia can return and send them to the hospital again. You’ll need regular follow-up visits with your healthcare provider to monitor your condition.