Tachycardia

Tachycardia is when your heart beats faster than normal while you're at rest, usually more than 100 beats per minute. It's often a harmless, temporary response to things like exercise or stress, but it can also be a sign of an underlying heart problem that needs treatment.

What are the symptoms of tachycardia?

Some people don't notice any symptoms at all, and a fast heart rate is only picked up during a routine check-up. Others notice:

• a racing, fluttering or pounding feeling in your chest (palpitations)
• dizziness, lightheadedness or weakness
• shortness of breath
• chest pain or discomfort
• feeling unusually tired, especially during exercise
• sweating.

In severe cases, a very fast heart rate can reduce blood flow to your brain and cause fainting, or even loss of consciousness.

What causes tachycardia and who is at risk?

A fast heart rate is often a normal, temporary response to things like exercise, stress, anxiety, pain, a fever or an infection. Caffeine, alcohol, dehydration, and some medications or recreational drugs can also speed up your heart rate for a while.

Tachycardia can also be linked to an underlying health condition, including:

• anaemia
• an overactive thyroid gland (hyperthyroidism)
• heart disease, including coronary artery disease, heart failure, cardiomyopathy or a previous heart attack
• a congenital heart condition, such as long QT syndrome or Wolff-Parkinson-White syndrome
• lung disease
• high blood pressure
• an imbalance of electrolytes (the body's salts and minerals).

You may be more likely to develop certain types of tachycardia if you:

• are pregnant (a resting heart rate rise of around 10–20 beats per minute is common during pregnancy)
• smoke, drink a lot of alcohol, or have a lot of caffeine
• are going through the menopause
• are a child or are middle-aged or older.

Are there different types of tachycardia?

Yes. Tachycardia is grouped into three main types, based on where in the heart the fast rhythm begins.

Sinus tachycardia happens when the heart's natural pacemaker, called the sinus node, sends out signals faster than usual. It's often the body's normal response to exercise, stress, fever or dehydration, and usually settles down on its own once the underlying cause does, without needing specific treatment.

Supraventricular tachycardia (SVT) starts in the upper chambers of the heart (the atria). It can begin and end suddenly, lasting anywhere from a few seconds to several minutes or longer. Atrial fibrillation and atrial flutter are common types of SVT; atrial fibrillation causes an irregular, rapid heartbeat and raises your risk of stroke.

Ventricular tachycardia (VT) starts in the heart's lower chambers (the ventricles). It's less common but more serious and tends to affect people with existing heart disease or previous heart damage. A related, more dangerous rhythm called ventricular fibrillation can stop the heart pumping properly, leading to cardiac arrest.

How is tachycardia diagnosed?

Your doctor will start by asking about your symptoms and medical history and will examine you. They may then arrange some tests, which can include:

• an electrocardiogram (ECG), which records your heart's electrical activity and is usually the first test used
• a Holter monitor or event recorder, a small portable ECG device you wear for a day or longer to help catch episodes that come and go
• an echocardiogram, an ultrasound scan that looks at the structure of your heart
• an exercise stress test, which checks how your heart responds while you're active, such as on a treadmill
• blood tests, to check for things like an overactive thyroid or anaemia.

If your tachycardia causes you to faint, you may also have a tilt table test, which checks how your heart rate and blood pressure respond as you move from lying down to standing.

Your results help your doctor work out what type of tachycardia you have and what's causing it.

How is tachycardia treated?

Many cases, especially sinus tachycardia, settle once the underlying trigger, such as stress, fever or dehydration, is treated or passes. Where further treatment is needed, non-surgical options include:

• lifestyle changes, such as cutting down on caffeine and alcohol, stopping smoking, and getting more sleep
• vagal manoeuvres, such as coughing, or holding your nose while gently trying to blow air out, which can help reset your heart's rhythm and should only be tried under a doctor's guidance
• medicines, such as beta-blockers or calcium channel blockers, to slow your heart rate, or blood thinners to help reduce the risk of stroke
• cardioversion, an electric shock (or sometimes medication given into a vein) used to restore a normal rhythm
• catheter ablation, a procedure where a thin, flexible tube is guided into your heart, usually through a blood vessel in your groin, to destroy the small area of tissue causing the abnormal signal.

If other treatments don't control your tachycardia, you may need a small device fitted, such as:

• an implantable cardioverter defibrillator (ICD), fitted under the skin of your chest to monitor your heart's rhythm and deliver a shock if it detects a dangerous fast rhythm
• a pacemaker, which sends regular pulses to help control your heartbeat.

Open-heart surgery is rarely needed, and is only considered if other treatments haven't worked.

When should I see a doctor?

See your doctor if you notice your heart beating unusually fast while you're at rest, even without other symptoms, so the cause can be checked.

Call 999 or go to your nearest A&E straight away if a fast heartbeat comes with:

• chest pain or discomfort
• fainting, or almost fainting
• severe shortness of breath
• dizziness or feeling faint.

If someone collapses and stops breathing or has no pulse, call 999, start CPR, and ask someone nearby to find a defibrillator (AED) if one's available; these are often kept in public places and don't need special training to use.