Arrhythmia (abnormal heart rhythm)

What is arrhythmia?

Arrhythmia is an abnormal heart rhythm which occurs when the heart’s normal rhythm is disrupted. The heart may beat too slowly, too quickly or irregularly.

Most arrhythmias are harmless. Sometimes it’s normal for you to have a fast heart rate (e.g. when exercising) or a slow heart rate (e.g. when sleeping). However, some arrhythmias can be serious or potentially fatal. Disturbed heart rhythms can restrict blood being pumped around the body, which may cause harm to the brain, heart and other organs.

Over two million people in the UK experience arrhythmias.

Types of arrhythmia

There are two different types of arrhythmias, grouped by heart rate speed:

• tachycardia
• bradycardia

Tachycardia is a fast heart, classed as a resting heart rate that is more than 100 beats per minute.

There are several different types of tachycardia, including:

• atrial fibrillation – a rapid and uncoordinated heart rate
• atrial flutter – similar to atrial fibrillation but more organised
• supraventricular tachycardia – which causes sudden heart palpitations (pounding heartbeat)
• ventricular fibrillation – when rapid electrical signals result in the lower heart chambers quivering and not pumping blood
• ventricular tachycardia – a rapid, regular heart rate that stops the ventricles from filling with blood

Bradycardia is a slow heartbeat, classed as a resting rate that is less than 60 beats per minute.

The different types of bradycardia include:

• sick sinus syndrome – when the sinus node that sets the pace of the heart doesn’t work properly, which may cause an alternation between a slow and fast heart rate
• conduction block – when a blockage of the electrical pathways slows down or stops the signals that trigger heartbeats

Arrhythmia symptoms

Arrhythmias may not cause any symptoms, or a doctor may identify an irregular heartbeat when you are being examined for something else.

When they do occur, initial symptoms of arrhythmias may include heart palpitations. This is when your heartbeat is thumping, racing, fluttering, or feels like it skips a beat.

The longer the arrhythmia lasts, the more likely that this condition can affect the way the heart works, causing a range of secondary symptoms, including:

• fatigue – a fast heart rate can cause you to be very tired
• blackouts (syncope) – if your palpitations are caused by a heart condition, your heart rate could drop and cause you to faint
• dizziness – accompanied by heart palpitations, in some cases dizziness could be a sign of a serious heart condition
• breathlessness – shortness of breath commonly accompanies heart palpitations
• chest pain (angina) – if you experience chest pain with palpitations, you should seek medical help.

In extreme cases, certain types of arrhythmia can cause sudden cardiac death. If you feel your heart beating too fast, slowly, fluttering or skipping a beat, you should make an appointment with your doctor. If heart palpitations are accompanied by chest pain, dizziness, fainting or shortness of breath, contact a medical professional immediately.

What causes arrythmia?

The heart’s electrical conduction system controls the rhythm and rate of the heartbeat, sending signals from the top to the bottom of the heart. The signal is a trigger for the heart to contract and pump blood.

Factors which can cause or exacerbate arrhythmia include:

• blocked arteries
• heart attack
• changes to the structure of the heart
• high blood pressure
• diabetes
• certain medications
• viral infections
• sleep apnoea
• overactive or underactive thyroid
• drug abuse
• alcohol
• caffeine
• smoking
• genetics
• anxiety
• stress

Arrhythmia risk factors

You are more likely to suffer from arrhythmias if you:

• have a pre-existing heart problem
• have had heart surgery
• have high blood pressure
• have thyroid disease (an overactive or underactive thyroid)
• have obstructive sleep apnoea
• have electrolyte imbalance
• regularly consume a lot of alcohol
• use a lot of stimulants such as caffeine

Diagnosing arrhythmia

Initially, your doctor will ask you questions about your symptoms, examine you, and look at your medical history. In order to confirm a diagnosis of arrhythmia you may be referred to a specialist for more tests.

A range of diagnostic tests for heart conditions are used to diagnose arrhythmia by our experts at Royal Brompton and Harefield hospitals.

Electrocardiogram (ECG or EKG) to diagnose arrhythmia

The main test used to detect abnormal heart rhythms is an electrocardiogram (ECG). Each beat of the heart is triggered by an electrical impulse generated by cells in the upper right heart chamber. An ECG translates this electrical activity into line tracings on paper.

Echocardiogram to evaluate heart function in relation to arrhythmia

An echocardiogram is a simple and painless test that uses ultrasound waves to build a picture of the heart’s size, structure and function.

Exercise or stress test to diagnose arrhythmia

A stress test – or exercise test – is usually carried out on patients when the arrhythmia is thought to be linked to exercise or to assess the heart’s electrical system’s response to exercise. Patients are asked to walk at a gradually increasing pace on a treadmill or ride an exercise bike whilst their heart rate and rhythm are monitored.

Holter monitor to diagnose arrhythmia

A holter monitor is a portable ECG device that records your heart’s activity over the day.

Event recorder to diagnose arrhythmia

An event recorder is a wearable ECG device that detects sporadic arrhythmias.

Implantable loop recorder to diagnose arrhythmia

An implantable loop recorder is inserted under the skin of your chest to record the heart’s electrical activity, detecting irregular heart rhythms.

Tilt test to diagnose arrhythmia

For people who have experienced recurrent fainting spells, a tilt test may help to expose slow arrhythmias (bradycardia) which may cause blackouts (syncope).

Arrhythmia treatment

If a significant arrhythmia is detected, our heart rhythm specialists will offer you a treatment plan specifically designed for you. Treatment may include one or a combination of lifestyle changes, medication, cardioversion (which delivers a shock to your heart to reset the heart rhythm), invasive procedures such as ablation for tachycardias, or cardiac devices like pacemakers of defibrillators .

The treatment for arrhythmia will depend on many factors including the type of arrhythmia and its severity and frequency but perhaps most importantly, the patients choice when fully informed about all options.

Arrhythmia medication

Medications such as beta-blockers, calcium channel blockers and specific drugs can be used to slow down or manage a fast arrhythmias , whilst a range of medications can be used to restore a normal heart rhythm. Blood thinning medications may also be used in specific arrhythmias to reduce the risk of blood clot and stroke.

Medical procedures to treat arrhythmia

A range of non-surgical medical procedures can be offered to help control arrhythmias. These include catheter ablation, which carefully and accurately eliminates the part of the heart causing the arrhythmia. This treatment is specifically for fast arrhythmias.

Patients who suffer slow arrhythmias may have pacemaker may be fitted. Patients who suffer life threatening arrhythmias may be offered a implantable defibrillator (ICD). Both of these devices are inserted under the skin in the chest and use electrical impulses to pace or shock the heart, which in turn helps to restore a normal heartbeat.