Arrhythmias

What is an arrhythmia?

An arrhythmia is an abnormal or irregular heartbeat. This can happen when there is abnormal electrical activity in the heart that drives the heart to beat too fast (tachycardia), too slow (bradycardia), or irregularly.

Some arrhythmias are not serious, while others are very serious and can result in the heart not being able to work properly.

There are a number of different types of arrhythmia, including:

• bradycardia – heart going too slow
• tachycardia – heart going too fast
• heart blocks – nerve conduction problem in the heart
• atrial arrhythmias – abnormal heartbeat caused by a problem in the atrium
• ventricular arrhythmias – abnormal heartbeat caused by a problem in the ventricle.

What does the cardiovascular system do?

The cardiovascular system is responsible for moving vital nutrients, gases and hormones around the body. It is made up of the heart, lungs and blood vessels, all working together.

More about the cardiovascular system

What are the causes of arrhythmias?

There are a number of things that can cause an arrhythmia. People who are most at risk of developing an arrhythmia are those who:

• have a weak heart muscle (heart failure)
• have had a heart attack
• have an imbalance in electrolytes (such as too much or too little potassium)
• have an over-active or under-active thyroid gland
• are taking medications that can cause arrhythmia as a side effect.

Other things that can cause an arrhythmia are:

• stimulants such as caffeine or nicotine
• extreme physical exertion
• stress
• shock
• pain
• extreme heat (hyperthermia)
• extreme cold (hypothermia).

What are the signs and symptoms of arrhythmias?

Signs and symptoms of an arrhythmia include:

• an irregular heart beat or pulse (palpitations)
• a slow heartbeat (bradycardia)
• a fast heartbeat (tachycardia)
• shortness of breath (dyspnoea)
• light headedness or dizziness (related to low blood pressure)
• loss of consciousness or fainting (related to low blood pressure)
• sweating
• paleness
• chest pain.

How are arrhythmias treated?

The treatment depends on the type of arrhythmia and how it affecting the person with it.

• No treatment – If there are no ill effects, there may be no need to treat the arrhythmia.
• Electrolyte replacement therapy – If the blood’s electrolyte levels are too low, electrolyte replacement therapy may be prescribed.
• Medication – A medication may be prescribed to try to restore normal heart rate and rhythm.
• Cardioversion – An electrical shock is passed through the chest to the heart to block any abnormal rhythm, and allow the natural pacemaker in the heart to generate a normal electrical signal. Unless the person is unconscious or their condition is immediate and life threatening, this is done under a light anaesthetic.
• Pacemaker – This is an electronic device placed under the skin in the chest. When the heart rate becomes too slow or irregular, it produces an electrical pulse that provides a more normal heart rate and rhythm.
• Implantable cardiac defibrillator (ICD) – This is a small device implanted into the chest to monitor the heart rate. If the heart beats too slowly or too quickly, the ICD sends out an electrical signal to stop the abnormal electrical activity and allow a normal heart rate and rhythm to return.

What happens in intensive care?

When someone is admitted to the intensive care unit (ICU) or the coronary care unit with an arrhythmia, the main aim of therapy is to treat the cause of their irregular heart rhythm.

Exactly what is done will depend on how critically ill they are.

• Their heart rate, blood pressure, respiratory rate, oxygen saturation and temperature will be monitored and displayed on a bedside monitor.
• They may have a central venous catheter inserted so medications and intravenous fluids can be given. Alternatively, drugs may be given using a normal drip and infusion pumps.
• They may be given oxygen via a face mask or nasal prongs.
• If needed, a breathing tube and ventilator may be used to help them breathe. If so, suctioning will be done to remove secretions from the lungs and airways, which can cause coughing.
• If they are unable to eat, a nasogastric tube may be used so nutrition can be given and fluid can be removed from the stomach.
• An indwelling urinary catheter may be inserted to drain and measure urine from the bladder.
• They may have tests done, such as blood tests, urine tests, chest x-ray, CT scan, magnetic resonance imaging (MRI) scan, echocardiogram, and electrocardiogram (ECG).

The length of time someone needs to stay in the ICU depends on what type of arrhythmia they have, and if there are any complications. Please ask the ICU nurse or doctor if you have any questions.

Useful links

• MedlinePlus: Arrythmias – US National Library of Medicine
• Heart arrhythmias: Understanding abnormal heart rhythm (PDF) – Heart Foundation