Your heart is like your body’s main engine room. It is a powerful and important muscle that pumps blood throughout your body. This blood delivers oxygen and food to muscles and vital organs as it travels through an amazing network of blood vessels. This constant fuel supply is what helps you carry on all the things you do in your everyday life.
Your heart sits in the centre of your chest, between your lungs and is protected by your rib cage. It is about the size of your clenched fist. Your heart is made of four chambers, or rooms. The top two rooms are called atria. The bottom two rooms are called ventricles.
Each room has a valve that works like an automatic gate. The valve opens and closes, making sure blood only travels in one direction - similar to a one-way traffic system.
Your heart is powered to pump blood using its own electrical conduction system. You might have seen your heart’s electrical activity on a graph if you have undergone a heart test called an electrocardiogram (ECG).
The conduction cycle
Your heart’s electrical system is made up of three main parts:
The sinoatrial (SA) node (Pacemaker)
The atrioventricular (AV) node
The His-Purkinje system.
A heartbeat is one cycle in which your heart’s ventricles relax (diastole) and squeeze (systole) to pump blood. This cycle includes the opening and closing of the valves in your heart.
When your heart’s ventricles relax, blood flows from the atria to the ventricles. Your heart’s atria squeeze and pump blood into the ventricles. The atria then relax. The ventricles follow by squeezing, pumping blood out of your heart.
In a healthy heart, each heartbeat (electrical impulse) begins from the SA node in your heart muscle. This node acts as your heart’s own in-built pacemaker. Your heart rate is the number of heartbeats the SA node produces per minute.
Powering the heart to pump
The SA node (generator) sends out an electrical signal
The signal makes cells in the atria squeeze, pumping blood into the ventricles
The signal travels to the AV node (hearts junction) and slows briefly to allow your ventricles to fill with blood
The signal follows a pathway called the Bundle of His down through the Purkinje fibres (hearts electical wiring) to your ventricles
The signal makes cells in the ventricles squeeze and the heart to beat, pumping blood out of the heart
The ventricles relax and wait for the next signal
While you are resting your heart will beat between 60 and 100 times per minute. The pulse you can feel, for example at the artery in your wrist, is the heart pumping the blood. Health care professionals can measure the rate and rhythm of your heart by taking your pulse. The rate is the speed at which the beats occur and the rhythm is the frequency of each beat.
Sometimes your pulse will be faster or slower, depending on your health and whether you have exercised or are resting.
A fast heartbeat is known as Sinus tachycardia while Sinus bradycardia refers to a slow heartbeat. These are generally normal heart rhythms.
What is Atrial Fibrillation (AF)?
Atrial Fibrillation (AF) is a common type of irregular heart rhythm that causes poor blood flow to the body.
When you have AF, the top two rooms of your heart (atria) start making extra fast and irregular electrical signals. These extra signals make the atria twitch or quiver (known as fibrillation). These signals also affect your pulse, making it irregular and sometimes fast.
About 4 in every 100 people aged over 65 has AF, making it the most common type of irregular heart rhythm (known as arrhythmia).
Around 1% of the population (about 46,000 people) is affected by AF. Atrial fibrillation is often picked up during a medical examination for something else.
The risk of developing AF increases with age. It affects 4 in every 100 people over the age of 65 and 10 in every 100 people above 80 years old.
Types of AF
Atrial Fibrillation affects each person differently. Understanding the type of AF you have will help you manage your condition better.
There are 3 types of AF:
Paroxysmal AF – This is a type of AF that comes and goes. Episodes can last for hours or days but not usually longer than a week. It goes away on its own without any medical treatment
Persistent AF – AF episodes that last longer than 7 days at a time and generally need medical treatment with pharmacological/chemical or electrical cardioversion to bring back your heart rhythm back to normal
Permanent AF – Your AF is there all the time and does not return to a normal rhythm even with medical treatment
Symptoms of AF
The symptoms of AF will vary between people. Some people will experience only mild symptoms while others will notice the symptoms in their daily life. You can have AF and have no symptoms. Other people may feel symptoms of AF straight away such as:
Over time, some people get used to being in AF and the symptoms are easier to deal with.
NOTE: Not all palpitations or irregular heartbeats are caused by AF. You may be experiencing early or extra beats (called ectopics) often caused by anxiety or stress. Most people who experience occasional ectopic beats generally don’t need to worry as these are not usually caused by an underlying heart condition, do not need treatment and are not dangerous.
Know your AF Symptoms: Some of the symptoms of AF can be signs of other more serious health problems. It is important to talk to your health professional if you have any symptoms of AF or if these symptoms change or get worse.
Causes of AF
The causes of AF are not always clear but the risk of developing AF increases with the following risk factors:
Age – AF can affect adults at any age, but it is more common as people get older, particularly over 65yrs
Alcohol – drinking large amounts of alcohol over a long period of time can greatly increase your risk of AF. Even young people can experience AF after binge-drinking episodes.
