How it Works
The Heart as a Pump
“The heart is a muscular pump.”
The heart circulates blood around your body. It has 4 chambers and 4 valves that work together to pump blood to the lungs and then to the rest of your body.
“The right heart pumps blood to the lungs.”
The right atrium receives blood as it returns from your body and pumps it into the right ventricle. The right ventricle then pumps blood to your lungs where it collects oxygen before returning to the left heart.
“The left heart pumps blood to the rest of the body.”
The “left heart”. The left atrium receives blood from your lungs and pumps it into the left ventricle. The left ventricle then pumps blood to the rest of your body. The left ventricle is the strongest and most important chamber of the heart and is what generates your blood pressure.
The Heart's Electrical System
“Your heart’s rhythm is regulated by an electrical system.”
Every normal heartbeat starts with an electrical impulse generated by the heart’s natural pacemaker, the sinus node.
The sinus node sets the heart’s normal rhythm, firing at a rate of 60 to 100 times a minute. It fires more rapidly during exercise and stress, and slows down when you are resting. It is sometimes called the sinoatrial or SA node.
Each electrical impulse first spreads through the atria, making them contract. When the impulse reaches the AV node in the centre of the heart, it is held up for a split second, then sent into the ventricles via special electrical cables.
The AV node is a critical structure in the heart as it is the only electrical connection between the upper and lower chambers.
“Sinus rhythm means normal rhythm.”
The sinus node, the AV node, and electrical cables of the lower chambers of the heart need to function correctly to generate the normal heartbeat.
When the normal sequence of electrical activity is disrupted, an abnormal heart rhythm will result.
We can determine if the heart is in normal rhythm by performing an ECG test. Normal rhythm is called “sinus rhythm”, in reference to the sinus node which normally controls the heart’s rhythm.
What is an Arrhythmia?
“An arrhythmia is an abnormal heart rhythm.”
There are many types of arrhythmias which may arise for different reasons. During an arrhythmia, the sinus node is no longer in normal control of the heartbeat.
Abnormal electrical activity within the heart may cause the heart to beat too slowly (bradycardia), too quickly (tachycardia), or even irregularly.
Individuals who are otherwise healthy and free of heart disease may experience arrhythmias. However, those with underlying heart disease are at the highest risk of arrhythmias.
Common heart problems such as heart attack and heart failure are important causes of arrhythmias.
What are Ectopic Heartbeats?
“Ectopic beats are almost always harmless, requiring no treatment at all.”
An ectopic heartbeat is an “out-of-place” heartbeat due to a single muscular twitch of the heart. Ectopic heartbeats occur in all individuals, and are almost always harmless.
An ectopic heartbeat is one that occurs ahead of time. This happens when a small cluster of muscle cells in the upper or lower chambers sends out a single electrical impulse early and out of rhythm.
The heart normally responds with a momentary pause before resuming its normal regular rhythm. Ectopic heartbeats generally go unnoticed.
Some individuals experience the pause as a “missed beat”. Others feel a “thump”, since the following beat is larger and stronger than usual.
These sensations are often more prominent when resting quietly or lying down.
Ectopic heartbeats may arise from a focus that lies anywhere in the heart.
- Atrial ectopics arise from the heart’s upper chambers, and are also termed premature atrial contractions (PACs).
- Ventricular ectopics arise from the heart’s lower chambers, also termed premature ventricular contractions (PVCs).
Why do I have ectopic heartbeats?
Ectopic heartbeats are usually nothing to worry about. They occur in perfectly health individuals for no reason at all, and they can occur at any age.
In some cases, ectopic beats may reflect:
- Normal physical states such as exercise, stress, pregnancy, menopause, and ageing
- Fluctuations in potassium and magnesium levels in the blood
- Intake of caffeine, alcohol, or recreational drugs
- Effects of medications such as asthma puffers and nasal decongestants
- Conditions affecting heart muscle including prior heart attack and heart failure
What are the consequence of ectopic heartbeats?
- Atrial ectopic beats – These rarely cause problems beyond occasional palpitations. In some cases, rapid runs of atrial ectopy can lead to a rapid irregular arrhythmia called atrial fibrillation.
- Ventricular ectopic beats – These also rarely cause problems beyond occasional palpitations. In some individuals with a very large number of ventricular ectopic beats, the abnormal beats may result in weakening of the heart muscle which may progress to heart failure.
Occasionally there may be runs of many ectopic beats in a row and this is called ventricular tachycardia. Early evaluation is important to identify those needing treatment for deteriorating heart function.
What tests do I need if I have ectopic heartbeats?
You may require the following initial tests:
- Blood tests – To determine if there is an underlying condition that has provoked the ectopic beats.
- ECG – To evaluate your heart rhythm and look for clues that may suggest underlying heart conditions.
- Holter monitor – To assess the frequency of ectopic beats over a 24 h period, and to look for other arrhythmias that may be present.
- Echocardiogram – To confirm that the structure and function of your heart is sound.
Do I need treatment for ectopic heartbeats?
If there is an underlying medical condition that is causing your ectopic heartbeats, then this needs to be addressed.
Atrial ectopic beats require no specific treatment. At times there may be troublesome or intrusive symptoms. These will often wax and wane according to changes in lifestyle and will eventually run their course. If required, medications are effective at suppressing symptoms.
Ventricular ectopic beats require no specific treatment if they are infrequent and asymptomatic, and if the heart is otherwise in good condition.
For frequent or symptomatic ventricular ectopic beats, options include:
- Observation, with periodic check-ups to review your heart function with echo and holter monitoring.
- Medications such as beta blockers or calcium channel blockers.
- Catheter ablation to eliminate the ectopic beats altogether, especially if they are associated with ventricular tachycardia or cardiomyopathy.
Maintaining a Healthy Heart
Maintaining a healthy heart reduces your lifetime risk of heart disease and arrhythmias.
- Eat a healthy low fat, high-fibre diet with plenty of vegetables, fruits, and other vitamin-rich foods.
- Commit to planned exercise for at least 30 min, 5 days per week. Cleaning the house and getting the groceries are usual physical activities that are considered incidental exercise, not planned exercise. Planned exercise means repetitive physical activity for the purpose of improving physical fitness.
- Maintain a healthy weight. Weight yourself regularly and aim for a body mass index (BMI) within the healthy range. Your BMI is your weight (kg) divided by the square of your height (m). Your doctor can help you calculate your BMI.
- Stop smoking and avoid second-hand smoke (smoke from other people). Tobacco contributes to as much as one-third of all heart disease.
- Avoid or limit the intake of caffeine, alcohol, and other substances that may contribute to arrhythmias or heart disease.
- Avoid unnecessary stress, such as anger, anxiety, or fear. Find ways to manage stressful situations that cannot be avoided.
Here are some further tips on living a “heart healthy” life:
- If you have a heart condition, follow-treatment plans, and take all your medications regularly as prescribed.
- Have regular physical exams with your GP and report any unusual symptoms you have.
- Talk to your GP about lifestyle changes and treatments that address your cardiac risk factors.
For more information, read our section on Keeping it Healthy.