Your heart is a muscle that pumps blood through your body. Your heart rate is how fast your heart beats. Your heart should always have a regular, rhythmic beat, like the ticking of a clock.
Your heart has four chambers. The atria are the two upper chambers. The ventricles are the two lower chambers. The atria pump blood into the ventricles. The ventricles pump blood to your lungs and your body (see also Biology of the Heart Biology of the Heart The heart is a hollow organ made of muscle. The heart and blood vessels are part of your cardiovascular system. Your heart pumps blood through your blood vessels Blood carries oxygen and nutrients... read more ).
Special pacemaker cells in a part of the atria called the SA node (sinoatrial node) send out regular electrical signals to your heart muscle to make it contract.
Your heart's conduction system has tiny strips of tissue sort of like electrical wires. The conduction system carries the pacemaker signals to the rest of your heart. The signals must get to all your heart muscle cells at just the right time so your heart gives a good, strong beat that pumps blood properly.
What are premature beats?
Premature beats are a type of abnormal heart rhythm Overview of Abnormal Heart Rhythms Your heart is a muscle that pumps blood through your body. Your heart rate is how fast your heart beats. Your heart should always have a regular, rhythmic beat, like the ticking of a clock.... read more 
. They're extra heartbeats caused by an electrical signal in your heart coming too early.
An atrial premature beat is when the early signal comes from your atria. These premature beats are common in many healthy people.
A ventricular premature beat is when the early signal comes from your ventricles. These premature beats are common among older people.
You may not have symptoms, or you may feel changes to your heartbeat (palpitations Palpitations Palpitations are the awareness of heartbeats. The sensation may feel like pounding, fluttering, racing, or skipping beats. Other symptoms—for example, chest discomfort or shortness of breath—may... read more )
You may not need treatment, but sometimes doctors prescribe medicines to control your heart rate
What causes premature beats?
Atrial premature beats are common, especially among older people who have lung disorders (such as COPD Chronic Obstructive Pulmonary Disease (COPD) COPD is a disease in your lungs that makes it hard to breathe. It's hard to push air out of your lungs. Difficulty pushing air out is called chronic airflow obstruction. Smoking cigarettes is... read more 
).
Ventricular premature beats are common among older people, especially those with coronary artery disease Overview of Coronary Artery Disease (CAD) The heart is a muscle that pumps blood. Like all muscles, the heart needs a steady supply of blood to work. Blood that pumps through the heart doesn't feed the heart muscle. Instead the heart... read more 
, heart failure, Heart Failure Your heart pumps blood to carry oxygen and nutrients to the rest of your body. Heart failure is when your heart doesn’t pump blood as well as it should. It doesn’t mean your heart has stopped... read more or heart valve disorders Overview of Heart Valve Disorders Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has... read more 
.
Premature beats can happen with:
Physical or emotional stress
Drinking coffee, tea, or alcohol
Using some cold, allergy, and asthma medicines
What are the symptoms of premature beats?
Premature beats don't usually cause symptoms.
Some people can feel the extra heartbeats (palpitations). If you have a lot of premature ventricular beats when you exercise, you may feel weak or unable to exert yourself as much as normal.
How can doctors tell if I have premature beats?
Doctors feel your pulse and do:
An ECG is a quick, painless test that measures your heart’s electrical activity using stickers and cables on your chest, arms, and legs.
How do doctors treat premature beats?
Usually no treatment is needed, other than avoiding:
Physical or emotional stress
Coffee, tea, or alcohol
Some cold, allergy, and asthma medicines
If you have many atrial premature beats that are very uncomfortable, doctors may give you medicines to make your heart beat in a normal rhythm.
If you have ventricular premature beats and recently had a heart attack or have heart failure that causes symptoms, doctors may prescribe medicine called beta-blockers.
