Understanding Premature Ventricular Contractions (PVCs)

Premature ventricular contractions (PVCs) are a type of abnormal heartbeat (arrhythmia). They are common ly found in people of all ages.  

How PVCs happen

Your heart has 4 chambers: 2 upper atria and 2 lower ventricles. Normally, a special group of cells begins the signal to start your heartbeat. These cells are in the sinoatrial (SA) node in the right atrium. The signal quickly travels down your heart’s conducting system. It travels to the left and right ventricle. As it travels, the signal triggers nearby parts of your heart to contract. This allows your heart to squeeze in a coordinated way.

During a premature ventricular contraction, the signal to start your heartbeat instead comes from one of the ventricles. This signal is premature, meaning it happens before the SA node has had a chance to fire. The signal spreads through the rest of your heart, causing a heartbeat. If this happens very soon after the previous heartbeat, your heart will push out very little blood. This causes a feeling of a pause between beats. If it happens a little later, your heart pushes out an almost normal amount of blood. This leads to a feeling of an extra heartbeat. So, the heart has a “premature” heartbeat in between normal heartbeats.

What causes PVCs?

Certain things can help set off a premature signal in the ventricles. These include:

• Advancing age

• Reduced blood flow to your heart (such as coronary artery disease)

• Scarring after a heart attack

• Electrolyte problems, such as low sodium or potassium levels

• Increased adrenaline, such as with anxiety

• Certain medicines, like digoxin

Many heart conditions raise the risk for PVCs. These include:

• Mitral valve prolapse

• High blood pressure

• Heart attack

• Coronary heart disease

• Dilated cardiomyopathy

• Hypertrophic cardiomyopathy

• Congenital heart disease

• Heart failure

They often happen in people without any heart disease. However, PVCs are somewhat more common in people with some kind of heart disease. 

What are the symptoms of PVCs?

Most people with occasional PVCs don’t have symptoms. The more PVCs you have, the more likely you are to feel them. When symptoms do happen, they are usually minor. Symptoms may include:

• An awareness of the heart beating

• A fluttering or flip-flop feeling in your chest

• Feeling of a “skipped” or “extra” heartbeat

• Dizziness and near-fainting

• A pulsing sensation in the neck

PVCs may cause more severe symptoms if you have another heart problem, such as heart failure. 

How are PVCs diagnosed?

Your healthcare provider will ask about your medical history and give you a physical exam. An electrocardiogram (ECG) is the main test for diagnosis. This test records the electrical activity of your heart. During an ECG, small pads (electrodes) are placed on your chest, arms, and legs. Wires connect the pads to a machine, which records your heart’s electrical signals. This test allows your provider to look at the signal of your heartbeat for a brief time. Any PVCs that occur during this time will show up on the ECG. In some cases, your healthcare provider might advise ECG monitoring over a day or more, up to 30 days. This can help to catch PVCs that don’t happen often. This is done with a monitor you wear night and day for the test period. Heart monitor. There are 2 types of external heart monitors:

• Holter monitor. This monitor can be worn for 1 to 7 days. It provides a constant recording of heart activity. After the test is done, your health care provider analyzes the recording.

• Event monitors. These monitors can be used for 3 to 4 weeks. One kind is a memory loop recorder. This monitor records constantly, but stores the recording only when you press a button. The other kind is a credit card-sized recorder. This monitor is turned on only during an episode. With both types, you send the recordings of symptoms to your health care provider over the phone.

These may be the only tests your healthcare provider will need. You may need more testing if you have PVCs often, or many in a row. Your provider may look at other causes, including possible heart problems. These tests might include:

• Echocardiography. This test looks at your heart’s structure and function.

• Cardiac stress testing. This test checks how your heart responds to exercise and to evaluate heart artery blood flow.

• Cardiac CT or MRI 

• Blood tests. This is done to check potassium and thyroid levels.