Premature Ventricular Contractions

Premature ventricular contractions (PVCs) are a type of arrhythmia (irregular heartbeat). They are common and can affect people of all ages. PVCs are often not dangerous. But if other heart problems are present, PVCs can cause serious health issues. This sheet tells you more about PVCs and how they are treated.

Understanding Your Heart's Electrical System

To understand how PVCs occur, it helps to first understand how your heart works. Your heart is a muscle that pumps blood throughout the body. It is made up of four chambers: two atria and two ventricles. Electrical signals are sent to these chambers, making them contract (squeeze) in a certain rhythm. This rhythm, which pumps blood through and out of your heart, is your heartbeat. The process begins in the sinoatrial (SA) or sinus node:

• The SA node: This group of cells in the right atrium sends a signal to both atria, telling them to contract. This pumps blood into the ventricles.

• The AV node: This is another group of cells in the right atrium. It receives the signal from the SA node after it passes through the atria. The AV node channels the signal through the bundle branches and into the ventricles.

• The bundle branches: These pathways of cells carry the signal through the ventricle walls. As the signal moves through the ventricles, the ventricles squeeze. This pumps blood out of the heart and into the body.

What Happens During a PVC?

During a PVC, an abnormal signal disrupts the normal heartbeat. This signal is sent from a group of cells (an ectopic focus) in the ventricles. The signal causes the ventricles to contract too soon, and the heart skips the next normal beat. This results in an irregular heartbeat.

What Are the Symptoms of PVCs?

Sometimes PVCs cause no symptoms at all. Other times, a patient may feel palpitations (irregular heartbeats). These can feel like "skipped" beats, or "flopping" in the chest. If PVCs are frequent, other symptoms can occur. These include tiredness, feeling faint, or shortness of breath. They also include fullness or pressure in the neck, and chest pain. These symptoms occur because less oxygen is delivered to the body. This is because PVCs make the heart pump blood less effectively.

What Causes PVCs?

In some cases, no cause of PVCs is found. When a cause is found, it is either chemical or structural.

• Chemical. Changes in the body's chemistry can prompt PVCs. For instance, raised levels of certain hormones, such as adrenaline or thyroid, can cause PVCs. Consuming substances such as alcohol and caffeine can also cause them.

• Structural. This involves existing problems in the heart and/or cardiovascular system. Coronary artery disease (CAD) is one type of problem that can be related to PVCs. Others are heart failure and heart valve problems.ÂÂ

How Are PVCs Diagnosed?

The doctor will take your medical history and ask you to describe your symptoms. You'll also have a physical exam. And certain tests may be done. These include:

• Electrocardiogram (ECG or EKG). 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.

• Echocardiogram (echo). This test creates a moving picture of the heart. During an echo, a probe moved over the chest emits harmless sound waves. The resulting picture shows the size and shape of the heart. It also shows how well heart chambers and valves are working.

• Heart monitor. There are two 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 healthcare 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 healthcare provider over the phone.

How Are PVCs Treated?

Treatment depends upon whether structural heart problems are present. It is also determined by the severity of symptoms.

• If you have no other heart problems and your symptoms are not bothersome, treatment may not be needed. If it is needed, treatment can involve:

  • Lifestyle changes. Your doctor may suggest that you exercise and limit caffeine and alcohol. If you smoke, you'll be advised to quit.

  • Medications. Two types of medication can help with PVCs. Beta-blockers and calcium channel blockers both can lower the heart rate and reduce blood pressure.

• If you have structural heart problems, you'll likely be referred to a doctor who specializes in heart rhythm problems. This may be a cardiologist or an electrophysiologist. This is because for you, PVCs can be a bigger threat to your health. They can lead to problems such as a more dangerous heart rhythm, or even death. In severe cases, an ICD (implantable cardioverter defibrillator) may be implanted. This can help normalize the heart rhythm.