Premature ventricular contractions (sometimes called PVCs or VPCs or benign ventricular ectopics) are a fairly common abnormal heart rhythm (arrhythmia). PVCs are often considered “added” beats that interrupt the normal heartbeat and regular rhythm of the heart.

During a normal heart rhythm, an electrical  impulse is generated in the upper right chamber of the heart (right atrium). It spreads through the heart, causing the upper chambers to contract then the lower chambers (ventricles) to contract. This impulse is generated at a steady, predictable rate, depending on the circumstances.

However, there are other cells throughout the heart that can generate electrical impulses. These cells may take over for the main pacemaker if necessary. Some of them are located in the ventricles. If these cells fire at the wrong time, the electrical impulse they generate will cause the ventricles to contract early, resulting in a premature ventricular contraction. They may be caused by fatigue, caffeine, alcohol, nicotine or a variety of other factors. In many cases, the cause of PVCs is unknown.

The vast majority of PVCs have no symptoms. However, some people may feel a skipped heartbeat or a galloping, rapid heartbeat called a palpitation or experience dizziness. In general, these abnormal beats are harmless, although there are certain patients in whom PVCs may cause more serious problems. In general, these include existing heart patients and those with concurrent cardiac conditions. Even among people without prior heart conditions, diagnosing PVCs and ruling out heart disease may be important. Individuals are urged to contact their physician if they experience chest pain or a sudden worsening of their PVCs. If necessary, treatment generally involves taking medication, such as beta blockers or antiarrhythmics.

Premature ventricular contractions (PVCs), also known as extrasystoles, are a fairly common type of irregular heart rhythm (arrhythmia). In a normal heartbeat, an area of specialized cells called the sinoatrial (SA) node, located in the upper right atrium, generates an electrical impulse. This impulse spreads through the heart along a specialized conduction system, causing it to beat in a predictable, rhythmic fashion. However, there are other cells throughout the heart that can also generate electrical impulses. Some of them are located in the ventricles. When these fire early, they may cause the ventricles to contract, overriding the impulse from the SA node. In this case, the ventricles may still be recovering when the impulse from the SA node arrives and be unable to contract. This will result in a skipped, or missed, heartbeat.

PVCs are generally harmless and often have no symptoms. However, in patients with underlying heart disease, frequent PVCs may signify an increased risk of ventricular tachycardia (VT) – a serious arrhythmia in which the ventricles beat too rapidly and are unable to pump enough blood to the body. Ventricular tachycardia can lead to ventricular fibrillation, a potentially fatal arrhythmia in which the ventricles quiver and are unable to pump blood. Ventricular fibrillation requires immediate emergency medical attention to reestablish a normal heart rhythm. Heart patients who may be at increased risk due to PVCs include:

• Patients with reduced left ventricular ejection fraction. This is a measure of how much blood is pumped from the left ventricle with each contraction. Patients with heart failure frequently have a reduced left ventricular ejection fraction.
  
  
• Patients who suffer from an abnormally slow heart rate (e.g., bradycardia).
  
  
• Among patients with a previous heart attack, PVCs are associated with worse outcomes. Among these patients, beta blocker therapy is preferred. If the patient doesn't respond, the next treatment of choice is amiodarone, a potassium-channel blocker that is often used to treat arrhythmias.

Among people without clinically apparent heart disease, researchers have conducted multiple studies to uncover the relationship between PVCs and sudden cardiac death. Data from the Framingham Heart Study suggests that men who have PVCs with no symptoms are at greater risk of cardiac events than men without PVCs, even after other cardiac risk factors are taken into account.

In some cases, the cause of PVCs is unknown. In other cases, they may be due to known causes, such as:

The vast majority of PVCs have no symptoms. However, individuals with PVCs may notice palpitations – a feeling that their heart is galloping, pounding or skipping beats. These palpitations may feel like the heart is wildly out of control, and they can be quite startling or frightening.

Other symptoms may also include chest pain, fainting spells (syncope) or sudden worsening palpitations. These symptoms may indicate more serious heart problems. People with any of these symptoms are urged to contact their physician immediately.

To diagnose PVSs, a physician will begin by obtaining the patient’s personal and family medical history and conducting a complete physical examination. As part of this examination, the physician may notice an irregular pulse, though blood pressure tends to be normal.

Additional tests that may be ordered include:

• Echocardiogram. This painless test uses sound waves to visualize the structures and functions of the heart. A moving image of the patient’s beating heart is displayed on a video screen, where a physician can study the heart’s thickness, size and function. The image also shows the motion pattern and structure of the four heart valves, revealing any potential leakage (regurgitation) or narrowing (stenosis). During this test, a Doppler ultrasound may also be done to evaluate cardiac blood flow.
  
  
  
  
  
• Exercise stress testing. Studies find that PVC symptoms which occur just after, rather than during, an exercise test may increase the overall risk of potentially fatal arrhythmias. In this case, an echocardiogram will be done in order to further analyze the heart’s function, and to help the physician plan any necessary treatments.

In general, no treatment is necessary for patients who are free of heart disease and are rarely bothered by symptoms of PVCs. For those who are bothered by their symptoms, the cause of the PVCs will be addressed if it can be identified. For example, patients whose PVCs are caused by excessive caffeine intake may be asked to limit or eliminate their use of caffeine. 

Patients whose PVCs appear to be associated with heart disease will be treated for those heart-related problems. For example, heart attack and heart failure patients may be prescribed beta blockers, while patients with high blood pressure may be prescribed antihypertensive medications to help prevent enlargement of the left ventricle.

If the cause of the PVCs cannot be identified, and symptoms are present, patients may be prescribed medications such as beta blockers. These drugs block certain actions of the sympathetic nervous system (e.g., the stress response) that could lead to a rapid heartbeat. Amiodarone, another anti-arrhythmic medication, may be used among people with symptomatic PVCs who cannot tolerate beta blockers. In rare cases, a procedure called catheter ablation may be necessary to eliminate the abnormal cells causing the PVCs. During this procedure, a specially designed catheter is used to destroy the parts of the heart that are causing the electrical disturbance.

Patients whose PVCs were successfully treated by eliminating the cause (e.g., caffeine) from their lifestyle are strongly encouraged to avoid that cause in the future. There are no known strategies for preventing PVCs in cases with no identifiable cause.  

There are a number of types of PVC, which are classified according to different standards. For example, they may be classified according to how often the PVCs alternate with normal heartbeats:

Alternatively, more than one PVC may occur in a row and be classified as follows:

• Couplets: Two PVCs in a row.
  
  
• Runs of “nonsustained” V-tach (short for ventricular tachycardia): At least three PVCs in a row. In patients with weakened pumping function of the heart due to a prior heart attack, any runs of nonsustained V-tach indicate a high risk of potentially fatal arrhythmias (such as ventricular tachycardia or ventricular fibrillation). These cases usually require further evaluation by tests that might include cardiac catheterization and an electrophysiology study.

Furthermore, PVCs may be classified according to where they arise within the heart:

• Unifocal PVCs. The PVCs arise from the same source and appear similar on an electrocardiogram (EKG).
  
  
• Multifocal PVCs. The PVCs arise from different sources within the heart and look different from each other on the EKG.

The timing of the PVCs in relation to the normal beats is very important. Certain PVCs may occur in a pattern where they affect the ventricle just as it is recovering from the previous contraction. This is known as the vulnerable period of the ventricle. These PVCs are called R on T PVCs and may trigger lethal arrhythmias.

Other classifications also exist. Patients are encouraged to speak with their physician for more information about PVCs and their effect on the heart.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to premature ventricular contractions:

1.   How will I know if I have PVCs?
   
   
2. What tests will I receive to evaluate my condition?
   
   
3. What type of PVCs do I have?
   
   
4. How serious is this condition for me?
   
   
5. Do the PVCs place me at higher risk for other heart-related problems?
   
   
6. Are there any lifestyle factors that may be causing the PVCs?
   
   
7. Can any lifestyle changes reduce the frequency or severity of the PVCs?
   
   
8. Do you recommend any medications for my condition? If so, which ones?
   
   
9. Will the PVCs worsen over time?
   
   
10. Will I always have PVCs or can they disappear on their own?
    
    
11. Should I avoid any activities with this condition?
    
    
12. What symptoms indicate a medical emergency with PVCs?
    
    
13. How will my condition be monitored?
    
    
14. Are my children at greater risk of developing PVCs?