Premature Ventricular Contractions

Premature ventricular contractions (PVCs) or "extra heartbeats" occur in the lower chambers (ventricles) of the heart and are a common cause of cardiac arrhythmias. Increased heartbeats affect heart rhythm, causing a heart flutter or fast, skipped beats.

 

What are premature ventricular contractions?

A premature ventricular contraction (PVC) is an extra heartbeat that arises from the lower half of the heart (otherwise known as the ventricle). The extra heartbeat disrupts the regular heartbeat, affecting the heart rhythm. The arrhythmia is characterised by the following “abnormal rhythm”:  A normal beat is followed by an extra beat from the ventricle (PVC). This is followed by a slight pause and a beat that is more vigorous than usual. During the pause that occurs after the PVV, the ventricles are filled with more than the usual volume of blood, which results in the extra beat contracting more vigorously. Sometimes the PVCs can occur in a very regular, predictable manner. A PVC that occurs after every normal beat is called ventricular bigeminy. If it occurs after every second normal beat, it is called ventricular trigeminy, and if it occurs after every third beat, it is called ventricular quadrigeminy. If more than three PVCs occur in a row, it can be identified as ventricular tachycardia.

What are the symptoms of PVCs?

As the beat following the PVC is more vigorous than usual, some common symptoms may include chest heaviness, discomfort or pain. Single PVCs give the feeling of a “missed” or “skipped” heartbeat. If the PVCs are more sustained, this may give a sensation of a fast heartbeat or heart flutter. Although it is quite unusual, PVCs can cause lowered blood pressure. This can lead to symptoms like dizziness or presyncope. If the PVCs are fast and sustained for long periods at a time (in the case of ventricular tachycardia, for example), the individual may experience what is known as “transient loss of consciousness”, a condition also referred to as syncope. In cases where the PVC burden is high, there is emerging evidence to demonstrate that this may lead to weakened ventricles, also known as ventricular dysfunction. This may cause symptoms of weakness or fatigue in some individuals.

Typical symptoms include:

• Skipped heartbeat
• Racing heart
• Heart flutter

Symptoms of occasionalventricular contractionsmay not be serious at first, but chronicventricular contractionssuggest an underlying heart condition that requires treatment urgently.

Who is at risk for PVCs?

PVCs occur in almost everyone at some stage. They can vary from 0.5% to 3% of the normal heartbeats in 24-hour Holter recordings. The percentage of PVCs typically increases with age.

Sometimes people with a structurally normal heart have a high burden of PVCs. These PVCs have a predilection for the outflow tract regions of the heart as this is close to where the major arteries exit the ventricles. Sometimes PVCs may reflect an underlying abnormal heart substrate, especially when the PVCs don't come from the outflow tracts, and this tends to occur more commonly in elderly people and in individuals with underlying structural heart disease, including a history of a heart attack. It may also be a marker for underlying cardiomyopathy, including ARVC.

What causes PVCs?

It is possible for individuals with structurally normal hearts of any age to experience PVCs. Triggers for the PVCs include medications that have a stimulant effect on the heart, as well as caffeine, alcohol, illicit drugs and states of heightened sympathetic activity like stress or exercise.

PVCs may also indicate an underlying structural heart disease such as ischaemic heart disease or cardiomyopathies, including ARVC.

Diagnostic tests

1. Standard 12 lead ECG : This test is done in a clinical or hospital setting where electrical signals from the heart are gathered via 12 electrodes that are attached to the chest wall. This data is fed to a "computer" to generate an "electrical graph" on a piece of paper, otherwise known as the 12 lead electro cardiogram (ECG). The ECG is useful in identifying the “extra beat” or PVC. Your cardiac electrophysiologist is able to use the ECG to identify the exact PVC location in the heart. There are certain ECG signatures that act as red flags for underlying structural cardiac disease. The ECG takes just a couple of minutes to perform.
2. Holter: A Holter is a portable ECG that your doctor will send you home with. You may wear it for 24 to 48 hours and sometimes longer. It typically consists of three leads and documents how often the PVCs are occurring, as well as the percentage of the PVCs when compared to normal heartbeats. It also correlates symptoms with the PVCs. The Holter may detect if the PVCs are more sustained and whether or not they can be characterised as ventricular tachycardia. The above findings help determine the most suitable treatment strategy. The Holter may also be used to assess a patient’s individual response to therapy.
3. Exercise stress test: This is a test that is performed by attaching a standard 12 lead ECG to an individual during exercise on a treadmill or bicycle. This test ascertains if the PVCs are suppressed or triggered by exercise. If suppressed by exercise, they usually tend to follow a benign course. Exercise-induced PVCs and ventricular tachycardia may indicate underlying structural heart diseases such as ischaemic heart disease or ARVC. However, this phenomenon may also occur in structurally normal hearts.

How are PVCs treated

In most cases, PVCs are infrequent and benign. In this case, treatment is recommended to improve the quality of life. However, if the PVCs are very frequent, treatment is offered not only to improve quality of life but to prevent heart failure and, in some cases, to reverse heart failure. If the PVCs are of a more sustained nature (ventricular tachycardia), therapy is directed not only to reduce the PVC burden but also to manage a possible underlying abnormal cardiac substrate.

Lifestyle and home remedies

The following self-care strategies can help control premature ventricular contractions and improve your heart health:

• Identify PVC Try and identify what triggers the PVCs. Triggers may include stress, exercise, alcohol, certain postures or certain meals. Avoiding the triggers may significantly reduce the PVC burden and improve your symptoms.
• Modify your substance use. Caffeine, alcohol and other recreational drugs are known triggers of premature ventricular contractions. Reducing or avoiding these substances can reduce your symptoms significantly.

Medications

• Beta-blockers and calcium channel blockers may suppress the PVCs in 60% of cases. Some individuals may experience intolerable side effects from these medications, resulting in the discontinuation of the drug.

• Antiarrhythmic drugs, such as flecainide, may be used if you have ventricular tachycardia or very frequent premature ventricular contractions that interfere with your heart's function, causing severe symptoms. It is contraindicated if there is underlying structural heart disease. Very rarely, amiodarone may be used to suppress the PVCs; however, this drug is generally avoided due to its long term side effects.

Radiofrequency catheter ablation

In heart ablation therapy, radiofrequency waves are used to vaporise tiny amounts of tissue in the area of the heart where the extra beat originates. Radiofrequency catheter ablation is a treatment option for patients with symptomatic PVCs or PVCs that are frequent or prolonged and is reserved for patients who develop intolerable side effects on medication or when medication does not suppress the PVCs or for those who cannot comply with long-term drug therapy.

Other therapies:

Coronary revascularisation (Percutaneous or surgical) may be considered in individual cases when it is suspected that the ischaemic is driving the PVCs /ventricular tachycardia.

An implantable cardiac defibrillator may be implanted after discussion with a cardiac electrophysiologist in selected cases.