Premature ventricular contractions (PVCs) are a common form of heart rhythm disturbance, or arrhythmia, affecting people with or without underlying heart disease. These extra heartbeats often cause a sensation that the heart has momentarily paused or “skipped a beat.” While this feeling can prompt anxiety and concern about heart health, PVCs are frequently harmless and do not indicate a serious problem. Understanding the mechanics of these extra beats and how medical professionals assess their significance is important for anyone who feels this intermittent flutter in their chest.
What are Premature Ventricular Contractions?
A PVC is a single, extra heartbeat that originates in the lower chambers of the heart (the ventricles) before the next regular beat is due. Normally, the heart’s rhythm is controlled by the sinoatrial (SA) node, a specialized group of cells that acts as the heart’s natural pacemaker. The SA node sends an electrical signal that travels through the heart in an organized manner, causing the atria and then the ventricles to contract.
In the case of a PVC, an abnormal electrical impulse is generated spontaneously within the ventricular muscle tissue, causing the ventricles to contract prematurely. Because this impulse fires outside the normal conduction system, the resulting beat is often less effective at pumping blood through the body. This early beat is typically followed by a brief pause, known as a compensatory pause, as the heart resets its rhythm. This pause allows the heart to fill with more blood than usual, causing the subsequent normal beat to feel noticeably stronger, which is the sensation often described as a “thump” or a “skipped beat.”
Recognizing the Sensations and Common Triggers
The experience of PVCs varies widely; some people feel no symptoms at all, while others are highly sensitive to every extra beat. Sensations are often described as a momentary fluttering, a flip-flop feeling, or a sudden, strong pounding in the chest. Less common symptoms include brief dizziness or mild shortness of breath, particularly when PVCs occur frequently in a row.
A variety of non-cardiac factors can increase the likelihood of these premature beats by heightening the heart’s electrical excitability. Lifestyle choices such as high consumption of caffeine, alcohol, or nicotine products are well-known triggers for PVCs. The body’s stress response also plays a role, as high levels of anxiety, emotional distress, or lack of sleep increase the amount of adrenaline circulating in the body. Furthermore, imbalances in key electrolytes like potassium and magnesium can disrupt the normal electrical stability of heart cells, leading to an increase in these extra contractions.
Determining the Severity of PVCs
Medical evaluation focuses on determining the underlying health of the heart to assess the risk associated with frequent PVCs. Diagnostic tools like the electrocardiogram (EKG) and the Holter monitor are used to capture the electrical activity of the heart. The EKG provides a snapshot of the heart rhythm, while the Holter monitor helps quantify the frequency and pattern of PVCs over a set period, typically 24 hours or longer.
A primary measure of severity is the “PVC burden,” which is the percentage of total heartbeats that are premature contractions. For most patients with structurally normal hearts and a low PVC burden, the extra beats are considered benign and carry a low risk of complications. However, if PVCs are highly frequent, sometimes defined as greater than 10 to 20 percent of all heartbeats, they can occasionally lead to a form of heart muscle weakness called cardiomyopathy, even in the absence of other heart disease.
The presence of underlying structural heart disease, such as coronary artery disease or a weak heart muscle, changes the risk profile significantly. PVCs in this context can indicate a higher risk for more serious rhythm disturbances. An echocardiogram, an ultrasound of the heart, is often used to ensure the heart muscle is healthy and rule out any hidden structural issue contributing to the extra beats.
Treatment and Lifestyle Management
For individuals with infrequent PVCs who have no symptoms and a structurally healthy heart, the most common approach is observation and reassurance. Intervention is often unnecessary in these benign cases. Management frequently begins with addressing the identified triggers and making targeted lifestyle adjustments.
Reducing or eliminating the intake of stimulants like caffeine, tobacco, and alcohol can significantly decrease the frequency of PVCs for many people. Learning to manage stress and ensuring adequate, consistent sleep are also actions that may help calm the heart’s excitability.
When PVCs are highly symptomatic or the burden is high enough to risk weakening the heart muscle, medical intervention is considered. Medications such as beta-blockers or calcium channel blockers are often the first-line pharmacological treatment, working to suppress the abnormal electrical activity and slow the heart rate. For patients who do not respond to medication or who have a very high PVC burden, a procedure called catheter ablation may be recommended to permanently neutralize the small area of heart tissue generating the premature impulses.