Premature ventricular contractions (PVCs) are extra heartbeats originating in the heart’s lower pumping chambers, known as the ventricles. These additional beats disrupt the heart’s regular rhythm, sometimes creating a sensation described as a skipped beat or a flutter in the chest. While unusual, occasional PVCs are common and generally not a serious concern for most individuals without underlying heart disease.
The Heart’s Electrical Rhythm
The heart’s consistent beating relies on a precise electrical conduction system. Normally, an electrical signal begins in the sinoatrial (SA) node, located in the right upper chamber (atrium). This signal spreads through the atria, causing them to contract and pump blood into the ventricles. The impulse briefly pauses at the atrioventricular (AV) node before traveling through specialized pathways, including the bundle of His and Purkinje fibers, to the ventricles, triggering their contraction and blood ejection.
A premature ventricular contraction occurs when an electrical impulse originates prematurely within the ventricles, outside the normal pathway. This early signal causes the ventricles to contract sooner than expected. The subsequent beat after a PVC often feels stronger due to increased blood filling the ventricle during the brief compensatory pause.
Common Causes and Triggers
Common causes of premature ventricular contractions include heightened adrenaline levels often associated with anxiety or stress. Lifestyle choices such as excessive caffeine intake, alcohol consumption, and nicotine use can contribute to PVCs. Dehydration and electrolyte imbalances, like low potassium or magnesium levels, are frequently implicated.
Certain medications, including decongestants and antihistamines, may also trigger PVCs. While many PVCs occur without a clear cause, they can sometimes be linked to underlying heart conditions like reduced blood flow, heart attack, heart failure, or cardiomyopathy.
When PVCs Warrant Concern
Certain circumstances warrant medical evaluation for PVCs. Frequent PVCs, especially those occurring thousands of times a day, can weaken the heart muscle over time, potentially leading to cardiomyopathy. A PVC burden exceeding 10% to 24% of all heartbeats is associated with an increased risk of developing cardiomyopathy. PVCs that occur in runs, such as bigeminy (every other beat is a PVC) or trigeminy (every third beat is a PVC), may be more concerning.
Symptoms accompanying PVCs, like dizziness, lightheadedness, chest pain, or fainting, signal a need for medical attention. Individuals with pre-existing heart conditions, including heart disease, structural heart abnormalities, or a history of heart attack, face a higher risk of complications from PVCs.
Identifying and Addressing PVCs
Diagnosing premature ventricular contractions begins with a healthcare provider listening to the heart and inquiring about symptoms and medical history. An electrocardiogram (ECG or EKG) is often the first diagnostic test, measuring the heart’s electrical activity and showing extra beats. Since PVCs may not happen consistently, a Holter monitor, a portable ECG device worn for 24 to 48 hours or longer, can continuously record the heart’s activity to capture infrequent PVCs.
Blood tests may be conducted to check for electrolyte imbalances or thyroid issues that could contribute to PVCs.
Management starts with lifestyle modifications to reduce triggers. Limiting or avoiding caffeine, alcohol, and tobacco products can help decrease PVC frequency. Stress management techniques, such as meditation or deep breathing exercises, are beneficial as anxiety can trigger PVCs. Ensuring adequate sleep and maintaining proper hydration contribute to heart health.
For symptomatic or highly frequent PVCs, medical interventions may be considered. Medications like beta-blockers or calcium channel blockers can slow the heart rate and reduce the force of contractions, alleviating symptoms. Antiarrhythmic medications are another option to regulate heart rhythm. In rare cases where PVCs are severe, persistent, and do not respond to other treatments, catheter ablation might be recommended. This minimally invasive procedure uses heat or cold energy to create tiny scars in the heart tissue at the origin of abnormal electrical signals, blocking them and restoring a normal rhythm.