Premature ventricular contractions (PVCs) are the most common cause of irregular heart rhythms. The heartbeat is created by an electrical signal that originates in an area of specialized cells in the heart’s upper right chamber, the right atrium. The electrical signal moves down through the heart to the atrioventricular (AV) node, a cluster of specialized cells in the center of the heart. From the AV node the signal passes along special fibers embedded in the heart walls to the ventricles, the lower chambers. When the electrical current arrives in the ventricles, it causes them to contract and pump oxygen-rich blood out to the body.
What are premature ventricular contractions?
A premature ventricular contraction (PVC) is a too-early heartbeat that originates in the ventricles and disrupts the heart’s normal rhythm. The pattern is a normal beat, an extra beat (the PVC), a slight pause, then a stronger-than-normal beat. The heart fills with more blood during the pause following the PVC, giving the next beat extra force. This pattern may occur randomly or at definite intervals.
What are the symptoms of PVCS?
When a PVC occurs as a single premature beat, patients may describe the feeling as a "palpitation" or "skipped beat." The beat following the PVC can be strong enough to cause pain or discomfort in the chest. Individuals who have frequent PVCs or a series of them may experience a fluttering sensation in the chest or neck. If PVCs are frequent enough to reduce the heart’s pumping ability, the individual may experience weakness, dizziness or fainting.
What causes PVCs?
Healthy people of any age can experience PVCs. In most cases of occasional PVCs the underlying cause cannot be identified. PVCs that occur frequently or for longer periods of time are more likely to be related to heart disease, an injury to the heart or other, non-cardiac conditions such as a chemical imbalance in the body. Certain medications, alcohol, illegal drugs and high levels of adrenaline due to stress, exercise or caffeine also can cause PVCs.