Premature Ventricular Contractions
Premature Ventricular Contractions or PVCS (also called VPBs or ventricular premature beats ), are a common cause of palpitations. They are similar to premature atrial contractions since they disrupt the heart rhythm and result in an irregular pulse. However, PACs arise from the atria, while PVCs arise from the ventricles. Since the abnormal heart beat arises from the bottom chambers of the heart it is accompanied by reversal of the normal timing of the heart chambers. In other words, instead of the atria contracting first and the ventricles following, the ventricles contract first. Often, the atrial contraction follows, but because the AV valves are in a closed position during ventricular contraction the blood stored in the atrium has no where to go but backwards into the veins. This can cause a fullness in the neck and chest (often described as "my heart is in my throat"). The pulsation in the main vein of the neck (the jugular vein) often shoots up briefly when this happens and the medical term for this is a "cannon A-wave." The pause that occurs after a PVC may be longer than after a PAC and so the overfilling of the ventricles and the resultant "heavy" beat following the pause can be exaggerated.
PVCs occur normally in most people, and they usually increase with age. Sometimes PVCs do not cause symptoms (those patients should consider themselves lucky!). If they cause severe palpitations, medical therapy can be used to suppress most of them. However, PVCs are usually benign, and they don't require therapy unless the symptoms are intolerable. Sometimes PVCs are associated with heart disease such as coronary artery blockages or heart muscle problems, so it is reasonable for a physician to send the patient with PVCs for further cardiac testing. Generally, if there is no other heart disease, this arrhythmia should not be treated unless the symptoms are severe. If significant heart disease is present, PVCs can be a marker of increased risk of more severe rhythm problems such as ventricular tachycardia (see the next chapter), and further testing may be beneficial to see if that patient could get in trouble in the future.