premature ventricular complex (PVC), a ventricular depolarization that occurs earlier than expected. It appears on the electrocardiogram as an early, wide QRS complex without a preceding related P wave. PVCs may be idiopathic or caused by stress, electrolyte imbalance, ischemia, hypoxemia, hypercapnia, ventricular enlargement, or a toxic reaction to drugs. They may occur occasionally, in a regular pattern, or as several in sequence. Occasional PVCs are not clinically significant in healthy individuals, but they may produce decreased cardiac output in people with heart disease. Frequent PVCs may be a precursor of ventricular tachycardia or fibrillation.
