A premature ventricular contraction (PVC) is a common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node.

However, when a PVC occurs the impulse nearly always travels through only one bundle fiber, so there is no neutralization effect; this results in the high voltage QRS wave in the electrocardiograph.

There are three main physiological explanations for premature ventricular contractions: enhanced ectopic nodal automaticity, re-entry signaling, and toxic/reperfusion triggered.

Ectopic enhanced nodal automaticity suggests foci of sub-pulmonic valvular pacemaker cells that have a subthreshold potential for firing.

This process is the underlying mechanism for arrhythmias due to excess catecholamines and some electrolyte deficiencies, particularly low blood potassium, known as hypokalemia.

This condition is frequently seen in patients with underlying heart disease that creates areas of differential conduction and recovery due to myocardial scarring or ischemia.

These are often seen in patients with ventricular arrhythmias due to digoxin toxicity and reperfusion therapy after myocardial infarction (MI).

This ectopy of the ventricles when associated with a structurally normal heart most commonly occurs from the right ventricular outflow tract (RVOT) under the pulmonic valve.

[2] The advantage of these monitors is that they allow a quantification of the amount of abnormal beats ("burden") and ensure that there are no heart arrhythmias present that might require attention, such as ventricular tachycardia.

[citation needed] On electrocardiography (ECG or Holter) premature ventricular contractions have a specific appearance of the QRS complexes and T waves, which are different from normal readings.

For patients with more than 1,000 PVCs per day, the risk of developing left ventricular systolic dysfunction after 5 years follow-up is low.

For patients with underlying chronic structural heart disease and complex ectopy, mortality is significantly increased.

[28] These differences may be due to rates of high blood pressure and atherosclerosis, which are more easy to find in older persons.

Heart disease was excluded after physical examination, chest x-ray, ECG, echocardiography, maximal exercise stress test, right- and left-heart catheterization and coronary angiography.