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INTRODUCTION

Ventricular ectopic beats are very common and may be identified during outpatient or inpatient telemetry monitoring either due to symptoms of palpitations or as an incidental finding. In most cases, ventricular ectopy, presenting as premature ventricular contractions (PVCs), nonsustained ventricular tachycardia (NSVT), and accelerated idioventricular rhythm (AIVR), is asymptomatic and does not require specific treatment. While most commonly benign when presenting in patients with structurally normal hearts and normal ECGs, these ventricular arrhythmias can rarely be associated with structural heart disease and a risk of sudden death.

PREMATURE VENTRICULAR CONTRACTIONS AND NON-SUSTAINED VT

PVCs are very common and can be due to enhanced automaticity, triggered automaticity, or reentry. PVCs are often sensitive to sympathetic stimulation and can be a sign of increased sympathetic tone, myocardial ischemia, hypoxia, electrolyte abnormalities, or underlying heart disease. During myocardial ischemia or in association with other structural heart disease, PVCs can be a harbinger of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF).

The electrocardiogram (ECG) characteristics of the arrhythmia are often suggestive of whether structural heart disease is present. PVCs with smooth uninterrupted contours and sharp QRS deflections may suggest an ectopic focus in relatively normal myocardium, whereas broad notching and slurred QRS deflections may suggest a diseased myocardial substrate. The QRS morphology also suggests the likely site of origin within the ventricle. PVCs that have a dominant S wave in V1, referred to as a left bundle branch block–like configuration, originate from the right ventricle or interventricular septum. Those with a dominant R wave in V1 originate from the left ventricle. A superior frontal plane axis (negative in II, III, aVF) indicates initial depolarization of the inferior wall (diaphragmatic aspect of the heart), whereas an inferior frontal plane axis (positive in II, III, aVF) indicates an origin in the cranial aspect of the heart. The location of arrhythmia origin often suggests the nature of underlying heart disease. Most common ventricular arrhythmias that are not associated with structural heart disease have a left bundle branch block–like configuration. PVCs with a right bundle branch block configuration are more likely to be associated with structural heart disease. Multiple morphologies of PVCs (multifocal PVCs) are also more likely to indicate structural heart disease or a myopathic disease process. In patients with heart disease, greater frequency and complexity (couplets and NSVT) of these arrhythmias are associated with more severe disease.

PVCs AND NSVT DURING ACUTE ILLNESS

These arrhythmias are often encountered in patients who are being evaluated in the emergency department or who have been hospitalized and are on a cardiac monitor. When encountered during acute illness or as a new finding, evaluation should focus on detection and correction of potential aggravating factors and causes, specifically myocardial ischemia, ventricular dysfunction, and electrolyte abnormalities, most commonly hypokalemia. If there is a suspicion of underlying heart disease, then this ...

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