Ventricular arrhythmias frequently encountered in small animal practice can range from benign to life-threatening. Their timely recognition and accurate diagnosis are fundamental to proper management. Severe ventricular arrhythmias can result in decreased cardiac output and clinical signs such as intolerance to activity, or syncope. Ventricular arrhythmias such as ventricular fibrillation are a cause of sudden death. Diagnosis is made by electrocardiography, and is usually characterised by wide and bizarre QRS complexes. Ventricular arrhythmias can be secondary to cardiac or extracardiac causes. Breeds such as Boxers and Doberman Pinschers are at high risk to develop ventricular arrhythmias and subsequent sudden death if they are affected by underlying cardiomyopathy. Treatment of ventricular arrhythmias is based on patient signalment; the presence or absence of clinical signs; and the complexity, rate, frequency and number of ventricular arrhythmias. Various intravenous or oral antiarrhythmic therapies are available to the practitioner. Antiarrhythmic medications act on various ion channels or receptors, and alter the myocardial action potential. Electrical defibrillation and cardioversion can also be used for certain life-threatening ventricular rhythms. Patient monitoring, including monitoring of treatment efficacy, is often performed using serial electrocardiograms or 24-hour ambulatory ECG (Holter) monitoring.

Éva Larouche-Lebel - Cardiology resident, Ryan Veterinary Hospital

Mark Oyama - Professor of Cardiology, Section Chief Section of Cardiology, Ryan Veterinary Hospital, University of Pennsylvania, School of Veterinary Medicine, 3800 Spruce Street, Philadelphia, PA 19104, USA