AIVR may also terminate abruptly. AIVR is particularly common with acute MI, and may be a sign of reperfusion after the use of thrombolytic agents or after interventional coronary artery procedures, or it occur spontaneously. The rate of AIVR is less than 100 bpm. Accelerated idioventricular rhythm (AIVR) results when the rate of an ectopic ventricular pacemaker causes a wide QRS rhythm that is faster than the sinus node but not fast enough to cause tachycardia (<100 bpm) (Fig. Underlying sinus rhythm with AV dissociation or retrograde ventriculo-atrial (VA) activation may be present. AIVR is a regular rhythm with a wide QRS complex (> 0.12 seconds). Often associated with increased vagal tone and decreased sympathetic tone. AIVR is often short lived and has no hemodynamic consequences. AIVR is defined by its rate (60 to 100 beats/min) and is sometimes referred to as slow VT. AIVR occurs in 8% to 20% of patients, usually during the first 2 days after MI. Idiopathic focal VTs can arise from the Purkinje system in either ventricle and can present as PVCs, Electrocardiography of Laboratory Animals. With AIVR the heart rate is usually between 50 and 100 beats/min, and the ECG shows wide QRS complexes without associated sinus P waves. Focal Purkinje VTs are typically induced by exercise and catecholamines and slowed or terminated by beta-blockers (and hence classified as “propranolol-sensitive” VTs) and lidocaine. In most cases (see Fig. When the sinus rate slows, AIVR appears; when the sinus rate speeds up, the arrhythmia disappears. It is a benign rhythm and does not progress to VT or VF. It is commonly seen during MI, occurring in 30% of inferior MIs and 5% of anterior MIs; it may or may not represent a reperfusion injury rhythm. 3.16) is an automatic rhythm, independent of the sinus node, that originates in the ventricle and competes with sinus rhythm. This arrhythmia is generally short-lived, lasting minutes or less, and usually requires no specific therapy. P waves may be absent, retrograde (following the QRS complex and negative in ECG leads II, III, and aVF), or independent of them (AV dissociation). Accelerated idioventricular rhythm (AIVR) is a slow ventricular rhythm that captures the heart because the sinus rate is even slower. 37.7). Also known as “accelerated ventricular rhythm” Tachyarrhythmia caused by increased automaticity in pacemaking cells of bundle branches and their fascicles Results when the rate of an ectopic ventricular pacemaker exceeds that of the sinus node Often associated with increased vagal tone and decreased sympathetic tone From: Goldberger's Clinical Electrocardiography (Ninth Edition), 2018, Dina M. Sparano, Judith A. Mackall, in Cardiac Intensive Care (Third Edition), 2019. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780323529938000163, URL: https://www.sciencedirect.com/science/article/pii/B9781416037736100205, URL: https://www.sciencedirect.com/science/article/pii/B9780323399685000032, URL: https://www.sciencedirect.com/science/article/pii/B9780323478700000374, URL: https://www.sciencedirect.com/science/article/pii/B9780750675727500242, URL: https://www.sciencedirect.com/science/article/pii/B9780323401692000160, URL: https://www.sciencedirect.com/science/article/pii/B9780323523561000220, URL: https://www.sciencedirect.com/science/article/pii/B9780750675840000136, URL: https://www.sciencedirect.com/science/article/pii/B9780323523561000244, Goldberger's Clinical Electrocardiography (Ninth Edition), 2018, Supraventricular and Ventricular Arrhythmias in Acute Myocardial Infarction, Ventricular and Supraventricular Arrhythmias in Acute Myocardial Infarction, Brian Olshansky MD, ... Nora Goldschlager MD, in, Ary L. Goldberger MD, FACC, ... Alexei Shvilkin MD, PhD, in, Goldberger's Clinical Electrocardiography (Ninth Edition), Ventricular Arrhythmias in Ischemic Heart Disease, Ziad F. Issa MD, ... Douglas P. Zipes MD, in, Clinical Arrhythmology and Electrophysiology (Third Edition), Ventricular arrhythmias upon reperfusion typically manifest as bursts of PVCs with long coupling intervals and, Electrocardiographic Technology of Cardiac Arrhythmias.