cardiovascular disorders
Ventricular Tachycardia (VT)
Introduction
Ventricular tachycardia is≥3 consecutive ventricular beats at a rate≥120 beats/minute. Symptoms depend on duration and vary from none to palpitations to hemodynamic collapse and death. Diagnosis is by electrocardiography. Treatment of more than brief episodes is with cardioversion or antiarrhythmics, depending on symptoms. If necessary, long-term treatment is with an implantable cardioverter defibrillator. (See also Overview of Arrhythmias .) Some experts use a cutoff rate of≥100 beats/minute for ventricular tachycardia (VT). Repetitive ventricular rhythms at slower rates are called accelerated idioventricular rhythms or slow VT; they are usually benign and are not treated unless patients have hemodynamic symptoms. Most patients with VT have a significant heart disorder, particularly prior Acute Myocardial Infarction (MI) or a Ventricular tachycardia may be monomorphic or polymorphic and nonsustained or sustained. Monomorphic VT: Single abnormal focus or reentrant pathway and thus regular, identical-appearing QRS complexes Polymorphic VT: Several different foci or pathways and thus irregular, varying QRS complexes Nonsustained VT: Lasts<30 seconds Sustained VT: Lasts≥30 seconds or is terminated sooner because of hemodynamic collapse Catecholaminergic Polymorphic Ventricular Tachycardia is a genetic disorder affecting intracellular calcium regulation in cardiac tissue. Patients are predisposed to atrial and/or ventricular tachyarrhythmias and sudden cardiac death, particularly during increased adrenergic activity. VT frequently deteriorates to Ventricular Fibrillation (VF) and thus 