What are the Guidelines for Permanent Pacemaker Implantation? What is the indication for EP testing in patients with preexcitation (WPW)? EPS is indicated in symptomatic patients with WPW (syncope, dizziness, recurrent palpitations, etc.) to determine the mechanism of the arrhythmias (orthodromic SVT, antidromic SVT, atrial fibrillation with rapid ventricular response via accessory pathway, and other SVTs), the electrophysiologic properties of the accessory pathway (primarily refractory period) and properties of the normal conduction system. In addition it helps to localize the accessory pathway and to plan the appropriate therapy. Radiofrequency catheter ablation is frequently the preferred type of therapy, with a success rate of more than 95% in experienced labs. Is EPS recommended in patients with bifascicular block? EPS is recommended only if patients have symptoms of syncope, near syncope or dizziness. Sudden death is patients with bifascicular block may not be caused by the development of complete AV block, but rather from ventricular tachycardia when there is serious heart disease. The progression to complete heart block is uncommon. Is there a role for EPS in nonischemic cardiomyopathy with sustained ventricular tachycardia? EPS has a role in this form of VT as it delineates the mechanism of VT; in particular, it is critical to diagnose bundle branch reentry, a specific form of ventricular tachycardia. This is due to a macroreentrant circuit utilizing the His-Purkinje system. This VT can be cured in virtually all instances by simply ablating the right bundle branch. What is ibutilide? It is a new type III antiarrhythmic that prolongs the cardiac action potential (and refractory periods). It is approved for acute intravenous use to convert recent onset atrial fibrillation or atrial flutter and as an alternative to direct current cardioversion. It is effective in about 65% of patients with atrial flutter and in about 40% of patients with atrial fibrillation. It has several side effects; the most important is the development of polymorphic ventricular tachycardia (torsade de pointes) which can be life threatening. This complication is uncommon, but observation on telemetry is essential. What is the role of EP study in patients with prolonged QT syndrome? Prolonged QT syndrome is a disorder in which certain channels in the cardiac cell membrane are defective. This results in prolongation of the action potential duration and can trigger polymorphic VT. Electrophysiologic study has a limited role in this disorder. However, some cases of occult long QT syndrome manifest only upon infusion of isoproterenol or epinephrine.