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Venlricular tachycardia is usually a regular tachycardia with broad QRS complexes and a rate of 100 to 200 bcats/min. Although a distinction from paroxysmal supraventricular tachycardia is often difficult when the QRS complex is widened, a diagnosis of ventricular tachycardia is strongly suggested by atrioventricular dissocialion, fusion beats, and ORS duration > 0.14 sec or a QRS axis between 90° and – 180°. Severe myocardial ischemia, acute myocardial infarction, digitalis toxicity, or heart failure commonly precipitates ventricular tachycardia in the elderly.
Sustained ventricular tachycardia requires immediate attention. If ventricular tachycardia is well tolerated hemodynamically, a rapid IV infusion (bolus) of lidocaine 50 to 75 mg, followed by anolher 50 mg 2 min later, may be given initially. Recurrent ventricular tachycardia or lidocaine-resislant ventricular tachycardia may be treated with IV procainamide or ?-blocking drugs. Current data, derived largely from studies of younger patients, suggest that hrctyliurn is the most effective

drug for ventricular tachycardia lhat is refractory to lidocaine. In the elderly, as in younger palienls. venlricular tachycardia associated with hypotension or syncope requires immediate electrical cardioversion.
Ventricular tachycardia precipilated by an acute event, such as myocardial infarction or digitalis toxicity, has a low recurrence and does no! require chronic prophylaxis. However, venlricular tachycardia without an obvious precipilanl is known as primary ventricular tachycardia; il has a l-yr recurrence of about 35% and requires aggressive prophylaxis. In one study, the mean age of patients who had an out-of-hospital cardiac arrest caused by a primary arrhythmia was dS.5 yr, and these patients had a l-yr mortality rate of 29%.
The most promising approach to patients wilh primary recurrent symptomatic ventricular tachycardia appears to be intracardiac programmed electrophysiologic stimulation, a technique in which the malignant arrhythmia is induced and the efficacy of various antiarrhythmic agents in preventing it is assessed in a special catheterization laboratory. In a randomized trial of 57 patients (86% men. mean age 59 yr). antiarrhythmic Iherapy determined by this method resulted in a lower rate of symptomatic ventricular tachyarrhythmia than did an empiric approach. Olhcr studies show a marked reduction in the I- to 2-yr mortalily rale when drug therapy tor recurrent ventricular tachycardia is determined by this technique. A less-invasive but similarly labor-intensive approach using ambulatory KCG monitoring with or without exercise testing has also been successful, ;is demonstrated by the preliminary results of the multicenler ESVCM (Hlectrophysiology Study Versus Electrocardiographic Monitoring) trial.
The availability of amiodarone and several other new antiarrhythmic drugs increases the likelihood that a successful medical regimen car be found. Patients in whom neither of the above approaches is successful are possible candidates for an automatic implantable cardioverter-defibrillator or endocardial resection guided by intraoperative mapping. In a large series of patients with recurrent venlricular tachycardia or venlricular fibrillation, about lh were treated wilh these invasive approaches. Long-term survival was similar in elderly and younger patients, although surgical mortalily was higher in the elderly.

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