How is hemodynamically stable ventricular tachycardia terminated?

Termination of hemodynamically stable ventricular tachycardia may be attempted medically. Treatment is begun with intravenous lidocaine or procainamide, followed by a maintenance infusion if the drug is successful. Levels of the drug should be checked and used to guide maintenance infusion rates. Bretylium may be used if the rhythm is refractory to first-line drugs. Bretylium is associated with a high incidence of orthostatic hypotension. Although quinidine is available, its use is limited to the oral and intramuscular routes of administration because of the hypotension associated with intravenous use.

Other intravenous drugs that are still investigational include amiodarone and several class III agents.

How is medically unresponsive ventricular tachycardia treated?

Stable medically refractory ventricular tachycardia may be terminated by insertion of a temporary transvenous pacing wire and ventricular pacing. This method is most useful for patients who have frequent recurrences of a hemodynamically stable ventricular rhythm. There is a small risk (about 5%) of acceleration of the rhythm and/or inducing ventricular fibrillation. Provisions for immediate defibrillation should be in place when attempting pace termination. Pace termination should be done only by physicians with adequate training and experience. There is inadequate experience with transcutaneous pacing to recommend its use to terminate sustained ventricular tachycardia. Rhythms that are refractory to medical therapy also may be electrically cardioverted with synchronized DC shock and appropriate patient sedation.

Once the acute episode is terminated, how is recurrence prevented?

Any potentially reversible cause should be sought and treated”specifically, ischemia or electrolyte abnormalities. Antiarrhythmic drugs have been the mainstay of preventive therapy. Appropriate drug therapy has been guided by Holter monitor or electrophysiologic testing. When single-drug therapy has failed, combination regimens have been tried. The long-term clinical success of medical regimens is low. Sotalol and amiodarone are the most effective medications.

Recent technologic advances have given patients the option of an implantable antitachycardia cardioverter-defibrillator. Such devices are capable of sensing the rhythm continuously and responding with an appropriate algorithm (either pacing or defibrillation), as previously programmed by the physician. The success rate for rhythm termination is high. Studies are under way to determine if such devices prolong long-term survival. Additional options include ablation of the arrhythmia focus either with catheter or surgical ablation. Ablation and device therapy demand specialized training on the part of the physician.

This chapter deals with the indications for pacing in the setting of atrioventricular (AV) block. Decisions about pacing arise in one of three settings: (1) acquired AV block, (2) AV block associated with myocardial infarction, and (3) bifascicular and trifascicular block. The indications presented are those for which there is widespread agreement that pacing is indicated and for which survival benefit is expected. Indications for which there is not a consensus are excluded.

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