MANAGEMENT OF CARDIAC ARRHYTHMIAS



Before initiating antiarrhythmic therapy, one must determine whether the arrhythmia should be treated. Any arrhythmia that causes symptomatic hypotension or sudden death should be sup­pressed. However, the situation in which the ar­rhythmia occurs dictates whether chronic, long-term therapy is necessary. For example, an epi­sode of ventricular fibrillation in a patient at the onset of an acute myocardial infarction does not necessarily require long-term drug therapy be­cause of the low likelihood of recurrence.

How­ever, ventricular fibrillation in a patient without an acute myocardial infarction carries a high risk of recurrence. Some patients may have arrhyth­mias that, while not life-threatening, produce dis­abling symptoms of dizziness or palpitations and require therapy. Rhythms that are tolerated well in patients with structurally normal hearts (for ex­ample, paroxysms of supraventricular tachycar­dia) may not be tolerated in patients with diseased hearts (for example, ischemic heart disease or mi­tral stenosis) and may require therapy. The de­cision to treat a patient with an asymptomatic tachyarrhythmia is more difficult. Certain ar­rhythmias, such as short episodes of asympto­matic nonsustained ventricular tachycardia, are in themselves harmless but may be forerunners of more serious sustained ventricular tachyarrhyth­mias. The decision to treat is complicated by the side effects, occasionally life-threatening, of an­tiarrhythmic drugs, such as exacerbation of ventricular arrhythmias in 5 to 15 per cent of cases. Even though patients with premature ventricular complexes and complex ventricular ectopy after myocardial infarction are at increased risk of sub­sequent sudden death, it is not clear that antiar­rhythmic treatment reduces the increased mor­tality.

Before beginning chronic antiarrhythmic ther­apy, factors contributing to the occurrence of the arrhythmia should be considered. These include digitalis excess, hypokalemia, Hypomagnesemia, hypoxia, thyrotoxicosis, and other severe meta­bolic derangements. Congestive heart failure, ane­mia, or infection should be corrected. Smoking, excessive alcohol intake, caffeine- or theophyl-line-containing beverages or foods, fatigue, emo­tional upset, and some over-the-counter drugs (for example, nasal decongestants) may exacerbate ar­rhythmias.







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