Irregular cardiac rhythm in a woman with asthma.

An obese (height, 62 inches; weight, 252 lb; body mass index, 46.2 kg/m2) 54-year-old woman with long-standing asthma and chronic cigarette smoking came to the hospital with an acute asthma attack manifested by dyspnea, wheezing, and chest tightness. Her electrocardiogram showed an irregular atrial tachycardia (114 P waves/minute) with multiple P-wave morphologies, frequent aberrant ventricular conduction, and one nonconducted P wave (Figure). Thus, the patient had multifocal atrial tachycardia, also called chaotic atrial mechanism (1), chaotic atrial tachycardia (2), or chaotic atrial rhythm (3). As the name implies, multifocal atrial tachycardia has generally been thought to originate from multiple atrial foci, but because variable conduction of impulses from a single focus cannot be excluded, the mechanistically noncommittal term multiform atrial tachycardia has been suggested (4). Figure 1 Electrocardiogram obtained at admission. See text for explication. Multifocal atrial tachycardia usually is seen in patients who are severely ill with a noncardiac problem, which often, as in this patient, is an acute exacerbation of chronic lung disease. Beta-adrenergic agonists and theophylline may be contributing factors. Multifocal atrial tachycardia is often mistaken for atrial fibrillation. Although it is a distinct nosological entity, multifocal atrial tachycardia is often preceded or followed by other atrial arrhythmias, such as atrial fibrillation, atrial flutter, and other atrial tachycardias (2, 4). Multifocal atrial tachycardia usually disappears when the underlying medical problem has been controlled.