Card iac Arrhythm ias du ri ng Theophylli ne Toxicity

To examine the effects of theophylline toxicity on cardiac rhythm, patients underwent continuous ambulatory ECG recording during acute theophyllme toxicity and recovery. The patients, who were recruited from inpatient wards, intensive care units, and emergency departments of a University Medical Center and a Veterans Administration Medical Center, had serum theophylline concentrations (STC) greater than 30 mgfL. There were 14 men and two women with a mean age of 66 years. Fourteen patients had COPD and developed toxicity following long-term thenphylline overmedication. Two patients had asthma and ingested an intentional overdose. The STC at the onset of ECG recording ranged from 23 to 67 mgfL. The principal rhythm was sinus in 15 patients; one patient had atrial fibrillation. Sinus tachycardia (heart rate > 100/mm) was common, and heart rate fell in proportion to STC as toxicity resolved. Supraventricular ectopic heats (SVEs) were noted in seven patients with multiple runs of SVE being present in four. One patient developed multifocal atrial tachycardia (MAT) during toxicity that resolved spontaneously. During the 11 ± 8 hours of recording during toxicity (STC >20 mg/ L), 80 percent of patients had ventricular premature beats (VPBs), 44 percent had paired VPBs, and 25 percent had ventricular runs. One elderly patient with heart disease developed sustained ventricular tachycardia (VT) when