The influence of exercise on atrial flutter.

To study the effect of exercise on atrial flutter the electrocardiogram was recorded continuously before, during and after low level treadmill walking in twenty-two ambulatory patients. Atrial flutter rates increased during exercise testing in four patients. Improved A-V conduction with consequent higher ventricular rates occurred during exercise in thirteen subjects. One patient, with 4:1 conduction at rest, continued with 4:1 block throughout exercise testing, was believed to be over-digitalized. During the recovery period after exercise, ten patients transiently developed periods of Wenckebach A-V block. Walking exercise induced 1:1 conduction in six patients and was promoted by the following circumstances: 1) atrial rates of 250/min or less; 2) inadequate dosage of digitalis; and 3) the administration of quinidine. For the patient with chronic atrial flutter, treadmill testing provides a simple method for demonstrating the range of changes of A-V conduction and for deriving implications for appropriate drug therapy.