Reversible electrocardiographic changes in severe acute asthma.

Previous reports have documented the occurrence of reversible electrocardiographic changes including right axis deviation, P pulmonale, right bundle-branch block, and ST-segment and T-wave abnormalities in patients with acute attacks of asthma. In a further systematic study, the electrocardiographs of 63 patients admitted with severe acute asthma have been evaluated. The most consistent change was an abnormally vertical P-wave axis in 78% of the patients. P pulmonale was present in 22% and right ventricular enlargement in only one patient. Right axis deviation, right bundle-branch block, and rhythm abnormality were not present in any patient. In 11%, ST-segment or T-wave abnormalities suggesting myocardial ischaemia were noted. These abnormalities persisted for up to nine days and were unexplained. Other ECG abnormalities in acute asthma may reflec positional changes of the heart due to overdistension of the lungs. All ECG changes resolved after clinical improvement.