The Ashman phenomenon

In the presence of atrial fibrillation, impulses of supraventricular origin that are transmitted through the ventricles during periods of relative refractoriness to impulse conduction exhibit anomalous configurations. These "aberrant beats" can be difficult to distinguish from ventricular ectopic beats, and groups of aberrant beats may be mistaken for ventricular tachycardia. Richard Ashman, PhD, a physiologist at Louisiana State University School of Medicine in New Orleans, noted that ventricular refractoriness varied with the lengths of cardiac cycles; that aberrant beats typically ended short cycles following long cycles; and that aberrant beats often have a right bundle branch block configuration. This observation, known as the "Ashman phenomenon," has become a principle of cardiology. Its recognition may allow clinicians to distinguish aberrant beats from ventricular ectopy. Ashman made a variety of other fundamental contributions to electrocardiography and was also an accomplished poet.