ladder diagram

a diagrammatic representation of the routes of cardiac conduction as determined by electrocardiographic recording, used in diagnosing arrhythmias. Vectors describing the origins and paths of individual normal or ectopic impulses as well as points of blocks to conduction are drawn across a series of horizontal lines representing the atria, atrioventricular node, ventricles, and sometimes additional regions of the conduction system. See illustration. Called also laddergram.

Ladder diagrams depicting different electrocardiographic (ECG) patterns. (1), Normal beat; (2), first degree atrioventricular block; (3), atrial premature complex, with an inverted P wave on the ECG; (4), ectopic impulse arising in the His bundle and conducting anterograde to the ventricle and retrograde through the AV node to the atrium; (5), ventricular ectopic beat conducting retrograde through the His bundle and AV node to the atrium. A star marks the point of origin of each premature or ectopic impulse. AV, atrioventricular.