What distinguishes narrow complex rhythms from wide complex rhythms?

Narrow complex rhythms are characterized by a QRS duration of less than 0.12 seconds. This measurement indicates that the electrical impulse is conducted through the ventricles via the normal conduction pathway, allowing for a timely contraction. Narrow complex rhythms typically arise from supraventricular sources, such as the atria or the junctional tissues, leading to a rapid and organized electrical activity.

In contrast, wide complex rhythms, which have a QRS duration of 0.12 seconds or greater, suggest that the impulse originated in the ventricles or has been conducted abnormally, often due to underlying issues such as a bundle branch block or ventricular ectopic rhythms. The distinction in the duration of the QRS complex is crucial for determining the origin of the rhythm and for guiding appropriate clinical management. Understanding this difference in duration and its implications helps healthcare providers accurately assess and treat patients with various cardiac conditions.