Re-entry loop

A re-entry loop is a pathological circuit in cardiac tissue where an electrical impulse continuously circulates, often due to a unidirectional block and slowed conduction. This mechanism is crucial in understanding arrhythmias, particularly atrial fibrillation and ventricular tachycardia, as it can lead to sustained abnormal heart rhythms. A key example is the re-entry loop in Wolff-Parkinson-White syndrome, which can result in paroxysmal tachycardia and potential hemodynamic instability.