What condition is described as triggered activity?

Triggered activity refers to a phenomenon where cardiac cells depolarize more than once following a single impulse. This occurs when the initial depolarization generates secondary depolarizations, usually due to abnormal ionic currents, which can lead to extrasystolic beats. This abnormality can be seen in cases like early after-depolarizations (EADs) or delayed after-depolarizations (DADs), both of which are mechanisms by which triggered activity can arise.

Understanding the mechanisms of myocardial depolarization is crucial in telemetry and cardiac monitoring, as these abnormal depolarizations can lead to arrhythmias. In contrast, other options refer to distinct physiological processes: changes in ion concentration or spontaneous depolarization contribute to different types of electrical activity in cardiac cells, but do not specifically define triggered activity. The slow response of pacemaker cells relates to how these cells react to external stimuli, which differs from the rapid-fire nature of triggered activity.