External non-invasive pacemaker units are utilized for which type of pacing?

External non-invasive pacemaker units are specifically used for ventricular pacing, which is essential when the heart's natural pacemaker fails to provide the necessary electrical impulses for a regular heartbeat. In situations where the ventricles are not contracting properly or the heart rate is significantly slow (bradycardia), an external pacemaker can stimulate the ventricles to contract effectively and restore an adequate heart rate.

Ventricular pacing is crucial in certain emergency situations or during transport when rapid intervention is necessary to maintain hemodynamic stability. The pacing leads are placed on the patient's chest, delivering electrical impulses that facilitate contraction of the ventricles, ensuring adequate blood flow to the body.

Meanwhile, the other types of procedures listed serve different purposes. Atrial pacing typically involves stimulating the atria, while cardioversion and defibrillation are used for specific arrhythmias or to reset the heart's rhythm rather than provide continuous pacing support. Thus, the focus on ventricular pacing highlights the role of external non-invasive pacemakers in addressing immediate and critical heart rate issues.