A single-chamber/unipolar pacemaker paces which chamber(s)?

A single-chamber/unipolar pacemaker paces which chamber(s)?

• A. Right atrium
• B. Right ventricle
• C. Either the right atrium or the right ventricle
• D. Both atria and ventricles

Answer: (C)

A single-chamber pacemaker delivers pacing to only one heart chamber. In a unipolar setup, there is one pacing lead delivering current to that chamber with the generator case serving as the return path, so pacing activity is localized to the chamber where the lead is placed. Therefore, such a device may be placed with the lead in the right atrium (pacing atrial) or in the right ventricle (pacing ventricular). It cannot pace both atria and ventricles—that would require a dual-chamber or biventricular system. This is why the best answer is that it can pace either the right atrium or the right ventricle.

A single-chamber pacemaker delivers pacing to only one heart chamber. In a unipolar setup, there is one pacing lead delivering current to that chamber with the generator case serving as the return path, so pacing activity is localized to the chamber where the lead is placed. Therefore, such a device may be placed with the lead in the right atrium (pacing atrial) or in the right ventricle (pacing ventricular). It cannot pace both atria and ventricles—that would require a dual-chamber or biventricular system. This is why the best answer is that it can pace either the right atrium or the right ventricle.