In cardiac pacemaker coding, what does the second letter represent?

In cardiac pacemaker coding, what does the second letter represent?

• A. The chamber paced
• B. The chamber sensed
• C. The response to sensing
• D. The pacing rate

Answer: (B)

The second letter shows which chamber the pacemaker monitors for intrinsic electrical activity. In the standard three-letter code, the first letter tells you the paced chamber, the second tells you the sensed chamber, and the third describes how the device responds to that sensing. So the second position is all about sensing: if it’s atrial sensing, the device watches the atrium; if it’s ventricular sensing, it watches the ventricle; if it’s both, it watches both chambers. This is separate from the pacing rate, which isn’t indicated by these letters.

The second letter shows which chamber the pacemaker monitors for intrinsic electrical activity. In the standard three-letter code, the first letter tells you the paced chamber, the second tells you the sensed chamber, and the third describes how the device responds to that sensing. So the second position is all about sensing: if it’s atrial sensing, the device watches the atrium; if it’s ventricular sensing, it watches the ventricle; if it’s both, it watches both chambers. This is separate from the pacing rate, which isn’t indicated by these letters.