Which of the following is listed as a precaution for transcutaneous electrical nerve stimulation (TENS)?

• A. Spinal cord stimulator
• B. Heart disease
• C. Eyes
• D. Presence of a demand-style pacemaker

Answer: (D)

The main idea is safety around implanted electronic devices. Transcutaneous electrical nerve stimulation can emit electrical signals that travel through the body, and those signals can be picked up by implanted devices in the chest. A demand-style pacemaker continuously monitors the heart and only paces when it senses that the heart needs it. External electrical energy from a TENS unit can be misinterpreted by the device as intrinsic heart activity or interfere with its sensing, potentially causing inappropriate pacing inhibition or pacing when it isn’t needed. That risk is why having a demand-style pacemaker is listed as a precaution during TENS use. In practice, clinicians screen for such devices and coordinate care or consider alternative therapies. The other options aren’t standard precautions for TENS in the same way; they don’t carry the same clear risk of electrical interference with critical cardiac devices.