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Interference with cardiac pacemakers by cellular telephones.

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Hayes DL, Wang PJ, Reynolds DW, Estes M 3rd, Griffith JL, Steffens RA, Carlo GL, Findlay GK, Johnson CM. · 1997

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Cellular phones can interfere with pacemakers in 20 percent of tests, but serious effects only occur when phones touch the device directly.

Plain English Summary

Summary written for general audiences

Researchers tested 980 pacemaker patients with five different types of cellular phones to see if the phones interfered with their heart devices. They found that phones caused some type of interference in 20 percent of tests, but serious problems only occurred in 1.7 percent of cases when phones were held directly over the pacemaker. When phones were used normally at the ear, there was no clinically significant interference.

Why This Matters

This landmark 1997 study represents one of the first comprehensive investigations into electromagnetic interference between wireless devices and medical implants. The research demonstrates that while cellular phones can indeed interfere with pacemakers, the risk is largely confined to direct contact scenarios that don't occur during normal phone use. What makes this study particularly significant is its scale and methodology - testing nearly 1,000 patients with multiple phone types at maximum power transmission. The findings reveal a critical distinction between theoretical interference potential and real-world health risks. The study also identified important variables affecting interference rates, including pacemaker design (dual-chamber devices showed higher interference rates at 25.3 percent versus 6.8 percent for single-chamber) and the presence of protective filtering technology. This research helped establish safety guidelines that are still relevant today, even as wireless technology has evolved.

Exposure Information

Specific exposure levels were not quantified in this study.

Study Details

The aim of this study is to investigate Interference with cardiac pacemakers by cellular telephones

In this multicenter, prospective, crossover study, we tested 980 patients with cardiac pacemakers wi...

The incidence of any type of interference was 20 percent in the 5533 tests, and the incidence of sym...

Cellular telephones can interfere with the function of implanted cardiac pacemakers. However, when telephones are placed over the ear, the normal position, this interference does not pose a health risk.

Cite This Study
Hayes DL, Wang PJ, Reynolds DW, Estes M 3rd, Griffith JL, Steffens RA, Carlo GL, Findlay GK, Johnson CM. (1997). Interference with cardiac pacemakers by cellular telephones. N Engl J Med 336(21):1473-1479, 1997.
Show BibTeX
@article{dl_1997_interference_with_cardiac_pacemakers_2190,
  author = {Hayes DL and Wang PJ and Reynolds DW and Estes M 3rd and Griffith JL and Steffens RA and Carlo GL and Findlay GK and Johnson CM.},
  title = {Interference with cardiac pacemakers by cellular telephones.},
  year = {1997},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/9154765/},
}
PubMed: 9154765

Cited By (186 papers)

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Quick Questions About This Study

Yes, 1990s cellular phones interfered with dual-chamber pacemakers 25.3% of the time compared to only 6.8% with single-chamber devices. However, clinically significant interference only occurred in 1.7% of tests when phones were held directly over the pacemaker, not during normal ear use.
Yes, pacemakers without feed-through filters experienced interference rates of 28.9% to 55.8% from cellular phones, while those with filters only had 0.4% to 0.8% interference rates. This represents a dramatically lower risk for patients with filtered devices.
Yes, it's completely safe to hold your cell phone in the normal position over your ear if you have a pacemaker. The 1997 study of 980 patients found zero clinically significant interference when phones were used normally at the ear.
About 7.2% of pacemaker patients experienced symptoms during cell phone testing, though only 1.7% had clinically significant interference. The study tested 980 patients across 5,533 different phone-pacemaker combinations to determine these rates.
Twenty percent of the 5,533 pacemaker tests showed some type of cellular phone interference. However, only 6.6% demonstrated clinically significant interference, and serious problems occurred in just 1.7% of cases when phones touched the pacemaker directly.