Sprawled out at home on the couch with your iPad, dozing off as you read the news, you’d never expect to be putting your health at a serious risk. But you could be doing exactly that if you have an implanted heart device, according to recent findings from a small study presented at the Heart Rhythm Society in Denver and reported by HealthDay News.

The study was led by 14-year-old high school freshman Gianna Chien, with help from her father, Walter Chien, MD, a cardiologist in Stockton, California. Together, they tested 27 patients at Central Valley Arrhythmia who had implantable cardiac defibrillators (ICDs), pacemakers or loop recorders in their hearts.

Researchers found that in 30 percent of subjects, tiny magnets imbedded in the iPad 2 and its Smart cover disrupted the heart device when placed on the person’s chest; this suspended the mechanism’s ability to prevent sudden rapid heart rates. What’s more, scientists said that for those with common heart diseases, such as tachycardia and fibrillation, falling asleep with an iPad could be potentially fatal.

Chien said the risks will continue to be problematic unless the design of tablets is changed. “With the aging of the population, there’s an expected increase in ICD placement, and, with more than 100 million iPads sold, it’s a concern,” she said.

But findings noted that no electromagnetic interference was found when the iPad was placed at a normal reading distance from the patient’s chest. In addition, researchers only saw effects in patients with ICDs, not those wearing pacemakers or loop recorders. Also, people with more fat on their bodies seemed less susceptible to the potential interference.

Last year, research found that the iPad 2 could interfere with magnetically programmable shunts in the brain. Other devices with imbedded magnets, such as cell phones and MRI machines, can also affect ICDs.

A 2008 study suggested that mobile phones—and by extension, tablets—could reduce sperm potency in men who use the devices for more than four hours a day.

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