Don’t try this at home.

An irate, hospitalized man who had developed an irregular heartbeat reverted to a normal rhythm after security personnel subdued him with a Taser, a team of doctors reports in an upcoming issue of the Annals of Emergency Medicine.

The incident in Connecticut last month is the first to suggest a beneficial cardiac effect from a Taser, an electroshock weapon that emits an incapacitating jolt of electricity. Police and military forces worldwide use Tasers as nonlethal devices for restraining prisoners or suspects who pose a threat.

It’s usually the other way around. Tasers have come under scrutiny in recent years because of concerns that they can trigger injury or death. The devices have been blamed for dozens of deaths, and the U.S. National Institute of Justice is investigating taser-related deaths among people in custody.

In the Connecticut incident, the 28-year-old man had been pursued by police and had tried to evade them by spending up to 40 minutes in a frigid lake. The police eventually took him into custody and transported him to Hartford Hospital, where doctors saw that his body temperature had dropped to 89° Fahrenheit and that his pulse was racing up to 150 beats per minute.

More concerning was an electrocardiogram test that showed the man had an irregular heart rhythm known as atrial fibrillation, or atrial flutter, says physician Kyle Richards, a cardiology fellow at the hospital. This happens when electrical signals regulating the atria, or blood-receiving, chambers of the heart get out of sync with signals regulating the lower, more muscular pumping chambers. It’s a dangerous condition because blood flow gets bogged down and a patient risks developing clots, says Richards, who was summoned to check the patient when the atrial fibrillation was detected.

The man seemed amenable when Richards began a second electrocardiogram, but soon he became agitated, threatened hospital staff and indicated he would pull out his intravenous lines.

“I left the room at that point,” Richards says. Hospital security arrived and zapped the man with a single shock from a Taser.

The man remained awake and immediately afterward allowed Richards to resume the second electrocardiogram test. It showed that the man’s heart rhythm had abruptly returned to normal.

It might have been coincidence, says Richards, who teamed with fellow doctors Peter Kleuser and Jeffrey Kluger, both also at Hartford Hospital, to write up the case. “But Taser devices themselves can produce electrical changes in heart rhythms,” he says.

A Taser can fire a projectile dartlike electrode. In the Connecticut case, the researchers report, the security officer used a hand-held Taser X26 in drive mode, the kind that is applied directly to the subject — in this case, the man’s chest, the team reports.