A rare, dangerous infection linked to a device commonly used in heart surgeries has prompted hospitals — including Maine’s two largest — to gauge the risks for thousands of past patients, at the urging of federal regulators.

Maine Medical Center in Portland said it is notifying more than 4,000 patients about the risk of the bacterial infection. Patients who have undergone open heart surgery at MMC over the last five years are potentially at risk.

MMC has seen no cases of the bacterial infection among its patients and stressed that the risk is low. But the hospital plans to issue the notices this week in accordance with federal recommendations.

The infection is tied to a device that circulates water to regulate the temperature of a patient’s blood and organs during bypass surgery. About 60 percent of U.S. hospitals that perform heart surgeries rely on the device, called the Sorin 3T heater-cooler.

The heater-cooler instruments may have become contaminated during their manufacturing in Germany, potentially putting patients at risk of the life-threatening infection, according to the U.S. Centers for Disease Control and Prevention.

The agency’s testing suggests a link between the heater-cooler devices and bacteria found in patients who were sickened in several states, including some who died as a result.

MMC has four of these machines, and Eastern Maine Medical Center in Bangor uses them for more than 350 heart surgeries each year.

EMMC has not issued notices but is “continuing to evaluate” the situation, according to a spokesman. The hospital reviewed all heart surgery cases dating back to 2010 and identified no infections resulting from use of the heater-cooler device, he said.

Central Maine Medical Center in Lewiston, the other hospital in Maine with a heart surgery center, does not use the device, according to a spokeswoman.

Who is at risk? The CDC is urging hospitals to notify patients who were exposed to the devices during open heart surgeries since Jan. 1, 2012. MMC is going back a bit further, to Oct. 1, 2011. The NTM bacteria are slow-growing, meaning infections may not show up for months. Some of the cases linked to the device so far were diagnosed up to several years after an open heart surgery.

Early information suggests that patients who had prosthetic implants could be at higher risk.

What is the risk of infection? It’s believed to be very low, according to the CDC. In hospitals where at least one infection has occurred, the risk is between about one in 100 and one in 1,000 patients, the agency reports.

MMC said it has tested its heater-cooler devices for the bacteria and all results came back negative. The hospital instituted new sanitizing protocols a year ago that exceed federal recommendations, according to a spokesman.

EMMC said it continues to follow the latest cleaning and use recommendations issued by the device’s manufacturer, the CDC and the Food and Drug Administration.

The NTM bacteria, commonly found in water and soil, rarely sickens healthy people, and infected people cannot spread it to others.

What are the symptoms? They may include night sweats, muscle aches, weight loss, fatigue or unexplained fever. Because those symptoms are nonspecific, diagnosis of an NTM infection can be missed or delayed, making the illness more difficult to treat, particularly in patients already weakened by heart disease. The CDC recommends that doctors consider checking for the infection among heart surgery patients who have unexplained chronic illness.

How can the device lead to infection? The bacteria can grow in a water tank on the unit. While the water isn’t designed to come into contact with the patient’s body, contaminated droplets may escape into the air of the operating room and infect the open chest cavity, according to the FDA.

Why are we just hearing about the risks now? Federal regulators acknowledge that they knew of the infection’s link to the heater-cooler devices by the summer of 2014. But they waited more than a year to issue a public alert about the risks, and held off until last month — more than two years later — on publicizing detailed recommendations for hospitals and patients, as Kaiser Health News reported.

Experts told the health news service that the cases are the latest to lay bare weaknesses in the nation’s system for identifying and responding to problems with medical devices.

Jackie Farwell

I'm the health editor for the Bangor Daily News, a Bangor native, a UMaine grad, and a weekend crossword warrior. I never get sick of writing about Maine people, geeking out over health care data, and...