Swedish Medical Center recently sent letters to all patients who had undergone cardiovascular surgeries where a particular heater-cooler system had been used. The device, manufactured by LivaNova, a London-based medical device manufacturer, is used to warm and cool patients and had been used in 60% of hospitals. The letter from Swedish said “Upon notification by the FDA and CDC, Swedish Medical Center tested its heating and cooling devices and found NTM bacteria in several of the machines.”

The problem is that bacteria from the devices is believed to be found in aerosolized droplets of water from the heating and cooling loops. Dangerous levels of bacteria — Mycobacterium — were found to have grown in the devices and were being released into the air by the exhaust fan. Once released, the bacteria can settle into the patient’s open chest or infect other equipment used in the surgeries. The result can be a very slow-growing infection that may not be recognized for months or even years after exposure.

The FDA reported 32 cases of patient infections arising from the devices between 2010 and 2015, but acknowledged there may be many more that are unreported. The slow growing nature of the infections makes it difficult for doctors to relate it back to the use of a machine many months earlier.

The infections are difficult to treat, may become chronic, and can lead to death. More than 250,000 patients have had surgeries with this particular device, every year, so the number of infections could be substantial. Some lawsuits have already been filed against the manufacturer and these are likely to increase as more infections are diagnosed.