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Announcement About Heater-Cooler Units Use in Cardiac Bypass Surgery

The Centers for Disease Control and Prevention (CDC) issued a public announcement on Thursday, Oct. 13, 2016, regarding the risks associated with heater-cooler units, which hospitals use during open-chest cardiac bypass surgery. During an ongoing investigation into the device, the CDC discovered that the Stöckert 3T heater-cooler devices manufactured by LivaNova PLC (formerly Sorin Group Deutschland GmbH) may put patients at risk for infection from slow-growing bacteria known as Mycobacterium chimaera.

While the risk appears to be very low and no cases of infection related to these devices have been identified at Johns Hopkins, we wanted to provide additional information about the heater-cooler devices, Mycobacterium chimaera and answers to common questions.

About Heater-Cooler Devices

These heater-cooler devices are used during cardiopulmonary bypass to help regulate the temperature of the patient’s blood during cardiac, vascular or transplant surgery. They are an essential part of the equipment needed for these types of procedures.

The machine uses water to warm or cool the blood as it is circulated outside of the patient’s body. The water in the device does not come into direct contact with the patient or the patient’s blood.

About the Bacterium

Nontuberculous mycobacteria (NTM) are a type of bacterium often found in soil and water. These organisms can cause infections but rarely make healthy people sick. The specific type of NTM involved is called Mycobacterium chimaera. Transmission of NTM from environmental sources to people can occur, with higher risk among immunocompromised patients. NTM infection can sometimes be associated with certain types of medical care or necessary procedures, such as surgery. 

Common Questions

What is the risk of infection?

Overall, the risk of infection from these devices is thought to be extremely low. No cases of infection related to these devices have been identified at Johns Hopkins. In hospitals where infection has been identified, the risk of infection was substantially less than 1 percent. Initial information suggests that most of the infections affected patients who had prosthetic heart valves or graft material implanted at the time of their surgery.

What symptoms might indicate an infection?

Patients who have had cardiopulmonary surgery and who are experiencing symptoms such as night sweats, muscle aches, weight loss, fatigue or unexplained fever should seek a medical evaluation. These symptoms are fairly general and may be present for a variety of reasons, so they do not necessarily indicate infection.

How long does it take for symptoms of an infection show up?

NTM cases associated with this device have usually been diagnosed within several months after a cardiopulmonary bypass surgery involving heater-cooler unit exposure.

Is an NTM infection contagious?

No, the bacteria cannot be spread to others from an infected patient. Also, it is important to keep in mind that NTM is common in soil and water but rarely makes healthy people sick.

Should everyone exposed to these devices during cardiac bypass surgery receive antibiotics?

The risk that patients will develop an infection following exposure to a heater-cooler unit is extremely low. There is no evidence that giving antibiotics to potentially exposed patients will prevent infection, and giving antibiotics can lead to harmful side effects.

How did the affected devices become contaminated?

NTM is common in water and soil. Recent CDC findings are consistent with previous reports suggesting that the heater-cooler units were contaminated during production. Testing conducted by the manufacturer in August 2014 found M. chimaera contamination on the production line and water supply at the 3T manufacturing facility.

Are the devices being recalled?

In 2015, the manufacturer recalled the instructions for use, but not the device itself. Information provided by the manufacturer reminded users that while water from the device itself is not intended to contact the patient directly, under certain circumstances, due to fluid leakage and/or aerosolization, NTM could reach a patient's surgical site. Heater-cooler devices are required equipment for several types of complex cardiac and transplant procedures.