Information for adult open heart surgery patients

London Health Sciences Centre (LHSC) is notifying approximately 2,200 former open heart surgery patients of the extremely low risk of infection related to potential exposure to bacteria during their procedure. Letters have been mailed to patients advising them of situation, and letting them know who to contact should they have any questions or concerns.

Heater-cooler units are used to heat and cool blood during open heart surgery. Some of these units have been linked to a Mycobacterium chimaera infection according to safety alerts issued to hospitals across North America by Health Canada and Public Health Ontario and the Federal Drug Administration (FDA) and Centers for Disease Control (CDC) in the United States.

The risk of infection is extremely low, less than one per cent. At this time, we are not aware of any patients who have developed this infection following open heart surgery at LHSC.

Individuals who have had open heart surgery at LHSC should monitor for the following symptoms:

  • Night sweats
  • Muscle aches
  • Weight loss
  • Fatigue
  • Unexplained fever and redness, heat, or pus around the sternal surgical incision

Patients with any of the symptoms or who have been diagnosed with sarcoidosis since their heart surgery are advised to contact their family physician. Patients can also contact the hospital at 1-844-358-1050 between the hours of 9:00am and 5:00pm, Monday to Friday.

LHSC is monitoring the situation very closely and will continue to follow Health Canada’s guidance and direction related to the use of heater-cooler units.

Frequently Asked Questions:

What is the heater cooler device used for?
HCU are commonly used during cardiac surgeries to warm or cool a patient in order to optimize medical care and improve patient outcomes.

Which heater cooler device is used at LHSC?
LHSC currently uses the Sorin 3T heater cooler.

How does this device cause infection?
This device requires water to operate. Although the water in the circuits does not come into direct contact with the patient, there is the very low potential for contaminated water to transmit bacteria through the air and into the environment around the patient in the operating room.

What is Mycobacterium chimaera?
Mycobacterium chimaera is one of a group of bacteria called nontuberculous Mycobacterium (NTM), which is commonly found in the environment, including soil and water. NTM typically is not harmful; however it can in very rare cases cause infections in post-operative surgical patients, especially in people with weakened immune systems.

What is the risk of infection?
Overall, the risk is thought to be very low based on the available data, The Center for Disease Control in the United States estimates somewhere in range of 1 in 100 to 1 in 1,000 patients in hospitals where an infection has already been identified. Initial information suggests that patients who had valve implants were at highest risk.

What are the symptoms and how can we detect this infection?
The symptoms associated with this infection are non-specific but last for a prolonged period of at least two weeks and include:

  • Fever, night sweats
  • Unexplained weight loss
  • Muscle and joint pain and fatigue
  • Enlarged lymph nodes
  • Persistently draining surgical wound

What should I do if I have symptoms?
If you have these symptoms for more than two weeks, we recommend that you contact your family physician for a complete clinical assessment. LHSC has also established a contact number 1-844-358-1050 for further questions.

How long does it usually take for symptoms to develop?
As Mycobacterium chimaera is a slow-growing bacteria, it can take up to 4 years after surgery for symptoms to develop.

If I have been exposed to Mycobacterium chimaera, is there a risk to others?
No, the Mycobacterium chimaera bacterium cannot be spread from person to person.

Who are you contacting?
We are sending a letter to all patients that have had open heart cardiac surgery that involved the use of this particular medical device.

How is this infection treated?
If the medical assessment and analysis confirm a diagnosis of Mycobacterium chimaera, an antibiotic treatment is available and would be prescribed.

Are you still using this device in surgery?
We are currently using the units at LHSC and are strictly adhering to all cleaning protocols. No LHSC patients have developed a Mycobacterium chimaera infection post open heart surgery to date. If you have any concerns, please follow up with your family doctor or call the dedicated LHSC telephone line.


Patients with any symptoms are advised to contact their family physician. Patients can also contact the hospital at 1-844-358-1050 between the hours of 9:00am and 5:00pm, Monday to Friday