Notice to Cardiac patients

Open heart surgery – risk of Mycobacterial infection

There is a risk that heater cooler units (HCUs) used in cardiac surgery may be contaminated with Mycobacterium chimaera, and that exposure of patients to the aerosolised exhaust from these units in the operating theatre may lead to the development of a serious infection up to several years post-surgery. A small number of cases of serious Mycobacterium chimaera infections have been reported in the United States, the UK/Europe and one case in Australia (Qld).

At all Healthscope hospitals that perform open heart surgery the following strategies are in effect to ensure the safety of our patients:

  • We work closely with the Department of Health and the manufacturers of the heater cooler units to ensure best practice
  • We strictly adhere to the most current version of the cleaning and disinfection instructions provided by the heater-cooler device’s manufacturer.
  • We only use sterile water recommended for the filling or refill the heater-cooler units
  • When making the ice needed for patient cooling during surgical procedures we use only sterile water or water that has been passed through the recommended filtration.
  • The heater-cooler’s vent exhaust is directed away from the operating table, or outside of the operating theatre to help prevent any droplets of water from the heater cooler’s water tank coming into contact with the patient
  • Regularly clean, disinfect and conduct regular maintenance for heater-cooler devices according to the manufacturers’ instructions to help prevent bacterial growth.
  • Regularly check for and immediately remove from service heater-cooler devices and accessories that show discoloration of internal surface’s or cloudiness in the fluid lines/circuits which may indicate bacterial growth.

Frequently Asked Questions

Mycobacterium chimaera is a type of bacterium known as a non-tuberculous mycobacterium (NTM). These are commonly found in the environment, including soil and water. NTM are generally not harmful although in very rare cases they can cause infection in surgical patients, especially in people with weakened immune systems. The infection may be treated with antibiotics.

People who have had open heart surgery during which an artificial (prosthetic) heart valve or other prosthetic material has been inserted are at the highest risk of Mycobacterium chimaera infection.

If you have had this type of heart surgery and you have the following symptoms, contact your doctor or call the hospital where the surgery was performed without delay:

  • prolonged fever
  • unexplained fever
  • night sweats
  • unintentional weight loss
  • marked fatigue
  • increased shortness of breath
  • joint or muscle pain
  • nausea, vomiting or abdominal pain
  • pain, redness, heat or pus around the surgical site.

Infection is a possible complication of surgery . A small number of people who have heart (cardiac) surgery (between three and six per cent) will develop an infection. This may happen shortly after their surgery or many months, even years, later.

A possible source of infection in a very small number of people who have open heart surgery is a bacterium called Mycobacterium chimaera. This bacterium has been found to contaminate the water tanks of a medical device called a heater cooler unit. This device is used to regulate body temperature during open heart surgery.

The risk of the bacteria being transferred from the heater cooler unit to the person having heart surgery is extremely low. Fewer than 100 people worldwide have contracted the infection when having heart surgery. This risk is being further minimised with more regular changing of the water in the heater cooler unit tanks and through the introduction of disinfection measures.

To date, no Victorians have been found to have this infection as a result of open heart surgery.

The risk of surgical complications, including infections, will be discussed with you as part of the informed consent process.

It is important to note that the risk for mycobacterial infection from heater cooler units is considered to be very low compared to the overall risk of surgical and valve infection. If you have particular questions about this, or any other type of infection, you should discuss these with your specialist surgeon during your pre-admission appointments.

Victorian health services where open heart surgery is performed, and the Department of Health and Human Services, have been working together to further minimise the risk of Mycobacterium chimaera infection. Health services have been testing and monitoring heater cooler units and are continuing with strict maintenance and hygiene measures. Some of the older units thought to be more prone to contamination have already been replaced.

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