Concerns have been raised across the medical profession regarding the development ofan invasive, yet slowly developing, infection in patients following cardiothoracic surgery.

The cause of the development of the infection, called Mycobacterium chimaera (M. Chimaera), has been traced back to a Sorin 3T heater-cooler machine which is commonly used during cardiothoracic procedures such as coronary bypass or valve replacement operations.

The Sorin 3T heater-cooler machine is manufactured by the Sorin Group which is now part of the LivaNova Group. In America, the machine is known as the Stockert 3T system.

Heater-cooler systems are commonly used during cardiac surgeries, as well as other medical and surgical procedures, to warm or cool a patient with the aim to optimize patient care and improve patient outcomes. Devices such as the Sorin 3T heater-cooler unit utilise water tanks which provide temperature-controlled water to warming or cooling blankets covering the patient during surgery.

According to the Food and Drug Administration (FDA), the federal agency of the United States Department of Health and Human Services and Public Health England, there is the potential for the Sorin 3T heater-cooler system to carry Mycobacterium chimaera (M. Chimaera) bacteria in its water tanks and transmit infection to the patient during the procedure through the air and via the device’s exhaust vent.

A recent study demonstrates a link between the Mycobacterium chimaera (M. Chimaera) which has infected European patients undergoing open-chest cardiac surgery and the Sorin 3T heater-cooler system. This has been supported by the Sorin Group’s own testing during which it found contamination in the water supply and production line at its heater-cooler manufacturing facility in Germany.

Between 2010 and 2015 the FDA was informed of 32 cases of the infection – 8 cases in the US and 24 cases in Europe – linked to this particular device. Examination of past medical records is leading to this number steadily increasing. Recently, inquests have been held or arranged into the death of patients who have suffered from this complication. Coroners have recorded that deaths have been caused by the Mycobacterium chimaera (M.Chimaera) infection following heart surgery.

The difficulty which faces doctors in diagnosing and treating patients who have developed a Mycobacterium chimaera (M. Chimera) infection is that the bacterium is very slow growing and it may take several months or years for patients to develop any symptoms. The infection proves fatal to approximately half of affected patients but until recently, Mycobacterium chimaera (M. Chimaera) has not been routinely tested for.

Symptoms of Mycobacterium chimaera (M. Chimaera) are:

  • Fever lasting more than one week

  • Loss of energy

  • Night sweats

  • Joint or muscle pain

  • Redness, heat or pus around a surgical incision

  • In infants, a failure to grow or gain weight

  • Difficulty breathing

  • Persistent cough or cough with blood

  • Nausea

  • Vomiting

Since September 2014, all newly manufactured Sorin 3T Systems have been subjected to a cleaning and disinfection procedure as part of the manufacturing process and the contamination is believed to have been eliminated from the Sorin 3T heater-cooler production line.

In 2015 Public Health England published advice to providers of cardiothoracic surgery warning that a high percentage of UK devices may be contaminated. Sorin has issued a Field Safety Notice advising that all machines be tested.

Public Health England also suspects that the infection risk may be applicable to other similar machines.

Hospitals which have provided treatment to patients using a Sorin 3T System have been directed to inform the operating surgeons and doctors of the possibility that patients may have been subjected to an Mycobacterium chimaera infection and to determine a method for patient follow-up and monitoring. Patients who become unwell after valve replacement surgery should be tested for Mycobacterium chimaera infection. There is, however, considerable concern at the delay in information about the risk of Mycobacterium chimaera (M. Chimaera) being publicised to doctors and patients.

Freeths LLP is currently advising relatives of patients who have been infected by Mycobacterium chimaera from the Sorin 3T heater-cooler system.

Should anyone have any queries regarding a potential claim relating to a Mycobacterium chimaera infection following heart surgery, please contact Paul Balen, Consultant, on 0845 0503289, or, for further information.