Heater-cooler devices used in heart surgery have been linked to serious bacterial infections with non-tuberculous mycobacteria (NTM). The devices are used in hospitals to heat and cool patients’ blood temperature during heart surgery.

Recent reports raise questions about the safety of the design of the products and the effectiveness of the manufacturers’ instructions about reducing the risk of contamination. Some of the units can release contaminated water within the unit into the air and infect patients undergoing surgery.

Rami Sommerstein, of Bern University Hospital in Switzerland and a lead author of a November 2016 study of infections caused by heater-cooler devices said that: "It is surprising that a global outbreak like this could go unnoticed for years. This dangerous infection has put many patients at risk all over the world.

"Now that we know [heater-cooler devices] are the source, individual action from the different players (healthcare institutions, manufacturers, etc.) is needed to contain the ongoing patient risk. The most important action a hospital can take is to remove contaminated [heater-cooler devices] from the operating room and other critical areas. That is the only way to ensure that patients are protected from this infection moving forward."

The risk of infection was identified in around 2014 following reports of NTM infections in the USA, Switzerland, the Netherlands and Germany in patients following heart surgery. Public Health England (PHE) published an investigation into the risks in the UK in 2015.

Serious infections of the heart and sepsis were linked to LivaNova PLC (formerly Sorin Group Deutschland GmbH) and Marquet Heater-cooler units. John Wilkinson, MHRA Director of Devices, said: “We are aware of a small number of patients who have undergone cardiac surgery, where cardiopulmonary bypass has been used, and subsequently developed endocarditis and/or septicaemia associated with Mycobacterium chimaera.”

Endocarditis is a rare and potentially fatal infection of the inner lining of the heart which can lead to heart failure and stroke. Septicaemia, more commonly known as blood poisoning, is an equally serious condition which if left untreated can harm vital organs and ultimately be fatal.

It can take months and even years following exposure during surgery before a patient develops symptoms. Symptoms include high temperature, chills, muscle pain and an elevated heart rate.

In 2015 PHE identified 17 patients with endocarditis due to the Mycobacterium chimaera following heart valve replacement or repair surgery in 10 different NHS Trusts. However, the PHE estimated that up to 42 heart surgery patients were infected between 2007 and 2014. The PHE noted that the numbers affected might be higher given reports from Switzerland that suggested over 16 times the estimated incidence in the UK.

PHE said that it is not clear whether the risk is limited to a particular model or manufacturer. There has been no information released of incidents in Northern Ireland or Scotland.

Chris Haan, an associate solicitor in Leigh Day’s product liability team, said: “Patients should be able to expect that heater-cooler devices used during heart surgery are safe and that appropriate steps are taken to reduce the risk of infection.”

If you have undergone heart surgery and have been experiencing the symptoms of an infection you should contact your hospital or surgeon for clinical advice as a matter of urgency.