Heater Cooler Device & NTM Infection

In recent years, bacterial infections have been linked to contaminated medical devices used in open-chest surgeries.

Heater-cooler devices are commonly used to regulate a patient’s body temperature during bypass surgeries. But one popular brand of the devices manufactured by LivaNova (formerly known as Sorin Group), has been linked to the spread of serious and potentially life-threatening bacteria called nontuberculous mycobacteria, or NTM.

Experts attribute this serious complication to a design flaw shared by several different heater-cooler devices manufactured by at least five other companies, according to Kaiser Health News.

In 2020, LivaNova developed a new design to reduce but not eliminate NTM infections. According to a June 2022 update, the FDA found LivaNova’s cleaning and disinfection validation as well as its aerosolization testing adequate. CardioQuip and Gentherm Medical have yet to turn in testing results as of December 2022.

In 2015, the Centers for Disease and Control Prevention said it had “identified a need for increased vigilance for NTM infections by health departments, health care facilities and individual health care providers.”

The U.S. Food and Drug Administration (FDA) also issued concerns about NTM infections and heater-cooler devices. Patients are urged to continue to look for signs of potential infection long after medical procedures involving heater-cooler devices because of the delay between exposure and infection.

Early diagnosis and treatment is crucial to lower a patient’s risk of severe and sometimes permanent lung damage and other complications from NTM infections. Untreated infections can be fatal.

Nontuberculous mycobacteria (NTM), a group of bacteria found naturally in soil and water as well as in some animals, is involved in infections linked to heater-cooler devices.

The bacteria are capable of causing severe infection and resulting lung disease when a person inhales, or otherwise comes into contact with the organism, such as during an open-chest surgery involving heater-cooler devices.

During such procedures, heater-cooler devices are used to warm and cool a patient’s blood. The devices use water and that water can become contaminated with bacteria.

Heater-cooler devices can propel the organisms into the air. Then they can enter a patient’s body through incisions during surgery.

Nontuberculous mycobacteria (NTM) can cause severe lung disease especially in individuals with impaired immune systems. In some cases, severe NTM infections from heater-cooler devices can cause permanent damage to the affected person’s lungs.

NTM infections result in inflammation in the affected patient’s respiratory system. Although NTM can affect all organs of the body, the bacteria primarily affect the lungs.

NTM infections may take months or even years to develop following exposure to the bacteria.

Likewise, symptoms typically progress slowly. Symptoms of a NTM infection are also similar to other lung conditions, and therefore, it is common for the condition to be misdiagnosed or not diagnosed at all.

Although symptoms associated with lung disease due to NTM may come and go, generally the condition will become exceedingly worse over time.

Chronic Illness

Over half of the individuals acquiring a lung infection will experience lifelong recurring symptoms and/or complications even after treatment. NTM infections can become chronic conditions requiring ongoing treatment for some individuals, with severe lung disease having a direct impact on a patient’s quality of life, or even causing death in some instances, according to the American Lung Association.

A CT scan can show small nodules (an abnormal lump or swelling of cells) or, in some more advanced or destructive forms of the infection, cavities or holes in the lungs. But a definitive diagnosis of NTM infection is made through the evaluation of a culture of a specimen obtained from the respiratory system, such as a sample of the patient’s mucous.

A full diagnostic evaluation may include:

• Detailed medical history, including knowledge of a recent open-heart/open-chest surgical procedure
• Physical examination
• Computed tomography (CT) scan
• Sputum (or mucous) culture

TB-Like Symptoms

NTM does not cause tuberculosis (TB), although symptoms can be almost identical. Even though the conditions can look very similar in tests, NTM infections and TB are very different diseases. TB can also be spread from person to person, whereas NTM is not contagious.

Who Is Most Susceptible to Illness?

Individuals with weakened immune systems may be more susceptible to infection and possible lung disease. The FDA concluded that NTM infections appeared more frequently in patients having open-chest surgery and receiving an implanted device, such as a heart valve or vascular graft.

Other individuals more susceptible to NTM infections may include those with the following conditions:

• Unknown defect in their lung structure or immune system
• Lung damage from a pre-existing chronic obstructive pulmonary disease (COPD), such as emphysema, bronchiectasis and asthma
• Immune deficiency disorder, such as HIV or AIDs
• Severe or chronic pneumonia or chronic bronchitis

How Common is NTM?

NTM infections are typically rare, affecting about two in every 100,000 people in the U.S. each year. However, authors of a study published in the Journal of Thoracic Disease in 2014 pointed out a possible uptick over the last three decades.

About 50,000 to 90,000 people are living with NTM pulmonary disease in the U.S., with the disease more frequently affecting the elderly population. This number is increasing by about 8 percent every year, according to Insmed, a biopharmaceutical company.

Hospitals where at least one infection has been identified following surgeries using certain heater-cooler devices, especially LivaNova’s Stockert 3T, the NTM risk infection is one in 100 or one in 1,000 patients, the CDC said.

Treatment of NTM infections and/or resulting lung disease is most effective when started early.

A prolonged course of therapeutic treatment with a combination of drugs will need to be started immediately. However, recurrent infections with new strains of NTM or a relapse of the initial infection is not uncommon, according to the Journal of Thoracic Disease.

Some heart-valve patients who develop the infection following a cardiac surgery involving heater-cooler devices may require additional surgeries.

In any case, most treatment options of NTM infection are long and often accompanied by several side effects from antibiotics. Regular blood testing and/or vision and hearing tests may be necessary to make sure patients are handling the drugs well. However, if left untreated, NTM infections can become deadly.

Since the bacteria is often resistant to antibiotics and/or can become resistant over time, treatment often requires the use of two or more antibiotics to effectively combat the illness. Treatment typically continues until a patient’s respiratory cultures produce negative results for at least 12 months.