Wednesday October 24, 2018
Monday, 12 February 2018 17:01

Kiwi open-heart surgery patients at small risk of infection

Bacteria was found in water in a number of blood-temperature regulating machines. Bacteria was found in water in a number of blood-temperature regulating machines. Stuff

Thousands of Kiwis who had open-heart surgery face a small, but serious risk of infection, due to a potentially contaminated device used in their procedure.

About 5900 patients who received artificial valves since 2013 at five major public hospitals have been sent letters from the Ministry of Health, via district health boards, telling them a device used in their surgery may have been contaminated with a germ.

One suspected case has already been identified and treated in New Zealand, the letter said, as officials confirm the machine is still in use.

The black exhaust, seen at the back of the machine, is the source of the possible contamination. Photo: CANTERBURY DHB

The rate of infection is estimated to be one in 5000 procedures, but the bacteria can take years to take hold, making it hard to identify the surgery as the cause of the issue.

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The device is a machine known as a heater-cooler, used in many open-heart surgeries to control the temperature of the blood.

About 5900 open heart surgery patients are being notified they may be at risk of infection due to a device used in their procedure Photo: Stuff

The units contained tanks of temperature-controlled water that was not intended to come in contact with the patient or their blood.

"Water within some of the heater-cooler units had become contaminated with bacteria and patients were potentially exposed to the bacteria when the water in the heater-cooler units became aerosolised during use," the ministry's chief medical officer Dr Andrew Simpson said. 

Those who had surgery from January 1, 2013, at five public hospitals across the country – Auckland, Starship, Waikato, Christchurch and Wellington, should have been notified or have letters en-route.

The heater-cooler unit, far left, used in open heart surgery across major hospitals in New Zealand has left patients with a small risk of infection from a germ that may have been present. Photo: CANTERBURY DHB

Those are the only public hospitals which perform this type of surgery, so patients could have come from anywhere in the country.

Some private hospitals, including Mercy Ascot in Auckland and St George's in Christchurch also perform open-heart surgery and should be notifying patients of the risk.

Symptoms can take between three months and five years to be diagnosed.

Symptoms are the same as for any infection and include fevers or night sweats, unexplained weight loss, fatigue, chest pain, infection around the site of surgery, increased shortness of breath, joint or muscle pain and nausea, vomiting or abdominal pain.

Canterbury DHB clinical microbiologist Dr Josh Freeman said treatment requires a long course of antibiotics and often surgery on the affected heart valves.

The infectious bacteria, known as mycobacterium chimaera, is commonly found in soil and water and rarely causes infections in healthy people.

But the bacteria "happily sticks to tissue valves", Freeman said. 

"The heart valve will sit there and slowly the bacteria will form a film on the valve. It slowly, slowly builds up overtime and slowly causes mischief elsewhere."

Freeman, who advised the ministry on the issue, declined to comment on where the New Zealand case was, but said it was a slightly different bacteria to the one at the centre of the issue.

A Waikato DHB spokeswoman said no cases of infection had occurred in the Waikato region, although a total of 1193 letters were sent to patients on Friday as a precaution.

Auckland DHB sent letters to 2,490 patients, including 950 children who had cardiac surgery at Starship Hospital.
"Auckland DHB is also notifying 321 patients, mainly children, from Pacific Island countries, who were treated as part of the health services we provide to the Pacific region," an Auckland DHB spokeswoman said.
An additional 347 patients who had operations at MercyAscot had been notified too, she said.

Wellington's Capital & Coast District Health Board (CCDHB) sent a notice to staff on Friday morning, which said local doctors' clinics and patients were being notified about the "small risk of infection" related to open heart surgery which involved artificial valves.

CCDHB sent out about 1080 letters to patients.

In April 2017, the Australian medicine watchdog announced it was conducting a product safety review around heater-cooler units after four people in Australia contracted a rare and serious infection following heart surgery. 

The patients contracted Mycobacterium chimaera (M. chimaera) from the units, following surgery they received in 2015.

Simpson said patients who had had cardiac surgery involving implantation of foreign material, such as heart valve replacement or repair surgery, since 1 January, 2013 and were experiencing symptoms should contact their doctor.

Machine still in use

Although the manufacturer flagged the issue in 2015, the Ministry of Health has confirmed the machine is still in use.

When it was first identified, hospital units were given a deep clean and DHBs  were told to monitor the issue, a ministry spokesman said.

It's understood the recent case of infection prompted the mass mailout. 

Freeman said there were not many manufacturers for this equipment. 

"It's hard to find alternatives and this is a really important machine for cardiac surgery.

"Before this happened nobody thought you had to disinfect these things because everything was sealed and water never came into contact with anything."

The manufacturer was retro-fitting the devices with gaskets and vacuum seals on all the joins, to minimise risk.

"So if droplets are released they will be carried away through an internal vacuum."

Health providers were still monitoring the devices, he said.

"I agree you want a definitive solution but you need to weigh risks and benefits. Delays would cause risks of their own."

Patients had to be made aware of the risk before surgery and give informed consent, he said. 

Freeman pointed out the standard infection risk after heart surgery was about one in 200-300.

​"We have singled this out because it's not good that patients are exposed to these things and can be hard to diagnose. We want to minimise the chance of that happening."

A Waikato DHB spokeswoman said the hospital's heater cooler devices had been checked and deep cleaned or were brand new.

"We have a system in place to ensure future patients are not exposed to the bacteria."

CCDHB infectious diseases physician Dr Tim Blackmore believed the risk for Wellington patients was even lower then the 1 in 5000 rate "as we've carried out additional testing of our facilities and systems".


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