Hospital bosses on Thursday said they have launched an investigation and temporarily stopped using a model of an X-ray imaging machine after the device malfunctioned during a procedure at Queen Elizabeth Hospital, leaving a patient fighting for his life.

The Hospital Authority said the 66-year-old male patient with cerebellar arteriovenous malformation, a condition involving abnormal connections between the arteries and veins in the brain, is in a high dependency unit in a critical state.

The authority said the angiography machine on Monday failed to show the normal flow of tissue glue injected into the patient to control bleeding during an embolisation, which is a procedure that stops blood flow to a certain part of the body.

"The clinician considered that the situation was unusual at the time and suspended the injection procedure immediately," the authority said.

"The clinician then used the angiography machine to scan the blood vessels in the patient's brain again, and found that tissue glue was found in other blood vessels in the brain. Besides, bleeding was found in the blood vessels in the cerebellum. The clinical team then immediately stabilised the patient's condition with appropriate treatment."

The exact cause of the incident is still under investigation, the authority added.

"Representatives of the [Hospital Authority] and [Queen Elizabeth Hospital] met with the equipment company on September 10 and learnt that the incident was rare and the cause had yet to be determined," it said.

"The angiography machine in [Queen Elizabeth Hospital] has been temporarily suspended from service. Another angiography machine of the same model is also temporarily suspended at Queen Mary Hospital. The two hospitals will utilise other medical equipment for relevant procedures such that patient services will not be affected."

The Department of Health said the medical device received its last maintenance check by German manufacturer Siemens on July 24 and no abnormalities were found.

Other than Queen Elizabeth and Queen Mary Hospitals, the department added the machine in question is also being used at another private hospital.