An extension to house a purpose-built cardiac hybrid theatre
The MRIHCT facility at Leeds General Infirmary is a purpose-built cardiac hybrid theatre for undertaking complex heart procedures on children and young people with an intraoperative MRI facility for neurosurgery.
The intraoperative facility is a fourth-storey steel extension with no lower storeys extended, linked to the existing Clarendon Wing. This enables cardiac surgeons and cardiologists to work together during the same procedure, reducing treatment time and increasing the chances for young patients.
The building is of steel construction supported on raking circular columns and a steel central core. The stability of the building comes from the braced steel central core. The building is constructed on pad foundations. By only extending the fourth floor, the building has a very interesting and unusual look.
Did you know …
A baby’s heart is the same size as a walnut, therefore, performing surgery with such a tiny margin for error requires the steadiest of hands. The best surgeon in the world could not perform this surgery with a bouncy floor. This is why the vibration in the building had to be so tightly controlled.
The Leeds General Infirmary (LGI) is the fourth busiest specialist cardiac surgical facility in the UK – only Great Ormond Street, Birmingham and Royal Brompton carry out more procedures on young children and babies.
An 8-tonne, 3 Tesla MRI is suspended with nothing but four storeys of air underneath it.
Project achievements and benefits
The extension is linked directly to the existing theatres on the Clarendon Wing. This allows cardiac surgeons and cardiologists to work together on the same procedure, reducing treatment times.
The new hybrid theatre houses a C arm scanner that will allow the surgeons to scan the patient during the surgery to review progress and adapt the surgery accordingly. Not only will this improve the chances of the young patients, it will also help to reduce the invasive nature of the surgeries and reduce the scars that the patients will carry for the rest of their lives.
The facility has been made possible with NHS funding and thanks to the generous donations of patients, their families, and the public through the Children’s Heart Surgery Fund’s ‘Keeping the Beat’ campaign and Leeds Cares. This shows how important this project was to a number of different stakeholders.
How the work was done
The foundation design considered the constructability of the building by checking the foundation was able to have the raking columns free-standing and not tied back to the core for lateral stability during construction.
This loading considered the eccentricity of the ranking column and wind loading that would be applied. The foundation and the connection didn’t need to be resized to allow for this as a building method.
Checking the foundation for such a load case gave the site team more options when constructing such a complicated structure.
The hybrid theatre and MRI room required the vibration performance with a response factor of less than 1.0.
Due to the nature of the structure gaining all stiffness from the central core and being cantilevered to meet the existing building, it wasn’t typical of most hospital theatres that meet this requirement. As a further challenge, the hybrid theatre has a corridor on three sides.
The vibration was controlled by limiting the deflection in the key areas. Deep and heavy beams in areas of importance were a necessity to make the building operational along with the column head positioning of the raking columns at each corner of the theatre.
To keep the beams as efficient as possible while still meeting the requirements, a finite element analysis model was used to determine the effect of the building in operation.
The facility was a complex project that had several engineering challenges that had to be overcome. These interesting aspects made common problem areas on hospital projects seem simple in comparison.