Published: 2 October 2025

Written by Elinor Fowler, Research Information Officer, Heart Research UK

Congenital heart disease (CHD) refers to heart conditions that develop during pregnancy. CHD is the most common form of birth defect and affects up to 13 babies born each day in the UK. These conditions can impact the heart in many different ways – while some may be relatively harmless, other types can be extremely complex and require surgical repair.

The ability to repair CHDs is still relatively new, with many advancements made in the 1960s at pioneering centres such as the old Killingbeck Hospital in Leeds. However, CHD continued to present significant challenges. Dr Leon Gerlis, a pathologist based at Killingbeck, decided that more needed to be done to better understand CHD and how best to fix it.

During the 1970s, Dr Gerlis established a collection of hearts with a range of congenital defects, with the intention of using them for study and education to improve the care of patients. Many of the specimens have accompanying anatomical drawings and clinical notes, making them an invaluable educational tool, and allowing Gerlis’s insights to persist beyond his lifetime. Due to changes to the law, collections such as Gerlis’ cannot be widely accessed in the modern era.

Ms Carin Van Doorn, a consultant congenital cardiac surgeon, embarked on an ambitious project that would capture the knowledge contained with the Gerlis collection. A multidisciplinary Gerlis project team was established, which was formed of clinicians and academics from Leeds Teaching Hospitals and the University of Leeds, with the work being carried out at Leeds General Infirmary (LGI).

At the start of the project, Ms Van Doorn and colleagues performed MRI scans of the hearts in the Gerlis Collection to obtain digital images. These scans, together with the accompanying clinical information, form the digital library of the Gerlis collection. 

The scans were then used to create virtual replicas of the hearts that can be displayed in different ways, such as images in smartphone apps or models generated using 3D printers. A particularly exciting and informative way to display the virtual hearts is through the creation of holograms. HoloCare, a company that specialises in using holograms for surgical training, partnered with the project to convert 25 Gerlis hearts into holograms, which could then be manipulated and interacted with via virtual reality (VR) headsets. This capability was recently demonstrated at the AMRC’s Medical Research Charity Showcase in Parliament, where attendees were able use a VR headset to experience the Gerlis collection in an entirely new dimension.

This image shows the Gerlis project team and the process of developing the original Gerlis collection into the holograms.  

This digital transformation will provide unparalleled access to the Gerlis collection for training and education. The virtual nature of the collection removes the physical barriers for access, meaning it can be used by the international surgical community once again, as well as the next generation of congenital cardiac surgeons.

The benefits, however, are not just for surgeons and clinicians. With the growing advancements in treatment and surgery, over 80% of babies born with a congenital heart defect will now survive to adulthood. The accessibility of the digital Gerlis collection will help this adult generation and their families learn about their conditions in interactive way, providing new levels of understanding and autonomy.