Researchers at Georgia Tech and Emory University have engineered an innovative computer program to help cardiac surgeons optimize surgical procedures before they enter the operating room. The image-based surgical-planning software lets surgeons manipulate a three-dimensional computer model of a patient's heart. Once the doctor has altered the model so that it includes the desired vascular configuration he or she wants to create during surgery, the program uses computational fluid dynamics to run a blood-flow simulation displaying how well the modified heart will perform.

A researcher using the image-based surgical-planning system manipulates a model of a patient’s vascular system with input devices shaped like scalpels. Once his envisioned design is complete, its blood-flow efficiency will be tested.
Jarek Rossignac, College of Computing/Georgia Tech

The aim of the project is to develop a complete system that addresses the demanding needs of cardiovascular surgery planning and assessment, says Ajit Yoganathan, the principal investigator on the project and associate chair of the Department of Biomedical Engineering at Georgia Tech and Emory University. The program was built to test one of the most common and complex congenital heart problems known: a single ventricle defect.

Children with this condition have only one heart ventricle (the left), instead of two, for pumping oxygenated and deoxygenated (dirty) blood throughout the body. In healthy patients the right ventricle pumps the deoxygenated blood through the arteries to the lungs, while the left ventricle receives the oxygenated blood through the veins and shoots it off to every organ in the body.

"The mixture of blood in the single ventricle greatly compromises circulation throughout the body," says Shiva Sharma, a private pediatric cardiologist. "The surgeon's job is to separate the circulation, meaning rerouting the deoxygenated blood directly and evenly to the lungs while minimizing resistance to flow, an operation called Fontan repair."

Designing the best connection is essential because too much resistance can increase blood pressure and cause a variety of life-threatening complications, explains Pedro del Nido, chief of cardiac surgery at Children's Hospital of Boston. "Surgical procedures are based on a surgeon's personal experience, experimentation, and, frankly, a lot of trial and error. There is no direct way of knowing whether or not we have made things better or if a slight variation in our technique will make a slight difference or not."

Before image-based surgical planning, surgeons worked somewhat like "freehand artists" in that they would look at the anatomy and then sketch out a plan for surgery, adds Sharma.

The program developed by Yoganathan and his colleagues works by creating a three-dimensional computer model of the heart using data from the child's magnetic resonance imaging (MRI) scans at different times in the cardiac cycle. After viewing the images and devising a few plans, the surgeon sits down at a computer and manipulates the model using "input devices" that look like scalpels, explains Yoganathan.