"What we have developed is a system that lets you grab the geometries as if you were holding them in your hands and then twist, rotate, and move them as three-dimensional models in front of you," says Jarek Rossignac, one of the system's designers and a professor at the College of Computing at Georgia Tech. "The result is a new three-dimensional model that reflects a particular shape that a surgeon envisions for the operation."

The new anatomically modified three-dimensional model is seamlessly exported and meshed for a computational fluid dynamics analysis (CFD). Using CFD creates a simulation of blood flow in the newly configured heart that can be viewed by the surgeon on the screen. After multiple mock models are designed and tested, the surgeon can decide which operation proved optimal for that particular patient. Thus far, the hearts of five patients have been designed and tested for surgery using the three-dimensional model.

At the moment, the system is only being used by a small group of surgeons involved in the research. Yoganathan says the technology is three to five years from being ready for general use, and there are still some challenges to overcome. The flow dynamics, he says, are very computer intensive and involve complex formulas. Converting the geometries back into computational meshes is "painstakingly slow."

Right now, the computer engineers have the surgeons draw out the design and then the engineers manually enter the geometries. It's a "very cumbersome process," says Yoganathan. "We are working on developing tools that, once the geometry is drawn, the computational mesh for analysis would be done automatically so there is no engineer involvement."

There are also no precise mathematical formulas for anatomical shapes, which are organic and have interesting material-property issues, so mimicking how they might evolve represents a new set of challenges, explains Rossignac.

The researchers want to provide "user-friendly" human-shape interface technology, which would let surgeons manipulate shapes in an intuitive, efficient way; right now it takes the surgeons two to three hours to manipulate a patient's heart to the configuration they visualize. According to del Nido, however, these shape-editing technologies "are pretty simple to use and intuitive for anyone who has done computer games."

Eventually, the researchers want the software to provide the optimal solution for the cardiac problem.

A group at Stanford University, led by Charles Taylor, is also working on image-based surgical-planning systems. Recently, his lab opened the Center for Simulation in Medicine at Stanford Hospital to focus on surgical planning for cardiovascular interventions for children with congenital heart disease and adults with atherosclerosis and aneurysms.

According to Taylor, simulation-based planning of cardiovascular treatments could lead to lower morbidity and mortality, reduced reoperative rates, and reduced time in the operating room.

Ultimately, image-based surgical planning will have an immense impact on surgical procedures, improving the quality of life of not just children but adults as well, says del Nido.