By Michelle Roberts
BBC News health reporter, in Washington DC
A virtual reality system could help surgeons see how heart operations pan out before undertaking them for real.
Will guesswork become a thing of the past for heart surgeons?
By using pictures of a patient's blood vessels and knowledge about how blood flows, it can predict likely outcomes of different surgical procedures.
Taking out the guesswork would help save lives and avoid patients having needless operations, says inventor Dr Charles Taylor of Stanford University.
It could become a standard pre-surgery procedure like taking scans, he said.
Currently, a surgeon can order a CT or MRI scan to get an idea of what the blood vessels look like and what is going on inside a patient.
But they have to use their best guess, based on their experience and knowledge of disease and operations, to decide whether surgery would help and what the likely outcome would be.
"But we need to know the answers to the 'what if' questions," said Dr Taylor.
"What if it is better to do nothing? What if the patient got a little better but there might have been another way of operating that could have made him or her a lot better?"
For example, if a surgeon operates on the body's main blood vessel - the aorta - to correct a blockage or an abnormal narrowing, it can lead to blood flow problems elsewhere in the body and cause organ damage, he said.
The computer system would help surgeons try out different options and spot potential problems without having to try it out first in the patient.
"The point is to intervene first on the computer before going to the patient.
This image from the computer shows blood flow to the lungs
"We don't care if something bad happens to the computer model - it won't harm the patient," he said.
Using data from animals and patients before and after surgery, he has been able to test how well the computer model predicts real life outcomes.
These trials show it is accurate at predicting what will happen to blood flow within 10%.
He said his team is working with surgeons at Stanford to get more data on patients undergoing blood vessel surgery.
"Ultimately, I believe it will be part of standard care. Surgeons would check the computer model before going to the patient," he said.