When Bethany Titus was 10, she had to cut back on sports; her heart would swing into a wild, erratic rhythm that pounded in her chest, leaving her light-headed and breathless. Sometimes her hands tingled. Fainting was a real possibility. And nothing particular seemed to trigger it. It just happened: at school, at home, at sleep and at play.

Now 15, she had surgery last month in which University Hospital doctors used a new computer-generated, 3-D "virtual heart" to find the spot where the odd heartbeat originated. Then they blasted it. The tiny amount of scar tissue left behind will prevent that irregular beat. And she has a less than 5 percent chance of having it recur -- good news for her because she'd had an earlier surgery that only solved the problem for a couple of years."I just feel a whole lot better," said the Woods Cross High School sophomore during a press conference at the hospital Friday to introduce the new Ensite mapping system, developed by Endocardial Solutions Inc.

The daughter of Sue and Phil Titus, she apparently inherited the heart rhythm disorder from her mother, who also has it.

Heart rhythm -- or lack of it -- is controlled by electrical impulses moving through the heart muscle. Abnormal electrical tissue creates an irregular heartbeat, a problem that afflicts 4 million Americans. Some of those people face a very real risk of sudden cardiac death.

Medications and surgery have been used to control the irregular heartbeats. But the new technology can make it much easier to find and destroy the problem.

Electrophysiologists -- doctors who specialize in the heart's electric system and therefore heart rhythms -- thread a single catheter that contains a balloon and 64 electrodes into the heart to look at the electrical activity and send the information back to the computer program, which creates a 3-D heart and clearly shows the irregular rhythm. The electrodes can capture the information with a single heart beat, unlike previous techniques, said Dr. Richard C. Klein, professor of medicine at the U. School of Medicine and an electrophysiologist.

Then doctors use a second catheter to deliver an electric charge that "zaps" the spot. And, almost like magic, the irregular beat is obliterated.

Doctors have long been able to find the specific location of the errant electrical impulse and zap it, but they had to use multiple catheters at the same time, and it was a much trickier process, Klein said. "We used to have four or five catheters in, and we'd move them all over the place trying to find the site."

Anyone with an abnormal heart rhythm could be a candidate for the new 3-D mapping surgery, he said, adding that the oldest patient he's performed the operation on is 89.

The U. Hospital is particularly pleased with the technology because it pioneered arrhythmia surgery techniques in the 1980s. A few years later, surgeons there performed the first catheter-based arrhythmia ablation in the Intermountain West. And while their new system, crated by Endocardial Solutions Inc., is the sixth one installed in the country, it is based on the research of Bruno Taccardi and his colleagues at the U.'s Cardiovascular Research and Training Institute a decade ago.

It took 10 years to come up with the mathematics to make the computer imaging work with the information sent by the electrodes to create the virtual heart, Taccardi said.