Doctors Peer Inside Unhurt Hearts : Health: Ultrasound machines and computers combine to produce 3-D pictures without any cutting.

Doctors are getting their first realistic view inside the beating heart without cutting it open, using experimental ultrasound machines and computers to shoot crisply detailed 3-D movies.

In one example that researchers displayed Monday, doctors oriented the picture so it looked like they were standing inside a baby’s heart, peering at a defect from different angles.

Doctors can simulate slicing through the heart at any angle, then peek inside and watch valves flap and chamber walls pulse. The startlingly sharp pictures look as though a miniature video camera had somehow been threaded into the heart and turned on.

“We can open the heart, almost like splitting a piece of fruit, and then put it back together without doing any damage,” said Dr. Natesa G. Pandian of New England Medical Center in Boston. A team headed by Pandian reported on the technology at this week’s meeting of the American College of Cardiology.

Ultrasound is already a mainstay of heart testing. But the pictures it has produced up to now have been grainy and flat. Like regular X-ray shots, they are two-dimensional and give no hint of thickness or depth.

The new generation of machines--a technological marriage of ultrasound and CT scanners--is dramatically different. They produce three-dimensional pictures that look like ordinary movies.

That should help doctors precisely diagnose bad valves, aneurysms and other structural defects inside the heart and better estimate the extent of damage from heart attacks.

“Once you have 3-D, you can cut the heart any way you like and look at whatever you want to see,” said Dr. Mani Vannan of New England Medical Center, where doctors have tested the device on about 40 patients.

The device, called echo-CT, was developed by Tomographic Technologies of Munich, Germany. It has not yet been approved by the U.S. Food and Drug Administration for routine use. Other companies are working on different approaches to 3-D ultrasound.

The scan takes about 20 minutes. Doctors insert a tube down the patient’s throat. Inside is an ultrasound transducer. A computer pulls the transducer up the tube at a steady pace, taking images in precisely parallel slices, each one millimeter thick.

The images are stored and processed in a desktop computer. Doctors can manipulate the pictures on the computer screen, looking inside the heart from various vantage points.

In one example, doctors showed the heart of a baby with an atrial septal defect--a hole in the wall that separates the two upper chambers of the heart.

First, the doctors oriented the picture so it seemed as though they were standing in the child’s left atrium, peering directly into the hole. Visible through it was the right atrium and the far side of the heart. Then they shifted to the right atrium and looked through the hole to the left side. Finally, they looked at the heart head on, showing the two atria side by side.

Advocates say the technology’s most promising advantage is giving surgeons an advance look at what they will see when they operate. “It boils down to a better capability of predicting surgical results,” Pandian said.

“We are really excited about this technology. It will be incredibly useful,” said Dr. Pravin Shah, who has used it on about 30 patients at Loma Linda University.

But Dr. Arthur Garson Jr. of the University of North Carolina said he isn’t convinced that the extra information is worth the cost of introducing a new kind of technology.

“The pictures sure are pretty,” he said, “but pretty pictures are expensive.”