Frazier said one ape didn't like the wand and when told to show his chest, covered it with hay before turning toward his trainer. Another animal, an older orangutan, has a large throat sack that must be moved to the side so the keeper can place the wand directly on his chest.
At best, an animal will hold still for 30 seconds, but most are calm for just a few seconds, long enough to get a usable image, before they wiggle free, Frazier said.
As zoos across the country begin to do awake ultrasounds, the information will be sent to Atlanta to be included in the Great Ape Heart Project's database, a single place researchers can go to find out more about ape cardiac health.
"The idea that everybody is pulling together resources and data and efforts to answer some of the questions on a much larger scale is really exciting," said Kristen Lukas, curator of conservation and science at Cleveland Park Metro Zoo in Ohio. "It's a significant issue."
There are more than 200 orangutans at 55 zoos across the United States. The animals hale from Sumatra and Borneo in Indonesia, where deforestation and population growth has caused the Sumatran orangutan numbers to plummet to just 4,500.
Researchers hope the heart project can help those populations grow, too.
"When you get to this level of endangerment, you have to bring every tool to bear," said Lori Perkins, vice president of collections at Zoo Atlanta and head of the species survival plan for orangutans in the U.S. "Every tool that could be critical to their survival, you've got to throw it in."
Associated Press writer Kate Brumback contributed to this report.
Follow Dorie Turner on Twitter at http://www.twitter.com/dorieturner .