In addition, half of the companies said FDA personnel responsible for reviews of products changed throughout the process and one-third reported that appropriate staff were absent from the meetings between the agency and the company when the review process was discussed.

"Given that it takes longer and costs more money to launch a product in the U.S., a reasonable question is what is gained from the additional time and costs that result from the FDA process," Makower said.

He acknowledged that the FDA was within its right to ask for clinical data when it deemed it necessary but changing the requirements without transparency or justification is a major obstacle for startups.

In his opening remarks, Henry A. Waxman (D-Calif.) criticized Makower's findings, saying that the study sample was too small to produce meaningful results. In addition, the companies included in the study had little experience dealing with the FDA's device approval process, he said.

Another panelist, Mark Deem, a partner at the medical device company incubator The Foundry, also expressed concern about new ventures in his testimony, saying that, "the most fragile end of the medical device ecosystem, the startups, are struggling."

Deem cited data from PricewaterhouseCoopers LLP and the National Venture Capital Association, which found that between 2007 and 2010, venture capital investment in the medical device sector declined by more than 37 percent. Funding for new startups dropped from 118 new companies in 2008 to 60 in 2010, according to data from Dow Jones Venturesource.

"We exist for our patients, but we live on venture capital," said Deem.

He said the slowness and inconsistency of the FDA approval process are the predominant threats to investment in the sector. "Given the lack of predictability in the U.S., and the relative stability and predictability of the CE mark system, we are no longer structuring, staffing or operating our companies for first commercial release in the U.S.," said Deem. "We develop our products here, and then run the same large, multicenter randomized trials we would otherwise have conducted in the U.S. overseas."

A clash of opinions: is the 510(k)approval process safe?

In a study that appeared online Monday in the Archives of Internal Medicine, researchers looked at 113 devices that the FDA recalled between 2005 and 2009 that posed serious health risks.

Examining FDA data, they determined if the recalled devices were approved using the premarket approval process, the 510(k) process or were exempt from review.

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