WASHINGTON — Dr. Jeffrey Shuren was adamant: The United States would never cut corners to fast-track the approval of medical devices.

“We don’t use our people as guinea pigs in the U.S.,” Shuren said, holding firm as the new director of the U.S. Food and Drug Administration’s medical devices division.

Again and again in 2011 — four times in all — Shuren was summoned before Congress. Lawmakers accused the agency of being too slow and too demanding in reviewing new devices like heart valves and spinal implants, driving U.S. manufacturers overseas where products faced less rigorous review. Each time, he pushed back.

And yet the next year, Shuren and his team adopted an approach that surprised even some of his closest colleagues: The FDA would strive to be “first in the world” to approve devices it considered important to public health.

The agency’s shift mirrored the talking points of the $400 billion medical device industry — a lobbying behemoth on Capitol Hill — and ushered in a series of changes that critics say have allowed manufacturers to seek regulatory approval for high-risk devices using smaller, shorter, less rigorous studies that provide less certainty of safety and effectiveness.

Under Shuren, annual new device approvals have more than tripled, while warnings letters to device manufacturers about product safety and quality issues have fallen roughly 80 percent, an Associated Press investigation found.

The assortment of medical devices now on the market includes spinal rods that can leave metal shards in children and a nerve-zapping obesity implant that may not work for many patients.

The cheaper and faster medical device approvals began despite multiple, high-profile safety problems involving pelvic mesh, hip replacements and other implants.

An AP analysis of FDA data shows that since 2012, tens of thousands of injury and death reports have been filed in connection with devices that were cleared through a streamlined pathway that minimizes clinical trial testing. The FDA’s database for reporting device problems often includes incomplete, unverified information submitted by manufacturers, physicians, lawyers and patients. Because of these limitations, it’s often unclear whether a device played any role in an injury or death.