HCA uncovered evidence that some cardiologists at several of its Florida hospitals were unable to justify many procedures they performed.

In summer 2010, a troubling letter reached the chief ethics officer of the hospital giant HCA, written by a former nurse at one of the company's hospitals in Florida.

In a follow-up interview, the nurse said a doctor at the Lawnwood Regional Medical Center, in the small coastal city of Fort Pierce, had been performing heart procedures on patients who did not need them, putting their lives at risk.

“It bothered me,” the nurse, C.T. Tomlinson, said in a telephone interview. “I'm a registered nurse. I care about my patients.”

In less than two months, an internal investigation by HCA concluded the nurse was right.

“The allegations related to unnecessary procedures being performed in the cath lab are substantiated,” according to a confidential memo written by a company ethics officer, Stephen Johnson, and reviewed by The New York Times.

Tomlinson's contract was not renewed, a move that Johnson said in the memo was in retaliation for his complaints.

But the nurse's complaint was far from the only evidence that unnecessary — even dangerous — procedures were taking place at some HCA hospitals, driving up costs and increasing profits.

HCA, the largest for-profit hospital chain in the United States with 163 facilities, had uncovered evidence as far back as 2002 and as recently as late 2010 showing that some cardiologists at several of its hospitals in Florida were unable to justify many of the procedures they were performing. Those hospitals included the Cedars Medical Center in Miami, which the University of Miami now owns, and the Regional Medical Center Bayonet Point in Hudson, near Tampa. In some cases, the doctors made misleading statements in medical records that made it appear the procedures were necessary, according to internal reports.

Questions about the necessity of medical procedures — especially in the realm of cardiology — are not uncommon. None of the internal documents reviewed calculate just how many such procedures there were or how many patients might have died or been injured as a result. But the documents suggest that the problems at HCA went beyond a rogue doctor or two.

At Lawnwood, where an invasive diagnostic test known as a cardiac catheterization is performed, about half the procedures, or 1,200, were determined to have been done on patients without significant heart disease, according to a confidential 2010 review. HCA countered recently with a different analysis, saying the percentage of patients without disease is much lower and in keeping with national averages. At Bayonet Point, a 44-year-old man who arrived at the emergency room complaining of chest pain suffered a punctured blood vessel and a near-fatal irregular heartbeat after a doctor performed a procedure that an outside expert later suggested might have been unnecessary, documents show. The man had to be revived. “They shocked him twice and got him back,” according to the testimony of Dr. Aaron Kugelmass in a medical hearing on the case.

On Monday morning, in a conference call with investors, company executives disclosed that in July the civil division of the U.S. attorney's office in Miami requested information on reviews assessing the medical necessity of interventional cardiology services provided at 10 of its hospitals, located largely in Florida, but also two or three hospitals in other states. The company also referred to inquiries by The Times. HCA's stock ended nearly 4 percent lower Monday, at $25.55.