Some extra testing may be understandable as doctors see new patients and may not have full access to prior records or trust testing performed elsewhere. Last year, the North Shore-Long Island Jewish Health System signed a three-year affiliation agreement with Boca Raton Regional Hospital in part to provide better continuity of care for patients who live in both areas.

But Florida has emerged over the years as an epicenter of Medicare abuse: The Medicare Fraud Strike Force, a joint initiative of the Department of Health and Human Services and the Department of Justice, was formed in response to widespread fraudulent claims in South Florida, and its periodic “takedowns” have charged far more providers in Miami than in the other cities where it operates.

And high-volume testing is also a good way for physicians to supplement income when insurers are cutting back on payments for individual services. From 1999 to 2008, as Medicare reduced reimbursement for many cardiology services, one study found that the number of Medicare claims soared for the types of testing recommended to Ms. Spencer’s husband. Claims for echocardiograms (which use sound waves to produce pictures of the heart’s wall and valves) increased by 90 percent. Peripheral vascular ultrasound tests (which look for clogged arteries) nearly tripled. Nuclear stress testing (a complex test for coronary artery disease) more than tripled, even though the procedure takes hours, involves an injection and radiation exposure, and costs thousands of dollars.

Doctors now often own the testing equipment or have a stake in a center where testing is performed. Medicare law generally forbids such self-referral because studies show it encourages overuse of services.

(While studies have not looked specifically at testing in Florida, one study there, by Christine Yee, an economist at the University of California, Berkeley, showed that physicians who were on the boards of ambulatory surgery centers did 27 percent more procedures than those who were not.)