I held my wife Veronica's hand as the technician applied cool gel to her chest. At first, the ultrasound images were the fuzzy black-and-whites I remembered from before our daughters Rebecca and Hannah were born. After a few touches to the LCD screen, a breathtaking three-dimensional movie began to run. It featured Veronica's heart, its thick walls beating yellow against a black background.

The technician maneuvered a trackball to reveal the various parts undulating in unison. Colored regions displayed blood velocity and turbulence through the different chambers. Suspended in virtual space, Veronica's heart looked every millimeter the impregnable pump I had always assumed it was.

Veronica is 46, does four hard workouts every week on the stepping machine, eats sensibly, and has a resting pulse of 60. So when she woke me at 2 A.M. and calmly reported funny chest pains radiating to her shoulder blades and down her arms, the obvious came to mind, but it was hard to really believe. Veronica and Rebecca had been coughing and feverish for a week. The three of us had embarrassing cold sores. Acid reflux, a sore diaphragm -- anything seemed more likely than a heart attack.

You need a hard head and a soft heart to manage a loved one's medical emergency. It's surprisingly easy for smart people to be nudged by circumstance and human frailty into doing careless or foolish things. We had two sleeping daughters across the hall. The thought of them waking up to flashing ambulance lights was daunting. We worried about leaving them or dragging them to an emergency room. Still, Veronica had never felt anything like this. We had to do something. So we threw on some clothes, and drove to the 24-hour urgent-care center a half-mile from our house.

Several people made mistakes in Veronica's care. The worst and most deadly mistake was ours: going to this urgent-care center. Veronica's symptoms demanded a 911 call. I knew better -- or I certainly should have. I am a certified expert, director of the University of Chicago Center for Health Administration Studies. I've served on expert panels of the Institute of Medicine, no less.

I was swayed to discount what was happening -- Veronica, a clinical nurse specialist, was, too -- by disbelief, by her recent illness, and by her general fitness. We were also swayed by the expected hassle and expense of an ER visit. We envisioned paying a large bill to be prescribed some Tums. Last year, Veronica went out-of-network for urgent care. That cost $700.

In part, we hesitated because that was exactly what the modern health-insurance system is designed to make us do. A quarter-century ago, the RAND Health Insurance Experiment (HIE) established the basic argument for deductibles and co-payments in insurance. HIE remains the most important policy experiment in American history. Its most potent finding was that people who got free care used 40 percent more services than did others assigned to cost-sharing plans. Yet the free care produced little measurable additional benefit for the average patient. These results are often cited in support of co-payments and deductibles designed to discourage inappropriate care. Policy-makers and payers are particularly concerned about the real and alleged over-use of emergency care. Charging higher co-payments is one obvious response.

It seems counterintuitive that demand for ER services would be sensitive to price. If you slice off your finger with a steak knife, you won't be thinking about the money. Yet it turns out that many ailments -- Veronica's included -- are ambiguous, and so price matters. RAND investigators found that individuals in cost-sharing plans reduced ER use by one-third when compared with the free-care group.

Co-payments did discourage wasteful use among HIE participants. ER visits in relatively non-urgent categories such as sprains and back pain were 47 percent less frequent in cost-sharing plans. Unfortunately, co-payments also discouraged appropriate use. Participants enrolled in the cost-sharing plans were 23 percent less likely to seek ER care for "more urgent" problems, including fractures and asthma.

Most patients cannot reliably distinguish appropriate from inappropriate ER use. In many cases, even experts find the distinction fuzzy. I once co-wrote a study of a managed behavioral health plan that imposed a 50 percent co-payment on psychiatric ER visits. Do we really want to impose these barriers? When someone feels that funny chest pain, how long do we want her to dither before seeking help?

Veronica and I made a critical decision in choosing the urgent-care clinic. Your first medical provider in an emergency determines who will frame the initial hypotheses of your illness, who will coordinate your care, and, often, the person who hears the cleanest direct account of what is wrong. I had never been inside this imposing structure, which advertises and charges as an emergency-department affiliate of a local hospital. We arrived to find it nearly empty. The staff promptly took an electrocardiogram (EKG) that looked normal and administered aspirin and nitroglycerin. Veronica took a gastrointestinal cocktail of antacid and lidocaine in case this was acid reflux. It seemed to help, which I found reassuring. They administered a chest X-ray. After bumpy preliminaries, they administered the standard cardiac-enzyme tests.