“Can you hear it?” she asked with a smile. The thin, pleasant lady seemed as struck by her murmur as I was. She was calm, perhaps amused by the clumsy second-year medical student listening to her heart.

“Yes, yes I can,” I replied, barely concealing my excitement. We had just learned about the heart sounds in class. This was my first time hearing anything abnormal on a patient, though it was impossible to miss — her heart was practically shouting at me.

Her mitral valve prolapse — a fairly common, benign condition — had progressed into acute mitral regurgitation. She came to the hospital short of breath because her faulty valve was letting blood back up into her lungs.

Though it was certainly frightening, surgery to fix the valve could wait a few weeks. But before doing anything, the surgical team wanted a picture of the blood vessels in her heart.

If the picture showed a blockage, the surgeons would have to perform two procedures: one to fix the blockage, and another to fix her valve. If her vessels were healthy, though, the surgeons could use a simpler approach focused just on her valve.

So she came to the interventional cardiologist who was teaching me for the day. Coronary angiograms are the interventionalists’ bread-and-butter procedure, done routinely to look for blockages and to guide stent placement. They involve snaking a catheter from the groin or arm through major blood vessels and up to the heart.

Under fluoroscopy (like a video X-ray), the cardiologists shoot contrast medium into the arteries, revealing the anatomy in exquisite detail.

The images are recorded electronically and accompanied by the cardiologist’s interpretation for anyone else who opens her medical record.

Though routine, these catheterizations aren’t trivial. Whenever you enter a blood vessel, you introduce the risk of bleeding and infection. Fluoroscopy is radiation, and contrast medium can damage the kidneys. And let’s not forget cost — reimbursing the interventional cardiologist, a radiology technician, and nursing staff costs Medicare almost $3,000 per case.

So I asked the cardiologist if such an invasive approach was really necessary.

I knew the rationale — the surgeons needed to know if any of her vessels were blocked, so they could incorporate repairing them into their surgical plan. In a young, otherwise healthy patient, the likelihood of a blockage was low. But in open-heart surgery, “unlikely” isn’t enough. They needed to know her anatomy definitively.

I still wondered if there was a less invasive approach to get the same information.

I knew I was entering delicate territory, since these catheterizations are how he makes his living. So I was surprised to hear his answer when I asked if CT angiography would’ve done the trick: “Probably, but the surgeons aren’t comfortable with it. They only trust catheterizations.”

CT angiography (CTA) is a noninvasive way to get detailed information about the anatomy of the heart. It’s like a regular CT scan, except that pictures are taken after an injection of contrast medium. The total costs to Medicare were about $500 in 2009.

A recent study shows that in low-risk patients with a positive stress test, starting with CTA (and catheterizing only when CTA is positive) can save an average of $789 per patient, with a small increase in radiation exposure but little change in accuracy.

Now, I’m just a medical student. I’m in no position to decide when interventions are necessary or needless. And I certainly won’t tell a cardiothoracic surgeon what information they need to operate.

But I’m very familiar with an old standby in the health policy world and the popular media: that high-tech imaging, like CT scans, has contributed to runaway growth in the cost of American health care.

Advanced scans cost much more than older techniques, reveal “incidentalomas” thatmay cause more harm than good, and create a profit motive to drive their own use unnecessarily. I have no doubt that this is true much of the time. But reducing the issue down to one axiom is deceptive and simplistic.

It’s not enough to ask what the costs, benefits, and harms of an imaging study will be. We also need to understand what we’re comparing it to. A CT or an MRI will always be more expensive than an X-ray, and if we can get the same information from the latter, the more advanced images are indeed wasteful. But compared to catheterization, exploratory surgery — or worse, misdiagnosis — advanced imaging is a steal. It’s cheaper and often less harmful than the more invasive alternatives.

The crucial question is who should undergo imaging. If our patient were likely to have a blockage and need catheterization anyway, it wouldn’t make sense to start with CTA. But since her “pre-test probability” of a blockage was low, CTA could’ve averted a catheterization. This also doesn’t mean hospitals should go on imaging technology shopping sprees in order to save our system money.

They are huge upfront investments, carrying perverse incentives to churn patients through in order to break even on the initial cost. And we already have far more of these devices than our peers in the developed world. We could probably make do with fewer.

Of course, this is probably not why the surgeons didn’t trust CTA. Their job is to operate safely and proficiently, not to police our use of advanced imaging, and they had no financial incentive to request catheterization. My guess is that when the stakes are as high as when opening someone’s chest, they tend to trust what they know for certain to work. But preferences like these change over time.

Our patient’s angiography showed beautiful, intact coronary arteries. Her surgeons will probably go with the less invasive surgical approach, because they have no blockages to bypass. This is great news for her and her family. It would be even greater news if our policymakers and pundits took note of her story, and adopted a more nuanced approach to medical imaging.

Eventually, the surgeons will come around too. The only dogma compatible with the realities of health care is: If it sounds too simple to be true, it probably is. High cost and high tech, in the right patients, can also be high value.

Karan Chhabra is a medical student and can be reached on Twitter @KRChhabra.

This post originally appeared on the Costs of Care Blog. Costs of Care is a 501c3 nonprofit that is transforming American health care delivery by empowering patients and their caregivers to deflate medical bills. Follow on Twitter @costsofcare.

Image credit: Shutterstock.com