Tuesday, February 26, 2008

Painless aortic dissection: an uncommon manifestation of an uncommon disease

Internist Lisa Sanders, M.D., writing for the New York Times Magazine, recently presented an uncommon presentation of an uncommon disease: painless aortic dissection. Actually the patient, later in his brief ER course, did develop ischemic leg pain but for practical purposes the dissection can be considered painless given the absence of typical chest and back pain. In the International Registry of Acute Aortic Dissection such atypical presentations were uncommon (6.4%) and were associated with increased mortality.

DB’s Med Rants linked to the article and attributed the successful outcome to the doctor’s avoidance of premature closure, a frequent cognitive error in diagnosis. (The doctors, apparently, were tempted to start immediate heparin to treat the patient’s ischemic limb). I’m not sure how often that particular error would be made in the real world. Before starting anticoagulation (which could delay the safe performance of limb saving invasive procedures) most clinicians, it would seem to me, would first want some type of vascular imaging study such as CTA or MRA to define anatomy and explore options for urgent limb salvage. Such a study would have likely diagnosed the dissection even if aortic dissection hadn’t been initially suspected.

A situation more likely to lead to premature closure is aortic dissection presenting with chest pain. It’s especially true with today’s convenient substitutes for thought, those handy templates and order sets in which anticoagulants are embedded in the chest pain protocols.

I have a couple of quibbles with the article. Immediately following the onset of symptoms the patient was taken to the ER via ambulance where a CT was performed within moments of arrival:

A few minutes later the patient-doctor was whisked out of the E.R. to get a CT scan of his head. If this was a stroke, there was a good chance it would show up.

That’s likely to drive already inflated public expectations of CT scans and other fancy imaging techniques. Given that the CT was performed very early following symptom onset it’s unlikely the scan would have shown a stroke unless it happened to be a hemorrhagic stroke.

The article, unfortunately, concludes with this:

An aortic dissection is one of the classic difficult diagnoses in medicine. Far too often it’s not even considered. Or as in the case of John Ritter, who died of a dissection in 2003, it is considered but too late. (That case is now being litigated in a Glendale, Calif., courtroom, with Ritter’s family charging wrongful death.)

Ritter’s doctors won’t be happy with that statement, I’d wager. While this story may contain lessons about premature closure we have no reason to believe his doctors made that error. How do we know Ritter’s doctors considered dissection “too late?” Equally likely, that possibility went through their minds immediately upon Ritter’s presentation, was considered in the brief time available, and rejected when symptoms, risk factors and initial diagnostic tests pointed to acute coronary syndrome as more likely than aortic dissection. Occasional wrong diagnosis is inevitable even with pristine care and does not equal error.


DHS said...

CT perfusion scanning is pretty good in the acute setting, even for ischaemic stroke. it looks pretty, at least.

Anonymous said...

I discovered your blog today when googling "John Ritter + trial" to see if there was anything new about the case (crossing my fingers that the family wisely dropped the suit, that it was thrown out, or that the medical professionals involved were vindicated... so now you know where i stand). Thank you for your intelligent consideration of the issue. And please, can you tell me why the hospital settled??

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