Welcome to the home of Noah Brier. I'm the co-founder of Variance and general internet tinkerer. Most of my writing these days is happening over at Why is this interesting?, a daily email full of interesting stuff. This site has been around since 2004. Feel free to get in touch. Good places to get started are my Framework of the Day posts or my favorite books and podcasts. Get in touch.

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Truths without Truth

I posted this story about unfounded medical truths over at GE Adventure, but it’s too good not to post here as well. Taken from How Doctors Think.

One of the most common congenital abnormalities of the heart is a hole between the two upper chambers, between the right atrium and the left atrium. Since the pressure in the left side of the heart is higher than in the right, blood will flow from the left atrium through the hole into the right atrium. This aberrant blood flow is called a shunt and can overload the right side of the heart, leading to heart failure and other complications. Lock told me that doctors send children for surgery to close these holes if there is a two-to-one shunt, meaning that twice as much blood flows through the right side of the heart than the left.

“Do you know where that two-to-one number came from?” [Dr. James] Lock [chief of cardiology at Boston’s Children’s Hospital] asked. I imagined it was from careful clinical studies of children with the hold. “You would think so. But you’d be wrong. At a medical meeting in the 1960s, a pediatrician presented the question ‘When should the hold be closed?’ to a group of cardiologists. There was a heated debate about how much shunting required a surgical fix. So the meeting organizers, out of desperation, took a vote. Some voted for a lower number, some for a higher number. The median ended up being two-to-one. This was published in the American Journal of Cardiology. So now all textbooks have as the truth that you should close a hole when the shunt is two-to-one.

June 22, 2009