We have more info on the Watchman, the mesh stent we covered last year, which is being studied for its ability to prevent blood clots in patients with atrial fibrillation. See, if you’ve got atrial fibrillation, you carry about a 2-3% annual chance of developing a stroke from these clots (above the matched baseline risk). To manage this risk, most patients get coumadin, an anticoagulant that’s unfortunately difficult to dose, and comes with a hefty risk of hemorrhage.
If the Watchman works, many patients could be spared the hassle, unpredictability, and risk of coumadin. There’s a nice article in the North Country Times about the state of Watchman research:
The Watchman blocks off the left atrial appendage so it’s no longer part of the circulatory system, Buchbinder said. In a matter of weeks, the sievelike cloth mesh is covered by living cells, which grow together, walling off the left atrial appendage. This changes the pattern of blood flow, reducing the likelihood that a blood clot will form. The Watchman does not treat atrial fibrillation itself, which must be handled separately.
So, what does that left atrial appendage do, anyway?
Closing off an area of the heart sounds drastic, but all the evidence indicates the left atrial appendage isn’t needed, Buchbinder said.
Buchbinder said closing it off doesn’t cause any disability to the patient because the appendage isn’t known to have any real function.
“It’s a vestigial, residual organ, and nobody really knows why it is there,” Buchbinder said. “It has no particular clear-cut function. It is a residue from when we were embryos.”
There’s a theory that the appendage senses the water concentration in blood, causing us to be thirsty when there’s too little water. However, Buchbinder said, all the medical evidence to date shows that people get along perfectly well without it, such as when it’s closed off during heart surgery.
The easy-to-insert mesh became dislodged in two of the 28 patients who received it, in one center, though they were apparently retrieved without bad outcomes. The centers are looking for more patients to study the device on, before they can get approval from the FDA. Their pilot study results are already available.
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