SAN FRANCISCO —
HEART RHYTHM PROBLEMS
Catheters can contain tools to vaporize or “ablate” bits of heart tissue that cause abnormal signals that control the heartbeat. This used to be done only for some serious or relatively rare problems, or surgically if a patient was having an operation for another heart issue.
Now catheter ablation is being used for the most common rhythm problem — atrial fibrillation, which plagues about 3 million Americans and 15 million people worldwide. The upper chambers of the heart quiver or beat too fast or too slow. That lets blood pool in a small pouch off one of these chambers. Clots can form in the pouch and travel to the brain, causing a stroke.
Ablation addresses the underlying rhythm problem. To address the stroke risk from pooled blood, several novel devices aim to plug or seal off the pouch. Only one has approval in the U.S. now — SentreHeart Inc.’s Lariat, a tiny lasso to cinch the pouch shut. It uses two catheters that act like chopsticks. One goes through a blood vessel and into the pouch to help guide placement of the device, which is contained in a second catheter poked under the ribs to the outside of the heart. A loop is released to circle the top of the pouch where it meets the heart, sealing off the pouch.
A different kind of device — Boston Scientific Corp.’s Watchman — is sold in Europe and parts of Asia, but is pending before the FDA in the U.S. It’s like a tiny umbrella pushed through a vein and then opened inside the heart to plug the troublesome pouch. Early results from a pivotal study released by the company suggested it would miss a key goal, making its future in the U.S. uncertain.
Some people have a hole in a heart wall called an atrial septal defect that causes abnormal blood flow. St. Jude Medical Inc.’s Amplatzer is a fabric-mesh patch threaded through catheters to plug the hole.
The patch is also being tested for a more common defect — PFO, a hole that results when the heart wall doesn’t seal the way it should after birth. This can raise the risk of stroke. In two new studies, the device did not meet the main goal of lowering the risk of repeat strokes in people who had already suffered one, but some doctors were encouraged by other results.