The heart sometimes loses its rhythm, like an orchestra where the violins suddenly start playing each on their own. Cardiologists in such cases look for the "out-of-tune" areas by reading the heart's electrical signals and precisely ablating them with a thin probe — a catheter. But there's a catch: the tool for listening (electrical mapping) and the tool for ablation are two different catheters, and they have to be inserted into the heart one after another through the vessels. Extra movements, extra time.

A group of researchers decided to combine these two devices into one. They took a hollow sheath tube (in English, "sheath"—a kind of guide cover through which catheters are introduced) and equipped it with its own electrical signal recording system. At the tip of the tube, using a thermal drawing method (like drawing ultra-thin fiberglass), they formed several flexible petals with electrodes. When folded, the petals are pressed against the tube and easily pass through vessels, but when the tip reaches the heart, they open into a basket shape. This "basket" conforms to the heart wall and records the electrical map — voltage and activation time at different points. And through the hollow center of the tube, a therapeutic catheter can be immediately passed for ablation.

The device was tested in several stages. First, on a bench, they confirmed that the petals withstand bending and don't break during movement inside vessels, and the electrodes clearly pick up signals. Then they tested it in a plastic model of the left atrium filled with a fluid mimicking blood. After that, on an isolated pig heart beating in a Langendorff apparatus (a device that keeps the heart working outside the body). Finally, they performed surgery on live pigs: inserted the tube through the femoral vein, guided it to the heart under X-ray, opened the basket, recorded electrical maps, and constructed voltage and activation maps. Everything worked.

Now doctors have a "two-in-one" tool: a mapping sheath that also delivers the therapeutic catheter. Fewer movements — less risk of complications, faster surgery. And the thermal drawing technology paves the way for mass production of such devices because it allows creating complex miniature shapes quickly and cheaply. The heart orchestra plays in harmony again, and the conductor now needs only one baton.