Reacción a "New pediatric cardiac stent grows with the piglet’s heart"

The press release reflects the key finding of this study: a nitinol stent is implanted in the pulmonary trunk of experimental piglets in a constrained state, and this stent self-expands as the animal grows by a significant number of millimeters without any further intervention, which is the main objective.

The study is of good quality for what it aims to demonstrate—that the stent achieves its intended purpose, namely adapting to growth in a preclinical phase. In this regard, it has been tested in different ways: numerous analyses of the device’s physical properties were conducted, starting with in vitro testing, followed by implantation in animals to observe what happens in the acute setting. A follow-up study was then carried out to assess what occurs over time.

The conclusion that the stent grows with the individual is well supported, as its dilation has been observed and various measurements have been taken.

However, the study also has some limitations. The prosthesis placed in this valve, upon follow-up, shows dysfunction, including pannus formation, and the valve presents moderate stenosis. In this sense, it cannot yet be said that it eliminates surgeries; in other words, this remains a hypothesis that still needs to be tested.

There are various studies on expandable pediatric valves, but most have examined dilation of these valves using balloons and interventional procedures. What this stent contributes is something novel: passive expansion without the need for any additional external intervention.

It is indeed innovative, but it has been tested in a very small number of experimental pigs, the follow-up period has been very short, and at that point degeneration appeared, with valve problems and increased gradients. Moreover, testing in piglets does not necessarily mean the same results will occur in humans, and it is not clear which valve is suitable for use with this stent. Therefore, in reality, the findings can be applied to the stent itself—which was the objective of the study—but not to a valve that, at present, could replace other pulmonary valves.

The results would need to be confirmed in longer studies, and it would be necessary to determine which valve truly adapts to the stent. If this can indeed be demonstrated in longer-term studies, with an appropriate valve and, of course, in humans, it could reduce repeated procedures. The concept is very interesting—the possibility of a stent that grows spontaneously is highly appealing—but at this time, there is no real clinical impact. It still needs to demonstrate durability, that the valve placed inside the stent functions in the medium or long term, and that it is safe in young children.