Preclinical Animal Study of a Dual-Set Artificial Chordae Mitral Valve Repair System in a Porcine Model

The human heart is a relentless pump, and for millions of people, its most critical valve—the mitral valve—begins to leak. This condition, known as mitral regurgitation, allows blood to flow backward into the upper chamber instead of moving forward to the body, straining the heart and shortening lives. For decades, fixing a leaky valve required opening the chest and stopping the heart, a major surgery with a long recovery. In recent years, doctors have developed less invasive ways to repair the valve while the heart continues to beat, using tiny threads to replace the natural cords that hold the valve leaflets in place. However, these newer techniques often demand that surgeons pierce the heart multiple times and adjust each thread one by one, a process that can be slow and technically difficult. The question remains: can we make this delicate repair faster and more reliable without sacrificing precision?

A team of researchers in Shenzhen, China, set out to test a new device designed to answer that question. They developed a system called HaloChord, which aims to deliver multiple repair threads in a single step rather than one at a time. To see if this approach works safely, they turned to a living model: five adult pigs. The researchers first created a controlled leak in the pigs' hearts by surgically cutting the natural cords that support the valve, mimicking the sudden failure seen in human patients. Once the leak was established, they used the HaloChord system to repair the damage. The device was inserted through a small opening at the tip of the heart. Unlike older tools that might place a single thread, this system was designed to grab the valve leaflet and pass two separate threads through it simultaneously. When pulled back, these threads formed four new artificial cords in a single motion. The surgeons then anchored these cords to the bottom of the heart, carefully adjusting their length while watching a live ultrasound image to ensure the valve closed tightly without creating a new blockage.

The results of the experiment were immediate and encouraging. In all five pigs, the surgeons successfully implanted the device while the hearts were beating. The procedure to place the threads took an average of about ten minutes per device, and the time spent adjusting the length of the cords varied, reflecting the careful, iterative process of finding the perfect fit. Before the repair, the pigs had moderate to severe leaks; immediately after the procedure, the leaks were reduced to mild or non-existent in every case. The researchers then watched the animals over time, with some being observed for one month, others for three months, and the rest for six months. Throughout this period, the repairs held firm. The new cords did not break, slip, or detach, and the leaks did not return. The pigs remained healthy, with no signs of blood clots forming on the new threads or damage to other organs.

When the researchers examined the hearts at the end of the study, they found that the body was accepting the new material well. The artificial threads, made from a strong, biocompatible plastic, became covered by the heart's own tissue over time. At the one-month mark, the area around the threads showed signs of active healing, with some inflammation and new blood vessel growth, which is a normal part of the body's repair process. By three and six months, this reaction had settled down, leaving behind a stable, fibrous layer that integrated the device into the heart tissue. The anchor point at the bottom of the heart was also secure, buried under a smooth layer of tissue with no signs of infection or rejection. The study confirmed that the device could be used safely on a beating heart, effectively stop a leak, and remain stable for at least six months.

This research does not claim that the device is a perfect solution for every patient or that it is superior to existing methods in every way. The study was a test of feasibility and safety in a specific, acute model of heart failure, not a long-term comparison against other commercial devices. The authors note that while the dual-thread design simplified the procedure by delivering more repair material in one go, the core challenge of adjusting the length of the cords to match the patient's unique anatomy remained a necessary, time-consuming step. The variability in the time it took to adjust the cords was not a sign of failure but rather a feature of the system, allowing surgeons to fine-tune the repair until the valve functioned perfectly. The study suggests that this new approach offers a more streamlined way to perform a complex repair, potentially making the procedure more accessible to surgeons who are not yet experts in these highly specialized techniques.

The findings provide a solid foundation for the next steps. The device has moved from the drawing board to a living model, proving that it can be implanted safely and effectively in a beating heart. The researchers have already begun clinical trials in humans, building on the confidence gained from these animal studies. While the long-term durability of the repair over many years remains to be seen, this work demonstrates that delivering multiple artificial cords in a single sequence is a viable strategy. It offers a potential path forward for treating a common and dangerous heart condition with a method that is both less invasive and more efficient than current standards, bringing hope for a future where complex heart repairs are simpler and more reliable for patients around the world.