A normal human heart has four valves that direct blood flow through the heart, making sure that blood travels in one direction. Many forms of congenital heart disease – disease that is present at birth – involve the pulmonary valve, which connects the heart to the blood vessels on the lungs. Many patients with this form of congenital heart disease require some form of open-heart surgery in which a tube is placed across this area to allow blood to freely pass to the lungs.
However, these tubes only last for several years. A variety of problems can occur:
- The child may outgrow the existing tube.
- The tube can become narrowed over time.
- If the tube does not have a valve in it, the blood that is pumped out from the heart can leak backward, making the heart work harder than it is supposed to.
Typically, if any of these occur, the child will require an open-heart surgery to replace the tube, usually with a larger tube with a working valve inside it.
With recent advances in technology, some of these patients can now get a new pulmonary valve using catheter-based techniques, thus avoiding open-heart surgery. A catheter is a thin, flexible tube that is inserted into a blood vessel to deliver treatments. This form of treatment requires only a puncture site in the skin, in contrast to more invasive open-heart surgery.
Not all patients who have problems with the pulmonary valve are candidates for catheter-based pulmonary valve implantation. To receive this treatment, patients must have a large enough existing tube in which to implant the valve. Patients who are not candidates for catheter-based techniques will still require open-heart surgery for valve replacement. Speak with your cardiologist regarding your child’s heart disease to see if he or she is a candidate.
During a catheter-based valve implantation, a large catheter is placed in a central vein, usually in the leg, and advanced to the heart and the pulmonary valve. Separate wire cages, or stents, are usually placed in the existing tube to strengthen it before the valve is placed. These stents are very stiff and protect the tube from compressing the new valve. The current valve used in the United States comes from a cow’s jugular vein and is sewn into a stent. It looks and functions very much like a human valve.
This valve is placed the same way other stents are placed: the stent is threaded to the procedure site via a catheter. A balloon tip on the catheter is opened to expand the stent into place. Then the balloon is deflated and the catheter is removed, leaving only the valve in the body. The new valve opens completely to let blood flow out freely and closes to prevent blood from leaking back into the heart.
Because of the large catheters placed in the vein, patients are usually watched in the hospital for a couple of days following the procedure to make sure the site where the catheter was inserted is healing well and will not bleed, as well as to make sure that the changes to the circulation are tolerated well. Children and adults undergoing this procedure can usually return to normal activity within a few days.
Currently, the pulmonary valve is the only valve that is placed by catheter techniques in both children and adults. In certain adults, an aortic valve may be placed with a catheter. The tricuspid and mitral valves are currently not placed with catheter techniques; open-heart surgery is still required to replace these valves.