Prosthetic Heart Valve Expands as the Child Grows

Developed by researchers at Boston Children's Hospital (BCH; MA, USA), the new paradigm of expandable mitral valve replacement has potential to revolutionize care for infants and children with complex mitral valve disease. The expandable valve is a modified version of the Melody valve, a stented bovine jugular vein conduit made by Medtronic (Fridley, MN, USA). But while The Melody valve is approved by the US Food and Drug Administration (FDA) for replacement of the pulmonary valve, these are the first cases of its use as a mitral valve replacement.

One of the patients, a nine-month-old baby, had a mitral valve that was deemed irreparable and was replaced with a modified Melody valve. Several months later, the researchers were able to successfully expand the replacement in a cardiac catheterization procedure. When compared to a major repeat chest operation, a cardiac catheterization--which involves insertion of a fine catheter into the heart through a vessel in the groin--is much less invasive and requires less recovery time. Since then, the researchers have carried out the procedure out on an additional three patients, two of which have already undergone the first growth-related valve dilations. The outcomes of the surgery were published in the October 2012 edition of Annals of Thoracic Surgery.

“We wanted to find a solution that would allow us to expand a valve as a child grows and avoid taking them back into the operating room,” said lead author Sitaram Emani, MD, of the department of cardiac surgery. “This modified valve can be expanded within a patient via cardiac catheterization, potentially allowing us to leave the valve in place until a patient reaches adulthood and reducing the number of operations and the risk of lung swelling related to valve leakage. It opens up the opportunity to carry out mitral valve replacement in more children and at an earlier time point than has historically been possible.”

The care of patients with disease of the mitral valve, which controls blood flow from the left atrium to the left ventricle, can be very complicated. If a child needs a mitral valve replacement, there are only a limited number of options available, all of which have one limitation in common: they have a fixed diameter and cannot grow with a child. Thus, children who undergo mitral valve replacement must undergo additional future surgeries to have new, larger valves implanted as they outgrow their replacements. However, once implanted, fixed-diameter valves restrict growth of the of the mitral valve annulus; this limits the size of the valves that can be implanted in subsequent repeat replacement operations.

Related Links:
Boston Children's Hospital
Medtronic