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ST. LOUIS, July 13, 2004 — St. Louis Children’s Hospital is one of seven centers in the United States participating in a phase one clinical trial of a new device to close defects involving the membranous or perimembranous ventricular septum. Dr. David Balzer, director of the hospital’s Cardiac Catheterization Lab and WUSM associate professor of pediatrics, is implanting St. Louis’s first Amplatzer perimembranous VSD occluders, one of only 30 devices implanted in the nation. "Assuming we receive FDA approval, we’ll move to phase two of the trial, which will greatly expand the number of patients who can receive the device," explains Dr. Balzer.
According to Dr. Balzer, if this device is shown to be safe and effective, it will be very useful for patients because they can avoid open-heart surgery to close these types of holes, and usually go home the next day.
One of Dr. Balzer’s patients, 11-year-old Rista Tweedy, was born with a perimembranous VSD. Tweedy’s cardiologist in Springfield, Mo., referred her to St. Louis Children’s Hospital for the procedure because of a concern that she was having some enlargement of the left side of her heart as a result of the extra blood flow that was circulating through the VSD. "Perimembranous VSD is one of the most common types of VSD that we see," adds Dr. Balzer. "Potentially, this device would be useful for a very large number of children."
Performed during a standard cardiac catheterization, Dr. Balzer first conducts a series of measurements in terms of pressure and oxygen saturation in different areas of the heart to calculate how much blood is passing through the hole. Dr. Balzer simultaneously performs a transesophageal echocardiogram.
To begin the procedure, Dr. Balzer takes a small catheter and comes from the artery into the left side of the heart and then passes the catheter across the hole over into the right side of the heart. "From the right side, we’ve come up the groin vein into the right side of the heart," Dr. Blazer describes. "We then grasp a long wire that passes through the catheter and pull it out of the vein. Over that wire from the vein, we pass a long sheath that is just a hollow tube, tracking along that wire from the vein up into the right side of the heart and then across the hole into the left side of the heart."
With everything removed except for the sheath, the Amplatzer perimembranous VSD device is inserted, passed through the long sheath and pushed out so that the left side of the device pops out into the left side of the heart. "We pull it back against the hole and then pull that sheath back so that the right side of this device will open up on the right side of the heart," Dr.
Balzer says. "The hole itself is sandwiched between the two sides of the device. It traps and blocks the hole. Because we haven’t attached the delivery system at this point, we can just pull it out and start all over again if we don’t like the way it’s positioned. If we’re satisfied that everything looks fine, we simply unscrew the device from the delivery wire and release it."
St. Louis Children's Hospital has provided specialized care for children for more than 125 years. Children's Hospital is affiliated with Washington University School of Medicine, ranked the second best medical school in the country by US News & World Report. Washington University is known for excellence in medical research, teaching and patient care. In 2003, Child magazine ranked St. Louis Children's Hospital sixth on its list of the 10 Best children's hospitals in the country, and fourth in neonatology/neonatal intensive care unit (NICU). St. Louis Children's Hospital also is a member of BJC HealthCare, the first fully integrated health-care system in the country to join an academic medical center with suburban, rural and metropolitan-based health-care facilities.