Friday, May 1, 2009

Information on Pulmonary Valve Replacements

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This is important to us because we know that Nathan's going to need a new pulmonary valve with his heart defect.

Congenital Heart Disease
Posted: 11:04 am EDT April 24, 2009

Congenital heart disease refers to structural abnormalities of the heart that are present at birth. According to the American Heart Association, every year, about 35,000 babies in the U.S. (about one out of every 1,000) are born with some type of congenital heart defect.

More than 35 different types of defects have been identified. Some defects lead to a hole in the wall of the heart, a malformed or missing chamber or improper positioning of the blood vessels that connect the heart, lungs and body. A heart valve defect may involve a missing or malformed valve, failure of the valve to fully open (valve stenosis, or narrowing) or an inability to close completely, causing blood to leak through (valve insufficiency).

Replacement of the Pulmonary Valve

The pulmonary valve is a one-way valve that controls the flow of deoxygenated blood from the heart to the lungs. A child born with a defective pulmonary valve may not need immediate treatment if the problem is minor. But in serious cases, the defective valve interferes with the ability of the heart to pump blood into the lungs, eventually weakening the heart muscle. In those instances, doctors may recommend a pulmonary valve replacement through open-heart surgery. An incision is made into the chest to access the valve. The diseased valve is removed and replaced with a cadaver or artificial valve conduit (tube with a valve inside) that connects the right ventricle to the pulmonary artery.

While pulmonary valve replacement can greatly improve a patient’s quality of life, the average lifespan of the device is only about ten years. Thus, patients face multiple surgeries to replace the worn valve as they grow older. Thomas Jones, M.D., Pediatric Cardiologist at Seattle Children’s Hospital, says re-operation is technically more challenging because the surgeon has to cut through scar tissue. The surgery is also riskier for the patient, due to an increased risk for bleeding and infection.

Surgeons at select U.S. centers are now testing a new type of replacement pulmonary valve, called the Melody™ Transcatheter Valve. It’s obtained from a valve section of a cow’s jugular vein. Jones says the jugular veins of cows are about the same diameter as the pulmonary artery in humans and have well developed valves.

Instead of making an incision into the chest, the Melody valve is placed nonsurgically, via a catheter. The stent is closed to compress the valve and placed onto the tip of the catheter. An incision is made into the groin and the catheter is fed through a leg vein up to the heart. Once in place, the stent is expanded to open up the Melody valve inside the worn out valve.

Currently, researchers are testing the Melody heart valve in children who have already had valve replacement surgery and need another replacement. Preliminary studies show the valve can be successfully and safely implanted and, at least in the short term, leads to improved heart function. Jones says placement of the valve from inside of the body avoids the pain, recovery and potential complications associated with open-heart surgery. Although the new valve is not expected to last forever, investigators are hopeful it will reduce the total number of surgeries patients will need throughout their lifetimes.

In addition to Seattle Children’s Hospital the Melody Transcatheter Valve is being studied at Children’s Hospital Boston, Morgan Stanley Children’s Hospital of New York-Presbyterian Columbia University Medical Center, Miami Children’s Hospital and Nationwide Children’s Hospital in Columbus, OH.

For information on congenital heart defects:
American Heart Association
Congenital Heart Information Network
March of Dimes
National Heart, Lung and Blood Institute

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