PHOENIX (FRONTLINE MEDICAL NEWS) – A prosthetic conduit that contains a porcine valve showed excellent intermediate-term durability for repairing the right ventricular outflow tract in 100 teenagers and young adults at a single U.S. center.

“The Carpentier-Edwards xenograft for right ventricular outflow tract [RVOT] reconstruction provides excellent freedom from reoperation and valve dysfunction, as well as sustained improvement in right-ventricular chamber size at intermediate-term follow-up,” Dr. Heidi B. Schubmehl said at the Society of Thoracic Surgeons annual meeting.

Dr. Schubmehl reported a 92% rate of freedom from valve dysfunction with follow-up out to about 10 years, and significant reductions in right ventricular size at follow-up, compared with baseline, as measured by both echocardiography and by MRI.

The Carpentier-Edwards porcine valve and conduit “seemed to hold up better than a lot of other [prosthetic] valves,” said Dr. George M. Alfieris , director of pediatric cardiac surgery at the University of Rochester (N.Y.), and senior author for the study. In addition to the valve’s durability over approximately the first 10 years following placement, the results also showed the positive impact the valve had on right ventricular size, an important result of the repair’s efficacy, Dr. Alfieris said.

“It’s a mistake to allow the right ventricle to be under high pressure or to reach a large volume. We now focus on preserving the right ventricle,” he said in an interview. “I’ve become very concerned about preventing right ventricular dilation and preserving right ventricular function.”

Dr. Alfieris noted that his prior experience using other types of valves in the pulmonary valve and RVOT position showed those valves “did great for the first 10 years and then failed. What’s different in this series is that after 10 years, we have not seen the same dysfunction as with the prior generation of valves. I will be very interested to see what happens to them” as follow-up continues beyond 10 years. He also expressed dismay that recently the company that had been marketing the valve and conduit used in the current study, the Carpentier-Edwards, stopped selling them. He expects that as his supply of conduits runs out he’ll have to start using a different commercial valve and conduit that he believes will not perform as well or create his own conduits with a porcine valve from a different supplier.

The series of 100 patients comprised individuals aged 17 or older who received a pulmonary artery and had RVOT reconstruction at the University of Rochester during 2000-2010, Dr. Schubmehl reported. The series included 78 patients with a history of tetralogy of Fallot, 8 patients born with transposition of their great arteries, 8 patients with truncus arteriosus, and 6 patients with other congenital heart diseases. Their median age at the time they received the RVOT conduit was 24 years, 59% were men, and 99 had undergone a prior sternotomy. At the time they received the conduit, 55 had pulmonary valve insufficiency, 30 had valve stenosis, and 15 had both. Follow-up occurred an average of 7 years after conduit placement.

Two recipients died: One death occurred perioperatively in a 41-year old who had a massive cerebrovascular event, and the second death was in a 39-year old who died 2.6 years after conduit placement from respiratory failure. Two additional patients required a reintervention during follow-up, said Dr. Schubmehl, a general surgeon at the University of Rochester. One reintervention occurred after 11 years to treat endocarditis, and the second after 11 years to perform balloon valvuloplasty because of valve stenosis.

The results reported by Dr. Schubmehl for echocardiography examinations showed that the patients had a statistically significant reduction in their RVOT pressure gradient from baseline to 1-year follow-up that was sustained through their intermediate-term follow-up. Seventy-seven patients had pulmonary valve insufficiency at baseline that resolved in all patients at 1-year follow-up and remained resolved in all but one patient at extended follow-up. Nineteen patients underwent additional imaging with MRI at an average follow-up of 7 years, and these findings confirmed the echo results.

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