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Ann Thorac Surg 2000;69:1924-1925
© 2000 The Society of Thoracic Surgeons
a Division of Cardiovascular-Thoracic Surgery, Children’s Memorial Hospital, 2300 Children’s Plaza, Box 22, Chicago, IL 60614, USA
e-mail: c-backer{at}nwu.edu
Aeba and colleagues have reviewed their results with 21 patients that had a Hemashield graft used as part of a congenital heart operation. Hemashield is a collagen-coated knitted Dacron graft with excellent compliance and hemostatic properties—it does not require preclotting. The graft was used for reconstruction of the aorta in 16 patients, the ventricular septum in 10 patients, and the right ventricular free wall or pulmonary artery in 6 patients. The authors have noted a very interesting sterile inflammatory reaction associated with Hemashield implantation marked by high fever, increased white blood count, and elevated plasma C-reactive protein. Their multivariate analysis identified the use of Hemashield on the right side of the heart as an incremental risk factor for elevation of C-reactive protein. The authors concluded that Hemashield can be used in a variety of unique situations for reconstructing congenital cardiovascular lesions in young patients. The advantages of the Hemashield, they feel are its greater compliance compared with uncoated Dacron fabric, its hemostatic capabilities (no preclotting required), and the dense anchoring of the neointima that forms, which helps prevent disruption of the neointima.
The word of caution that we would emphasize results from our experience using Hemashield as a conduit for patients undergoing either primary Rastelli procedure or reoperation for conduit change. Of significant note, the series of patients reported by Aeba and colleagues included only 6 patients in whom the Hemashield was used on the right side of the heart and of those 6 patients only 2 had use of the Hemashield as a conduit. Three of the 6 patients had the Hemashield as a patch in the right ventricular outflow tract. Hence, only 2 patients in this series would be considered patients that had a circumferential Hemashield graft between the right ventricle and the pulmonary arteries. In this subgroup of 6 patients the follow-up was relatively short at only 2.8 years.
Our experience with Hemashield when used as part of a conduit from the right ventricle to the pulmonary artery is that a sporadic, but high percentage of patients develop significant neointimal hyperplasia leading to conduit obstruction within a very short time period after the surgery [1]. In our series (published in 1993) we reported 17 children with 18 right ventricle to pulmonary artery conduits placed using a composite of an aortic or pulmonary valved homograft and a Hemashield extension to the ventricle. In our original report 6 of those 18 conduits were replaced within 10 to 18 months (mean, 14 months) after insertion of the original conduit. Thus, a full one-third of these Hemashield right ventricular to pulmonary artery conduits failed within 18 months from a thick neointimal peel that was impossible to separate from the Hemashield. This accelerated neointimal formation led us to abandon the use of the Hemashield as an extension for a right ventricular to pulmonary artery conduit. A current update on that original cohort is that of 15 patients (16 conduits) for whom follow-up is available, 13 of the 16 conduits have required conduit replacement between 0.9 and 8 years (mean 3.0 ± 2.3 years, median 1.9 years) following the original conduit insertion. This is clearly premature conduit failure, and in all cases there was dense, circumferential-neonitimal hyperplasia in the conduit. In addition, following publication of our 1993 review, 1 of our patients who had Hemashield used as an intracardiac tunnel for a Kawashima type repair of Taussig-Bing anomaly required reoperation for a significant left vetricular outflow tract obstruction from neointima formation on the Hemashield [2]. Our experience with this significant number of patients would indicate that Hemashield should not be used as a conduit extension for right ventricular to pulmonary artery conduits, and its use as an intraventricular patch is also suspect. Doctor Aeba’s finding that use of Hemashield on the right side of the heart resulted in elevation of plasma C-reactive protein may be a clue to the clinical problem we have observed. It may be that in some patients the significant inflammatory reaction to the Hemashield on the right side of the heart does not slow down after several weeks.
This commentary is written to advise caution regarding the use of Hemashield as a right ventricle to pulmonary artery conduit. It is our strong feeling that the article by Aeba and colleagues should not be considered a "green light" to use Hemashield for right ventricular outflow tract reconstructions. We have continued to use Hemashield in our clinical practice for aortic reconstructions and have had good results with the use of Hemashield in the ascending and descending thoracic aorta. We have stopped using Hemashield as an intraventricular patch or as a right ventricular to pulmonary artery conduit because of this experience.
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