J Thorac Cardiovasc Surg 1998;115:963-964
© 1998 Mosby, Inc.
Early failure of freehand aortic stentless xenograft valves
Giovanni Battista Luciani, MD,
Paolo Bertolini, MD,
Alessandro Mazzucco, MD
Reply to the Editor:
We read with interest the thought-provoking comments of O'Brien on our report of two cases of structural valve deterioration observed with the O'Brien-Angell stentless porcine aortic xenograft (Bravo Cardiovascular model 300, CryoLife, Inc., Atlanta, Ga.).
1 Several assertions in O'Brien's letter, however, deserve a reply.
Regarding the first case of structural deterioration caused by rupture of the porcine aortic wall support of the valve, the explanation offered by O'Brien suggests incorrect suprannular positioning of the graft. Accordingly, incomplete incorporation of all the aortic wall support by the suture line may have promoted rupture of the support itself. We believe this to be a possible interpretation for the failure of the device, although unlikely the correct one. It is, indeed, unclear how one could demonstrate that incorrect seating of the xenograft would have occurred based on the iconography presented in the manuscript. On the contrary, because of space constraints imposed by the format of the article, additional photographs of the explanted device could not be provided, which demonstrate how the profile of the xenograft was perfectly preserved. This observation is incompatible with the hypothesis of intraannular positioning of the xenograft, which, as we have observed on other occasions, 2 leads to profound distortion of the xenograft. The morphologic alterations of xenografts explanted for nonstructural valve deterioration persist after removal of the bioprosthesis and are thus readily apparent from the specimen. More important, as evident from Fig. 1 in our article, rupture of the support occurred at the level of the right noncoronary commissural pillar. At this point, incomplete incorporation of the aortic wall support by the suture line has no bearing on the final positioning of the xenograft relative to the anulus. We therefore believe that the diagram (Fig. 1) proposed by O'Brien, in which a stitch is shown passing through the nadir of the excised aortic leaflet, adds little insight to the interpretation of our case. Furthermore, we are well aware of O'Brien's outstanding results and the reported freedom from structural failure of the xenografts in his series. O'Brien quotes Hvass's experience with the O' Brien-Angell xenograft to support his own excellent results. However, Hvass did observe two cases of dehiscence of the xenograft resulting from slack suture and rupture of the suture, respectively. Both cases were labeled as technical (nonstructural) failure of the device because the xenografts were reported to be intact and "refixing the valves on the anulus would have been sufficient." 3 It is, however, unclear why both xenografts were replaced with mechanical prostheses. On the contrary, several aspects of those two cases are consistent with structural failure. Indeed, it is difficult to conceive how rupture of a suture line in the one case may result in perivalvular leak 10 months after an "initially perfect result." 3 In addition, one wonders whether the suture may be slack in the other case because it has not been correctly tightened or rather because the support has torn, as occurred in one of our cases.
The question whether connective tissue ingrowth will recur in our second patient can only be answered in the short term. Eighteen months after replacement of the O'Brien-Angell stentless valve with a Hancock II bioprosthesis (Hancock Extracoporeal Inc., Anaheim, Calif.), obstruction of the xenograft has not been shown at echocardiographic assessment and thus significant pannus formation can be ruled out.
We are grateful to O'Brien for further supplementing his technical description on how to implant the O'Brien-Angell stentless xenografts 5 with the three diagrams he has provided. We believe these technical suggestions to be of premiere importance in avoiding nonstructural failure of the xenograft resulting from inadequate suprannular positioning of the valve, which has occurred in our experience 2 as well as in Dr. Hvass's. 3,4 We remain convinced, however, that structural failure of this valve, certainly caused by pannus ingrowth and possibly caused by rupture of the support, can occur and is thus worth reporting.
Division of Cardiac SurgeryUniversity of Verona,
Verona, Italy12/8/88051
References
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Luciani GB, Bertolini P, Mazzucco A. Early failure of freehand aortic stentless xenograft valves. J Thorac Cardiovasc Surg 1997;113:1109-10.[Free Full Text]
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Luciani GB, Bertolini P, Vecchi B, Mazzucco A. Mid-term results after aortic valve replacement with freehand stentless xenografts: a comparison of three prostheses. J Thorac Cardiovasc Surg. In press.
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Hvass U, Chatel D, Ouroudji M, et al. The O'Brien-Angell stentless valve: early results of 100 implants. Eur J Cardiothorac Surg 1994;8:384-7.[Abstract]
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Hvass U, Chatel D, Assayag P, et al. The O'Brien-Angell stentless porcine valve: early results with 150 implants. Ann Thorac Surg 1995;60:S414-7.
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O'Brien MF. The CryoLife-O'Brien composite aortic stentless xenograft: surgical technique of implantation. Ann Thorac Surg 1995;60:S410-3.
