HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Etienne Tatou Roger Brenot Michel David Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tatou, E. Articles by David, M. Search for Related Content PubMed PubMed Citation Articles by Tatou, E. Articles by David, M. Related Collections Valve disease

Ann Thorac Surg 2001;71:1366-1369
© 2001 The Society of Thoracic Surgeons

---

Case report

Fracture-embolization of Duromedics valve prosthesis and microscopic uncommon lesions

^a Service de Chirurgie Cardio-vasculaire, Centre Hospitalier Universitaire de Dijon, Dijon, France
^b Service de Cardiologie, Centre Hospitalier Universitaire de Dijon, Dijon, France

Accepted for publication May 2, 2000.

Address reprint requests to Dr Tatou, Service de Chirurgie Cardio-Vasculaire, 2 Bd maréchal de Lattre de Tassigny, BP 1542, 21034 Dijon, France
e-mail: etatou{at}ipac.fr

	Abstract

Top Abstract Introduction Comment References

 
We report a sudden leaflet fracture of a Duromedics mitral valve 6 years after implantation. The patient had cardiogenic shock and complained of asthenia, orthopnea, and tachycardia. Transesophageal echocardiography showed the lack of one leaflet of the prosthesis and regurgitation. An emergency mitral replacement was successfully performed. Angiographic computed tomography scan localized the sequestrum that embolized the common iliac arteries. Examination of the deficient prosthesis showed multiple lesions and, in particular, a subsurface lesion that may be characteristic of carbon pyrolytic valves.

	Introduction

Top Abstract Introduction Comment References

 
The primary restriction of the artificial heart valve is its potentially uncertain lifetime due to degradation by cyclic fatigue or stress corrosion under complex physiological loading. Frequently used in biomedical devices, pyrolytic carbon has found its greatest application in mechanical cardiac valves, as it has been shown to be highly thromboresistant and to have a cellular biocompatibility with blood and soft tissue. Surgeons are conscious that implantation damage to the prosthesis valve may always be a possibility, leading to fracture in certain cases. However the fact that cracks in the pyrolytic carbon could be the result of the manufacturing process itself is a new piece of information.

In 1991, a 22-year-old man, known to have a bicuspid aortic valve, presented with streptococcal endocarditis, with grade III to IV regurgitation in the aortic, mitral, and tricuspid valves. Cardiac cavities were dilated with preserved function. An aortomitral replacement with tricuspid annuloplasty was performed. In the mitral position a bileaflet Edwards-Duromedics prosthesis (29 mm) was inserted and a 23-mm-diameter prosthesis placed in the aortic position. A follow-up examination after 62 months showed no complications. However in 1997 the patient complained of a rapid onset of asthenia, orthopnea, and tachycardia. Organic murmur, hypoxia, and cardiogenic shock were present. After intensive resuscitation a transesophageal echocardiography showed massive mitral regurgitation and a missing mitral prosthesis leaflet. The aortic prosthesis was normal. An immediate operation was carried out in which a St. Jude mitral prosthesis (St. Jude Medical, Minneapolis, MN) was inserted in place of the old, deficient mitral prosthesis. The missing leaflet was not found either in the left ventricle or left atrium or in the pulmonary veins. Forty-eight hours after the cardiac surgery, an abdominal scan showed that the leaflet sequestrum, which had divided into two fragments, had embolized the right common iliac artery and the left iliac birfurcation. At laparotomy we observed preperforating lesions. The sequestra were drawn out through bilateral iliotomy. At 16-month follow-up the patient was in excellent condition.

Examination of the prosthesis (Baxter CER 97-C1213-7, model 9120 R, 29 mm, V C 3050) by roentgenography revealed one missing leaflet that appeared to have split into two nearly equal pieces. Microscopic inspection revealed many lesions on the fractured leaflet and its corresponding housing seating lip (Fig 1A) with some matching damage, but also on the housing seating lip of the intact leaflet (Fig 1B). Most of the damage was either in or within 300 µm of the seating lip contact band and corresponded in location to seating lip damage. The fractured leaflet highlights the point of fracture origin. This examination also highlights contact and damage locations on the housing seating lip. One of them (arrow 23) corresponds to the original site of the fracture. The material loss is consistent with high impact or asynchronous closure as illustrated by the chipped appearance of the pitted side on the leaflet (Fig 2A). There was some chipping type of material loss on the seating lip (Fig 2B, Fig 1A, arrow 24), but this damage did not correspond to the site of the fracture origin. The housing seating lip opposite the intact leaflet also shows a contact damage mark (Fig 1B). Gross analysis of the housing damage (arrow 4) revealed in this circular area spiderweb-type cracks indicative of a potential material issue that was not present on the surface at the time of manufacture (Fig 2D). However, this could have been a subsurface condition that would have been undetectable by any known test. This potential material issue could be related to the material loss shown above on the left of the spider-web-type cracks lesion (Fig 2C).

View larger version (92K): [in this window] [in a new window]   Fig 1. (A) Fractured leaflet with many lesions and its corresponding housing seating lip with some matching damage. (B) Intact leaflet and its corresponding housing seating lip with a contact damage mark.

View larger version (141K): [in this window] [in a new window]   Fig 2. (A) Gross analysis of the fracture site with chipped appearance of the pitted side on the leaflet. (B) Gross analysis of one of the material loss on the seating lip of the fractured leaflet (Fig 1A). (C) Circular area with spiderweb-type cracks with gross analysis of probable corresponding lesion. (D) Circular area with spiderweb-type cracks evident by gross analysis of one of the damage marks on the housing seating lip opposite the intact leaflet (Fig 1B).

	Comment

Top Abstract Introduction Comment References

In 1987 an initial series of 40 patients was reported by Jamieson and colleagues [2] with no case of failure during a 24-month follow-up period. When catastrophic failure occurred in a limited number of the Duromedics valves the manufacturer, Baxter Edwards immediately (1988) interrupted the commercialization of the device worldwide. The rate of missing leaflets was significant at 0.029% per patient-year and was higher in the mitral than in the aortic position. Extensive corrections were made to the original prosthesis to eliminate these problems. Five factors have been identified that may contribute to leaflet damage: cavitation bubbles, asymmetric closure and localized stresses, inadequate compliance of the calcified sewing ring, clustered microporosity of the pyrolytic carbon, and surgical mishandling during implantation [3]. These technical considerations allowed the manufacturer to release the modified Tekna valve on the international market in 1990. The development of this new valve design must not obscure the fact that many patients with Duromedics prosthesis need careful follow-up; the risk of leaflet loss has not disappeared even with the new design. In our case, looking for the cause of the failure according to the five previously mentioned factors we did not find any "cavitation erosion," but its mechanism has not been conclusively proved to date and no mechanical heart valve design other than Duromedics has been scientifically documented to have had "cavitation-related" structural failures in human subjects [4]. Our patient was young and there was no annular ring calcification suggesting inadequate compliance of the sewing ring and shock absorption problems. On both sides of the intact and damaged leaflets there were asymmetric annular lesions with the conflicting area between the leaflet and the housing seating lip, probably in relation to the asymmetric closure and localized stresses. The consequences are an abrupt and asynchronous closure, with one leaflet closing first with low impact and the second closing with higher impact as shown here by the one-sidedness of the damage. Thus we agree with Wu and Wang [5] about the effect of the gravitational field on the asynchronous closure of valve leaflet. Another explanation is the possible presence of clustered microporosity of the pyrolytic carbon on the edges of the valve housing, leading to surface microcracks and deep pits. More important is the circular lesion with the spiderweb-type cracks, indicative of a potential material issue that was not evident on the surface at the time of manufacture. These undetectable subsurface cracks undoubtedly define a specific lesion that is as yet undescribed and is not typical of previous events with this valve model. We agree with Ritchie [6] who maintains that cracks in pyrolytic carbon are often subsurface and thus invisible to optical and electron microscopy. Does this condition apply to all pyrolytic carbon heart valve designs or can we consider that a subsurface lesion is not a material property but rather a consequence of the manufacturing process? This complex problem needs to be studied and answered to ensure the lifetime durability of the carbon pyrolytic heart valve design.

In conclusion, the asynchronous closure and the clustered microporosity are obvious causes of valve lesions in our case. The microscopic analysis of the valve reveals other subsurface lesions. Hence it would appear to be important to investigate whether any relationship exists between this lesion and the ultimate failure of the valve.

	References

Top Abstract Introduction Comment References

 

1. Tsui B.C., Kinley C.E., Miller R.M. Optimal imaging technic for locating leaflets escaped from prosthetic heart valves. Can Assoc Radiol J 1994;45:93-96.[Medline]
2. Jamieson W.R.E., Iyrala A.J., Tyers G.F.O., et al. Duromedics heart valve prosthesis; indications and early results. Thai J Cardiovasc Thorac Surg 1987;8:209-213.
3. Baudet E., Roques X., McBride J., Grimaud J.P., Panes F. An 8 years follow-up of the Edwards-Duromedics bileaflet prosthesis. J Cardiovasc Surg 1995;36:437-442.[Medline]
4. Yoganathan A.P. Overview: an engineer’s perspective. J Heart Valve Dis 1996;5:S3-S6.
5. Wu Z.J., Hwang N.H.C. Asynchronous closure and leaflet impact velocity of bileaflet mechanical heart valves. J Heart Valve Dis 1995;4:S38-S49.
6. Ritchie R.O. Fatigue and fracture of pyrolytic carbon: a damage-tolerant approach to structural integrity and life prediction in "ceramic" heart valve prosthesis. J Heart Valve Dis 1996;5:S9-S31.

This article has been cited by other articles:

				H. Mohammadi, R. J. Klassen, and W.-K. Wan A finite element model on effects of impact load and cavitation on fatigue crack propagation in mechanical bileaflet aortic heart valve Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, October 1, 2008; 222(7): 1115 - 1125. [Abstract] [PDF]

				K. Yamazaki, K. Nishimura, A. Iwakura, K. Uehara, T. Okada, and T. Sugita Fracture Embolization of an Edwards-Duromedics Valve with Asymmetrical Closure Asian Cardiovasc Thorac Ann, June 1, 2008; 16(3): 242 - 245. [Abstract] [Full Text] [PDF]

				L. Hansen, M. Danne, B. Hoffmann, and F.-C. Riess Structural valve failure with every beat regurgitation observed using the Medtronic Advantage aortic valve. J. Thorac. Cardiovasc. Surg., November 1, 2007; 134(5): 1344 - 1345. [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Etienne Tatou Roger Brenot Michel David Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tatou, E. Articles by David, M. Search for Related Content PubMed PubMed Citation Articles by Tatou, E. Articles by David, M. Related Collections Valve disease