Ann Thorac Surg 2008;86:643-645. doi:10.1016/j.athoracsur.2008.01.092
© 2008 The Society of Thoracic Surgeons
Case Reports
Traumatic Dehiscence of Medtronic Freestyle Stentless Bioprosthesis
Turki Albacker, MD,
Adil Al Kindi, MD,
Benoit de Varennes, MD*
Division of Cardiac Surgery, McGill University, Montreal, Canada
Accepted for publication January 28, 2008.
* Address correspondence to Dr de Varennes, Royal Victoria Hospital, 687 Pine Ave W, Room S8.44, Montreal, Quebec, H3A 1A1, Canada (Email: benoit.devarennes{at}muhc.mcgill.ca).
 |
Abstract
|
|---|
We report a case of deceleration injury causing traumatic dehiscence of a Medtronic Freestyle aortic bioprosthesis (Medtronic Inc, Minneapolis, MN) in a 70-year-old patient 5 years after a total root reconstruction. The patient presented with progressive exertional dyspnea 6 months after a significant impact during a hockey game. Intraoperatively, there was a posterior dehiscence of the proximal suture line and almost complete tear of the left coronary leaflet. At reoperation, the patient underwent reconstruction of the aortic root and Bentall procedure with a size 23 mechanical aortic valved conduit.
|
Introduction
|
|---|
The Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) has gained wide popularity in the aortic position due to its good hemodynamic performance [1]. Endocarditis has been reported as the most common cause for reoperation [1], whereas spontaneous failure due to structural degeneration was rare [2–4]. Traumatic dehiscence has not been reported.
We report a 70-year-old patient who first presented in 2002 with symptomatic aortic stenosis. The valve was bicuspid and the aortic root was dilated, measuring 5 cm. Because of the active lifestyle of the patient, it was decided to perform a full aortic root reconstruction with a Freestyle bioprosthesis (Medtronic Inc). After complete excision of the aortic root and mobilization of the two coronary buttons, the prosthesis was sutured to the patient's aortic annulus using a single running 3-0 polypropylene suture. The coronary buttons were anastomosed to the prosthesis with single, running 6-0 polypropylene sutures. The distal anastomosis between the Freestyle conduit (Medtronic Inc) and the ascending aorta was done with a running 4-0 polypropylene suture.
The postoperative course was uneventful until the patient presented in the spring of 2007 with new, progressive dyspnea of 6-month duration. The symptoms had started right after he was quite violently hit during a hockey game, and the patient rapidly became dyspneic, even with light activity. On physical examination he was found to have loud diastolic and systolic murmurs, and his pulse pressure was 125 mm Hg. Echocardiography demonstrated severe aortic regurgitation with what was interpreted as a paravalvular jet. Severe tricuspid regurgitation was also present. A computed tomographic angiogram suggested the presence of a pseudoaneurysm and a leak of contrast at the posterior part of the aortic root (Fig 1).
View larger version (71K):
[in this window]
[in a new window]
|
Fig 1. Computed tomographic angiogram of the aortic valve and the aortic root. (A) The black arrow shows the posterior pseudoaneurysm at the aortic root. (B) Sagittal section showing the communication between the true aortic lumen and the pseudoaneurysm (black arrow).
|
|
At surgery, distal ascending aortic and bi-caval cannulation was established. After cardioplegic arrest, the dissection around the aortic root, which was densely fibrosed with heavy calcifications, was carried out. A transverse aortotomy was done at the level of the previous distal anastomosis, and the aortic valve and root were inspected. The left coronary cusp was completely avulsed from the prosthetic aortic wall and a full thickness tear was identified from where the leaflet had originated. This tear led into the false aneurysm cavity on the posterior aspect of the aortic root. The proximal suture line at the same level was dehisced with the Dacron cuff (DuPont, Wilmington, DE) floating freely in the left ventricular outflow tract and was attached at the level of the two adjacent commissures (explaining the paravalvular leak). The 3-0 polypropylene suture appeared intact. The native annular and peri-annular tissues at that level seemed healthy and were noncalcified, whereas the aortic root graft was extensively calcified. The remaining leaflets were excised along with the dehisced part of the Dacron graft (DuPont). The left coronary button was mobilized, whereas the right one was ligated after being injured during dissection mobilization. A modified Bentall procedure was completed with a 23-mm St. Jude mechanical aortic valved conduit. Pledgeted sutures were placed in the native aortic annulus for the proximal suture line. The left coronary button was implanted into the conduit, whereas the right coronary artery was bypassed with a vein graft. The tricuspid valve was repaired with a size 30 Carpentier ring (Edwards Lifesciences, Irvine, CA). The patient was successfully weaned from cardiopulmonary bypass. The patient had an uneventful course and was discharged home.
The pathology of the explanted bioprosthetic valve showed dense fibrosis and chronic inflammation with calcification of the aortic wall. The three valve leaflets appeared normal. All the blood and tissue cultures were negative with no evidence of infective endocarditis.
|
Comment
|
|---|
Dehiscence of the Freestyle bioprostheses has been reported early and late postoperatively [2, 4, 5]. Although early dehiscence has been attributed to technical problems, late dehiscence was usually caused by structural degeneration. Histologic examination of the dehisced tissues that was previously reported [6] suggested that loss of cuspal corrugation, fibrosis of lamina spongiosa, and the loss of elastic tissue staining were the basic microscopic alterations. In addition, calcification was rare and was only found in the infected valve of two cases. These microscopic features were absent in the tissues examined from our patient, which may suggest an alternative cause such as trauma. The combined partial dehiscence of the bioprosthetic cuff from the aortic wall and the leaflet torn away from the root may indicate the stress forces that were applied on the rigidly fixed cuff by the trauma of sudden deceleration. The dense fibrosis and heavy calcification around the prosthesis is an unusual finding in these Freestyle bioprostheses due to the inherent characteristics acquired during fixation and anti-calcification treatment that may inhibit such changes [7]. Despite the sterility of the blood and tissues cultured from the operative site, the possibility of a low-grade chronic infection must always be considered. The patient did not remember whether or not he used any antibiotic for other reasons during the course of this problem.
In addition to the superior hemodynamic performance of the Freestyle stentless bioprostheses, these valves have the advantage of freedom from anticoagulation. The trauma in our patient may have been the primary cause of dehiscence of the prosthesis or may have precipitated the dehiscence of a previously structurally degenerated prosthesis. The calcification of the prosthetic aortic wall, by its reduced elasticity, may have contributed to the deceleration dehiscence of the leaflet. A single, running suture at the proximal anastomosis has been used by our group for an extensive period of time without any problem, as care is taken to thoroughly decalcify the native annulus and leave intact a 2-mm to 4-mm cuff of proximal aorta that can be incorporated with surrounding tissues in the suture line. This provides for a highly reliable hemostatic suture line. An interrupted suture technique might have prevented or limited the dehiscence of the suture line, but not the leaflet from detaching from the wall. In either way, our reported case raises the question of whether this category of patients needs a special follow-up or a change in their lifestyle when considering this type of prostheses.
|
References
|
|---|
- Doty DB, Cafferty A, Cartier P, et al. Aortic valve replacement with Medtronic Freestyle bioprosthesis: 5-year results Semin Thorac Cardiovasc Surg 1999;11:35-41.[Medline]
- Schoof PH, Baur LH, Kappetein AP, Hazekamp MG, van Rijk-Zwikker GL, Huysmans HA. Dehiscence of the Freestyle stentless bioprosthesis Semin Thorac Cardiovasc Surg 1999;11(4 Suppl 1):133-138.[Medline]
- Mohammadi S, Baillot R, Voisine P, Mathieu P, Dagenais F. Structural deterioration of the Freestyle aortic valve: mode of presentation and mechanisms J Thorac Cardiovas Surg 2006;132:401-406.[Abstract/Free Full Text]
- Takami Y, Masumoto H, Fyfe-Kirschner B. Late disruption of a Freestyle stentless bioprosthesis used for repair of sinus of valsalva aneurysm of noncoronary cusp Ann Thorac Surg 2007;83:2210-2213.[Abstract/Free Full Text]
- Murayama H, Asano S, Oba M, Owada H, Tatuno K. A case of early failure of the Freestyle stentless bioprosthesis due to cuspal tear Ann Thorac Cardiovasc Surg 2004;10:382-385.[Medline]
- Fyfe BS, Schoen FJ. Pathological analysis of nonstented Freestyle aortic root bioprostheses treated with amino oleic acid Semin Thorac Cardiovasc Surg 1999;11(Suppl 1):151-156.[Medline]
- Deeb GM, Smolens IA, Bolling SF, Eppinger MJ, Pagani FD, Prager RL. Re-operation for Freestyle stentless aortic valves Semin Thorac Cardiovasc Surg 2001;13(4 Suppl 1):16-23.[Medline]
Top
Abstract
Introduction
