Ann Thorac Surg 2009;88:e34-e36. doi:10.1016/j.athoracsur.2009.06.117
© 2009 The Society of Thoracic Surgeons
Case Reports
Ross Procedure With a Composite Autograft Using Stretch Gore-Tex Material
Andras C. Kollar, MD, PhDa,*,
Scott D. Lick, MDa,
Diana M. Palacio, MDb,
Raleigh F. Johnson, Jr, PhDb
a Department of Surgery, University of Texas Medical Branch in Galveston, Galveston, Texas
b Department of Radiology, University of Texas Medical Branch in Galveston, Galveston, Texas
Accepted for publication June 30, 2009.
* Address correspondence to Dr Kollar, University of Texas Medical Branch, Department of Surgery, 301 University Blvd, John Sealy Annex 6.120, Galveston, TX 77555-0528 (Email: ankollar{at}utmb.edu).
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Abstract
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In an attempt to allow physiologic expansion of the pulmonary autograft, yet limit late root dilation, we used stretch Gore-Tex material (W. L. Gore & Assoc, Flagstaff, AZ) as an external wrap. Follow-up cardiac computed tomography with reconstructed three-dimensional and dynamic images confirmed normal "triple bulge" sinus Valsalva geometry and preserved natural systolic expansion of the neoaortic root.
Progressive neoaortic root dilatation and aneurysm formation with subsequent valvular regurgitation are well described late complications after aortic root replacement with the pulmonary autograft [1, 2]. It has been suggested that this dilatation could be prevented by wrapping the pulmonary root with pericardium [3] or pulling it into a synthetic polyester graft [4], but these techniques essentially eliminate elastic expansion of the native tissues and are therefore not universally accepted [5].
At the University of Texas Medical Branch in Galveston, we recently performed the Ross procedure in a young adult male patient, and in an attempt to provide elastic support to the pulmonary autograft we used expanded polytetrafluoroethylene stretch vascular prosthesis (W. L. Gore & Assoc, Flagstaff, AZ) as an external wrap.
The 44-year-old patient's cardiac workup confirmed severe calcific aortic stenosis with mild aortic regurgitation, and he gave his consent for the Ross procedure. To support the thin pulmonary artery while preserving elasticity, we selected an expanded polytetrafluoroethylene stretch vascular prosthesis that has mechanical properties allowing longitudinal (but not radial) "extensibility" of 39% [6]. A long, 18-mm diameter vascular prosthesis was cut open longitudinally and folded around the autograft horizontally without stretch, and a cone-shaped composite valved-conduit was created (Fig 1). Additional externally pledgeted subcommissural annuloplasty sutures, as described earlier [7], were used to increase semilunar valve coaptation and to facilitate the triple bulge geometry. Root replacement was then completed with running Prolene sutures (Ethicon, Somerville, NJ), and particular attention was paid to incorporate both polytetrafluoroethylene and native pulmonary artery when reimplanting the coronary arteries. Intraoperative transesophageal echocardiography confirmed normal neoaortic valve function with trace central aortic regurgitation. His postoperative course was uneventful with minimal bleeding (360 cc in 24 hours). Early postoperative hypertension was controlled by continuous nitroprusside infusion. He was then discharged from the hospital on postoperative day 8 on oral metoprolol.
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Fig 1. Intraoperative photograph of the cone-shaped composite autograft before implantation. Valve competency was tested with the old fashioned "water probe."
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Serial transthoracic echocardiography studies for up to 6 months follow-up confirmed stable root diameters, unchanged trace to mild central aortic regurgitation and rapid regression of previous left ventricular hypertrophy (septal wall diameter, 1.5 to 1.1 cm; posterior wall diameter, 1.3 to 1.0 cm). The acoustic shadows created by the prosthetic graft did not allow us to accurately assess root dimensions from the echocardiographic images, and therefore 1 month after surgery we performed an electrocardiography-gated cardiac computed tomographic scan using a 64 multi-detector computed tomographic scanner (VCT General Electric, Milwaukee WI). The raw data images were sent through a secure picture archiving and communicating system network to a separate workstation (General Electric Advantage Windows Volume Share 2; GE Healthcare Institute, Waukesha, WI) for post-processing. A three-dimensional, volume-rendered model generation of the cardiac anatomy was completed, and reconstructed dynamic images of the entire cardiac cycle were obtained in the coronal oblique plane along the aortic root axis and through the true aortic root/valve, cross-sectional plane at mid-sinus level.
The neoaortic root had normal overall geometry with the usual triple-bulge pattern on three-dimensional reconstruction (Fig 2) and on the cross-sectional view (Fig 3). In addition, the cross-sectional reconstructed dynamic images (Fig 3; an accompanying video for this article can be viewed on the Internet at http://ats.ctsnetjournals.org/content/vol88/issue4/images/data/e34/DC1/kollar.mpg) confirm well-maintained systolic expansion of the composite graft (diameter measurements from both axial and cross-sectional computed tomographic images are: base, 6.3% to 14.2%; mid-sinus level, 6.7% to 9.7%; and sinotubular junction, 7.7% to 17.6%).
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Fig 2. Volume-rendered three-dimensional reconstruction of the left ventricle and aorta demonstrating normal sinus Valsalva bulges of the neoaortic root (right anterior oblique view).
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Comment
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The natural aortic root is a highly compliant anatomical structure with significant tissue elasticity that has been well-characterized under static conditions [8, 9]. In animal experiments using sonomicrometric crystals [10], most tissue expansion occurred at the commissural level (as much as 25% at peak systole), with the basal ring being the least compliant (10% expansion). However, in vivo confirmation of similar tissue elasticity in humans has not been fully successful [11], which is most likely due to the additional and very complex three-dimensional aortic root ("rocking") motion [12].
According to in vitro studies, the native pulmonary artery wall is approximately 30% more compliant than the aorta [9], rendering the pulmonary autograft vulnerable to dilatation when subjected to systemic pressures [1, 2]. Although it is technically feasible to use the autograft as an aortic valve implant, most surgeons prefer the root replacement (whole unit) method, because none of the suture lines disturb the anatomical and functional relationships between valve leaflets and sinuses, and the three-dimensional geometry of the more delicate pulmonary valve is clearly better maintained. Moreover, recent experimental observations [13] strongly suggest that natural sinus wall compliance is an integral part of the normal semilunar valve function, and the observed "stress shearing" between sinus and leaflet may have a significant role in preserving longevity.
In an attempt to provide external support while preserving the desired elasticity of the neoaortic root, we decided to use a stretch polytetrafluoroethylene vascular prosthesis to wrap the pulmonary autograft. Although the described digitally reconstructed imaging modality may not be completely accurate in distinguishing aortic root motion from systolic expansion, the data from this case report, together with the reconstructed dynamic images (Fig 3 [Video]), suggest that the composite graft continued to exhibit systolic expansion comparable with the native aortic root. In addition, the prosthetic material significantly strengthened the weaker pulmonary artery tissues, and the suture lines proved to be very hemostatic. More cases with serial studies are necessary to see if the stretch Gore-Tex material (W. L. Gore & Assoc) used in such configuration would maintain its mechanical properties and/or if it could prevent pulmonary autograft dilatation in the long run.
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References
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- David TE, Omran A, Ivanov J, et al. Dilation of the pulmonary autograft after the Ross procedure J Thorac Cardiovasc Surg 2000;119:210-220.[Abstract/Free Full Text]
- Brown JW, Ruzmetov M, Rodefeld, MD, Mahomed Y, Turrentine MW. Incidence of and risk factors for pulmonary autograft dilation after Ross aortic valve replacement Ann Thorac Surg 2007;83:1781-1787.[Abstract/Free Full Text]
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- Swanson M, Clark RE. Dimensions and geometric relationships of the human aortic valve as a function of pressure Circ Res 1974;35:871-882.[Abstract/Free Full Text]
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- Lansac E, Lim HS, Shomura Y, et al. A four-dimensional study of the aortic root dynamics Eur J Cardiothorac Surg 2002;22:497-503.[Abstract/Free Full Text]
- Kazui T, Izumoto H, Yoshioka K, Kawazoe K. Dynamic morphologic changes in the normal aortic annulus during systole and diastole J Heart Valve Dis 2006;15:617-621.[Medline]
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- Robicsek F, Thubrikar MJ. Role of sinus wall compliance in aortic leaflet function Am J Cardiol 1999;84:944-946.[Medline]
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Abstract
Introduction
