Ann Thorac Surg 2002;73:667-670
© 2002 The Society of Thoracic Surgeons
How to do it
Enlargement of the aortic annulus using a double-patch technique: a safe and effective method
J. Ernesto Molina, MD, PhD*a
a Division of Cardiovascular and Thoracic Surgery, University of Minnesota Medical School, Minneapolis, Minnesota, USA
Accepted for publication October 10, 2001.
* Address reprint requests to Dr Molina, Division of Cardiovascular and Thoracic Surgery, University of Minnesota, 420 Delaware St SE, MMC 182, Minneapolis, MN 55455, USA
e-mail: molin001{at}umn.edu
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Abstract
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We have tested a new method to enlarge the aortic annulus using a double-patch technique after the Manouguian principle. Our study included 14 patients who had no operative mortality and no complications; long-term follow-up was 13 years. The method prevented mitral insufficiency and operative bleeding at the aortic root.
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Introduction
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It is not uncommon for patients with aortic stenosis who require valve replacement to have a small aortic annulus, particularly women. There are three possible solutions to a narrow aortic annulus: (1) Use a stentless tissue prosthesis (a homograft valve, a Toronto [St. Jude Medical, St. Paul, MN] stentless prosthetic valve, or a Medtronic [Minneapolis, MN] freestyle valve) if feasible and available. (2) Enlarge the aortic annulus to allow insertion of a mechanical or stented tissue valve of adequate dimensions, depending on what is available and what is more convenient for the patient. (3) Implant an adequate-sized prosthesis in a tilted supraannular position.
In many institutions around the world, neither homografts nor stentless valves are available. Therefore, the surgeon should be able to enlarge the aortic annulus and fit a proper-sized prosthetic valve. Many publications indicate that the implantation of a small prosthetic valve in a large patient may increase mortality [1], may not solve the degree of aortic stenosis at all [2], or may necessitate a later reoperation [3]. Moreover, the left ventricular mass will not decrease, long-term survival may be shortened [4], and reoperation, if needed, will result in higher morbidity and mortality [5]. Therefore, we have tested a new method to enlarge the aortic annulus using a double-patch technique after the Manouguian principle.
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Technique
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An S-shaped incision is extended toward the noncoronary cusp. After the native valve is excised, the annulus is measured; if it is too small to implant an adequate-sized prosthetic valve, the annulus should be enlarged at that point.
The vertical incision coming from the ascending aorta is then extended across the aortic annulus (Fig 1),
into the anterior leaflet of the mitral valve (Manouguian technique) [6] down to a few millimeters away from the free edge of the leaflet. The roof of the left atrium is automatically entered, but only for a short distance. The annulus will immediately open widely (Fig 2).
The orifice is now measured for the proper size prosthesis. Usually, sizes 23 to 27 can be easily placed. Stitches are placed in the true annulus to hold the aortic prosthetic valve, and then the reconstruction of the enlarged annulus is undertaken.
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Fig 1. An S-shaped incision is carried down to the aortic annulus in the noncoronary cusp. After the aortic valve has been excised, the incision is extended into the mitral leaflet, as well as into the roof of the left atrium.
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Fig 2. The aortic annulus has been divided and the incision cuts into the roof of the left atrium a short distance, more extensively toward the free edge of the mitral leaflet.
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A triangle-shaped patch of Gore-Tex (W. L. Gore, Flagstaff, AZ) patching material, of 0.39-mm (0.015-inch) thickness with a pore size of 22 µm, is cut and placed to fill the gap in the mitral valve leaflet. The suture line starts at the corner of this triangular patch with 6-0 Prolene (Ethicon, Somerville, NJ; Fig 3).
A small piece of Teflon (DuPont, Parkersburg, WV) felt pledget should be used to prevent the suture from cutting through the thin valvular tissue. The suture is placed in a running fashion, from that corner back toward the base of the leaflet, until the level of the aortic annulus is reached. The suture is continued past the level of the annulus for a few millimeters, and tied. The patch must not be too tight or stretched laterally, but rather loose, even hooded. No tension should exist at its base. The base of this triangular patch is now cut parallel to and slightly above the level of the aortic annulus.
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Fig 3. The gap created in the mitral leaflet is now patched with a triangular piece of polytetrafluoroethylene (PTFE) using 6-0 Prolene (Ethicon, Somerville, NJ) suture starting at the tip of the gap and running it toward its base at the aortic annulus.
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Now, a triangular piece of Dacron (C. R. Bard, Haverhill, PA) material—preferably one that is impervious to blood (ie, Hemashield, Boston Scientifics, Watertown, MA)—is tailored to the proper size. It is placed at the base of the aortic annulus, overlapping the Gore-Tex patch by a couple of millimeters (Fig 4). These two patches are back-to-back, with the Dacron filling the ascending aortic gap. To anchor the aortic prosthesis to the new annulus, finer suture material (3-0 or 4-0 Ethibond) is used. These mattress-type stitches (usually six) are placed without any Teflon pledgets, from the skirt of the prosthesis and pass through the base of both patches (Gore-Tex and Dacron) to the outside. Each stitch needs to be made meticulously. The first stitch (a double-armed suture) must extend from the skirt of the prosthesis to the commissure between the left and the noncoronary cusps, with the first needle going through the aortic tissue to the outside and the second needle going through the base of the Gore-Tex patch and the Dacron patch to the outside, as well.
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Fig 4. The aortic valve prosthesis has been brought into the field. All the stitches in the native aortic annulus are placed first. The triangular patch filling the gap in the mitral leaflet has been sutured in place already, and another triangular piece of Dacron (C. R. Bard, Haverhill, PA) is positioned at the aortic annulus to fill the gap in the ascending aorta. Anchoring of the aortic prosthesis at the level of the gap is shown, with mattress stitches being passed from the skirt of the prosthesis without pledgets, through the base of the polytetrafluoroethylene patch, then through the base of the Dacron patch that will fill the gap in the ascending aorta. The same stitch is passed through the lip of the left atrial opening and through a strip of Teflon felt to reinforce it. These stitches are tied on the outside, bringing all five layers together.
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Both of the needles are now passed through the lip of the left atrium. They are then passed through a strip of Teflon felt material positioned along the atrial rim to prevent tearing or bleeding of the atrial roof. All the rest of the stitches at this level are placed in the same manner, from one corner of the gap to the other, until the closure of the annulus is completed (Fig 4).
The valve is now lowered into place. The regular valve sutures, which were placed in the true annulus, are tied down and the valve secured in place. The stitches corresponding to the gap of the annulus are tied last, without tension, to bring the left atrial wall against the two patches that are already in place. Each stitch that anchors the skirt of the prosthesis to the newly created prosthetic aortic annulus, therefore, passes through five layers (Fig 5):
the skirt of the prosthesis, the base of the Gore-Tex patch, the base of the Dacron patch, the left atrial wall, and the Teflon felt strip on the outside.
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Fig 5. Final outlook of the repair, showing the five layers of material that close the gap created by the enlargement of the aortic annulus: 1 = Aortic valve prosthetic skirt. 2 = Polytetrafluoroethylene (PTFE) patch filling the gap in the mitral leaflet. 3 = Dacron (C.R. Bard, Haverhill, PA) patch filling the gap in the ascending aorta. 4 = Left atrial wall sandwiched between the Dacron patch. 5 = The Teflon felt strip used to reinforce the atrium.
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To suture the Dacron patch to the ascending aorta, a suture everting both structures (the Dacron and the aorta itself) is preferred, to ensure hemostasis. A running whipping stitch is placed over the everted edges. Therefore, two sutures are used, one for each corner of the patch. The two suture lines meet at the tip of the triangular patch where the rest of the aorta can be closed in a standard manner.
The protection of the heart may be accomplished either by retrograde continuous cardioplegia through the coronary sinus, or by intermittently applying a blunt-tipped cardioplegia cannula to the left coronary artery.
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Comment
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Fourteen patients have undergone operations with this technique in which the aortic annulus was judged severely narrow. An aortic annulus was considered to be as such if it met the following criteria: it did not allow the placement of a 23-mm prosthetic valve or larger in a patient weighing more than 70 kg with a body mass index higher than 30; or it did not allow the placement of a 21-mm prosthetic valve in a patient weighing less than 70 kg with a body mass index lower than 30. Before enlargement, the aortic orifices in these patients admitted only a 19-mm or 21-mm prosthetic valve.
All 14 patients received St. Jude valves. With this aortic annulus enlargement maneuver, we were able to implant valve sizes 23 or 23HP in 6 patients, size 25 in 6 patients, and size 27 in 2 patients. The postoperative mean pressure gradient across the valve orifice, measured by two-dimensional echo, had a mean of 8.7 ± 7.1 mm Hg (range 0 to 18 mm Hg). No intraoperative or postoperative bleeding occurred in any of the patients in any groups, and none of them show mitral regurgitation, as late as 13 years after this operation.
One interesting finding of the follow-up with two-dimensional echoes is that the Gore-Tex patch used to fill the gap in the mitral valve remained pliable and mobile; it followed the general movements of the native mitral valve in its mechanism of closing with each ventricular contraction. This has not been noted to happen when only Dacron material is used to fill the gap in the mitral leaflet as described in the original Manouguian technique. There was no operative mortality in this group, and only one late death, of noncardiac causes, which occurred 4 years postimplant.
The thin Gore-Tex material, as a substitute for the mitral leaflet, appears to perform well, as long as the pore size of the patch is no larger than 22 µm. This size prevents heavy invasion by fibrous tissue that will make the leaflet more rigid. This consideration must be kept in mind when comparing the functioning of different prosthetic materials in a structure subjected to motility. Therefore, this technique is recommended when enlarging the aortic annulus becomes necessary to implant an adequate-sized prosthetic valve in the aortic position.
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References
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Adams D.H., Chen R.H., Kadner A., et al. Impact of small prosthetic valve size on operative mortality in elderly patients after aortic valve replacement for aortic stenosis: does gender matter?. J Thorac Cardiovasc Surg 1999;118:815-822.[Abstract/Free Full Text]
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Sawant D., Singh A.K., Feng W.C., et al. St. Jude Medical cardiac valves in small aortic roots: follow-up to sixteen years. J Thorac Cardiovasc Surg 1997;113:499-509.[Abstract/Free Full Text]
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Kratz J.M., Sade R.M., Crawford F.A., Jr, et al. The risk of small St. Jude aortic valve prostheses. Ann Thorac Surg 1994;57:114-119.
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Pibarot P., Dumesnie J.G. Patient-prosthesis mismatch is not negligible. Ann Thorac Surg 2000;69:1983-1984.[Free Full Text]
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Pibarot P., Dumesnie J.G., Lemieux M., et al. Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity, and mortality after aortic valve replacement with a bioprosthetic heart valve. J Heart Valve Dis 1998;7:211-218.[Medline]
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Manouguian S., Seybold-Epting W. Patch enlargement of the aortic valve ring by extending the aortic incisions into the anterior mitral leaflet. New operative technique. J Thorac Cardiovasc Surg 1979;78:402-412.[Abstract]
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Abstract
Introduction
