Ann Thorac Surg 2000;69:648-650
© 2000 The Society of Thoracic Surgeons
How to Do It
Methods for graft size selection in aortic valve-sparing operations
Donald B. Doty, MDa,
Joseph M. Arcidi, Jr, MDa
a Department of Surgery, LDS Hospital, Salt Lake City, Utah, USA
Address reprint requests to Dr Doty, Department of Surgery, LDS Hospital, 324 Tenth Ave, Salt Lake City, UT 84103
e-mail: ldddoty{at}ihc.com
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Abstract
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Simple and reproducible methods for accurate restoration of aortic root dimensions during aortic valve-sparing operations are described. The methods are based on choice of an appropriate size vascular graft based on the measured or desired diameter of the aortic annulus.
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Introduction
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Methods that preserve the aortic valve during reconstructive operations on the aortic root in patients with aneurysm of the aorta and aortic valve incompetence are becoming more widely practiced. This paper describes methods for accurate restoration of aortic root dimensions that we have found reproducible.
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Technique
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Intraoperative transesophageal echocardiography is performed after induction of anesthesia and before incision. Aortic root dimensions are determined at the sinotubular junction and at the aortoventricular junction (annulus). Operations are performed on cardiopulmonary bypass using a single two-stage cannula for venous uptake with oxygenated blood returned to a cannula placed high in the ascending aorta or arch or in the femoral artery. Deep hypothermia is used when the aneurysm extends beyond the ascending aorta.
The aorta is divided above the sinotubular junction. The aortic valve is thoroughly examined. Normal aortic valve leaflets suggest the possibility of a valve-sparing operation. The diameter of the sinotubular junction and the diameter at the ventriculoaortic junction (annulus) are measured using Hegar dilators or accurate valve sizers such as those supplied for the Freestyle Bioprosthesis (Medtronic, Minneapolis, MN). Alterations of aortic root dimensions are noted and will guide the steps that may be taken to restore dimensions to normal.
Aortic anulus normal, sinotubular junction enlarged
This situation is found in patients with aortic ectasia and aneurysm of the ascending aorta not involving the aortic sinuses. A vascular graft the same diameter as the aortic annulus is selected. A 4-to-5-mm segment of the graft is prepared for placement on the outside of the aorta at the sinotubular junction. The thickness of the aortic wall when compressed within the graft will reduce the inside diameter of the aorta to restore the normal dimension, which is 15% less than the diameter of the aortic anulus. Using this short segment of graft is easier and more accurate than trying to attach a longer graft directly to the sinotubular junction (Fig 1).
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Fig 1. Method for restoration of aortic root dimensions in an aortic valve-sparing operation when the aortic annulus is normal, and the sinotubular junction is enlarged. A 4-to-5-mm segment of a graft the same diameter as the annulus is placed on the outside of the aorta at the sinotubular junction to reduce the inside diameter 10%.
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Aortic annulus normal, sinotubular junction normal
This situation is found in patients with aortic dissection. A vascular graft 10% smaller than the diameter of the aortic annulus is selected. For an average size annulus of 24 mm, a 22-mm graft is chosen. Three incisions are made into the annulus at 120 degrees from each other. The tips are removed from the flaps that are created. The number of flaps depends on the sinuses that are involved is the dissection. The entire flap is removed corresponding to uninvolved sinuses. Dissected aortic sinus tissue is removed. The abnormal tissues do not cross the hinge point of the aortic valve leaflets (annulus). The flaps of the graft are used to reconstruct the sinuses and, if necessary, the coronary arteries are reimplanted. The diameter at the sinotubular junction is restored by the diameter of the graft (Fig 2).
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Fig 2. Method for restoration of aortic root dimensions in an aortic valve-sparing operation when the aortic annulus is normal, and the sinotubular junction is normal. A vascular graft 10% less than the diameter of the aortic annulus is used to remodel the aortic root.
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Aortic annulus enlarged, sinotubular junction enlarged
This situation is found in patients with annuloaortic ectasia, some of whom have Marfan syndrome. The sinus aorta is removed. The aortic annulus is reduced to a diameter appropriate for the patient’s body size (Fig 3). That would generally be 25 mm for the average adult male, 27 mm for a very large male, and 23 mm for an adult female. A vascular graft 10% to 15% less than that diameter is selected. Thus, for a 25-mm annulus, a 22-mm graft is chosen. Two 4-to-5-mm segments (rings) of the graft are prepared for adjustment of the diameter of the annulus, and the graft is tailored by making three incisions and trimming the flaps for sinus reconstruction and replacement of the ascending aorta. To achieve a 25-mm diameter left ventricular outflow tract at the ventriculoaortic junction (anulus), the circumference of the aorta must be reduced to 78 mm (25 x 
= 78). This will be accomplished by "annuloplasty" using the short segments of graft to accurately size the annulus and to support the repair. Anuloplasty mattress stitches are placed in the left ventricular outflow tract (LVOT) at a level plane just below the hinge point of the aortic valve. The stitches will be placed beginning below the nadir or mid point of the right coronary cusp of the aortic valve and working counterclockwise to the commissure between the non- and right coronary cusps. This places the stitches on five-sixths of the circumference, avoiding stitches in the one-sixth of the ventricular septum, which contains the conduction system. A strip of fabric to cover five-sixths of the circumference and achieve a diameter of 25 mm is 65 mm in length (78 x 
= 65). It is convenient that a 22-mm crimped tubular polyester graft provides a strip of fabric 75 mm in length when the 4-to-5-mm segment is cut, opened, and stretched to length. Ten millimeters of the length on one strip of the graft is removed. The annuloplasty stitches are placed through the fabric strip and passed through the left ventricular outflow tract to the outside as described. The thickness of tissue through which the needles pass is about 3 mm. Hence, the outside diameter to be supported will be about 28 mm in diameter. The length of fabric needed to support this diameter is, conveniently, about 75 mm (28 x x = 74). The annuloplasty stitches are passed through the outside fabric strip. A 25-mm diameter Hegar dilator is placed in the left ventricular outflow tract (LVOT) while the sutures are tied down. This narrows the LVOT to a calculated diameter while distributing the tension equally over five-sixths of the circumference of the LVOT. The sinus aorta is reconstructed to the flap graft. The diameter of the sinotubular junction is accurately restored by the diameter of the graft chosen for the repair. These relationships should hold for the various graft sizes that might be chosen for reconstruction of the aortic root.
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Fig 3. Method for restoration of aortic root dimensions in an aortic valve-sparing operation when the aortic annulus is enlarged, and the sinotubular junction is enlarged. A vascular graft 10% less than the desired diameter of the aortic annulus is used to provide 4-to-5-mm strips of fabric, which are used to support a reduction annuloplasty of five-sixths of the circumference of the LVOT (avoiding the conduction system) just below the aortic valve. The graft adjusts the diameter at the sinotubular junction.
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Intraoperative transesophageal echocardiography is performed with the heart contracting and ejecting at normal pressure to determine the adequacy of the repair.
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Comment
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Beginning in 1979, Yacoub and associates [1] performed valve-preserving operations in patients with aneurysms of the ascending aorta and root. The operation consists of removing all of the sinus aorta except for a small rim of aortic tissue around the coronary ostia. The commissures are positioned to achieve good coaptation of the aortic valve leaflets. The distance between the commissures is measured, and because this represents one-third of the circumference at the sinotubular junction, a tubular graft three times that dimension is chosen. Three slits are cut in the graft that are about 1.5 times the depth of the patient sinuses. The graft is then attached to the aortic anulus. There is no circumferential fixation of reduction of the diameter of the aortic anulus. Long-term results have been good, with freedom from reoperation 11% at 10 years.
David and associates [2] described an aortic valve-sparing operation for patients with aortic valve incompetence and aneurysm of the ascending aorta in which the aortic valve is reimplanted within a polyester tubular graft. The graft is secured to a level plane in the LVOT just below the valve, except in the one-sixth of the circumference that is occupied by the conduction system. Here, the stitches are placed through the annulus and a small wedge is removed from the graft to account for the higher level of suture placement. This fixes the diameter of the LVOT and may also reduce the diameter if necessary. The aortic valve is attached to the inside of the prosthetic graft (reimplanted). The graft determines the diameter of the sinotubular junction and is the same or slightly larger than the diameter of the annulus. This operation has been championed for patients with Marfan syndrome where there may be significant dilation of the ventriculoaortic junction and the potential for further dilation after the repair. It could also be useful in aortic dissection by placing abnormal aortic tissues within the graft, thereby reducing chance for hemorrhage. Cochrane and associates [3] modified the David operation to create pseudo sinuses in the graft by removing three symmetric scallops from the graft, thereby lengthening the proximal suture line and restoring the proper relationships at the sinotubular junction. Again, the graft determines the diameter of the sinotubular junction, which in this operation should be smaller than the diameter of the annulus. The relationships of the diameters at various levels in the aortic root were previously studied by Kunzelman and associates [4], showing that the diameter at the sinotubular junction should be about 15% less than the diameter at the base (annulus or ventriculoaortic junction). Frater [5] demonstrated that simply adjusting the dimensions of the sinus rim or sinotubular junction corrects aortic valve insufficiency due to aortic dilation. David [6, 7] recommended that when aortic root remodeling operations like the Yacoub operation are performed in patients with Marfan syndrome, an aortic annuloplasty be performed using a strip of prosthetic material on the outside of the LVOT below the aortic valve to correct dilation of the fibrous components of the LVOT due to myxomatous changes in these tissues. The method of aortic reduction described in this paper adds an additional strip of prosthetic material on the inside of the LVOT for added strength and accuracy of the adjustment of annular diameter. The potential risks of this method could be emboli or turbulence over the foreign material in the outflow tract.
Identification of the alterations of the aortic root dimensions is the fundamental principle that allows accurate and reproducible aortic root reconstruction and restoration of aortic valve competence when the valve leaflets are judged to be normal or nearly normal and morphology is thought to be related to abnormalities in the aorta. The tubular graft used for reconstruction of the aortic root then provides the unifying factor for accurate restoration of aortic root dimensions for predictable aortic valve function. The graft is chosen after measurement of the diameter of the LVOT at the ventriculo-aortic junction, defined here as the aortic annulus. This is a dimension that can be measured in all forms of aortic root abnormalities. Measurement of the diameter of the aortic annulus is easier and more accurate than measurement of the average length of the free edge of aortic valve leaflets as proposed by David and associates [6] or the distance between commissures as suggested by Morishita and colleagues [8]. The formulae for choice of proper graft diameter suggested by these workers involve difficult and quite complicated mathematical geometric relationships. Choo and Duran [9] point out that the aortic root is dynamic, responding to pressure changes during the cardiac cycle that expands the aorta at the sinotubular junction 35%, while the area at the base (annulus) expands only 5%. Thus, they propose measurement of the aortic root diameter at the base of the leaflets as the most reliable method for appropriate graft sizing. The method proposed herein is based on the measured diameter of the aortic annulus and very simple arithmetic figuring. When the diameter of the aortic annulus is normal, a graft is chosen that will narrow the sinotubular junction by 10% to 15%. When the diameter of the aortic annulus is enlarged, it is adjusted to normal diameter for body size using a graft diameter approximately 10% less than the desired aortic annular diameter. The geometry conveniently allows strips of the graft to support a reduction annuloplasty of five-sixths of the circumference of the annulus (avoiding the conduction system) while the graft adjusts the diameter of the sinotubular junction.
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References
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Yacoub M.H., Gehle P., Chandrasekaran V., Birks E.J., Child A., Radley-Smith R. Late results of a valve-preserving operation in patients with aneurysms of the ascending aorta and root. J Thorac Cardiovasc Surg 1998;115:1080-1090.[Abstract/Free Full Text]
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David T.E., Feindel C.M. An aortic valve-sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta. J Thorac Cardiovasc Surg 1992;103:617-622.[Abstract]
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Cochran R.P., Kunzelman K.S., Eddy A.C., Hofer B.O., Verrier E.D. Modified conduit preparation creates a pseudosinus in an aortic valve-sparing procedure for aneurysm of the ascending aorta. J Thorac Cardiovasc Surg 1995;109:1049-1058.
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Kunzelman K.S., Grande J., David T.E., Cochran R.P., Verrier E.D. Aortic root and valve relationships. J Thorac Cardiovasc Surg 1994;107:162-170.[Abstract/Free Full Text]
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Frater R.W.M. Aortic valve insufficiency due to aortic dilatation. Circulation 1986;74(Suppl I):136-142.
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David T.E., Feindel C.M., Bos J. Repair of the aortic valve in patients with aortic insufficiency and aortic root aneurysm. J Thorac Cardiovasc Surg 1995;109:345-352.[Abstract/Free Full Text]
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David T.E. Current practice in Marfan’s aortic root surgery. J Card Surg 1997;12:147-150.[Medline]
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Morishita K., Abe T., Fukada J., Sato H., Shiiku C. A surgical method for selecting appropriate size of graft in aortic root remodeling. Ann Thorac Surg 1998:1795-1796.
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Choo S.J., Duran C.M.G. A surgical method for selecting appropriate size of graft in aortic root remodeling. Ann Thorac Surg 1999;67:599-600.[Free Full Text]
Accepted for publication November 3, 1999.
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Abstract
Introduction
