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Ann Thorac Surg 2000;70:542-546
© 2000 The Society of Thoracic Surgeons

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Original articles: cardiovascular

Remodeling of the aortic root and reconstruction of the bicuspid aortic valve

^a Department of Thoracic and Cardiovascular Surgery, University Hospitals Homburg, Homburg, Germany

Address reprint requests to Dr Schäfers, Department of Thoracic and Cardiovascular Surgery, University Hospitals Homburg, 66421 Homburg/Saar, Germany
e-mail: chhjsc{at}med-rz.uni-sb.de

	Abstract

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Background. Currently, isolated reconstruction of a regurgitant bicuspid aortic valve can be performed with adequate early results. Dilatation of the proximal aorta is known to be associated with this valve anomaly and may be partially responsible for the development of primary regurgitation or secondary failure of valve repair. We have used repair of the bicuspid valve with remodeling of the aortic root as an alternative to insertion of a composite graft.

Methods. Between October 1995 and May 1999, 16 patients (12 men, 4 women, aged 35 to 73 years) were seen with a regurgitant bicuspid aortic valve and dilatation of the proximal aorta of more than 50 mm. All patients underwent repair of the valve using either coapting sutures alone (n = 12) or in combination with triangular resection of a median raphe (n = 4). Using a Dacron graft, the aortic root was remodeled and the ascending aorta (n = 16) and proximal arch (n = 4) replaced.

Results. No patient died. The postoperative degree of aortic regurgitation was less than grade II in all patients. Valve function has remained stable in all patients between 2 and 43 months postoperatively.

Conclusions. Reconstruction of the regurgitant bicuspid valve in the presence of proximal aortic dilatation is feasible with good results by combining the root remodeling technique with valve repair.

	Introduction

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Based on the documented advantages of mitral valve reconstruction over prosthetic valve replacement, the possibility of repair has also been pursued for the regurgitant aortic valve. Different approaches have been propagated for the tricuspid aortic valve depending on the individual valve and root pathology [1–4]. Reconstruction has also been proposed for the bicuspid aortic valve [5], although the anatomy is considered less suitable by many surgeons because of its limited functional prognosis.

Although bicuspid anatomy is found in more than 35% of patients undergoing aortic valve replacement [6], many patients with this anomaly may have normal or adequate valve function until their sixth or seventh decade of life [7]. Based on these considerations, Cosgrove and coworkers [5–8] used techniques of valve repair in patients with a bicuspid, regurgitant aortic valve and published excellent early results. Others, using similar techniques, reported an incidence of reoperation approaching 50% in the early and intermediate postoperative phase [9]. The researchers found recurrent valve regurgitation particularly in conjunction with dilatation of the aortic root and attributed the repair failures to this aortic pathology. The combined occurrence of bicuspid aortic valve and aortic dilatation has been observed even in the presence of a hemodynamically normal bicuspid valve, indicating a common denominator for valve and aortic wall pathology, at least in a subset of these individuals [10, 11].

Thus it appears reasonable in root dilatation in conjunction with a bicuspid valve to extend the current reconstructive approach to the aortic valve by adding a procedure that will stabilize the aortic root and replace the dilated aortic segment. We have used such a combined approach that addresses both aspects of the disease. Whenever aortic diameter exceeded 50 mm and root diameter (as measured at the height of the sinutubular junction) exceeded 35 mm in the presence of a bicuspid valve and normal pliability of the leaflets, the valve was reconstructed and the aortic root stabilized with a Dacron graft. The initial experience is reported.

	Material and methods

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Between October 1995 and May 1999, 16 patients (12 men, 4 women) presented with aortic regurgitation because of a bicuspid aortic valve and concomitant aortic dilatation. Their ages ranged from 35 to 73 years. Stable disease was present in 15 instances; 1 patient underwent emergency surgery for acute aortic dissection type A. Maximal ascending aortic diameter, as measured by computed tomography, ranged from 50 to 70 mm, and the degree of preoperative aortic regurgitation ranged from II to IV (mean 2.8 ± 0.6) (Table 1). Concomitant triple vessel coronary artery disease was present in 1 patient.

In all patients the chest was opened by a median sternotomy and the patient placed on extracorporeal circulation by aortic and right atrial cannulation. Following aortic cross-clamping, cardioplegic arrest was induced by infusion of St. Thomas Hospital solution directly into the coronary ostia. The aortic root was inspected carefully, and diameters of aortoventricular junction and sinutubular junction were measured. Particular care was taken to assess the geometry of the aortic valve. The relative proportion of the single normal cusp as part of the root circumference was estimated. The height of the rudimentary commissure between the two parts of the congenitally fused leaflet—commonly between right and left coronary sinus—was measured relative to the remaining two commissures. Likewise the relative depth of the two rudimentary sinuses and one normal sinus was assessed.

The geometry of the valve leaflets was then studied carefully. In all patients the free margin of the fused leaflet was found to be elongated with a resulting prolapse of this leaflet. A median raphe was present in 14 patients. In the remaining 2 patients, a rudimentary commissure was present but not associated with a raphe extending toward the leaflet margin.

The sinuses of Valsalva were excised, leaving approximately 3 to 4 mm of aortic wall adjacent to the insertion of the leaflet. The two parts of the fused leaflets were then approximated at the free margin using interrupted 5-0 Prolene sutures (Ethicon, Hamburg, Germany). Shortening of the leaflet margin was considered adequate if both leaflets were at identical height after applying radial tension on the two commissures of the normal leaflet (Fig 1). Triangular resection of the median raphe with more extensive reapproximation of the two rudimentary leaflets was performed in 4 patients in whom the thickness of valve tissue in this area made direct suture adaptation difficult to achieve.

View larger version (27K): [in this window] [in a new window]   Fig 1. Schematic drawing of valve repair. The congenitally fused leaflet consists of rudimentary right and left coronary leaflets with a median raphe. The rudimentary commissure between the rudimentary leaflets is lower than the two true commissures of the noncoronary leaflet. The prolapse of the fused leaflet at its free margin has been corrected by two plicating sutures. The aortic sinuses have been resected in preparation for subsequent root remodeling.

View larger version (50K): [in this window] [in a new window]   Fig 2. Schematic drawing of the Dacron graft prepared for root remodeling in a bicuspid root. The Dacron is tailored to accommodate the large noncoronary sinus and the two rudimentary sinuses with respect to circumference and sinus depth.

View larger version (37K): [in this window] [in a new window]   Fig 3. Transesophageal echocardiogram after valve repair and root remodeling. There is a normal configuration of the aortic root with minimal regurgitation as seen by color Doppler.

All data were reviewed retrospectively. Mean values and standard deviations were calculated.

	Results

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All patients underwent valve repair, remodeling of the root, and replacement of the ascending aorta. Additional proximal replacement of the aortic arch was performed in 4 patients. Concomitant coronary artery bypass surgery was necessary in 1 instance.

Mean cardiopulmonary bypass time was 117 minutes (range 75 to 218), aortic cross-clamp time ranged from 56 to 132 minutes (mean 81). One patient required reexploration for hemorrhage. There was no cardiac conduction disturbance. One patient suffered from hemiparesis that resolved over a period of 10 days.

All patients survived the operation and were discharged after a hospital stay of 10 ± 3 days. All patients were alive and well at the time of this report, 2 to 43 months following the operation (cumulative follow-up 208 patient months).

Early postoperatively, the degree of aortic regurgitation was reduced from 2.8 ± 0.6 to 0.4 ± 0.6. In 12 patients no or trivial regurgitation was seen and 4 had minimal regurgitation. No patient exhibited regurgitation grade II or greater. During the postoperative follow-up (mean 13 ± 11 months) new regurgitation or an increase in the degree of regurgitation was not observed. Mean systolic gradients ranged from 3 to 14 mm Hg (mean of 5 ± 3).

No patient required reoperation on the aortic valve or root. One 47-year-old female patient with a coronary anomaly (origin of the left anterior descending artery from the right coronary artery and the left circumflex coronary artery from the left coronary sinus) developed a new coronary stenosis of the left coronary artery several millimeters distal to the ostium and most likely because of local trauma from the administration of cardioplegia. This patient underwent coronary bypass surgery using a single internal thoracic artery graft to a circumflex branch 1 year following the initial procedure and recovered uneventfully.

	Comment

Top Abstract Introduction Material and methods Results Comment References

 
Although reconstructive procedures are well established in the treatment of mitral valve disease and have consistently shown advantages over valve replacement, controversy still exists as to the role of reconstruction in aortic valve disease. Reconstruction of the tricuspid aortic valve has been suggested repeatedly using a number of individualized approaches [2]. If regurgitation results from aortic root dilatation, reconstructive procedures focusing primarily on the root have resulted in good functional results [3, 4, 15]. Reconstruction of the bicuspid aortic valve has gained growing interest more recently and good early results have been reported [5, 8].

Others found a high incidence of failure both in the early and intermediate postoperative course [9]. These researchers attributed the failures to preexisting or increasing root dilatation. A recent report from the Cleveland Clinic group indicated significant regurgitation in more than 25% of their patients in addition to an overall prevalence of reoperation at 5 years [16]. Breakdown after triangular leaflet resection appeared as the most important mechanism of failure. For this reason we have avoided triangular resection whenever leaflet pliability allowed for direct plication. No data on aortic root diameters were described or analyzed in that report. These observations again raise the controversial question as to what mechanisms may result in failure of the repair, and whether aortic dilatation may play a role in the development of aortic insufficiency in individuals with a bicuspid valve, as is known for the tricuspid valve [3, 4].

Bicuspid anatomy of the aortic valve is one of the main causes of aortic regurgitation [17] and appears to affect predominantly a younger population [7]. In approximately 60% of individuals, however, a bicuspid valve is associated with a normal life expectancy without evidence of hemodynamically significant valve pathology [7, 18]. Thus, the bicuspid nature of the valve per se does not appear to contraindicate reconstruction in the presence of pliable leaflet tissue. In fact, we agree with Haydar and coworkers [19] that repair of the bicuspid valve appears to yield more reproducible results compared with the tricuspid anatomy.

Clinical observations indicate that the bicuspid nature of the valve is associated with an increased incidence of dissection [20, 21], and dilatation of the proximal aorta [11, 22, 23], suggesting a common denominator for valve anatomy and aortic wall alterations [10, 24]. This observation may not necessarily apply to all patients with a bicuspid aortic valve, because we see a significant number of patients who come for aortic valve replacement because of stenosis with normal root dimensions and a bicuspid aortic valve. The marked dilatation of the aortic root and ascending aorta in this current subgroup lends additional support to the assumption of combined valve and aortic wall abnormality and emphasizes the need for correction of root pathology.

The concept that we propose attempts to achieve exactly this goal, that is, correcting the pathologies of both valve and root by applying the established techniques of valve reconstruction and stabilization of the root using a synthetic graft [3]. This method appears particularly justified in patients with ascending aortic diameters in excess of 50 mm, for whom a limited spontaneous prognosis is generally accepted. All patients in the current report belonged to this category. With the remodeling approach, restoration of normal sinotubular dimensions and almost normal configuration of the sinus can be achieved [3]. Compared with its use in the tricupid valve, however, the asymmetric geometry of valve and root in conjunction with a bicuspid valve may be more challenging to the surgeon. We have found that a systematic approach taking into consideration the relative ring circumference of the two leaflets, the relative height of the one rudimentary and the two normal commissures and the relative depth of the sinuses will result in reproducible configuration of the Dacron graft and reproducible valve and root reconstruction.

Replacement of the proximal aorta in the face of aortic dilatation has the established prophylactic value of preventing dissection or rupture. An additional advantage of this approach within the context of valve repair may be the stabilization of the root to preserve valve anatomy following reconstruction. Sinotubular and aortoventricular junctions define the borders of the valve and may thus be considered as equivalent of a valve ring that will be stabilized by valve-preserving root replacement. The approach described herein—valve reconstruction in conjunction with root stabilization—thus can be considered equivalent to the well-established techniques of mitral reconstruction, that is, restoration of leaflet geometry and stabilization of the ring. Should its medium-term and long-term results be superior to valve reconstruction alone, a more liberal use might be justified also in patients with less pronounced aortic dilatation.

Although the current results of this combined approach are promising, further follow-up will be required to determine its relative value compared with isolated valve reconstruction. This operation carries the complexity and potential risks of root replacement, which may be considered higher than in simple valve procedures. Tailoring of the graft to the preexistent asymmetry of the bicuspid valve and root differs from the root in the trileaflet valve and requires careful judgment. The risk of root replacement, however, is low in experienced hands [3, 4], and with a systematic approach to the root geometry we have been able to achieve reproducible results. Apart from the patients reported here, no patient was seen in our experience in whom repair of a bicuspid valve failed, requiring immediate or later valve replacement.

We conclude that in patients with a dilated aortic root and aortic regurgitation because of a bicuspid valve, the combined application of valve reconstruction and root remodeling is feasible and leads to good early results. Further experience and follow-up will show whether this approach may be useful to improve the long-term results in reconstruction of the bicupid aortic valve.

	Footnotes

 
This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/

	References

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This Article Abstract Full Text (PDF) Online Discussion Alert me when this article is cited Alert me if a correction is posted Citation Map 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): Olaf Wendler Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schäfers, H.-J. Articles by Wendler, O. Search for Related Content PubMed PubMed Citation Articles by Schäfers, H.-J. Articles by Wendler, O.