Ann Thorac Surg 2004;77:1857-1859
© 2004 The Society of Thoracic Surgeons
How to do it
Overlapping annuloplasty of the mitral valve in children
René Prêtre, MD*a,
Alexander Kadner, MDa,
Hitendu Dave, MDa,
Dominique Bettex, MDb,
Marko I. Turina, MDa
a Departments of Cardiovascular Surgery, University Hospital, Zurich, Switzerland
b Anesthesia, University Hospital, Zurich, Switzerland
Accepted for publication July 8, 2003.
* Address reprint requests to Dr Prêtre, Department of Cardiovascular Surgery, University Hospital, 100 Ramistrasse, 8091 Zurich, Switzerland
e-mail: rene.pretre{at}usz.ch
Presented at the Video Session of the Thirty-ninth Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Jan 31–Feb 2, 2003.
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Abstract
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Harmonious reduction of the posterior annulus of the mitral valve can be a useful adjunct to obtain complete valve competence in case of annular dilatation. We present a technique with the use of two resorbable sutures that overlap over the middle third of the posterior annulus that was used in 10 children with good short-term results. Resorption of the sutures should permit subsequent normal growth of the mitral valve. If the primary cause of valvular regurgitation was corrected, it can be expected that the repair will remain stable after resorption of the sutures.
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Introduction
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Dilatation of the left ventricle frequently leads to dilatation of the mitral annulus, which can result in the progressive loss of coaptation of the mitral valve leaflets. Reduction of the mitral valve annulus, particularly the antero-posterior diameter, improves coaptation of the leaflets and promotes valvular competence. It has long been established that the annular dilatation of the mitral annulus occurs almost exclusively along the posterior leaflet [1]. The implantation of a ring on the entire annulus or only on its posterior part to reduce the annular size has proven its efficacy in clinical practice and has been a widely used technique in adults [2]. In children, however, these rings present the major disadvantages of not being adapted to the unusual morphology of the mitral annulus and of preventing a harmonious subsequent growth of the valvular annulus. Furthermore, the rings block the mobility of the basal part of the left ventricle during the cardiac cycle and may, therefore, interfere with the elasticity of the left ventricle and its filling characteristics. We present a technique of reduction of the posterior annulus of the mitral valve prone to restore proper coaptation of the mitral valve leaflets, which should be suitable to all kinds of annular morphology and which should not interfere with the contractile characteristics of the left ventricle. The use of resorbable material should allow subsequent harmonious growth of the mitral valve annulus.
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Technique
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The operations were performed with the aid of cardiopulmonary bypass under mild hypothermia. Myocardial protection was achieved during aortic cross-clamping by intermittent delivery of sanguineous cold cardioplegic solution in the aortic root. The mitral valve was approached through a transseptal (4 patients with atrio-ventricular canal) or an interatrial groove incision (the other 6 patients). After repair of the primary valvular lesion, the valve was tested for competence with instillation of saline water in the left ventricle. The characteristics of the leaflet coaptation were carefully analyzed. When residual regurgitation was associated with a failure of coaptation along most of the free edge of the mitral leaflets, a complete posterior annuloplasty was performed. When the regurgitation was eccentric and associated with a failure of coaptation along only a limited part of leaflets free edge, a partial posterior annuloplasty was selected.
In complete posterior annuloplasty, a resorbable 5-0 or 6-0 suture of polyglyconate (Maxon CV, Tyco Heathcare UK Ltd) was passed across the posterior annulus, starting at one of the commissures and covering two-thirds of the posterior annulus (Fig 1).
Bites between 2 and 3 mm in length were performed with both ends of the thread, paying attention that the sutures were not getting intertwined. The same maneuver was performed from the other commissure over again two-thirds of the posterior annulus. In this way, the sutures overlapped each other over the median third of the posterior annulus. Both ends of each suture were passed through a tourniquet. The annulus was progressively reduced by pulling the threads either under direct vision or over a calibrating hegar sonde. The valve was tested for competence, which usually was reached immediately. Further adjustments of the annuloplasty were possible before the threads were tightened up securely. The rest of the operation was performed as usual.
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Fig 1. Annuloplasty of the posterior annulus with two sutures that run over two-thirds of the annulus (top). The annulus size is reduced harmoniously and calibrated over a hegar sonde by pulling the sutures through a tourniquet (middle). The valve competence is tested by injecting saline in the left ventricle (bottom).
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In partial posterior annuloplasty, one resorbable suture was used to reduce about one-half of the posterior annulus. The segment of annulus elected for reduction was facing the part of defective leaflet coaptation. When the annuloplasty required reduction of the posterior annulus over more than one-half of the annular length, the two-suture technique was elected because it provides a harmonious reduction of the posterior annulus.
Transesophageal echocardiography was performed during weaning off cardiopulmonary bypass in all patients to control the accuracy of the operative repair. Transthoracic echocardiography was performed during hospitalization and at first out-clinic control between 3 and 6 months. Patients with an ongoing pathology (such as a dilatative cardiomyopathy or anomalous left coronary artery from pulmonary artery [ALCAPA]) were controlled every 6 months.
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Patients
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From January 2000 to December 2002, 10 patients underwent a posterior annuloplasty of the mitral valve. Demographic and diagnostic data are summarized in Table 1.
The posterior annuloplasty was complete in 6 patients and partial in 4 patients. Complete annuloplasty was selected in patients presenting a global left ventricular dilatation as found in dilatative cardiomyopathy, in chronic mitral, or aortic valve regurgitation, and in univentricular hearts with chronic volume overload. Partial posterior annuloplasty was possible in 3 patients with atrio-ventricular canal and in 1 patient with mitral valve endocarditis.
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Results
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There were no early deaths. One patient died 6 months after operation of a cause unrelated to the cardiac procedure. Mitral valve insufficiency was no more than mild in all patients during perioperative and at 3-month control echocardiographies. At 6 months, the repair remained stable in all but 1 patient (with dilatative cardiomyopathy) who had a slight increase in regurgitation. At last control, 1 year after repair, the regurgitation was moderate (Table 2).
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Comment
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Elimination of mitral valve regurgitation is an important step in the repair of many congenital heart diseases. Patients with severely depressed ventricular function, like those presenting with dilatative cardiomyopathy or ALCAPA, or those undergoing a Fontan type of correction, hardly support a significant residual valvular regurgitation. Annular dilatation, commonly due to a chronic volume overload or to a primary dilatation of the left ventricle, is a frequent abnormality of the mitral valve [3, 4]. In these cases, simple reduction of the dilated part of the annulus is prone to restore competence of the valve. Implantation of a ring is ill-advised in children, because of the subsequent prevention of harmonious valvular growth. Furthermore, the morphology of the annulus (particularly in atrio-ventricular canal) is frequently different from that of a normal valve. Finally, a rigid annulus blocks the contraction of the basal part of the left ventricle and interferes with its elastic characteristics. Preservation of normal myocardial elasticity may be important in the young heart to achieve subsequent harmonious growth and rapidly adapt to new hemodynamic conditions.
This technique, with the use of two sutures overlapping each other over the median third of the posterior annulus, evenly reduces the posterior annulus (Fig 1). The use of only one suture, passed from one commissure to the other, might result in overplication of one-half of the annulus and underplication of the other half, with subsequent distortion of the valvular geometry. The technique, furthermore, does not disturb the mobility of the basal part of the left ventricle, because the annulus itself is not fixed.
The technique seems particularly appropriate in disorders where the cause of the mitral valve dilatation can be simultaneously corrected. This includes cases of left ventricular dilatation due to chronic volume overload secondary to shunts or valve regurgitation. Competence of the mitral valve should remain stable after resorption of the annuloplasty suture if the volume load of the heart has been corrected. A same favorable evolution can be expected in case of ALCAPA, because of the spontaneous improvement in ventricular function that is usually observed after restoration of a normal coronary artery perfusion. The fate of our technique is less certain in cases where the primary cause of mitral valve dilatation has not been addressed. One of our patients with dilatative cardiomyopathy had a good result with only trivial regurgitation shortly after surgery. The repair remained stable for 3 months, but regurgitation started to recur after 6 months.
This study cannot confirm our postulate that the mitral annulus would subsequently growth harmoniously. It has, however, been the rule to observe correct growth of cardiovascular structures after the use of resorbable sutures. The normal development of the aorta after neonatal repair of aortic coarctation or of the great arteries after an arterial switch repair of transposed great arteries are reassuring examples. Still, only a longer follow-up will be able to settle this capital issue.
In summary, the overlapping posterior annuloplasty of the mitral valve with resorbable sutures can restore competence of the mitral valve in a large spectrum of cardiac defects. The technique does not interfere with contraction and relaxation of the left ventricle and should not prevent subsequent growth of the mitral valve. It seems particularly recommended in patients where the primary cause of annular dilatation can be definitely corrected or improved.
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References
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- Hueb A.C., Jatene F.B., Moreira L.F., Pomerantzeff P.M., Kallas E., De Oliveira S.A. Ventricular remodeling and mitral valve modifications in dilated cardiomyopathy: new insights from anatomic study. J Thorac Cardiovasc Surg 2002;124:1216-1224.[Abstract/Free Full Text]
- Gillinov A.M., Cosgrove D.M. Mitral valve repair for degenerative disease. J Heart Valve Dis 2002;11(Suppl 1):S15-20.
- Prifti E., Vanini V., Bonacchi M., et al. Repair of congenital malformations of the mitral valve: early and midterm results. Ann Thorac Surg 2002;73:614-621.[Abstract/Free Full Text]
- Ohno H., Imai Y., Terada M., Hiramatsu T. The long-term results of commissure plication annuloplasty for congenital mitral insufficiency. Ann Thorac Surg 1999;68:537-541.[Abstract/Free Full Text]
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