Asian Cardiovasc Thorac Ann 2007;15:258-260
© 2007 Asia Publishing EXchange Ltd
Mitral Valve Repair in Infants and Children
Devi P Shetty, MS,
Colin N John, FRACS,
Shekar Rao, MCh,
Sankaran J Puthenveetil, FRACS,
R Benedict Raj, MCh
Department of Pediatric Cardiac surgery, Narayana Hrudayalaya, Bangalore, India
For reprint information contact: R Benedict Raj, MCh Tel: 91 80 2783 5000 Fax: 91 80 783 5222 Email: raj_benedict{at}yahoo.co.uk, Narayana Hrudayalaya, 258/A, Bommasandra Industrial Area, Anekal Taluk, Bangalore 560 099, India.
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ABSTRACT
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A number of children are born with myxomatous deformity of the mitral valve, causing mitral regurgitation. Traditional techniques of repair may be daunting in these children because apart from their small size, their valves appear grossly deformed and the tissues are friable. Techniques to circumvent these problems and ensure a predictable and satisfactory outcome are described.
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INTRODUCTION
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A number of children are born with myxomatous deformity of the mitral valve (MV), causing mitral regurgitation. Surgeons have a tendency to wait because suitable prosthetic valves are not available in the event of a failed repair attempt.1 Mitral valve repair should always be attempted, especially in infants, despite the frequent severity of MV dysplasia, to avoid the drawbacks of the currently available prostheses.2 The advantage is that they have plenty of valve leaflet tissue available for tailoring the valve to competency. Traditional techniques of repair may be daunting in these children because apart from their small size, their valves appear grossly deformed and the tissues are friable.3–5 Mitral valve repair can be achieved in the majority of cases by using different techniques. Pericardial extension of the retracted posterior leaflet allows insertion of a larger prosthetic ring. Intermediate functional results are good, but follow-up is short and does not allow us to draw conclusions about the long-term results of the repair in these rheumatic patients.6 As no single technique is perfect, a combination of additional techniques is proposed to circumvent the following problems: adequacy of MV exposure in very small babies, evaluation of regurgitation for planning and assessing the adequacy of repair, reliable fixation of the artificial chordae to the left ventricle (LV), and avoiding residual regurgitation after chordal repair.
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TECHNIQUES
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EXPOSURE
Preoperative evaluation by transthoracic and transesophageal echocardiography is essential to identify the site and degree of MV regurgitation, anatomy of the subvalvular apparatus, and morphology of the valve leaflets. Following sternotomy, pericardiotomy is performed to the right of the midline. The left pericardial edge is not raised, but the right pericardial edge is pulled up considerably to rotate the heart to maximize exposure of the atria. Both venae cavae are mobilized maximally by a combination of blunt and sharp dissection, to enable retraction and rotation of the heart. Cardiopulmonary bypass is established with aortic and distal bicaval cannulation with angled cannulae. The right pericardial edge is further extensively pulled up to bring the heart to the level of the sternal retractor and rotate it sufficiently before tightening the tapes around the cavae. The tapes are also pulled up and fixed. Before opening the left atrium, the Waterston’s (Sondergaard) groove is developed extensively. The roof of the left atrium is released from the right pulmonary artery to help extend the incision superiorly. The inferior vena cava is released from the inferior surface of the left inferior pulmonary vein to help extend the incision inferiorly. The left atrium is opened through the Waterston groove after cardioplegic arrest. Two small Langenbeck retractors are sufficient to elevate the atrial septum, and with these measures, it is possible to get a good view of the MV through the left atrium, even in small babies.
EVALUATION OF REGURGITATION
With a mental picture of the functioning MV obtained through transthoracic and transesophageal echocardiography, the valve is inspected. Using an Asepto syringe, saline is flushed rapidly across the valve to evaluate regurgitation and the valve apparatus. All prolapsing points of the posterior and anterior leaflets are identified with hooks.
FIXATION OF ARTIFICIAL CHORDAE
The best way to repair prolapse of both anterior and posterior leaflets is to use Gore-Tex sutures (Gore-Tex, Flagstaff, AZ, USA) to fix the leaflets and replace ruptured chordae. However, the papillary muscles may be too fragile to hold the Gore-Tex sutures without tearing. To fix the chordae on the ventricle, we adopted a new technique of Gore-Tex suture anchoring. A Gore-Tex CV4 suture is chosen. Both needles are passed through a large Teflon pledget and straightened. A suitable entry point near the LV apex, avoiding the left anterior descending coronary artery, is chosen.
The straightened needles are speared across the apex and the needle is retrieved from inside the LV. This needle is passed through another Teflon pledget. The needles of the second suture are also passed through this pledget. These needles are kept on standby, and the straightened needles of the previous Gore-Tex suture that was passed through the same Teflon pledget are held up, the second Teflon disk is lowered into the LV apex and fixed with the pledgets on either side of the LV wall. These are the 4 artificial chordae with needles. The sutures can also be fixed to a white thickened area of endocardium at the apex of the ventricle.
Two prolapsing points on each leaflet are chosen and needles are passed through their thickened edges from below upwards and from the middle laterally, 2 to 4 times. A sliding knot is made on each suture and temporarily fixed with a vascular clip. After adjusting and checking the height of the artificial chordae by sliding the knots up or down, the valve is checked until competence is achieved. Three final knots are made and the clips are removed. The chordae should be long enough to enable the anterior mitral leaflet to reach the posterior MV annulus without pulling up the flaccid ventricular free wall.
AVOIDING RESIDUAL REGURGITATION
Usually, we find some leakage at the commissures, and it is necessary to narrow the commissures on both sides to prevent regurgitation. Invariably these children have a grossly dilated MV and narrowing the commissures does not cause mitral stenosis. When satisfactory competence is achieved, the left atrium is closed. The patient is weaned off bypass after re-warming. The valve is checked with transesophageal echocardiography and if unsatisfactory, the repair is repeated.
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DISCUSSION
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Mitral valve repair was carried out in 21 pediatric patients over 3 years in our hospital, mostly in the last year. Ten patients were < 5 years old and only 3 were over 10 years old. Details are given in Table 1
. There was substantial improvement following repair in all except 2 patients with complex cardiac lesions where MV regurgitation progressed in the early postoperative period from nil to trivial and from trivial to mild. Those who benefited most were the 15 with severe and moderate regurgitation that improved to nil (4), trivial (3), mild (4), and moderate (4). The LV apex as seen was not indented on postoperative echocardiograms, and LV dimensions were unremarkable on the short-term follow-up echocardiograms.
The advantage of adopting this combination of these reproducible steps is to make the MV repair safe in the hands of the average pediatric cardiac surgeon. This helps most of the otherwise rejected pediatric patients grow to an age at which MV replacement and good long-term outcome are possible. We suggest the use of these techniques in all cases of MV repair. The excellent exposure, accurate assessment, adequate and secure repair are the most important features of these techniques, with the added benefit of retaining the native valve.
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ACKNOWLEDGMENTS
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We thank Mathew Thomas for his assistance in preparing the manuscript.
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REFERENCES
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- Almeida RS, Elliott MJ, Robinson PJ, Wyse RK, Taylor JF, Stark J, et al. Surgery for congenital abnormalities of the mitral valve at the Hospital for Sick Children, London from 1969–1983. J Cardiovasc Surg (Torino) 1988;29:95–9.[Medline]
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ABSTRACT
INTRODUCTION
