Mitral Regurgitation in Congenital Heart Defects: Surgical Techniques for Reconstruction Richard G. Ohye Mitral valve regurgitation (MR) is an important source of morbidity and mortality worldwide. While globally the primary etiology is rheumatic, the incidence of MR appears to be increasing in the United States as well. There are multiple etiologies for MR, and the specific pathologic anatomy varies widely. Similarly, there are a multitude of options for operative repair, and recent series report very good survival rates as well as freedom from re-intervention. Semin Thorac Cardiovasc Surg Pediatr Card Surg Ann 15:75-79 2012 Elsevier Inc. All rights reserved. Introduction The clinical problem of atrioventricular valve regurgitation (AVVR) in children is an area of increasing concern for pediatric cardiologists and pediatric cardiac surgeons. Worldwide, rheumatic heart disease and associated AVVR is a significant health issue, affecting an estimated 12 million people. 1 Of these 12 million people, many will require surgical intervention and a large proportion of these patients will be children. 2 Because of a variety of factors, the incidence of AVVR requiring surgical intervention also appears to be increasing in the United States. These factors include an apparent increase in the incidence of childhood rheumatic fever, and improving survival for complex congenital heart disease. 3,4 Etiology Associate Professor of Cardiac Surgery, Section of Pediatric Cardiovascular Surgery, Department of Cardiac Surgery, University of Michigan Medical School, Ann Arbor, MI. Address correspondence to Richard G. Ohye, MD Room 11-742, 1540 E. Hospital Drive/SPC 4204, Ann Arbor, MI 48109-4204; E-mail: ohye@umich.edu. While the predominant etiology in mitral stenosis is rheumatic disease, there are multiple causes of mitral regurgitation (MR) (Table 1). 5 Of these causes, the most commonly encountered etiology in the congenital population would be in the setting of a repaired atrioventricular septal defect (AVSD). In a series of pediatric patients (n 17) undergoing repair for MR, Delmo Walter and colleagues 6 reported incidence of the various etiologies as congenital 76% (13), rheumatic 11% (2), infectious 6% (1), and traumatic 6% (1). However, regardless of the etiology, a descriptive approach of the pathologic anatomy, such as described by Carpentier, 7 may be of greater practical utility. The incidence of the anatomies by Carpentier Classification has been published in case series by Lee et al 8 (n 125) and Stellin et al 9 (n 48) (Tables 2 and 3). Mitral Valve Repair Surgical intervention for MR is predicated on attempted repair, rather than replacement. Mitral valve (MV) replacement, particularly in children, is less desirable because of the need for anticoagulation, the lack of growth potential, the risk of thromboembolism, the risk of endocarditis, and the lack of availability of small sized prostheses. MV repair in the pediatric population results in lower rates of morbidity, such as heart block, thromboembolism, and endocarditis, when compared with MV replacement. 10, 11 Multiple techniques have been described for the repair of MR and are tailored to the particular pathologic anatomy. The most straightforward is the closure of a MV cleft, most often seen in the setting of an AVSD; although it can also occur as an isolated congenital lesion. The cleft is simply closed with interrupted, non-absorbable monofilament suture (Fig. 1), with the caveat that the left lateral leaflet (in the setting of an AVSD) or the posterior leaflet (in the setting of an isolated cleft) must be adequate enough to allow an acceptable remaining MV orifice. Several types of annuloplasty have been described that may be useful in the setting of a dilated mitral annulus. While complete annuloplasty rings can be very effective 1092-9126/12/$-see front matter 2012 Elsevier Inc. All rights reserved. doi:10.1053/j.pcsu.2012.01.012 75
76 R.G. Ohye Table 1 Causes of Mitral Regurgitation Congenital malformations (eg, AVSD, isolated clefts) Trauma Mitral valve prolapse Endocarditis (active or healed) Collagen-vascular disorders (eg, lupus) Marfan s and other connective tissue disorders Mucopolysaccharidoses (eg, Hurler s) Dilated and hypertrophic cardiomyopathies Papillary muscle dysfunction Annular calcification Idiopathic chordal rupture Endocardial fibrosis for the treatment of MR, a partial annuloplasty is preferable in the growing pediatric patient. Techniques that can be selectively applied include a very limited annular plication in the region of the commissures only (Fig. 2), longer plications involving regions of the annulus, or complete plication along the entire posterior leaflet (Fig. 3). These annuloplasties can be unsupported running suture lines of non-absorbable monofilament, or supported with autologous pericardium, xenograft (eg, bovine pericardium), or polytetrafluoroethylene (PTFE) strips or felt (Fig. 4). In older patients, commercially available complete or partial annuloplasty rings can be used. Recently, Dr. Kalangos developed a bioabsorbable intra-annular annuloplasty ring. 12 Although this ring is not currently commercially available, it has the advantage of gradually undergoing hydrolytic degradation over 6 months, allowing for the potential for growth in pediatric patients. Leaflet prolapse may be caused by chordal rupture or elongation. Many techniques have been described for chordal shortening, papillary muscle shortening, chordal translocation and creation of artificial chordae. Fig. 5 shows techniques for papillary and chordal shortening, although often simple pledgeted monofilament mattress sutures will suffice because the chordae are often thickened from the regurgitant flow. For chordal translocation, either individual chordae Table 3 Incidence of Anatomic Pathology by Carpentier Classification Classification can be transferred or chordae with a wedge of attached leaflet can be transferred. Artificial PTFE chordae can be constructed as shown in Fig. 6. Prolapsing segments of the leaflet can also be resected (Fig. 7). Failure of coaptation, particularly in the setting of a nondilated annulus, can be addressed with leaflet augmentation with autologous pericardium or other tissue. This technique is illustrated in Fig. 8. One of the keys to leaflet augmentation is the mobilization of the underlying papillary muscle and chordal apparatus, as simple leaflet augmentation without increasing the excursion of the free edge, will not improve coaptation. Results of MV Repair Lee 8 (n 125) Stellin 9 (n 48) Type I Normal leaflet motion 55% 67% Type II Leaflet prolapse 37% 19% Type III Restricted leaflet motion 8% 15% The reported results of MV repair are very good. However, most manuscripts do not separate out the results for MR and mitral stenosis. Stellin and colleagues 9 reported their experience over 36 years with 93 patients (median age, 4.5 years; range, 0.16 to 19.8 years) with congenital MV malformations (52% predominant MR). There was a 7.5% (7/93) early mortality, and an 8% (7/86) late mortality at a median follow-up of 8.4 years. Twelve patients required Table 2 Carpentier Classification of Mitral Valve Malformations Type I (normal leaflet motion) Annular dilatation Cleft anterior leaflet Leaflet defect Type II (leaflet prolapse) Elongated chordae Type III (restricted leaflet motion) Type A (normal papillary muscles) Papillary muscles commissure fusion Short chordae Type B (abnormal papillary muscles) Parachute MV Hammock MV Figure 1 MV cleft closure. Illustration also shows the addition of a partial annuloplasty to improve leaflet coaptation. (Reprinted with permission from Pediatric Cardiac Surgery, Mavroudis C, Backer CL. 2003. p. 594, with permission from Mosby.)
Mitral regurgitation in congenital heart defects 77 Figure 2 Wooler -type partial annuloplasty. (Reprinted with permission from Pediatric Cardiac Surgery, Mavroudis C, Backer CL. 2003. p. 591, with permission from Mosby.) Figure 3 Paneth -type partial annuloplasty. (Modified and reprinted with permission from Delmo Walter EM, Siniawski H, Ovroutski S, Hetzer R. Mitral valve growth after posterior annular stabilization with untreated autologous pericardial strip in children with mitral valve insufficiency. Ann Thorac Surg 2010;90:1580.) Figure 4 Various options for supported partial annuloplasties (Modified and reprinted with permission from Oppido G, et al. Surgical treatment of congenital mitral valve disease: Midterm results of a repairoriented policy. J Thorac Cardiovasc Surg 2008;135:1315). Figure 5 (A) Chordal shortening. (B) Papillary muscle shortening. (Modified and reprinted with permission from Oppido G, et al. Surgical treatment of congenital mitral valve disease: Midterm results of a repair-oriented policy. J Thorac Cardiovasc Surg 2008; 135:1315.)
78 R.G. Ohye Figure 6 Two techniques for creation of artificial chordae. (Modified and reprinted with permission from Pediatric Cardiac Surgery, Mavourdis C, Backer CL. 2003. Figure 32-14, p. 593, with permission from Mosby and from Oppido G, et al. Surgical treatment of congenital mitral valve disease: Midterm results of a repair-oriented policy. J Thorac Cardiovasc Surg 2008; 135:1315 [Figure 2].) MV reintervention, including 11 replacements and one re-repair. Lee and associates 8 reported 139 patients less than age 18 years of age (median age, 2.3 years; range, 2 months to 17.6 years), of whom 125 (90%) had predominantly MR. There were no early deaths and 97.2 2.1% actuarial survival at 15 years. At 15 years, actuarial freedom from re-operation was 76.9 4.6% and freedom from MV replacement was 89.5 3.4%. Delmo Walter and colleagues 10 reported 17 children (mean age, 9.4 6.0 years) who underwent repair for MR. Their repair technique consisted of one of two techniques for posterior annuloplasty, supported by an autologous pericardial strip (Fig. 3). They achieved 100% complete follow-up at a mean of 13.6 2.4 years. There were no early or late deaths. The 3-year actuarial freedom from re-operation was 81.9% and anterior leaflet size paralleled somatic growth over time. When necessary, MV replacement can be undertaken with similar good results, with the majority of the mortality occurring in the peri-operative period, despite the need for chronic anticoagulation. Caldarone 11 reported the experience of the Pediatric Cardiac Care Consortium. There were 176 MV replacements in 139 patients less than 5 years of age. Mean age at initial MV replacement was 1.9 1.4 years; median follow-up was 6.2 years (range, 0 to 20 years) and was 96% complete. Actuarial survival was 82% at 30 days, 79% at 1 year, 75% at 5 years, and 74% at 10 years. Among survivors, the 5-year freedom from reoperation was 81% with 32 patients undergoing a second replacement, and five patients undergoing a third replace- Figure 7 Quadrangular resection. A, Area of resection. B, Resection of prolapsing segment of leaflet. C, Closure of the resulting defect. Associated annuloplasty has been accomplished. D, Completed repair with partial annuloplasty ring in place. (Reprinted with permission from Pediatric Cardiac Surgery, Mavroudis C, Backer CL. 2003. Figure 32-12, p. 591, with permission from Mosby.)
Mitral regurgitation in congenital heart defects 79 Figure 8 Leaflet augmentation. 1, Leaflet is divided at the annulus. 2, Papillary muscles and cordae are mobilize. 3, Leaflet is augmented with autologous pericardium. (Modified from Oppido G, et al. Surgical treatment of congenital mitral valve disease: Midterm results of a repair-oriented policy. J Thorac Cardiovasc Surg 2008;135:1315 [Figures 3].) ment 16% required implantation of a permanent pacemaker; bacterial endocarditis occurred in 6%, thrombosis in 3%, and stroke in 2%. References 1. Murray CJ: Global health statistics. Cambridge, MA; Harvard University Press; 1996: pp 64-67 2. Kaplan EL: Recent epidemiology of group A streptococcal infections in North America and abroad: an overview. Pediatrics 1996;97:945-948 3. World Health Organization. Rheumatic fever and rheumatic heart disease. Geneva, Switzerland; World Health Organization; 2004 4. Veasy LG, Tani LY, Hill HR: Persistence of acute rheumatic fever in the intermountain area of the United States. J Pediatr 1994;124:9-16 5. Waller BF, Howard J, Fess S: Pathology of mitral valve stenosis and pure mitral regurgitation Part II. Clin Cardiol 1994;17:395-402 6. Delmo Walter EM, Siniawski H, Ovroutski S, et al: Mitral valve growth after posterior annular stabilization with untreated autologous pericardial strip in children with mitral valve insufficiency. Ann Thorac Surg 2010;90:1577-1585 7. Carpentier A, Branchini B, Cour JC, et al: Congenital malformations of the mitral valve in children. Pathology and surgical treatment. J Thorac Cardiovasc Surg 1976;72:854-866 8. Lee C, Lee C-H, Kwak JG, et al: Long-term results after mitral valve repair in children. Eur J Cardiothorac Surg 2010;37:267-272 9. Stellin G, Padalino MA, Vida VL, et al: Surgical repair of congenital mitral valve malformations in infancy and childhood: A single-center 36-year experience. J Thorac Cardiovasc Surg 2010;140:1238-1244 10. Delmo Walter EM, Siniawski H, Ovroutski S, et al: Mitral valve growth after posterior annular stabilization with untreated autologous pericardial strip in children with mitral valve insufficiency. Ann Thorac Surg 2010;90:1577-1585 11. Caldarone CA: Long-term survival after mitral valve replacement in children aged 5 years: a multi-institutional study. Circulation 2001; 104(suppl 1):I143-I147 12. Kalangos A, et al. Annuloplasty for valve repair with a new biodegradable ring: an experimental study. J Heart Valve Dis 2006;15:783-790