Midterm outcome of mitral valve repair for congenital mitral regurgitation in infants and children
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《血管的通路杂志》
a Department of Cardiovascular Surgery, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
b Cardiac Care Unit, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
Presented at the joint 18th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 12th Annual Meeting of the European Society of Thoracic Surgeons, Leipzig, Germany, September 12–15, 2004.
Abstract
We analyzed the midterm results of children undergoing mitral valve repair without the use of prosthetic materials focusing on mitral annulus growth. From 1991 to 2004, 17 children (median age: 11 months) underwent mitral valve repair (grade III=9, IV=8). Regurgitation was due to prolapsed leaflet in 8 patients, annular dilatation in 4, and restrictive leaflet motion in 5. Preoperative indexed mitral valve diameter and Z-value were compared with those obtained at follow-up. There were no early or late deaths. All patients had an improved regurgitation grade after surgery. MV repair resulted in reduction in the indexed mitral valve diameter (58.2±22.9 vs. 47.3±18.9 mm/m2, P<0.05) and Z-value (3.3±2.3 vs. 0.79±2.2, P<0.05). One patient underwent re-repair, but no patients required mitral valve replacement during the median follow-up period of 95 months. The latest regurgitation grade was absent or I in 4 patients, II in 10 patients, and III in 3 patients. Mitral valve annulus increased by 23% at 3 years and by 49% at 5 years compared with that at surgery. Mitral valve repair without the use of prosthetic materials is feasible for the majority of patients and carries an appropriate growth pattern of the mitral valve annulus after surgery.
Key Words: Congenital heart disease; Valve disease; Mitral valve
1. Introduction
Surgical management for congenital mitral valve (MV) regurgitation in infants and children has been a therapeutic challenge because of a wide spectrum of morphologic abnormalities and high prevalence of associated anomalies [1]. Since MV replacement in small children is associated with high mortality and reoperation rates [2,3], reconstructive surgery has been developed as a first-line surgical approach to patients with congenital MV lesions [4–7]. Despite recent improvement in surgical procedures, high rates of reoperation and subsequent MV replacement remains a problem, especially in small infants and children [4].
Several techniques using prosthetic materials have been utilized for MV repair in children. These techniques include annuloplasty with a prosthetic ring combined with a cusp extension technique [4] and chordal replacement with artificial chordae [8], an approach that has been widely used in adult patients. However, prosthetic rings and artificial chordae have no growth potential, and there are concerns about the use of such prosthetic materials: somatic growth of the heart may result in progressive mitral stenosis in patients with a rigid prosthetic ring, and proportional changes in the repaired valve may lead to recurrence of regurgitation in patients with artificial chordae. To preserve growth potential of the MV in children, we have attempted to repair congenital MV regurgitation without the use of prosthetic materials. We analyzed the midterm results for 17 patients with congenital MV regurgitation who had undergone MV repair, focusing on MV annulus growth after repair.
2. Patients and methods
2.1. Patient population
We conducted a retrospective study of children who underwent MV repairs for congenital MV regurgitation from November 1991 to December 2004 at Okayama University Hospital. The Institutional Review Board approved this retrospective study and patient consent was waived for the study. Ten infants and 7 children (6 male and 11 female) underwent a total of 18 MV repairs. Patients with mitral cleft, atrioventricular septal defect, L-transposition, single ventricle, and Bland-White-Garland syndrome were excluded from this study. Age at operation ranged from 3 months to 13 years (median age, 11 months), and ten (59%) of the 17 patients were <1 year of age. Weight at operation ranged from 3.8 to 44 kg (median weight, 6.4 kg). Associated cardiac anomalies were present in 11 (65%) of the patients as shown in Table 1. Fifteen of the 17 patients presented with congestive heart failure, and 3 (18%) patients required mechanical ventilation prior to surgery. The MV malformations were classified according to Carpentier's functional classification [9]: MV regurgitation associated with normal leaflet motion (type I), prolapsed leaflet motion (type II), and restricted leaflet motion (type III) (Table 2).
2.2. Mitral valve repair
Cardiopulmonary bypass was established by ascending aortic and bicaval cannulations with moderate hypothermia, and myocardial protection was obtained by antegrade crystalloid cardioplegia. The MV was approached via the vertical left atriotomy in 6 patients and through the intraatrial septum in 11 patients. A list of the procedures used is shown in Table 3. Several techniques were used in the same patient. Commissuroplasty was used for repairing commissural prolapse or poor coaptation of commissures. A prosthetic ring was used in one patient who had sufficient size of the mitral annulus (31 mm). Concurrent repair of associated lesions was performed in 9 (53%) of the 17 patients.
2.3. Evaluation of mitral valve regurgitation
MV regurgitation was estimated by a semiquantitative grading according to the maximum length and width of the abnormal jet relative to the atrium: 0, no regurgitation; I, if the jet was less than one third of the length and width of the atrium; II, if the jet was one third to one half of the length and width of the atrium; III, if the jet was one half to two thirds of the length and width of the atrium; and IV, if the jet exceeded two thirds of the length and width of the atrium [10]. Postoperative evaluation was performed before discharge, and follow-up echocardiography was obtained at 3 to 6 months following surgery and every 6 to 12 months thereafter.
2.4. Evaluation of mitral valve annulus
MV annulus was measured by two-dimensional echocardiogram before and after surgery. The lateral dimension of the MV was measured from the apical or subcostal 4-chamber view. The lateral dimension of the MV annulus was considered to be the distance between the proximal attachments of the leaflets at each side of the MV annulus [11]. The largest dimension occurring during the cardiac cycle was chosen for analysis. MV annulus diameter obtained from echocardiography was compared with the predicted value calculated according to Rowlatt et al. [12]. We regarded the mean normal value of MV annulus obtained from Rowlatt's table as 100%. MV diameter was indexed to the patient's body surface area (Indexed MV diameter, mm/m2) and preoperative indexed MV diameter was compared with those obtained at discharge and at follow-up. Deviation of MV annulus size was evaluated by calculating Z-value of individual MV annulus [13].
2.5. Statistical methods
Survival and reoperation rates were calculated by the Kaplan–Meier method. Wilcoxon test was used for comparison of variables in two groups. Data are presented as mean ±S.D. The level of statistical significance was set at P=0.05.
3. Results
Reconstructive surgery was possible in all patients. There were no early and late mortalities. Clinical follow-up was completed for all 17 patients. The median follow-up period was 95 months (mean, 85 months; range, 31–153 months). There were no thromboembolic events during the follow-up period. Reoperation was necessary in 1 patient two years after the initial surgery. The patient underwent initial MV repair, chordal shortening and Reed annuloplasty at 6 months of age. Intraoperative findings at reoperation showed that MV regurgitation was due only to recurrent annular dilatation, not due to chordal elongation, and the valve repair was accomplished by commissuroplasty and Reed annuloplasty. None of the patients required MV replacement or developed mitral stenosis during the follow-up period. Actuarial freedom from reoperation was 92% at 3 (95% confidence interval [CI]: 81–100%) and 92% at 5 (95% CI: 81–100%) years (Fig. 1). All 17 patients were asymptomatic and clinically well at last follow-up.
3.1. Mitral valve regurgitation
Preoperative MV regurgitation was grade III in 9 patients and grade IV in 8 patients. All patients had an improved MV regurgitation grade after surgery (Fig. 2). At the last echocardiography, 15 (88%) of the 17 patients maintained the same MV regurgitation grade as that obtained at discharge: absent or I in 4 patients, II in 10 patients, and III in 3 patients (Fig. 2). There was no evidence of chordal re-elongation or rupture in the 7 patients who underwent chordal augmentation.
3.2. Mitral valve annulus
Preoperative mean MV annulus diameter was 22.2±4.3 mm (range, 14.1–31.2 mm), 146±29% of the predicted normal value. MV repair resulted in significant reduction in the mean indexed MV diameter (58.2±22.9 mm/m2 vs. 47.3±18.9 mm/m2, P<0.05) (Fig. 3) and the mean Z-value (3.3±2.3 vs. 0.79±2.2, P<0.01) (Fig. 4), respectively. Follow-up echocardiography at 3 and 5 years after surgery was obtained from 7 patients in each time point. Mean MV annulus diameter was 20.7±4.4 mm, 117±11% of the normal value 3 years after repair, and 24.4±3.7 mm, 118±4% of the normal value, 5 years after repair (Fig. 5). MV diameter increased by 23% at 3 years and by 49% at 5 years compared with that measured at immediate postoperative period (Fig. 5). There was a further decrease in the mean indexed MV diameter at 3 years, but there was no difference between the mean indexed MV annulus obtained at 3 years and that obtained at 5 years (Fig. 3). The mean Z-value has normalized further by 3 years after surgery, and remained unchanged at 5 years after surgery (Fig. 4).
4. Discussion
Reconstructive surgery without prosthetic materials was possible in all patients with congenital MV regurgitation with a low reoperation rate. Postoperative echocardiography showed mild or moderate residual MV regurgitation in 13 (76%) patients; however, there was no progressive MV regurgitation or evidence of excessive MV annular dilatation during the follow-up period in these patients. Indeed, 90% of the patients maintained the same MV regurgitation grade during the follow-up period, and Z-value of the MV annulus at follow-up was normalized in most of the patients, indicating the MV annulus grew along the normal growth curve after MV repair. Despite the presence of residual MV regurgitation in some cases, our reconstructive approach provided not only a low reoperation rate but also an almost appropriate growth pattern of the MV annulus regardless of the degree of residual MV regurgitation.
MV repair in small infants and children remains a surgical challenge because of the small size of the MV annulus and the thin and fragile MV leaflets [4,7]. Chauvaud et al. reported that hospital death occurred in two (10%) of the 18 patients <2 years of age due to postoperative ventricular failure and that an additional 3 patients required MV replacement following MV repair [4]. Since the MV in patients requiring surgery in the infantile period tends to be severely malformed, several techniques involving the annulus, leaflets, and subvalvular apparatus might be necessary to repair the MV. Most hospital mortalities, however, have resulted from ventricular failure associated with a poor preoperative condition [4], and simpler reconstructive techniques should therefore be employed to avoid prolonged myocardial ischemia and subsequent ventricular dysfunction. Our simple reconstructive approach toward MV repair might attenuate early mortality and morbidity and the need for immediate MV replacement or re-repair in high-risk infants with severe MV regurgitation.
There is controversy regarding the techniques of annuloplasty in children. Chauvaud et al. suggested the concept of annular remodeling with a prosthetic ring combined with leaflet enlargement in patients older than 2 years of age [4]. Other series, however, have demonstrated successful MV repairs without the use of a prosthetic ring and with a low reoperation rate [5–7]. In this series, prosthetic ring was used in only one patient who had an MV annulus of 31 mm in diameter. We agree that a prosthetic ring should be used in older children who have an MV annulus of sufficient size for the ring to be inserted. However, rigid ring insertion in the small infants may not only compromise the growth potential of the mitral annulus but also may make reoperation difficult. Therefore, we prefer to repair congenital MV regurgitation associated with annular dilatation without prosthetic materials for patients who have a small MV annulus.
Chordal augmentation using native chordae is still the first-line technique for repairing a prolapsed mitral leaflet in children [4,9]; however, replacement of ruptured chordae using artificial chordae versus shortening or transfer [14] has been widely used in adults. Some authors have recently used this technique in children with reasonable midterm outcome [8]. However, there is concern regarding the long-term durability of this technique following somatic growth. Finite element studies showed that shortened artificial chordae produced not only poor coaptation, but also excessive stress to the adjacent native chordae and the edge of the leaflet [15]. These studies indicate that excessive stress to the edge of the leaflet or adjacent chordae may occur as the patient grows. We prefer to use native chordae if they can be shortened or transferred, but we also do not hesitate to use artificial chordae if there is no available native chordae for transfer. The midterm results of chordal augmentation with native chordae are encouraging, and chordal repair using native tissue versus artificial chordae is expected to better preserve the proportion of the MV.
5. Conclusions
MV repair without the use of prosthetic materials is feasible and carries a low reoperation rate for the majority of patients with congenital MV regurgitation. Despite residual MV regurgitation in some patients, most patients did not develop MV regurgitation requiring reoperation and there was an appropriate growth pattern of the MV annulus during the follow-up period. We believe this strategy would have potential advantages that would attenuate early mortality and morbidity and augment long-term growth of the MV annulus in children.
References
Carpentier A, Branchini B, Cour JC, Asfaou E, Villani M, Deloche A, Relland J, D'Allaines C, Blondeau P, Piwnica A, Parenzan L, Brom G. Congenital malformation of the mitral valve in children. J Thorac Cardiovasc Surg 1976; 72:854–866.
Caldarone CA, Raghuveer G, Hills CB, Atkins DL, Burns TL, Behrendt DM, Moller JH. Long-term survival after mitral valve replacement in children aged <5 years. Circulation 2001; 104:Suppl I, I143–147.
Eble BK, Fiser WP, Simpson P, Dugan J, Drummond-Webb JJ, Yetman AT. Mitral valve replacement in children: predictors of long-term outcome. Ann Thorac Surg 2003; 76:853–860.
Chauvaud S, Fuzellier JF, Houel R, Berrebi A, Mihaileanu S, Carpentier A. Reconstructive surgery in congenital mitral valve insufficiency (Carpentier's techniques): long-term results. J Thorac Cardiovasc Surg 1998; 115:84–93.
Stellin G, Padalino M, Milanesi O, Vida V, Favaro A, Rubino M, Biffanti R, Casarotto D. Repair of congenital mitral valve dysplasia in infants and children: is it always possible Eur J Cardio-Thorac Surg 2000; 18:74–82.
Zias EA, Mavroudis C, Backer CL, Kohr LM, Gotteiner NL, Rocchini AP. Surgical repair of the congenitally malformed mitral valve in infants and children. Ann Thorac Surg 1998; 66:1551–1559.
Uva MS, Galletti L, Gayet FL, Piot D, Serraf A, Bruniaux J, Comas J, Roussin R, Touchot A, Binet JP, Planche C. Surgery for congenital mitral valve disease in the first year of life. J Thorac Cardiovasc Surg 1995; 109:164–176.
Minami K, Kado H, Sai S, Tatewaki H, Shiokawa Y, Nakashima A, Fukae K, Hirose H. Midterm results of mitral valve repair with artificial chordae in children. J Thorac Cardiovasc Surg 2005; 129:336–342.
Carpentier A. Cardiac valve surgery – the ‘French correction’. J Thorac Cardiovasc Surg 1983; 86:323–337.
Sheikh KH, Bengtson JR, Rankin JS, de Bruijn NP, Kisslon J. Intraoperative transesophageal Doppler color flow imaging used to guide patient selection and operative treatment of ischemic mitral regurgitation. Circulation 1991; 84:594–604.
King DH, Smith EO, Huhta JC, Gutgesell P. Mitral and tricuspid diameter in normal children determined by two-dimensional echocardiography. Am J Cardiol 1985; 55:787–789.
Rowlatt UF, Rimoldi HJA, Lev M. The quantitative anatomy of the child's heart. Pediat Clin North Amer 1963; 10:499–588.
Kouchoukos NT, Blackstone EH, Doty DB, Hanley FL, Karp RB. Anatomy, dimensions, and terminology. In: Kouchoukos NT. editor Kirklin/Barratt-Boyes Cardiac Surgery Philadelphia: Elsevier Science, 2003:40–44. In:.
Smedira NG, Selman R, Cosgrove DM, McCarthy PM, Lytle BW, Taylor PC, Apperson-Hansen C, Stewart RW, Loop FD. Repair of anterior leaflet prolapse: chordal transfer is superior to chordal shortening. J Thorac Cardiovasc Surg 1996; 112:287–292.
Reimink MS, Kunzelman KS, Cochran RP. The effect of chordal replacement suture length on function and stresses in repaired mitral valve: a finite element study. J Heart Valve Dis 1996; 5:365–375.(Osami Honjo, Kozo Ishino,)
b Cardiac Care Unit, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
Presented at the joint 18th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 12th Annual Meeting of the European Society of Thoracic Surgeons, Leipzig, Germany, September 12–15, 2004.
Abstract
We analyzed the midterm results of children undergoing mitral valve repair without the use of prosthetic materials focusing on mitral annulus growth. From 1991 to 2004, 17 children (median age: 11 months) underwent mitral valve repair (grade III=9, IV=8). Regurgitation was due to prolapsed leaflet in 8 patients, annular dilatation in 4, and restrictive leaflet motion in 5. Preoperative indexed mitral valve diameter and Z-value were compared with those obtained at follow-up. There were no early or late deaths. All patients had an improved regurgitation grade after surgery. MV repair resulted in reduction in the indexed mitral valve diameter (58.2±22.9 vs. 47.3±18.9 mm/m2, P<0.05) and Z-value (3.3±2.3 vs. 0.79±2.2, P<0.05). One patient underwent re-repair, but no patients required mitral valve replacement during the median follow-up period of 95 months. The latest regurgitation grade was absent or I in 4 patients, II in 10 patients, and III in 3 patients. Mitral valve annulus increased by 23% at 3 years and by 49% at 5 years compared with that at surgery. Mitral valve repair without the use of prosthetic materials is feasible for the majority of patients and carries an appropriate growth pattern of the mitral valve annulus after surgery.
Key Words: Congenital heart disease; Valve disease; Mitral valve
1. Introduction
Surgical management for congenital mitral valve (MV) regurgitation in infants and children has been a therapeutic challenge because of a wide spectrum of morphologic abnormalities and high prevalence of associated anomalies [1]. Since MV replacement in small children is associated with high mortality and reoperation rates [2,3], reconstructive surgery has been developed as a first-line surgical approach to patients with congenital MV lesions [4–7]. Despite recent improvement in surgical procedures, high rates of reoperation and subsequent MV replacement remains a problem, especially in small infants and children [4].
Several techniques using prosthetic materials have been utilized for MV repair in children. These techniques include annuloplasty with a prosthetic ring combined with a cusp extension technique [4] and chordal replacement with artificial chordae [8], an approach that has been widely used in adult patients. However, prosthetic rings and artificial chordae have no growth potential, and there are concerns about the use of such prosthetic materials: somatic growth of the heart may result in progressive mitral stenosis in patients with a rigid prosthetic ring, and proportional changes in the repaired valve may lead to recurrence of regurgitation in patients with artificial chordae. To preserve growth potential of the MV in children, we have attempted to repair congenital MV regurgitation without the use of prosthetic materials. We analyzed the midterm results for 17 patients with congenital MV regurgitation who had undergone MV repair, focusing on MV annulus growth after repair.
2. Patients and methods
2.1. Patient population
We conducted a retrospective study of children who underwent MV repairs for congenital MV regurgitation from November 1991 to December 2004 at Okayama University Hospital. The Institutional Review Board approved this retrospective study and patient consent was waived for the study. Ten infants and 7 children (6 male and 11 female) underwent a total of 18 MV repairs. Patients with mitral cleft, atrioventricular septal defect, L-transposition, single ventricle, and Bland-White-Garland syndrome were excluded from this study. Age at operation ranged from 3 months to 13 years (median age, 11 months), and ten (59%) of the 17 patients were <1 year of age. Weight at operation ranged from 3.8 to 44 kg (median weight, 6.4 kg). Associated cardiac anomalies were present in 11 (65%) of the patients as shown in Table 1. Fifteen of the 17 patients presented with congestive heart failure, and 3 (18%) patients required mechanical ventilation prior to surgery. The MV malformations were classified according to Carpentier's functional classification [9]: MV regurgitation associated with normal leaflet motion (type I), prolapsed leaflet motion (type II), and restricted leaflet motion (type III) (Table 2).
2.2. Mitral valve repair
Cardiopulmonary bypass was established by ascending aortic and bicaval cannulations with moderate hypothermia, and myocardial protection was obtained by antegrade crystalloid cardioplegia. The MV was approached via the vertical left atriotomy in 6 patients and through the intraatrial septum in 11 patients. A list of the procedures used is shown in Table 3. Several techniques were used in the same patient. Commissuroplasty was used for repairing commissural prolapse or poor coaptation of commissures. A prosthetic ring was used in one patient who had sufficient size of the mitral annulus (31 mm). Concurrent repair of associated lesions was performed in 9 (53%) of the 17 patients.
2.3. Evaluation of mitral valve regurgitation
MV regurgitation was estimated by a semiquantitative grading according to the maximum length and width of the abnormal jet relative to the atrium: 0, no regurgitation; I, if the jet was less than one third of the length and width of the atrium; II, if the jet was one third to one half of the length and width of the atrium; III, if the jet was one half to two thirds of the length and width of the atrium; and IV, if the jet exceeded two thirds of the length and width of the atrium [10]. Postoperative evaluation was performed before discharge, and follow-up echocardiography was obtained at 3 to 6 months following surgery and every 6 to 12 months thereafter.
2.4. Evaluation of mitral valve annulus
MV annulus was measured by two-dimensional echocardiogram before and after surgery. The lateral dimension of the MV was measured from the apical or subcostal 4-chamber view. The lateral dimension of the MV annulus was considered to be the distance between the proximal attachments of the leaflets at each side of the MV annulus [11]. The largest dimension occurring during the cardiac cycle was chosen for analysis. MV annulus diameter obtained from echocardiography was compared with the predicted value calculated according to Rowlatt et al. [12]. We regarded the mean normal value of MV annulus obtained from Rowlatt's table as 100%. MV diameter was indexed to the patient's body surface area (Indexed MV diameter, mm/m2) and preoperative indexed MV diameter was compared with those obtained at discharge and at follow-up. Deviation of MV annulus size was evaluated by calculating Z-value of individual MV annulus [13].
2.5. Statistical methods
Survival and reoperation rates were calculated by the Kaplan–Meier method. Wilcoxon test was used for comparison of variables in two groups. Data are presented as mean ±S.D. The level of statistical significance was set at P=0.05.
3. Results
Reconstructive surgery was possible in all patients. There were no early and late mortalities. Clinical follow-up was completed for all 17 patients. The median follow-up period was 95 months (mean, 85 months; range, 31–153 months). There were no thromboembolic events during the follow-up period. Reoperation was necessary in 1 patient two years after the initial surgery. The patient underwent initial MV repair, chordal shortening and Reed annuloplasty at 6 months of age. Intraoperative findings at reoperation showed that MV regurgitation was due only to recurrent annular dilatation, not due to chordal elongation, and the valve repair was accomplished by commissuroplasty and Reed annuloplasty. None of the patients required MV replacement or developed mitral stenosis during the follow-up period. Actuarial freedom from reoperation was 92% at 3 (95% confidence interval [CI]: 81–100%) and 92% at 5 (95% CI: 81–100%) years (Fig. 1). All 17 patients were asymptomatic and clinically well at last follow-up.
3.1. Mitral valve regurgitation
Preoperative MV regurgitation was grade III in 9 patients and grade IV in 8 patients. All patients had an improved MV regurgitation grade after surgery (Fig. 2). At the last echocardiography, 15 (88%) of the 17 patients maintained the same MV regurgitation grade as that obtained at discharge: absent or I in 4 patients, II in 10 patients, and III in 3 patients (Fig. 2). There was no evidence of chordal re-elongation or rupture in the 7 patients who underwent chordal augmentation.
3.2. Mitral valve annulus
Preoperative mean MV annulus diameter was 22.2±4.3 mm (range, 14.1–31.2 mm), 146±29% of the predicted normal value. MV repair resulted in significant reduction in the mean indexed MV diameter (58.2±22.9 mm/m2 vs. 47.3±18.9 mm/m2, P<0.05) (Fig. 3) and the mean Z-value (3.3±2.3 vs. 0.79±2.2, P<0.01) (Fig. 4), respectively. Follow-up echocardiography at 3 and 5 years after surgery was obtained from 7 patients in each time point. Mean MV annulus diameter was 20.7±4.4 mm, 117±11% of the normal value 3 years after repair, and 24.4±3.7 mm, 118±4% of the normal value, 5 years after repair (Fig. 5). MV diameter increased by 23% at 3 years and by 49% at 5 years compared with that measured at immediate postoperative period (Fig. 5). There was a further decrease in the mean indexed MV diameter at 3 years, but there was no difference between the mean indexed MV annulus obtained at 3 years and that obtained at 5 years (Fig. 3). The mean Z-value has normalized further by 3 years after surgery, and remained unchanged at 5 years after surgery (Fig. 4).
4. Discussion
Reconstructive surgery without prosthetic materials was possible in all patients with congenital MV regurgitation with a low reoperation rate. Postoperative echocardiography showed mild or moderate residual MV regurgitation in 13 (76%) patients; however, there was no progressive MV regurgitation or evidence of excessive MV annular dilatation during the follow-up period in these patients. Indeed, 90% of the patients maintained the same MV regurgitation grade during the follow-up period, and Z-value of the MV annulus at follow-up was normalized in most of the patients, indicating the MV annulus grew along the normal growth curve after MV repair. Despite the presence of residual MV regurgitation in some cases, our reconstructive approach provided not only a low reoperation rate but also an almost appropriate growth pattern of the MV annulus regardless of the degree of residual MV regurgitation.
MV repair in small infants and children remains a surgical challenge because of the small size of the MV annulus and the thin and fragile MV leaflets [4,7]. Chauvaud et al. reported that hospital death occurred in two (10%) of the 18 patients <2 years of age due to postoperative ventricular failure and that an additional 3 patients required MV replacement following MV repair [4]. Since the MV in patients requiring surgery in the infantile period tends to be severely malformed, several techniques involving the annulus, leaflets, and subvalvular apparatus might be necessary to repair the MV. Most hospital mortalities, however, have resulted from ventricular failure associated with a poor preoperative condition [4], and simpler reconstructive techniques should therefore be employed to avoid prolonged myocardial ischemia and subsequent ventricular dysfunction. Our simple reconstructive approach toward MV repair might attenuate early mortality and morbidity and the need for immediate MV replacement or re-repair in high-risk infants with severe MV regurgitation.
There is controversy regarding the techniques of annuloplasty in children. Chauvaud et al. suggested the concept of annular remodeling with a prosthetic ring combined with leaflet enlargement in patients older than 2 years of age [4]. Other series, however, have demonstrated successful MV repairs without the use of a prosthetic ring and with a low reoperation rate [5–7]. In this series, prosthetic ring was used in only one patient who had an MV annulus of 31 mm in diameter. We agree that a prosthetic ring should be used in older children who have an MV annulus of sufficient size for the ring to be inserted. However, rigid ring insertion in the small infants may not only compromise the growth potential of the mitral annulus but also may make reoperation difficult. Therefore, we prefer to repair congenital MV regurgitation associated with annular dilatation without prosthetic materials for patients who have a small MV annulus.
Chordal augmentation using native chordae is still the first-line technique for repairing a prolapsed mitral leaflet in children [4,9]; however, replacement of ruptured chordae using artificial chordae versus shortening or transfer [14] has been widely used in adults. Some authors have recently used this technique in children with reasonable midterm outcome [8]. However, there is concern regarding the long-term durability of this technique following somatic growth. Finite element studies showed that shortened artificial chordae produced not only poor coaptation, but also excessive stress to the adjacent native chordae and the edge of the leaflet [15]. These studies indicate that excessive stress to the edge of the leaflet or adjacent chordae may occur as the patient grows. We prefer to use native chordae if they can be shortened or transferred, but we also do not hesitate to use artificial chordae if there is no available native chordae for transfer. The midterm results of chordal augmentation with native chordae are encouraging, and chordal repair using native tissue versus artificial chordae is expected to better preserve the proportion of the MV.
5. Conclusions
MV repair without the use of prosthetic materials is feasible and carries a low reoperation rate for the majority of patients with congenital MV regurgitation. Despite residual MV regurgitation in some patients, most patients did not develop MV regurgitation requiring reoperation and there was an appropriate growth pattern of the MV annulus during the follow-up period. We believe this strategy would have potential advantages that would attenuate early mortality and morbidity and augment long-term growth of the MV annulus in children.
References
Carpentier A, Branchini B, Cour JC, Asfaou E, Villani M, Deloche A, Relland J, D'Allaines C, Blondeau P, Piwnica A, Parenzan L, Brom G. Congenital malformation of the mitral valve in children. J Thorac Cardiovasc Surg 1976; 72:854–866.
Caldarone CA, Raghuveer G, Hills CB, Atkins DL, Burns TL, Behrendt DM, Moller JH. Long-term survival after mitral valve replacement in children aged <5 years. Circulation 2001; 104:Suppl I, I143–147.
Eble BK, Fiser WP, Simpson P, Dugan J, Drummond-Webb JJ, Yetman AT. Mitral valve replacement in children: predictors of long-term outcome. Ann Thorac Surg 2003; 76:853–860.
Chauvaud S, Fuzellier JF, Houel R, Berrebi A, Mihaileanu S, Carpentier A. Reconstructive surgery in congenital mitral valve insufficiency (Carpentier's techniques): long-term results. J Thorac Cardiovasc Surg 1998; 115:84–93.
Stellin G, Padalino M, Milanesi O, Vida V, Favaro A, Rubino M, Biffanti R, Casarotto D. Repair of congenital mitral valve dysplasia in infants and children: is it always possible Eur J Cardio-Thorac Surg 2000; 18:74–82.
Zias EA, Mavroudis C, Backer CL, Kohr LM, Gotteiner NL, Rocchini AP. Surgical repair of the congenitally malformed mitral valve in infants and children. Ann Thorac Surg 1998; 66:1551–1559.
Uva MS, Galletti L, Gayet FL, Piot D, Serraf A, Bruniaux J, Comas J, Roussin R, Touchot A, Binet JP, Planche C. Surgery for congenital mitral valve disease in the first year of life. J Thorac Cardiovasc Surg 1995; 109:164–176.
Minami K, Kado H, Sai S, Tatewaki H, Shiokawa Y, Nakashima A, Fukae K, Hirose H. Midterm results of mitral valve repair with artificial chordae in children. J Thorac Cardiovasc Surg 2005; 129:336–342.
Carpentier A. Cardiac valve surgery – the ‘French correction’. J Thorac Cardiovasc Surg 1983; 86:323–337.
Sheikh KH, Bengtson JR, Rankin JS, de Bruijn NP, Kisslon J. Intraoperative transesophageal Doppler color flow imaging used to guide patient selection and operative treatment of ischemic mitral regurgitation. Circulation 1991; 84:594–604.
King DH, Smith EO, Huhta JC, Gutgesell P. Mitral and tricuspid diameter in normal children determined by two-dimensional echocardiography. Am J Cardiol 1985; 55:787–789.
Rowlatt UF, Rimoldi HJA, Lev M. The quantitative anatomy of the child's heart. Pediat Clin North Amer 1963; 10:499–588.
Kouchoukos NT, Blackstone EH, Doty DB, Hanley FL, Karp RB. Anatomy, dimensions, and terminology. In: Kouchoukos NT. editor Kirklin/Barratt-Boyes Cardiac Surgery Philadelphia: Elsevier Science, 2003:40–44. In:.
Smedira NG, Selman R, Cosgrove DM, McCarthy PM, Lytle BW, Taylor PC, Apperson-Hansen C, Stewart RW, Loop FD. Repair of anterior leaflet prolapse: chordal transfer is superior to chordal shortening. J Thorac Cardiovasc Surg 1996; 112:287–292.
Reimink MS, Kunzelman KS, Cochran RP. The effect of chordal replacement suture length on function and stresses in repaired mitral valve: a finite element study. J Heart Valve Dis 1996; 5:365–375.(Osami Honjo, Kozo Ishino,)