Asian Cardiovasc Thorac Ann 2003;11:135-138
© 2003 Asia Publishing EXchange Ltd
Mitral Clefts and Interatrial Septum Defects: 15-Year Results
Kaan Kirali, MD,
Denyan Mansuro
lu, MD,
Yücel Özen, MD,
Nilgün Ulusoy Bozbua, MD,
Altu Tuncer, MD,
Mehmet Erdem Toker, MD,
Mesut 
i
manolu, MD,
Cevat Yakut, MD
Department of Cardiovascular Surgery, Kosuyolu Heart and Research Hospital, Istanbul, Turkey
For reprint information contact: Kaan Kirali, MD Tel: 90 216 326 6969 Fax: 90 216 339 0441 email: imkkirali{at}yamoo.com Department of Cardiovascular Surgery, Kosuyolu Heart and Research Hospital, Kadikoy 81020, Istanbul, Turkey.
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ABSTRACT
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Between 1985 and 2002, 60 patients (58% female) with a mean age of 20.3 ± 12.1 years (range, 2–55 years) were treated for anterior mitral leaflet cleft. There was a primum atrial septal defect in 52 patients (87%) and a secundum type in 8 (13%). Concomitant cardiac defects were patent foramen ovale in 6 patients, cleft tricuspid valve in 3, ventricular septal defect in 2, cor triatriatum in 1, and persistent left superior vena cava in 1. Mean grade (1–4) of mitral insufficiency was 2.28 ± 0.74. Atrial septal defects were closed with a pericardial patch in 45 patients, with a prosthetic patch in 11, and primarily in 4. Mitral leaflet clefts were repaired using interrupted sutures. There was no early or late mortality. Two patients (3%) needed a permanent pacemaker. Postoperatively, severe (
grade 3) mitral insufficiency developed in 2 patients; valve replacement was performed in one, cleft recurrence and leakage from the patch were treated in the other. Freedom from reoperation was 92.2% ± 5.6% at 15 years. Surgical intervention can be performed for congenital anterior mitral leaflet cleft and interatrial septal defect with good results in both pediatric and adult age groups.
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INTRODUCTION
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Congenital cleft of the mitral leaflet is a rare cause of mitral insufficiency, resulting from various degrees of failure of fusion of the embryonic atrioventricular (AV) endocardial cushions.1 Sigfusson and colleagues2 suggested that a cleft in an otherwise normal mitral valve should be classified separately from atrioventricular canal defects (AVCD) with a common junction. In such cases, the anterior leaflet is comparable in size to that of the normal mitral valve, unlike hearts with AVCD, and the cleft is separated by well-formed AV structures from the right side of the heart. In isolated cleft of the anterior mitral leaflet, the annulus is in the normal position and incompetence is caused by flail segments of the anterior leaflet. The direction of the cleft is never toward the right atrium (as in classic AVCD) but toward the left ventricular outflow tract, and the mitral and tricuspid valves are attached to the septum at different levels, with the tricuspid valve more inferior. The conduction system is very close to the apex of the cleft, in contrast to AVCD, but rarely injured during cleft repair. Congenital cleft malformation in an otherwise normal mitral valve usually presents with concomitant cardiac defects, mainly atrial septal defect (ASD). Down syndrome is the most common noncardiac anomaly.3 It is very unusual to see such a cleft with an intact interatrial septum, or a cleft in the posterior mitral leaflet.4 Surgical repair of this malformation is well described.5,6 Early intervention is usually preferred in infants or children.7,8 We report our 15-year experience of treatment of congenital anterior mitral leaflet cleft with ASD in adults and children.
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PATIENTS AND METHODS
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A retrospective review was carried out of the records of patients who underwent surgery for mitral valve insufficiency caused by a congenital leaflet defect between 1985 and April 2002. A cleft of the anterior mitral leaflet was diagnosed in 60 patients (Table 1
) who were divided into 2 age groups: adolescents and adults ( 15 years), and pediatric patients (0–14 years). There were 39 patients (65%) aged 15 to 55 years, and 21 (35%) < 15 years. The female/male ratio was 1.4. All patients had an interatrial communication via an ostium primum or secundum ASD, other associated anomalies are shown in Table 1. No patient had a cleft in the posterior mitral leaflet or an anterior leaflet cleft with an intact interatrial septum. Three patients (5%) had a cleft in the tricuspid septal leaflet. Patients with phenotypical AVCD with a common AV junction and a cleft in the superior bridging leaflet were excluded from this study (12 patients with complete AVCD).
Electrocardiography demonstrated that 57 patients had sinus rhythm, 2 adults had atrial fibrillation, and one adult had junctional rhythm. A normal QRS axis was noted in 55 patients, 3 had right bundle branch block, and 1 had left bundle branch block. Preoperative echocardiography with standard parasternal long- and short-axis views showed mitral valve regurgitation that was mild (grade 1) in 8 patients (13%), moderate (grade 2) in 29, and severe (grades 3–4) in 23. Tricuspid regurgitation was mild in 44 patients, moderate in 10, and severe in 6. The parasternal short-axis view clearly demonstrated the anterior mitral leaflet cleft in all patients. Annular dilatation and deformation were seen in only one patient. The subvalvular apparatus had normal anatomic features in all cases. The mean pulmonary artery pressure was 37.4 ± 15 mm Hg (> 60 mm Hg in 3 patients). The left-to-right shunt (QP/QS ratio) was between 1.2 and 4.8 (mean 2.6 ± 0.9). The indication for operative intervention was mainly an ASD with a high QP/QS ratio (> 1.5) with or without severe mitral regurgitation, despite normal functional capacity. The indication was severe mitral regurgitation and impaired functional capacity in 3 patients with a small ASD (QP/QS ratio < 1.5).
All operations were performed through a median sternotomy, using standard cardiopulmonary bypass with ascending aortic and bicaval venous cannulation, and mild or moderate (28°C–32°C) hypothermia. Intermittent antegrade hypothermic crystalloid or blood cardioplegia was used for myocardial protection. After aortic crossclamping, the right atrium was opened and the annulus, leaflets, chordae tendineae, and papillary muscles were carefully inspected to determine the precise cause of the lesion. When a cleft of the anterior mitral leaflet was established to be the only cause of mitral regurgitation, the competency of the mitral valve was assessed under cardioplegic arrest by filling the left ventricle with cold saline. In all cases, the apex and base of the cleft were identified. Stay sutures were inserted in the free edge of the cleft at its junction with the major chordae. Clefts were closed with 2 to 6 interrupted horizontal mattress sutures of 5/0 polypropylene; no patient was left unrepaired. Associated annular dilatation was diagnosed in one case and repaired with a ring annuloplasty technique. Saline solution was injected into the left ventricle to test the competency of the repaired valves, and the mobilization and coaptation of the leaflets. Interatrial defects were closed with an autologous pericardial patch in 45 patients and with prosthetic material in 11 patients (early in the series), according to the surgeon’s preference. A patent foramen ovale was closed together with a combined primum ASD in 6 patients, using a fine monofilament continuous suture placed along the mitral annulus to avoid the conduction system and leave the coronary sinus drainage physiologically to the systemic venous side; the coronary sinus was left in the left atrium in 3 cases to avoid injury to the conduction system. A foramen ovale type secundum ASD < 2 cm in diameter was closed primarily in 4 patients. Associated ventricular septal defect was closed with a synthetic patch. Tricuspid valve repair was performed using DeVega annuloplasty in 4 patients, Kay annuloplasty in one, and direct cleft repair in 3. Mean aortic crossclamp time was 54.7 ± 15.8 min, and mean cardiopulmonary bypass time was 80.5 ± 25.5 min.
Follow-up was 100% complete. The total follow-up was 360.3 patient-years, with a mean of 6 ± 4 years (range, 0.2 to 15.7 years). Statistical analyses were performed using SPSS version 10.0 software (SPSS, Inc., Chicago, IL, USA). Actuarial data for reoperation were analyzed using Kaplan-Meier formulae. Results are presented as mean ± standard error. Cox proportional hazard regression analysis was used to assess risk factors as independent predictors of reoperation. Differences between continuous variables were tested using the paired t test. A p value 
0.05 was considered statistically significant.
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RESULTS
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There was no operative or late mortality. Morbidity included AV block in 3 patients (5%), with permanent pacemaker implantation in 1 (2%). There was no conduction system complication in patients whose coronary sinus drainage was left in the left atrium. The patient with preoperative junctional rhythm also received a permanent pacemaker. Two patients (3%) underwent reoperation due to recurrence of mitral regurgitation. On reoperation, it was observed that the sutures on the mitral leaflet had opened and the defect had recurred at the original site; one patient required mitral valve replacement 3 years after the first operation, the other underwent repeat repair of the cleft and primary closure of leakage from the patch 5 years postoperatively. Freedom from reoperation was 100% at 3 years, 97.3% ± 2.7% at 5 years, 92.2% ± 5.6% at 10 and 15 years. Univariate analysis showed that postoperative severe mitral valve insufficiency was the only significant risk factor for late reoperation (Table 2). Cox proportional hazard regression analysis revealed no significant risk factors.
Comparison of the New York Heart Association functional class before and after surgery demonstrated significant functional improvement postoperatively: 30 versus 53 patients were in class I; 20 versus 5 patients were in class II; 10 versus 2 patients were in class III. No patient was in class IV before or after the operation. Mean functional class before and after surgery was 1.67 ± 0.75 and 1.15 ± 0.4 (p < 0.001), respectively.
Postoperative echocardiography confirmed satisfactory results of the mitral and tricuspid valve repairs. Mitral regurgitation was mild in 53 patients, moderate in 5, and severe in 2. Tricuspid regurgitation was mild in 57 patients and moderate in 3. The mean grade of mitral valve insufficiency improved from 2.28 ± 0.74 to 0.4 ± 0.85 (p < 0.001), and the mean grade of tricuspid valve regurgitation changed from 0.7 ± 1 to 0.15 ± 0.5 postoperatively (p < 0.001).
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DISCUSSION
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A cleft in an otherwise normal mitral valve differs from the defect in the left AV valve in AVCD in that the two edges of the cleft restore the normal anatomy of the anterior the mitral leaflet. A cleft in the anterior leaflet usually causes mitral regurgitation and requires surgical intervention in those with moderate to severe mitral regurgitation, which probably should be carried out early after diagnosis. It is generally agreed that mitral repair is preferable to valve replacement. Direct suture of the cleft is the preferred procedure, but glutaraldehyde-treated autologous pericardium can be used if there is a lack of valvular tissue. Long-standing regurgitation produces annular dilatation which can be corrected by additional annuloplasty. Mitral valve repair is well established in adults, and various techniques (ring annuloplasty, DeVega annuloplasty, chordal transfer) are available.5,9–11 Direct suture of the cleft without tension is possible in adults as well as children.8,11–13 Mitral valve replacement is performed in adult patients (6%) whose valves cannot be repaired initially.13 It is more often carried out at reoperation (38.5%–58.3%).14,15
We preferred interrupted sutures for repair of the mitral leaflet cleft in all patients, and we did not need to replace the valve in the first operation. Although annuloplasty has been suggested for prevention of annular dilatation, it was required in only one patient in this series.16 We believe that annuloplasty is unnecessary when no annular dilatation is present; we did not observe any late annular dilatation during follow-up. We agree with Chauvaud and colleagues16 that ring annuloplasty is more effective in patients with annular dilatation. To avoid late mitral valve regurgitation after the first operation, complete closure of the anterior leaflet cleft is most important. Successful repair also depends on the anatomic structure and a sufficiency of leaflet tissue. It has been recommended that the cleft be left untouched when it causes mild or no mitral regurgitation, on the basis that the cleft works as a commissure.14 We do not agree the cleft works as a commissure, but sometimes it does not cause any valve insufficiency. Our protocol is to repair all clefts causing any degree of regurgitation; in this series, all patients had mild or significant mitral regurgitation. It has been reported that preoperative left AV valve insufficiency is the most significant risk factor for late left AV valve insufficiency in patients with partial AVCD.14 We showed that significant late mitral regurgitation was the only risk factor for reoperation. We try to repair the mitral valve at reoperation whenever possible, but we had to replaced it in one adult in whom the valve was thickened and not amenable to repair.
Repair techniques can be successfully applied in congenital mitral valve disease, especially in children less than 1 year of age, with no hospital mortality and acceptable long-term survival in those with a cleft in an otherwise normal mitral valve.5,6,8,9,17 Adolescent and adult patients also benefit from surgical repair of the defect.10,18 In developing countries, some patients cannot be diagnosed or treated for mitral cleft and ASD in childhood. In our series, 8 patients were in the 4th decade and 5 were older than 40 years, however, we have not seen any such advanced cases since 1995.
We did not observe any early or late mortality, perhaps due to the fact that all patients underwent elective surgery and none had a serious associated cardiac anomaly. Early complications such as AV block are more important in patients with a mitral leaflet cleft and primum ASD, because more attention must be paid to the suture line when a primum ASD is closed with a patch. If necessary, coronary sinus drainage can be left in the left atrium. It does not cause any significant right-to-left shunt or cyanosis. In our series, only one patient with preoperative sinus rhythm received a permanent pacemaker because of injury to the conduction system during closure of a primum ASD. We preferred to close interatrial septal defects with a pericardial patch, but a small secundum ASD was closed primarily in 4 patients.19
We concluded that repair of congenital cleft of the anterior mitral leaflet with concomitant cardiac malformations could be achieved successfully even in older patients. The most important complication of cleft repair was the need for reoperation. Complete correction of mitral valve insufficiency was the most important factor affecting long-term outcome. Appropriate repair of such clefts restores valve function, relieves symptoms, and preserves ventricular function.
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Footnotes
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Presented at the 10th Annual Meeting of the Asian Society for Cardiovascular Surgery, Jeju Island, Korea, April 17–19, 2002, and at the 51st International Congress of the European Society for Cardiovascular Surgery, Helsinki, Finland, June 28 – July 1, 2002.
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ABSTRACT
INTRODUCTION
