Congenital Mitral Regurgitation Repair Based on Carpentier’s Classification: Long-term Outcomes

doi:10.21203/rs.3.rs-1743296/v1

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Congenital Mitral Regurgitation Repair Based on Carpentier’s Classification: Long-term Outcomes

https://doi.org/10.21203/rs.3.rs-1743296/v1

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Background

Mitral valve repair (MVR) in children is challenging because of the broad spectrum of lesions and anticipated patient growth, and the lack of reports on standardized surgical management outcomes. We evaluated the long-term outcomes of MVR in children according to Carpentier’s classification.

Methods

We reviewed the records of patients with congenital mitral regurgitation (MR) who underwent MVR at our institution between January 2000 and December 2021. We analyzed preoperative data, surgical techniques, and outcomes according to Carpentier’s classification. The proportion of patients free of mitral valve replacement and reoperation was estimated with Kaplan–Meier analysis.

Results

Twenty-four patients (median age, 4 months; range, 1 month to 8 years) were followed up for 10 (range, 2–21) years. Preoperative MR grade was severe in 12 and moderate in 12 patients. Nine, five, seven, and three patients had Carpentier’s type 1, 2, 3, and 4 MR, respectively. There were no cases of operative mortality or deaths during the follow-up. Reoperation was performed in six patients, two of whom required mitral valve replacement. The overall 5-year rate of freedom from mitral valve replacement was 92%, while the 5-year rate of freedom from reoperation was 78%, 80%, 71%, and 67% in type 1, 2, 3 and 4 MR, respectively. Postoperative MR grade at last follow-up was moderate in three, and less than mild in 21 patients.

Conclusion

Current surgical management of congenital MR is generally considered adequate; however, more complicated cases (type 4 MR) required a combination of various surgical techniques.

congenital mitral valve regurgitation

mitral valve repair

Carpentier’s classification

children

Long term surgical outcome

The surgical treatment for congenital mitral valve regurgitation in children remains a significant challenge due to variations in patient anatomy, congenital anatomic limitations in annulus size, dysmorphic valve tissue, underdeveloped subvalvular apparatus, and maldeveloped papillary muscles [1–3]. In addition, the patients’ growth potential and the desire to avoid valve replacement require good outcomes of mitral valve repair in children [1, 4, 5].

In 1976, Carpentier published the first pathophysiological classification of mitral valve regurgitation, categorizing it into four different types; this definition was subsequently revised in 1998 [6, 7]. Carpentier type 1 mitral valve pathology designates isolated annular dilation, cleft leaflet, and leaflet agenesis; type 2 designates isolated chordae elongation, papillary muscle elongation, and chordae agenesis; type 3 designates commissural papillary muscle fusion, short chordae, and excess valvular tissue; and type 4 designates parachute valve, hammock valve, and papillary muscle agenesis. There are only a few reports of the outcomes of standardized surgical management that address the etiologic and morphologic aspects of mitral valve malformation according to Carpentier’s classification.

Therefore, this study aimed to evaluate the mid- to long-term outcomes of mitral valve repair in children with congenital mitral valve regurgitation, according to Carpenter’s classification.

Ethical considerations

Ethics approval for this study was obtained from the Ethics Committee and Institutional Review Board Committee of Osaka Women’s and Children’s Hospital (approval number: 1537). Clinical data were obtained via a retrospective review of medical records. The requirement for written informed consent was waived because of the retrospective design of the study.

Study Design and Population

This retrospective cohort study included patients who underwent mitral valve repair for congenital mitral valve regurgitation at the Osaka Women’s and Children’s Hospital, Osaka, Japan, between January 2000 and December 2021. Patients with mitral regurgitation associated with atrioventricular septal defect, Marfan’s syndrome, or single ventricle morphology were excluded.

We reviewed the patients’ records and extracted demographic and clinical data, including echocardiography findings, operative findings and techniques, and surgical outcomes, and analyzed these according to Carpentier’s classification.

Diagnosis and Surgical indication

Mitral regurgitation was diagnosed using two-dimensional and color Doppler echocardiography in the parasternal long axis view and was graded according to the American Society of Echocardiography Guidelines as trivial, mild, moderate, or severe based on quantitative measures, namely the vena contracta width and regurgitant fraction) [8]. In addition, all patients routinely underwent preoperative cardiac catheterization. The surgical indication for mitral valve repair was when the disease state became more severe than moderate mitral regurgitation.

Operative Technique

All procedures were performed by the same surgical team based on the same surgical strategy (Fig. 1). All patients underwent a median sternotomy, with cardiopulmonary bypass and mild hypothermia at 32℃ core temperature. Mitral valve exposure was achieved through left atriotomy or interatrial septum incision. Injection of saline solution into the left ventricle was used to assess the morphology of mitral valve dysfunction.

In patients with type 1 mitral valve malformation, particularly those with annular dilation, Kay − Reed’s commissural annuloplasty was applied [9]. A 6 − 0 polypropylene suture with synthetic pledgets was used for the annuloplasty. In patients with a cleft leaflet, a cleft suture was applied. The cleft was closed with interrupted fine stitches, taking care not to cause leaflet distortion or reduced leaflet coaptation. In one patient with a leaflet defect due to infective endocarditis, the defect was augmented using interrupted sutures of glutaraldehyde-treated autologous pericardium.

In patients with types 2 and 3 mitral valve malformation, commissural annuloplasty according to the Kay − Reed method was the first choice. For those with type 3 mitral valve malformation, edge-to-edge paracommisural repair was also performed if commissural annuloplasty was not sufficient to control the mitral regurgitation [10]. The edge-to-edge technique was performed with interrupted fine stitches.

In patients with type 4 mitral valve malformation, various techniques were applied, including cusp elongation, artificial chordae placement, papillary muscle splitting, and edge-to-edge paracommisural repair. For cusp elongation, we used glutaraldehyde-treated autologous pericardial tissue. For artificial chordae placement, we used a 5.0 Gore-Tex suture. In cases of reoperation, we applied a partial ring with either glutaraldehyde-treated autologous pericardium or a rigid partial ring.

Postoperative Medication Regimen

All patients started receiving aspirin (minimal dose: 5 mg/kg/day) and enalapril (minimal dose: 0.2 mg/kg/day). The administration of aspirin was discontinued at three months post-operatively, and the administration of enalapril was discontinued when the mitral regurgitation was less than mild at one year post-operatively.

Follow-up

Follow-ups included clinical examination and transthoracic echocardiography. All patients were routinely followed-up by echocardiography before discharge, 1 year postoperatively, and every 5 years thereafter.

Statistical Analysis

Statistical analysis was performed using IBM SPSS Statistics, version 18.0 (IBM Corp., Armonk, NY, USA). Frequencies are presented as absolute numbers and percentages. Continuous data are presented as mean ± standard deviation or median values with ranges, as appropriate. Mean values were compared using Student’s t-test. Kaplan–Meier analysis was used to estimate the proportion of patients free of mitral valve replacement and reoperation. Freedom from reoperation rates were compared by log-rank test. For all tests, p < 0.05 was considered statistically significant.

Preoperative Characteristics

The patients’ demographic characteristics are described in Table 1. A total of 24 patients with a median age of 4 months (range, 1 month to 8 years) were included, of whom 14 (58%) were less than 1 year old. Ventricular septal defect (n = 9; 38%) and double outlet of the great arteries from the right ventricle (n = 3; 12%) were the most commonly associated cardiac malformations. In half of the patients (n = 12; 50%), severe mitral regurgitation was observed by preoperative echocardiography. The most common pathophysiological changes of the mitral valve according to Carpentier’s classification were type 1 (n = 9; 38%) and type 3 (n = 7; 29%).

Table 1

Baseline patient characteristics
Characteristic	Value
Median age, months (range, months − years)	4 (1 − 8.0)
Median weight, kg (range)	7.5 (3.0 − 29.0)
Mitral regurgitation grade, n (%)
Severe	12 (50)
Moderate	12 (50)
Carpentier’s classification type, n (%)
Type 1	9 (38)
Type 2	5 (21)
Type 3	7 (29)
Type 4	3 (12)
Associated cardiac malformations, n (%)
Ventricular septal defect	9 (38)
DORV	3 (12)
Transposition of great arteries	2 (8)
Atrial septal defect	2 (8)
Ebstein anomaly	1 (4)
ALCAPA	1 (4)
LMCAA	1 (4)
Endocarditis	1 (4)
Idiopathic rupture of chordae tendineae	1 (4)
DORV, double outlet right ventricle; ALCAPA, anomalous left coronary artery from the pulmonary artery; LMCAA, left main coronary artery atresia

Primary Mitral Valve Repair

For primary mitral valve repair, Kay − Reed’s annuloplasty without prosthetic materials was applied in 16 patients, cleft suture in six, cusp elongation with autologous pericardial patch in two, edge-to-edge paracommisural repair in two, and artificial chord reconstruction in two patients. More than two techniques were applied in five patients (21%) (Table 2).

Table 2

Surgical techniques for primary mitral valve repair in each Carpentier’s classification type
Carpentier’s classification type	Surgical technique	N = 24
Type 1, n (%)		9 (38)
	Cleft suture	5
	Kay − Reed annuloplasty	2
	Cleft suture + Kay − Reed annuloplasty	1
	Patch closure of cusp defect	1
Type 2, n (%)		5 (21)
	Kay − Reed annuloplasty	5
Type 3, n (%)		7 (29)
	Kay − Reed annuloplasty	6
	Edge-to-edge repair	1
Type 4, n (%)		3 (13)
	Artificial chordae + Kay annuloplasty	1
	Cusp elongation + Artificial chordae + Kay annuloplasty	1
	Cusp elongation + Edge-to-edge repair	1

Follow-up

The mean follow-up period for the entire population was 10 years (range, 2 − 21 years). There were no operative mortalities or deaths during the hospital stay or follow-up period. All patients had a normal sinus rhythm, and none required pacemaker implantation. Among the six patients who underwent reoperation, two required mitral valve replacement (Table 3). The overall 5-year rate of freedom from mitral valve replacement was 92%, while the 5-year rate of freedom from reoperation was 78%, 80%, 71%, and 67% in types 1, 2, 3 and 4 MR, respectively (Fig. 2). The postoperative mitral regurgitation grade on echocardiography at the last follow-up was moderate in three patients and less than mild in 21 patients.

Table 3

Details of patients who required reoperation
Case	Carpentier's classification and pathology	Diagnosis	Age at primary repair	Technique of primary repair	Mitral valve diameter, % of normal	Time to reoperation from first surgery	Cause of MR	Technique of reoperation	Outcomes
1	type 1, annular dilation	congenital MR	3 months	Kay	preop: 125; postop: 100	1 month	annular dilation	partial annuloplasty	less than mild MR
2	type 1, cleft leaflet	DORV, CoA	14 months	cleft suture + Reed	postop: 100	4 months	defect at repair site	defect closure	MVR at reoperation
3	type 2, A2 prolapse	congenital MR	6 years	Kay	preop: 126; postop: 113	2 years	A2 prolapse	annuloplasty with Duran ring, artificial chordae	removed Duran ring at age 16
4	type 3, posterior leaflet tethering	ccTGA, VSD	4.6 years	Kay	preop: 144; postop: 108	16 months	regurgitation at AL commissure	edge-to-edge paracommisural repair	less than mild MR
5	type 3, thickened anterior leaflet	congenital MR, VSD	3 months	edge-to-edge paracommisural repair	postop: 102	1 year	thickened anterior leaflet	Kay + edge-to-edge double orifice repair	moderate MR controlled by diuretics, ACE-I
6	type 4, hammock mitral valve	idiopathic rupture of chordae tendineae	8 months	artificial chordae + Kay	preop: 119; postop: 97	2 months	hammock mitral valve	cusp elongation + Reed + edge-to-edge paracommisural repair	MVR at 1 year postoperatively
MR, mitral regurgitation; DORV, double outlet right ventricle; CoA, coarctation of aorta; MVR, mitral valve replacement; ccTGA, congenitally corrected transposition of the great arteries; VSD, ventricular septal defect; AL, anterolateral; ACE-I, angiotensin-converting enzyme inhibitors.

Surgical Management and Outcomes According to Carpentier’s Classification

Type 1: Normal leaflet motion. Cleft suture was performed in five patients, Kay − Reed’s annuloplasty in two, cleft suture and Kay − Reed’s annuloplasty in one, and cusp defect closure in one. In patients who underwent Kay − Reed’s annuloplasty, the mitral valve diameter changed from 129 ± 5% to 102 ± 3% of the normal diameter. In seven of the nine patients (78%), the mitral regurgitation grade improved to less than mild. Reoperation was performed in two patients, one of whom required mitral valve replacement (Fig. 3a).

Type 2: Leaflet prolapse. Kay − Reed’s annuloplasty was performed in all five patients. The mitral valve diameter changed from 126 ± 18% to 107 ± 8% of the normal diameter. In four patients (80%), the mitral regurgitation grade improved to less than mild. Only one patient required reoperation (Fig. 3b).

Type 3: Restricted leaflet motion with normal papillary muscles. Kay − Reed’s annuloplasty was performed in six patients, and edge-to-edge repair in one. The mitral valve diameter changed from 129 ± 9% to 96 ± 6% of the normal diameter. In four patients (57%), the mitral regurgitation grade improved to less than mild. Two patients required reoperation; in these patients, the mitral regurgitation grade at last follow-up was mild to moderate (Fig. 3c).

Type 4: Restricted leaflet motion with abnormal papillary muscles. There were three patients with this type of mitral valve malformation. In two of them, cusp elongation was performed, which resulted in improvement of the mitral regurgitation grade to less than mild. One patient underwent artificial chordae placement and Kay annuloplasty, and needed reoperation; finally, we performed mitral valve replacement for this patient (Fig. 3d).

Reoperation Cases According to Carpentier’s Classification

Type 1: Normal leaflet motion. Two patients (Cases 1 and 2, Table 3), who both had type 1 mitral valve malformation, required reoperation. In Case 1, 1 month after the primary repair with Kay’s annuloplasty, annular dilation was observed, and we performed partial ring annuloplasty using glutaraldehyde-treated autologous pericardial material, which resulted in reduction of the mitral valve diameter from 120–75% of the normal diameter.

In Case 2, we performed the Yasui procedure due to double outlet of the great arteries from the right ventricle with coarctation of the aorta. As there was a large cleft reaching the annulus at the anterior mitral valve leaflet, we performed cleft suture and Reed’s annuloplasty. However, reoperation was required 4 months postoperatively due to a defect at the mitral valve repair site. We performed cleft re-suture but were unable to control the mitral regurgitation; therefore, mitral valve replacement was performed.

Type 2: Leaflet prolapse. Only one of the patients with type 2 mitral valve malformation (Case 3; Table 3) required reoperation. This patient had congenital mitral regurgitation with leaflet prolapse caused by a defect of the strut chordae at the A2 position, for which Kay’s annuloplasty was performed, resulting in reduction of the mitral valve diameter from 126–113% of the normal diameter. Reoperation was performed approximately 2 years later by partial annuloplasty with a Duran ring, and the mitral valve diameter was reduced from 164–92% of the normal diameter. Artificial chordae placement was performed as well. Eventually, at the age of 16, the Duran ring was removed to prevent mitral stenosis.

Type 3: Restricted leaflet motion with normal papillary muscles. Two patients with this type of mitral valve malformation (Cases 4 and 5, Table 3) required reoperation. In Case 4, due to corrected complete transposition of the great arteries and ventricular septal defect, we performed a double-switch operation, with the hemi-Mustard procedure and Kay’s annuloplasty for posterior mitral valve leaflet tethering. Reoperation was required due to regurgitation at the anterolateral commissure, which was treated using the edge-to-edge technique as paracommisural repair.

Case 5 was a patient with ventricular septal defect and congenital mitral regurgitation at the posteromedial commissure because of restricted leaflet motion due to a thickened anterior leaflet. We performed ventricular septal defect closure and edge-to-edge paracommisural repair. Reoperation was performed approximately 1 year later by Kay’s annuloplasty and the edge-to-edge technique used as a double orifice repair.

Type 4: Restricted leaflet motion with abnormal papillary muscles. Only one of the patients with this type of mitral valve malformation (Case 6, Table 3) required reoperation. This patient was diagnosed with idiopathic rupture of chordae tendineae and underwent artificial chordae placement and Kay’s annuloplasty. However, 2 months postoperatively, hammock mitral valve was observed, which had not been noticed previously. We performed cusp elongation, edge-to-edge paracommisural repair, and Reed’s annuloplasty, but were unable to control the mitral regurgitation; therefore, mitral valve replacement was performed.

The results of this study showed that surgical management of congenital mitral valve regurgitation according to Carpentier’s classification produces good mid- and long-term outcomes.

In our study, the mortality rate was 0%, the overall 5-year rate of freedom from mitral valve replacement was 92%, and the 5-year rate of freedom from reoperation was 67 − 80% among the four Carpentier’s types. Chauvaud et al. reported a 10-year mortality rate of 88% and a rate of freedom from reoperation of 68% [7]. This demonstrates that the mid-term outcomes of children who underwent mitral valve repair at our institution are acceptable.

In patients with Carpentier’s type 1 mitral valve malformation, the lesions were localized and surgical outcomes were satisfactory when using Kay − Reed’s annuloplasty for annular dilation, and cleft suture for cleft leaflet. Previous studies have reported similar results [4, 12, 13]. However, in patients with a large cleft reaching the annular ring (such as our Case 2), performing only cleft suture could influence the valve leaflet dimensions and worsen the mitral regurgitation. Therefore, patch augmentation seems to be a better choice for these patients [14].

For Carpentier’s type 2 mitral valve malformation, previous studies have reported that artificial chordae placement is an effective treatment [15–17]. However, Minami et al. reported a 5-year rate of freedom from reoperation of 89% and emphasized that it is difficult to decide on the size of the artificial chordae, due to considerations concerning the patients’ growth [15]. For the same reason, we opted for Kay − Reed’s annuloplasty as the initial treatment in these patients. If the mitral regurgitation could not be controlled, artificial chordae placement was also performed, particularly in cases of leaflet prolapse caused by a defect of the strut chordae, such as in Case 3.

For Carpentier’s type 3 mitral valve malformation, we initially performed Kay − Reed’s annuloplasty, which was then supplemented by edge-to-edge paracommisural repair in cases of insufficient mitral regurgitation control, such as Cases 4 and 5 [18].

In cases of Carpentier’s type 4 mitral valve malformation, Chauvaud et al. reported that mitral valve repair is extremely difficult and surgical outcomes tend to be unsatisfactory [7]. Type 4 lesions are usually not isolated and are often characterized by a constellation of other pathological changes of the mitral valve leaflets, annulus, and ring. Therefore, the majority of patients require one or more surgical techniques. Among the techniques performed in these patients at our institution, cusp elongation seemed to be the most effective. However, this technique has been reported to have some limitations. Namely, in some cases, papillary muscle splitting is required in addition to cusp elongation, and good effects can only be obtained with sufficient mitral valve diameter [11]. In cases where cusp elongation was ineffective, we had no choice other than mitral valve replacement. This is because we generally opted for minimally invasive methods, such as edge-to-edge repair and Kay − Reed’s annuloplasty, and if these were found to be insufficient to control the mitral regurgitation, we performed cusp elongation. In Case 6, at primary repair, we evaluated the mechanism of mitral regurgitation as idiopathic rupture of the chordae tendineae and performed artificial chordae placement. However, the true mechanism underlying mitral regurgitation was a hammock mitral valve, which was only perceived at the time of reoperation. This case highlights the importance of accurate assessment of the pathophysiology of mitral regurgitation based on preoperative echocardiography and intraoperative findings.

The study had some limitations. First, this was a single-center, retrospective study that only included a small number of patients. Second, the effect of improvements in surgical technique with increasing surgical experience was not measured.

In conclusion, surgical management of congenital mitral valve regurgitation according to Carpentier’s classification provided good mid- and long-term outcomes in our patients, with a surgical mortality rate of 0% and a 5-year rate of freedom from mitral valve replacement of 92%. The surgical outcomes of Carpentier’s type 1, 2, and 3 mitral lesions were good, while the more complicated type 4 lesions required a combination of surgical techniques, including annuloplasty, artificial chordae placement, edge-to-edge repair, and cusp elongation.

Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflicts of Interest: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

IRB Approval/Patient Consent: The study was approved by the IRB (approval number: 1537; approval date: April 12, 2022).

Meeting Presentation: None

Author contributions: Conceptualization; Koji Miwa, Methodology; Shigemitsu Iwai, Revies and editing; Tomomistu Kanaya and Shota Kawai.

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No competing interests reported.

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Congenital Mitral Regurgitation Repair Based on Carpentier’s Classification: Long-term Outcomes

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Abstract

Background

Methods

Results

Conclusion

Figures

Introduction

Patients And Methods

Ethical considerations

Study Design and Population

Diagnosis and Surgical indication

Operative Technique

Postoperative Medication Regimen

Follow-up

Statistical Analysis

Results

Preoperative Characteristics

Primary Mitral Valve Repair

Follow-up

Surgical Management and Outcomes According to Carpentier’s Classification

Reoperation Cases According to Carpentier’s Classification

Discussion

Declarations

References

Additional Declarations

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