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Ann Thorac Surg 2000;69:S132-S146
© 2000 The Society of Thoracic Surgeons
a Children’s Heart Institute, San Diego Children’s Hospital and Health Center, San Diego, California, USA
Address reprint requests to Dr Lamberti, Cardiothoracic Surgery, San Diego Children’s Hospital and Health Center, 3030 Children’s Way, Suite 310, San Diego, CA 92123
Presented at the International Nomenclature and Database Conferences for Pediatric Cardiac Surgery, 1998–1999.
Abstract
The extant nomenclature for mitral valve disease is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. Mitral valve disease has been subdivided into stenotic and regurgitant lesions. Lesions have been characterized further by etiology and by anatomic location: supravalvar, valvar, and subvalvar. A comprehensive database set is presented which is based on a hierarchical scheme. Data are entered at various levels of complexity and detail which can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented which will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.
I. Background
The mitral valve consists of an annulus, leaflets, chordae tendineae, and papillary muscles. The mitral annulus is an integral part of the fibrous skeleton of the heart. The normal mitral valve has two leaflets, anterior and posterior. The larger anterior (ie, septal or aortic) leaflet attaches to 150 degrees of the annulus, and is squat and trapezoidal in shape. As a consequence of being in fibrous continuity with the aortic valve, it forms the posterior boundary of the left ventricular outflow tract. The scalloped posterior (ie, mural) leaflet is narrower and occupies 210 degrees of the annulus. There remains controversy regarding the most accurate terminology for the mitral valve leaflets. While some notable authors advocate aortic and mural leaflets [1], the convention (as utilized in this text) remains anterior and posterior. The mitral valve leaflets are separated by the anterolateral and posteromedial commissures. Beneath the commissures lie two corresponding papillary muscles, which are extensions of the subendocardial ventricular myocardium. Chordae tendineae from the papillary muscles insert on both sides of the corresponding commissure, so each valve leaflet receives chordae from both papillary muscles. Considerable variation can be found in the morphology of the normal mitral valve.
A congenitally abnormal mitral valve affects less than 1% of all infants born with a normal sized left ventricle. Patients born with various types of atrioventricular canal defects, single ventricle, and congenitally corrected transposition are not regarded as having an anatomic mitral valve as the systemic atrioventricular valve. In up to 60% of cases, congenital anomalies of the mitral valve occur in association with other cardiac lesions, and often more than one component of the mitral apparatus is involved [2].
The Carpentier classification of congenital mitral valve disease is the most commonly utilized nomenclature [3]. This 1976 classification is predicated on a functional analysis of the mitral valve leaflet. Type 1 lesions typically have normal leaflet motion, but produce valvar insufficiency from a dilated or deformed annulus, or by a defect or cleft in the leaflet. These lesions are subdivided into annular dilatation, cleft leaflet, and partial leaflet agenesis [4]. Type 2 lesions involve leaflet prolapse, which results from the absence or elongation of the chordae or papillary muscles, and produces valvar insufficiency. These defects are subdivided into chordal elongation, papillary muscle elongation, and chordal agenesis [4]. Type 3 lesions involve restricted leaflet motion, and hence, mitral stenosis, although valvar insufficiency can also be observed with certain lesions. Stenosis results from commissural fusion, imperforation, thickening, or shortening of the subvalvar apparatus. These lesions are divided into group A, normal papillary muscles and group B, abnormal papillary muscles. Group A is further subdivided into papillary muscle commissural fusion and shortened chordae. Also included in this group are excessive leaflet tissue, valvar ring, and annular hypoplasia. Group B is further subdivided into parachute mitral valve, hammock mitral valve, and papillary muscle hypoplasia [5].
In 1978, Ruckman and Van Praagh [6], in a postmortem analysis of 49 children with mitral valve stenosis, proposed four types of congenital mitral stenosis. Type A were typical abnormalities of the mitral valve commonly seen in biventricular hearts. These lesions were subdivided into short chordae, abnormal mitral valve attachments, and loss of interpapillary distance. Type B lesions were found in patients with a hypoplastic left ventricle. The type C lesion consisted of a supravalvar mitral ring. The type D lesion was the parachute mitral valve. Although the Van Praagh classification was not widely adopted, it helped to establish congenital mitral valve disease as a specific anatomic defect. Several authors have provided comprehensive lists of mitral valve abnormalities in an attempt to identify and delineate the defects [7–9]. However, only Carpentier defined a systematic classification based on an objective assessment of valvar function.
IIA. Analysis
The Carpentier classification is based on a functional analysis of leaflet mobility. Typically, lesions resulting from normal leaflet motion or prolapsing leaflets produce mitral valve insufficiency, whereas lesions with restricted leaflet motion produce mitral valve stenosis. However, there are two limitations to this classification, which can produce observer variability, and therefore potential inconsistency in data reporting. Firstly, a purely stenotic or insufficient valvar lesion is rarely observed. Secondly, the surgical literature has generally divided, reported, and risk stratified congenital mitral valve lesions based on stenosis versus insufficiency, not leaflet function. In addition, the Carpentier classification was developed before routine two-dimensional echocardiography was available. Functional evaluation of the leaflets by direct vision in the operating room may be difficult, despite saline insufflation of the flaccid left ventricle. Accurate and thorough preoperative echocardiography becomes mandatory to define lesions based on leaflet motion and to effect the appropriate repair [4, 5]. In addition, preoperative cardiac catheterization and angiography do not provide much information regarding the anatomic malformation of the mitral valve. Furthermore, visualization of leaflet function by preoperative transthoracic two-dimensional echocardiography and cardiac catheterization may be variable [10]. Individual interpretations of the functional anatomy introduce variability, which makes the reliability and reproducibility of a classification difficult.
At the present time, transesophageal echocardiography provides considerable information regarding mitral valve structure and function. Surgeons now have much more information before the valve is inspected. This permits preoperative classification which may be enhanced by direct observation of the valve at the time of operation.
In addition to the congenital malformations of the mitral valve are the acquired lesions of the mitral valve. These lesions can be the result of tumors, infectious disease, genetic disorders, and iatrogenic injuries, to name a few. A comprehensive hierarchical database scheme must take into consideration all lesions of the mitral valve which includes: congenital, acquired, and lesions that occur status post cardiac operation.
We propose a contemporary unifying anatomic classification for congenital abnormalities of the mitral valve based on a consideration of whether the valve is stenotic or insufficient. Adoption of an optimal standard nomenclature that could be widely utilized, consistent, and reproducible would minimize observer variability in the diagnosis. This classification makes the issues of leaflet function a consequence of the altered valvar anatomy. This, in turn, allows a segmental and systematic approach for considering the therapeutic options.
The anatomic contemporary classification for congenital mitral valve disease is presented below. In the anatomic contemporary classification for congenital mitral valve disease, type 1 lesions are supravalvar, and type 2 lesions are valvar, with the category divided into group A or annular defects and group B or leaflet defects. Type 3 are subvalvar lesions with group A involving abnormalities of the chordae tendineae and group B involving defects of the papillary muscles. Type 4 are mixed lesions. This simplified anatomic approach is noted in the diagnostic scheme at hierarchy level 4 which is preceded by mitral valve disease (hierarchy 1), mitral regurgitation, stenosis, regurgitation and stenosis (hierarchy 2) and congenital, acquired, status post cardiac surgery (hierarchy 3). When numerous defects of the valve apparatus exist, the predominant defect causing the functional effect will direct the classification of the lesion. Multiple types of mitral valve pathology can be coded in the hierarchical system by selecting the predominant lesion as the first diagnosis and each additional lesion as a subsequent diagnosis in decreasing order of importance. We anticipate that this segmental approach will allow a systematic and consistent analysis of the valvar abnormality.
Acquired lesions of the mitral valve have been subcategorized in the hierarchical scheme by valvar function, and etiologic cause. Thus, together with congenital lesions a complete hierarchical nomenclature system is developed based on multiple levels of important diagnostic considerations.
Important definitions
Congenital mitral valve disease (CMVD)
An anatomic abnormality of the mitral valve of a functional left ventricle that results in structural and/or functional alterations.
CMVD, type 1—supravalvar
An abnormality of the mitral valve above the level of the leaflets or annulus.
CMVD, type 2—valvar
An abnormality of the mitral valve at the level of the leaflets or annulus.
CMVD, type 3—subvalvar
An abnormality of the mitral valve at the level of the chordae tendineae or the papillary muscles.
CMVD, type 4—mixed
An abnormality of the mitral valve that is best described as a mixture or combination of two or more of the above three types.
CMVD, type 1 (supravalvar), mitral ring
This defect is formed by a circumferential ridge of endocardial tissue that is attached to the anterior leaflet below its insertion on the annulus. It is also attached to the atrium slightly above the attachment of the mural leaflet. Varying degrees of obstruction exist, depending on the diameter of the ring. Usually the underlying valve is abnormal, and frequently stenotic or hypoplastic. In many cases this lesion is associated with other stenotic lesions such as parachute or hammock valve, papillary muscle fusion, and double orifice mitral valve.
Supravalvar mitral ring must be differentiated from cor triatriatum. In both cor triatriatum and supravalvar mitral ring, the left atrium is divided into two compartments. In cor triatriatum, the posterior compartment contains the pulmonary veins, while the anterior compartment contains the left atrial appendage and the mitral valve orifice. In supravalvar mitral membrane, the posterior compartment contains the pulmonary veins and the left atrial appendage while the anterior compartment contains only the mitral valve orifice.
CMVD, type 2 (valvar), annulus
A mitral valve defect at the level of the annulus, distinct from the leaflets, and typically involving the fibrous skeleton of the valve (eg, hypoplasia).
CMVD, type 2 (valvar), leaflet
A mitral valve defect at the level of the leaflet, distinct from the annulus, but in the plane of the valve (eg, cleft).
CMVD, type 3 (subvalvar), chordae tendineae
A mitral valve defect below the level of the valve, and predominantly involving the chordae tendineae (eg, hammock valve).
CMVD, type 3 (subvalvar), papillary muscles
A mitral valve defect below the level of the valve and predominantly involving the papillary muscles (eg, parachute valve).
CMVD, type 4 (mixed)
A congenital mitral valve abnormality involving multiple lesions at a given level of the valve or multiple lesions at different levels.
CMVD, type 2 (valvar) (annulus), midvalvar ring
A fibrous mitral ring found within the substance of the valve leaflets causing valvar stenosis as well as leaflet restriction [11]. Often associated obstructive lesions are found such as excess valvar tissue and fused papillary muscles.
CMVD, type 2 (valvar) (annulus), hypoplasia
A valvar defect involving annular underdevelopment with consequent mitral valve stenosis. It is most commonly associated with hypoplastic left ventricles, ventricular septal defect (VSD), and aortic coarctation, but rarely occurs as an isolated anomaly. This lesion is distinguished from mitral valve hypoplasia and mitral valve atresia, which are typically components of the hypoplastic left heart syndrome (HLHS). The defect can involve absence of the valve commissures associated with shortened and thickened chordae, or thickened and immobile leaflets in the presence of normal commissures.
CMVD, type 2 (valvar) (annulus), dilatation
A valvar defect involving annular dilatation, typically in the anterior-posterior axis, with normal leaflet motion and mitral insufficiency. In up to 50% of cases, these lesions are associated with a secundum atrial septal defect (ASD). The posterior leaflet may be thickened due to imperforate interchordal spaces.
CMVD, type 2 (valvar) (annulus), deformation
A valvar defect involving annular deformation as a consequence of associated lesions, and resulting in stenosis or insufficiency.
CMVD, type 2 (valvar) (leaflet), hypoplasia/agenesis
These defects consist of leaflet agenesis or holes in the leaflets. The edge of the defect is either free or attached to thin chordae tendineae. Normal leaflet motion and mitral insufficiency result.
CMVD, type 2 (valvar) (leaflet), cleft
Typically the anterior leaflet is divided by a vertical cleft into two hemileaflets, causing poor leaflet coaptation and mitral insufficiency. Although abnormal chordae tendineae often attach to the free edges of the cleft, the papillary muscles and commissures are usually normal. The three leaflet atrioventricular (AV) valve (AV septal defect type) may be functionally competent despite lateral displacement of the leaflets and papillary muscles.
CMVD, type 2 (valvar) (leaflet), excessive tissue
In this lesion, a large bridge of excessive valve tissue with normal chordae and papillary muscles joins the anterior and posterior leaflets. This can be accessory valve tissue and is usually associated with AV septal defects. This can result in valvar stenosis or insufficiency.
CMVD, type 2 (valvar) (leaflet), double orifice mitral valve
Double orifice mitral valve is caused by a reduplication of the orifice with each suborifice supported by its own tension apparatus. The smaller orifice is usually to the right of the larger one. The bridging valvar apparatus is comprised of leaflet tissue and is not subtended by chordal attachments or papillary muscles.
CMVD, type 3 (subvalvar) (chordae tendineae), agenesis
In this lesion, leaflet prolapse and mitral insufficiency results from the absence of chordal attachment to the free edge of the leaflet. Secondary chordae may be attached to the ventricular surface of the prolapsed leaflet.
CMVD, type 3 (subvalvar) (chordae tendineae), shortened—funnel valve
Chordal shortening results in limited mobility of the leaflets which in turn results in valvar incompetence. The well delineated, slightly thickened, nonfused chordae arise from the normally placed papillary muscles. The interchordal spaces are obstructed by abnormal valvar tissue, forming a funnel shaped orifice. The reduced interchordal spaces, with papillary muscle hypertrophy, may also create associated mitral stenosis. The central orifice of the mitral valve between the two papillary muscles is severely narrowed, forming the funnel valve, and is formed by continuity of the fused chordae with the abnormally thickened valve leaflets. A variant involves the insertion of two thick and obstructive papillary muscles directly onto the valve commissures in the absence of chordae tendineae. The commissural areas are fused and thickened, and leaflet motion is restricted.
CMVD, type 3 (subvalvar) (chordae tendineae), elongated
This defect typically involves all of the chordae arising from one papillary muscle, causing leaflet prolapse and mitral insufficiency. Occasionally two or three chordae of the mural leaflet are elongated, and the annulus can be dilated. This defect is associated with the Marfan’s syndrome.
CMVD, type 3 (subvalvar) (papillary muscles), hypoplasia/agenesis
This defect is characterized by poor development or absence of one or both papillary muscles. The chordae are attached to a single papillary muscle if one is present, or numerous intermixed chordae are attached to the ventricular wall with imperforate interchordal spaces, if both papillary muscles are absent. Valvar incompetence results from abnormal tension on the chordae or underdevelopment of the leaflet tissue that corresponds to the absent papillary muscle. Anterior papillary muscle hypoplasia is the most common defect. The corresponding half of the anterior leaflet is underdeveloped, as is the anterior commissure.
CMVD, type 3 (subvalvar) (papillary muscles), shortened
In this defect, thin delicate multiperforated tissue obliterates the commissural areas. The chordae are short, and the papillary muscles are normal or hypertrophied and will commonly adhere to the commissures. Mitral stenosis with valvar incompetence results from retraction or indentation of the anterior leaflet or annular dilatation or both.
CMVD, type 3 (subvalvar) (papillary muscles), elongated
The papillary muscle in this defect is typically thin, flattened, elongated, or occasionally infarcted, and allows the leaflet to prolapse through the mitral valve orifice. Mitral insufficiency results and is usually associated with other congenital cardiac defects such as anomalous origin of the left coronary artery from the pulmonary trunk, or aortic stenosis.
CMVD, type 3 (subvalvar) (papillary muscles), single—parachute valve
In this defect, all chordae are attached to a single papillary muscle originating from the posterior ventricular wall. When the interchordal spaces are partially obliterated by excess valve tissue, valvar stenosis results. This defect also causes valvar insufficiency; most commonly due to a cleft leaflet, a poorly developed anterior leaflet, short chordae, or annular dilatation. This defect is one of the most common lesions causing mitral valve stenosis. This lesion is also part of the Shone’s anomaly [12], which consists of the parachute mitral valve, supravalvar mitral ring, subaortic stenosis, and coarctation of the aorta. The atrial aspect of the leaflets and chordae may appear grossly normal, masking the severe subvalvar papillary muscle abnormality.
CMVD, type 3 (subvalvar) (papillary muscles), multiple—hammock valve
The mitral valve orifice is obstructed by intermixed chordae and abnormal papillary muscles implanted high on the posterior wall of the left ventricle just under the mural leaflet. Typically the second papillary muscle is absent. Leaflet tissue may be normal or abnormal with no clear delineation between anterior and posterior leaflets. The thick chordae from the posterior papillary muscle crosses the mitral orifice to insert on the anterior leaflet, producing the characteristic hammock appearance, as well as the stenosis. Valvar insufficiency can also result, produced by cleft leaflet, anterior leaflet hypoplasia, shortened chordae, or annular dilatation. Variants of this lesion include the mitral arcade (typical congenital mitral stenosis, obstructive papillary muscle, and hypertrophied papillary muscle). In this defect, the leaflet tissue is normal although the commissures are fused. If leaflet restriction is observed, it most commonly is seen with the posterior leaflet. The arcade valve is present when the anterior and posterior groups of papillary muscles join together and fuse with the entire edge of the leaflet without well formed interposed chordae. This lesion is frequently associated with aortic stenosis, aortic coarctation, patent ductus arteriosus, and VSD. Occasionally the valve has several orifices as a result of the papillary muscle and chordal arrangement.
Treatment
The therapeutic options for CMVD are somewhat limited. There is no truly satisfactory substitute for the mitral valve in a patient of any age. The limitations of replacing the mitral valve with a mechanical valve in infants and children are well recognized. Techniques for the repair of the mitral valve have become increasingly sophisticated in recent years and may provide improvement in mitral valve function which permits delay in mitral valve replacement. It is possible that homograft replacement of the mitral valve will be a useful technique at some time in the future, but the technique must be considered investigational at the present time. Often, infants and children are referred for mitral valve operation in the absence of obvious symptoms. Gross cardiomegaly and dilatation of the left atrium in a seemingly asymptomatic child may provide an adequate basis for operation if the preoperative echocardiographic analysis suggests that the valve is amenable to repair. In patients with a markedly abnormal valve or in those who have previously undergone repair, mitral valve replacement may be the only option. In general, most cardiologists and surgeons wait longer before referring a patient for mitral valve replacement than they would for a first time attempt at mitral valve repair. Thus, surgical intervention is considered when symptoms become severe or when exercise limitations become unacceptable. Valve repair is the optimal course of action. Mitral valve replacement is considered a last resort.
We will now discuss treatment options for all of the congenital mitral valve lesions given below. Later in this manuscript, we incorporate these treatment options into a complete hierarchical nomenclature for mitral valve disease.
CMVD, type 1 (supravalvar), mitral ring
A resection of the fibrous tissue taking care not to damage the anterior leaflet is the procedure of choice. The ring is usually easily separated from the valve with the resection begun posteriorly and extended anteriorly. Rarely, mitral valve replacement is necessary.
CMVD, type 2 (valvar) (annulus), hypoplasia
This complex lesion is not usually repairable, necessitating suprannular valve replacement (if a biventricular repair is possible).
CMVD, type 2 (valvar) (annulus), dilatation
The treatment for this disorder is typically a form of annuloplasty. In children less than 10 years of age, rectangular resection of the mural leaflet, annular plication, and suturing of the leaflet edges will usually reduce regurgitation and allow for future annular growth. The Wooler (eccentric) annuloplasty involves a reduction of the dilated posterior mitral annulus by two sutures placed anterior to each commissure and directed a variable distance along the mural annulus. Tightening the sutures narrows the annulus. This technique permits a substantial reduction in regurgitation without interfering with annular growth. The modified De Vega annuloplasty involves a reduction of the circumference of the posterior annulus by the placement of horizontal mattress sutures in the atrial wall around the annulus which are tightened until the valve becomes competent. This technique also allows interruption of the annuloplasty, thereby permitting annular growth [13]. When a ring annuloplasty is selected, a flexible ring seems to provide optimal function with less risk of subaortic stenosis [14].
CMVD, type 2 (valvar) (annulus), deformation
Optimal therapy addresses the associated lesion with concomitant annuloplasty. Valve replacement is necessary if valve integrity cannot be preserved.
CMVD, type 2 (valvar) (leaflet), hypoplasia/agenesis
The treatment for leaflet agenesis consists of a rectangular resection with suturing of the free edge of the leaflet remnants after a sliding valvuloplasty of the remnants has been performed. A defect in the anterior leaflet may be treated by direct suturing or by application of an autologous pericardial patch depending on the size of the defect [4, 15].
CMVD, type 2 (valvar) (leaflet), cleft
The optimal treatment consists of closure of the leaflet cleft. Anterior leaflet clefts are repaired by direct suture technique. Care must be taken to avoid extending the suture line beyond the site of primary chordal insertion to avoid limiting the valve opening. Posterior clefts may be treated by quadrangular resection or simple closure. In the case of a three leaflet mitral valve, commisuroplasties at the anterolateral and posteromedial commissures are indicated. Suturing of the free edges of a cleft posterior leaflet, and plication of the annulus, also offers good palliation. If there is associated annular dilatation annuloplasty is concurrently performed [16].
CMVD, type 2 (valvar) (leaflet), excessive tissue—funnel valve
Treatment by chordal fenestration to open the interchordal spaces is occasionally effective in relieving the stenosis. Two approaches are possible to the double orifice mitral valve. Leaving the accessory orifice intact or oversewing and obliterating the second orifice if the first is competent and of adequate diameter. If the valve is stenotic, the treatment is more complicated, as transection of the bridging tissue will often render the valve incompetent, necessitating extensive repair or replacement [17]. Up to one-half of the posterior leaflet is amenable to resection, but only a small wedge of the anterior leaflet can be safely resected. Larger areas of unsupported anterior leaflet can be treated by chordal shortening, transfer, or replacement. Due to the subsequent increase in the disparity between mitral orifice size and leaflet area after leaflet resection, concomitant annuloplasty is usually necessary. Valve replacement is occasionally necessary.
CMVD, type 3 (subvalvar) (chordae tendineae), agenesis
The absence of primary chordae is most effectively dealt with by rectangular leaflet resection and direct suturing. Artificial chordae of Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) have proven useful in some cases [18]. Secondary chordal defects are addressed by suturing the free edges of the leaflet to the secondary chordae.
CMVD, type 3 (subvalvar) (chordae tendineae), shortened—funnel valve
Splitting of the papillary muscle to enlarge the interchordal spaces and restore leaflet mobility is the preferred treatment. Annular remodeling is usually necessary. When leaflet mobility is limited by abnormally short chordae or malformed papillary muscles (as in parachute or hammock valves), splitting the papillary muscles may improve leaflet excursion. Persistence of interchordal tissue can impede left ventricular inflow. Removal of the tissue between primary chordae and resection of secondary chordae can increase the effective mitral orifice [19].
CMVD, type 3 (subvalvar) (chordae tendineae), elongated
The treatment of choice is chordal shortening by splitting the papillary muscle and suturing the chord in the depth of the papillary muscle stalk. If two or three chords of the mural leaflet are elongated, then chordal shortening or resection and suturing of the prolapsed portion of the leaflet is effective. Alternatively, an unsupported portion of the anterior leaflet can be repaired with quadrangular resection of the opposing segment of the posterior leaflet, and transfer of the primary chordae by suturing the segment to the atrial surface of the anterior leaflet. Polytetrafluoroethylene (PTFE) suture reconstruction as a method of chordal replacement is an option, although experience in children is limited [18].
CMVD, type 3 (subvalvar) (papillary muscles), hypoplasia/agenesis
A modified prosthetic ring is typically the only therapy required for this defect. Fenestration of the interchordal spaces will occasionally be effective, however valve replacement is usually necessary to restore the integrity of the valve.
CMVD, type 3 (subvalvar) (papillary muscles), shortened
The treatment of choice is commissurotomy, papillary muscle fenestration and elongation, and removal of secondary chordae.
CMVD, type 3 (subvalvar) (papillary muscles), elongated
This defect is treated by papillary muscle or chordal shortening. Incising the left ventricle above the insertion point of the papillary muscle, burying the muscle in the groove, and closure of the papillary muscle within it has been described [18]. Artificial chordae of Gore-Tex may also be useful.
CMVD, type 3 (subvalvar) (papillary muscles), single—parachute
Fenestration of the papillary muscle (split into anterior and posterior) with fenestration of the interchordal leaflet spaces will typically release the subvalvar stenosis. Valvar incompetence can be treated by leaflet suturing or annular remodeling [20].
CMVD, type 3 (subvalvar) (papillary muscles), multiple—hammock
This lesion is optimally treated by excision of excess papillary muscle beneath the mural leaflet, fenestration of the interchordal spaces, cleft suturing, or annular remodeling. Separation of the anterior from the posterior leaflet, and removal of the chordae and papillary muscles that are not attached to the free edges of the leaflets will occasionally be successful. Valve replacement is often necessary [20].
CMVD, type 4 (mixed)
Treatment is by addressing the individual anomalies and annular remodeling. Often, valve replacement is the only viable option.
Additional therapeutic interventions
Balloon dilatation for congenital mitral stenosis
This technique is most useful in patients affected with rheumatic mitral stenosis. The best result is observed in patients with pure stenosis and flexible leaflets. The worst results have been observed in children with congenital mitral valve stenosis and concomitant papillary muscle abnormalities. The lack of a sustained functional response to balloon dilatation of the congenitally abnormal valve and the risk of acute severe regurgitation limits the application of this procedure [21].
Commissurotomy
This procedure for mitral stenosis is most applicable when the commissures are fused. If the leaflets are pliable, commissurotomy may be very effective in restoring valvar function. When the commissure area is not well supported the annulus should not be incised, as mitral regurgitation can result.
Extracardiac valved conduit
In cases when the mitral valve is not reparable and valve replacement is not feasible, due to annular hypoplasia in the setting of a normal-sized left ventricle, an extracardiac porcine valved conduit may be used [22]. The operation may be performed through a left thoracotomy or a median sternotomy. The conduit is attached to the left atrium utilizing an incision placed between the base of the left atrial appendage and the pulmonary veins. The distal end of the graft is attached to the apex of the left ventricle.
Mitral valve replacement
The results from mitral valve repair are superior to those of mitral valve replacement in most published series. With the wide array of techniques currently available, satisfactory repair of congenitally anomalous mitral valves is possible in 80% of cases. Attempted repair of mitral stenosis, particularly due to defects in the subvalvar apparatus (such as parachute and hammock deformities), is often accompanied by florid insufficiency. Valve replacement is often the only remaining option in this situation. Although preservation of chordal attachments is considered important in preserving ventricular function, this is often not feasible in infants and small children. If the annulus measures 20 mm or larger, the method of valve replacement is identical to that in adults. When the annulus is not large enough to accept a prosthesis in the orthotopic position, the valve may be placed in the supraannular position within the left atrium. The most appropriate prosthesis for mitral replacement in children is a low profile bileaflet mechanical prosthesis [23]. Heterograft valves degenerate too rapidly to justify their routine use.
In the recent past, the operative mortality for valve replacement in infants and children approached 30% to 50% [24]. However, with improved myocardial preservation techniques, better valve prostheses, tighter control of postoperative anticoagulation, and improved postoperative intensive care unit management, the operative mortality for mitral valve replacement in children now approaches 0% in some series [25]. However, repeat valve replacement is common, with nearly 50% of patients requiring reoperations within 3 years. Long term survival remains poor, with an actuarial 5 year survival of approximately 50% [25].
IIB. A unified mitral valve disease diagnostic hierarchical nomenclature system
Mitral valve disease hierarchy level 1
Mitral valve disease hierarchy level 1 definitions
Mitral valve disease
A spectrum of lesions characterized by the presence of mitral regurgitation, mitral stenosis or a combination of both.
Mitral valve disease hierarchy level 2
Mitral valve disease hierarchy level 2 definitions
Mitral valve disease, mitral regurgitation
Mitral regurgitation can be caused by a number of congenital and acquired lesions.
Mitral valve disease, mitral stenosis
Mitral stenosis can be caused by congenital or acquired lesions which can result in left atrial hypertension and/or a left to right atrial shunt in the presence of an atrial septal defect.
Mitral valve disease, mitral stenosis and regurgitation
Mitral stenosis and regurgitation can occur simultaneously and be due to congenital and/or acquired lesions.
Mitral valve disease hierarchy level 3
Mitral valve disease hierarchy level 3 definitions
Mitral valve disease, mitral regurgitation, congenital
The numerous etiologies of congenital mitral valve disease discussed earlier in this manuscript may cause mitral regurgitation.
Mitral valve disease, mitral regurgitation, acquired
Acquired causes of mitral regurgitation include rheumatic heart disease, infective endocarditis, ischemia, myxomatomous degeneration, trauma, and cardiomyopathy.
Mitral valve disease, mitral regurgitation, status post-cardiac surgery
Mitral regurgitation can occur following previous cardiac operations that may include atrioventricular canal defect repair, subaortic stenosis repair, and previous valve repair or valve replacement, to name a few. Significant mitral regurgitation can also occur following orthotopic cardiac transplantation.
Mitral valve disease, mitral stenosis, congenital
The numerous etiologies of congenital mitral valve disease discussed earlier in this manuscript may cause mitral stenosis.
Mitral valve disease, mitral stenosis, acquired
Acquired causes of mitral stenosis is most commonly caused by rheumatic valvar heart disease.
Mitral valve disease, mitral stenosis, status post cardiac surgery
Mitral stenosis after cardiac surgery can be due to valvuloplasty techniques or complications stemming from operations involving the mitral valve.
Mitral valve disease, mitral stenosis and regurgitation, congenital
A combination of mitral stenosis and mitral regurgitation can be due to the numerous etiologies of congenital mitral valve disease discussed earlier in this manuscript.
Mitral valve disease, mitral stenosis and regurgitation, acquired
A combination of mitral stenosis and mitral regurgitation due to an acquired cause.
Mitral valve disease hierarchy level 4
Mitral valve disease hierarchy level 5
Mitral valve disease hierarchy level 6
III. A unified mitral valve disease therapeutic hierarchical nomenclature system
Mitral valve disease treatment hierarchy level 1
Mitral valve disease treatment hierarchy level 2
Mitral valve disease treatment hierarchy level 3
IV. Diagnosis and procedure short lists
V. Diagnosis-related potential risk factors
The formulation of a comprehensive international congenital cardiac surgery database is prudent, considering the number and excellence of congenital cardiac surgery programs currently performing complex repairs on the abnormal mitral valve. The difficulty that has been encountered in a review of the most recent series on the subject is the lack of uniformity among centers in the naming and categorization of the defects into anatomically based groups. The analysis of valvar function is interpretable by different surgeons in different ways, and hence introduces variability in the nomenclature, and consequently the database. Our purpose in proposing an anatomically based classification system is to minimize operator variability, allow uniform interpretation of valvar defects, and define preoperative, intraoperative, and postoperative risk factors for reporting outcomes.
VI. Database studies and outcome analysis
Mitral valve disease type (by year)
This table will show the number and percentage of each major mitral valve disease type for each year. (All tables below will break down the date for each given year of data collection and also will provide the total data of the cumulative experience.)
Mitral valve disease age (years) at operation for each EA type (by year)
This table will show the distribution of age at operation for each major mitral valve disease type for each year.
Mitral valve disease gender distribution for each EA type (by year)
This table will show the gender for each major mitral valve disease type for each year.
Mitral valve disease features of repair—cardiopulmonary bypass (by year)
This table will show the number and percentage of each major mitral valve disease type treated with cardiopulmonary bypass for each year.
Mitral valve disease features of repair—aortic cross-clamp (by year)
This table will show the number and percentage of each major mitral valve disease type treated with aortic cross-clamping for each year.
Mitral valve disease features of repair—myocardial preservation [cardioplegia type] (by year)
For patients treated with cross-clamping, this table will show the number and percentage of each major mitral valve disease type treated with various cardioplegia types including blood, crystalloid, substrate enriched, and other.
Mitral valve disease features of repair (by year)
This table will show the number and percentage of each repair technique for each major mitral valve disease type for each year.
Mitral valve disease features of replacement (by year)
This table will show the number and percentage of mitral valve replacement done for each major mitral valve disease type for each year.
Mitral valve disease complication incidence (including operative death) (by year)
This table will show the number and percentage of operative deaths and complications (both transient and permanent, for each major organ system, including cardiac, pulmonary, renal, infectious, neurologic) for each major mitral valve disease type for each year.
Mitral valve disease complication incidence (including operative death) patients less than 1 year of age (by year)
For patients less than 1 year, this table will show the number and percentage of operative deaths and complications (both transient and permanent, for each major organ system, including cardiac, pulmonary, renal, infectious, and neurologic) for each major mitral valve disease type for each year.
Mitral valve disease complication incidence (including operative death) patients greater than or equal to 1 year of age (by year)
For patients greater than or equal to 1 year of age, this table will show the number and percentage of operative deaths and complications (both transient and permanent, for each major organ system, including cardiac, pulmonary, renal, infectious, and neurologic) for each major mitral valve disease type for each year.
Mitral valve disease postoperative length of ventilation (hours) (by year)
This table will show the postoperative length of ventilation for each major mitral valve disease type for each year.
Mitral valve disease total length of ventilation (hours) (by year)
This table will show the total length of ventilation for each major mitral valve disease type for each year.
Mitral valve disease postoperative length of stay (days) (by year)
This table will show the postoperative length of stay for each major mitral valve disease type for each year.
Mitral valve disease total length of stay (days) (by year)
This table will show the total length of stay for each mitral valve disease type for each year.
Mitral valve disease postoperative length of stay (days) by patient age (by year)
This table will show the postoperative length of stay for each major mitral valve disease type for each year, comparing patients less than 1 year to those greater than or equal to 1 year of age.
Mitral valve disease total length of stay (days) by patient age (by year)
This table will show the total length of stay for each major mitral valve disease type for each year, comparing patients less than 1 year to those greater than or equal to 1 year.
Kaplan-Meier curves
Kaplan-Meier survival curves should be generated for each major mitral valve disease type for each year, comparing the total mitral valve disease cohort to patients less than 1 year to those greater than or equal to 1 year.
Mitral valve disease complication incidence (including operative death) versus myocardial preservation [cardioplegia type] (by year)
This table will compare the number and percentage of operative deaths and complications (both transient and permanent, for each major organ system, including cardiac, pulmonary, renal, infectious, and neurologic), in patients treated with various cardioplegia types including blood, crystalloid, substrate enriched, and other, for each major mitral valve disease type for each year.
Mitral valve disease complication incidence (including operative death) versus repair vs replacement (by year)
This table will compare the number and percentage of operative deaths and complications (both transient and permanent, for each major organ system, including cardiac, pulmonary, renal, infectious, and neurologic), in patients treated with repair versus replacement, for each major mitral valve disease type for each year.
Mitral valve disease postoperative length of ventilation (hours) versus repair and replacement technique (by year)
This table will compare the postoperative length of ventilation, in patients treated with repair versus replacement, for each major mitral valve disease type for each year.
Mitral valve disease preoperative length of stay (days) (by year)
This table will show the preoperative length of stay for each major mitral valve disease type for each year.
Mitral valve disease same day surgery (by year)
This table will show the number and percentage of day of surgery admissions for each major mitral valve disease type for each year.
Mitral valve disease preoperative length of stay (days) by patient age (by year)
This table will show the preoperative length of stay for each major mitral valve disease type for each year, comparing patients less than 1 year to those greater than or equal to 1 year.
Mitral valve disease same day surgery by patient age (by year)
This table will show the number and percentage of day of surgery admissions for each major mitral valve disease type for each year, comparing patients less than 1 year to those greater than or equal to 1 year.
Mitral valve disease complication incidence (including operative death) versus preoperative ventilation (by year)
This table will compare the number and percentage of operative deaths and complications (both transient and permanent, for each major organ system, including cardiac, pulmonary, renal, infectious, and neurologic), in patients treated with and without preoperative ventilation, for each major mitral valve disease type for each year.
Mitral valve disease postoperative length of ventilation (hours) versus preoperative ventilation (by year)
This table will compare the postoperative length of ventilation, in patients treated with and without preoperative ventilation, for each major mitral valve disease type for each year.
Mitral valve disease postoperative length of stay (days) versus preoperative ventilation (by year)
This table will compare the postoperative length of stay, in patients treated with and without preoperative ventilation for each major mitral valve disease type for each year.
References
This article has been cited by other articles:
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  G. Oppido, B. Davies, D. M. McMullan, A. D. Cochrane, M. M.H. Cheung, Y. d'Udekem, and C. P. Brizard Surgical treatment of congenital mitral valve disease: Midterm results of a repair-oriented policy. J. Thorac. Cardiovasc. Surg., June 1, 2008; 135(6): 1313 - 1321.e4. [Abstract] [Full Text] [PDF]
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 K. Hashimoto, M. Oshiumi, H. Takakura, T. Sasaki, and K. Onoguchi Congenital mitral regurgitation from absence of the anterolateral papillary muscle Ann. Thorac. Surg., October 1, 2001; 72(4): 1386 - 1387. [Abstract] [Full Text] [PDF]
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