- Email: [email protected]
Cleft anterior leaflet of the mitral valve with intact septa
MARCH 15, 1983
The American
, J o u r n a l of C A R D I O L O G Y
®
VOLUME 51 NUMBER 6
CONGENITAL HEART DISEASE
Cleft Anterior Leaflet of the Mitral Valve With Intact Septa A Study of 20 Cases ELIO DI SEGNI, MD and JESSE E. EDWARDS, MD
Twenty pathologic specimens of heart, each with a cleft in the anterior leaflet of the mitral valve not associated with septal defects of persistent common atrioventricular canal (isolated cleft of the mitral valve), were studied. In 9 cases, there were either no associated anomalies or ones not of functional significance. In each of the other 11 cases there were other significant associated cardiac anomalies, including ventricular septal defect and d-transpo-
sition of the great arteries. Functional consequences of the mitral anomaly were mitral insufficiency, subaortic stenosis, or both. Mitral insufficiency was related principally to the width of the cleft. Subaortic stenosis, when present, was due to the position of insertion of accessory chordae in the ventricular septum in a position under the commissure, between the left and right aortic cusps or under the right aortic cusp.
Cleft anterior leaflet of the mitral valve, when not associated with septal defect of p e r s i s t e n t c o m m o n atrioventricular canal (so-called endocardial cushion defect) is rare. T w e n t y such cases observed in autopsy-derived specimens are described. A review of this material seems a p p r o p r i a t e in t h a t the condition is not well known, and only a few reports have dealt with its clinical and pathologic featuresi-2i; the clinical recognition of this a n o m a l y is now potentially possible with characteristics of 2-dimensional echocardiograpby.2i, 22
syndrome was present in 4 cases. The ages ranged from stillborn to 74 years. The mean age at death was about 4 years. Situs solitus was present in each subject. The specimens were derived from numerous sources over a period exceeding 22 years. The clinical data supplied to us varied. To some extent this was related to the time when any given specimen was received. Therefore, interpretation of functional consequences of the anomaly, whether mitral insufficiency, subaortic stenosis, or both were present or absent, was judged primarily from the details observed in the pathologic specimens. Our evaluation of the anatomy of the mitral valve included measurements of the dimensions of the mitral valve and of the cleft as shown in Figure 1. Certain terms were derived from these measurements: (1) width of cleft, (2) depth of cleft, (3) width of base of anterior leaflet, and (4) depth of anterior leaflet. Certain ratios were derived from these absolute measurements. The presence and the insertion of ectopic chordae were recorded. The position of ventricular insertion of such chordae was related to the specific bverlying aortic cusps, as shown in Figure 2.
Methods Twenty specimens of heart with a cleft in the center of the anterior mitral leaflet were available for restudy. There was an equal distribution among males and females. Down's From the Departments of Pediatric Cardiology and Pathology, University of Minnesota, Minneapolis, and the Department of Pathology, United
Hospitals, St. Paul, Minnesota. This study was supported in part by Public Health Service Research Grant 5 R01 HL05694 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland. Manuscript received July 2, 1982; revised manuscript received October 21, 1982, accepted October 28, 1982. Address for reprints: Jesse E. Edwards, MD, Department of Pathology, United Hospitals, 333 North Smith Avenue, St. Paul, Minnesota 55102.
Results T h e 20 cases could be classified into 2 groups as defined later (Table I). G r o u p I consisted of 9 cases in which the cleft of the anterior mitral leaflet was asso919
920
CLEFTANTERIOR LEAFLET OF THE MITRAL VALVE
A L
I
I
I ~'~
',
FI
2
-C
C_
FIGURE 1. Schematic drawing of the anterior mitral leaflet showing the measurements taken. A = width of the base of anterior leaflet; B and B 1 = distance from the commissural chorda to the respective edge of the cleft; C = commissural chordae; D = width of the cleft (this width was calculated according to the formula D = A - [B + B1]); E = depth of the anterior leaflet; F = depth of the cleft.
ciated either with no anomalies or anomalies of minor significance. In Group I, additional anomalies were present in 4 cases. These were fossa ovalis type (secundum) atrial septal defect in 2 cases, and small left ventricular-right atrial communication and floppy tricuspid valve in 1 case each. In each of the 11 cases in Group II, a cleft in the anterior mitral leaflet was associated with other cardiac anomalies, each of significant nature. These cases were further subdivided according to whether transposition was absent or present. Thus, in our cases transposition was absent (Group IIA). Some form of transposition was present in 7 cases (6 with dtransposition, Group IIB) and 1 with classical corrected transposition (1-transposition, Gro(lp IIC). In the latter case, the cleft was in the right-sided mitral valve.
5
4
I I I t
5
6
FIGURE 2. Schematic drawing showing the different positions (1 to 6) of ventricular insertion of ectopic chordae in relation to the aortic cusps, R = right, P = posterior, and L = left aortic cusps, respectively, The circles in R and L represent corresponding coronary arterial ostia,
Anatomic
TABLE I
I I
I I I I
Features
of the Mitral Valve
I n the normal case, the w i d t h of the base of the anterior leaflet is less than that of the posterior leaflet by
a ratio of about 1:2.23 In 13 of our 20 cases this ratio was different, the width of the anterior leaflet at its base being equal to or greater •than the corresponding part of the posterior leaflet. This discrepancy from the usual was about equally distributed among cases of Groups I and II. The leaflets of the mitral valve and the papillary muscles were normally oriented in 8 cases and rotated clockwise in 12 cases. This rotation appeared to have resulted from the abnormally posterior position of the anterolateral papillary muscle. This phenomenon was seen in 12 cases (4 of Group I, 3 of Group IIA, and 5 of Group IIB). The cleft of the anterior mitral leaflet was usually shaped like an inverted V, with the apex pointing toward the valve ring. In 2 cases the cleft had a rectangular shape. The cleft extended for from 30 to 90% of the distance between the free margin and the base of the anterior mitral leaflet. The anterior leaflet was divided into halves except at its base, where the halves of the cleft leaflet were continuous. In 8 specimens, the cleft was located exactly in the center of the anterior mitral leaflet (Fig. 3). In the remaining cases, the cleft was
Classification and Associated Lesions in 20 Cases of Isolated Mitral Valve Cleft Group
I
The isolated cleft of the mitral valve is the predominant lesion
II
The associated defects are predominant
Associated Defects
Cases (n)
None Atrial septal defect secundum Left ventricular-right atrial communication Floppy tricuspid valve Total IIA Ventricular septal defect Ventricular septal defect and coarctation Aortic atresia Tricuspid atresia Total liB D-transposition of great arteries D-transposition of great arteries and tricuspid atresia Total IIC L-transposition of great arteries Total
5 2 1 1 9 1 1 1 1 4 4 2 6 1 11
March 15, 1983 THE AMERICAN JOURNAL OF CARDIOLOGY Volume 51
921
FIGURE 3. Cleft mitral valve from a stillborn infant in whom an atrial septal defect at the fossa ovalis was also present, a, opened mitral valve and related chambers. The cleft is in the center of the anterior mitral leaflet. The edges of the cleft are thin and smooth, b, left ventricle, aortic valve, and ventricular aspect of anterior mitral leaflet. A raphe-like fibrous ridge extends (arrow) from the anterior mitral leaflet to the ventricular septum. In both views A = anterior portion of the anterior mitral leaflet; AL = anterolateral papillary muscle; Ao = aorta; LV = left ventricle; P = posterior portion of the anterior mitral leaflet; PM -- posteromedial papillary muscle.
eccentric. In 5 cases (4 of Group I) the anterior portion of the cleft leaflet was wider than the posterior. The posterior portion of the anterior leaflet was wider than the anterior in 7 cases, 4 being among the cases with d-transposition of the great arteries (Fig. 4).
FIGURE 4. From a 2-year-old child with d-transposition of the great arteries. The atrial aspect of the cieft anterior mitral leaflet is shown. The POsterior portion of the leaflet is wider than the anterior. The edges of the cleft are thin. Abbreviations as in Figure 3.
The edges of the cleft were thin and smooth in 8 specimens (Fig. 3 and 4). In the other 12 cases, the edges of the defect were thickened by nodular fibrous tissue, while elsewhere the leaflet remained thin (Fig. 5 to 7). The thickness of the edges was 2 to 4 mm in these cases. A clear positive relation existed between the ages of the subjects and the thickness of the edges of the cleft. Normal chordae tendineae extended from the anterior portion Of the anterior leaflet to the anterolateral papillary muscle and from the posterior portion of the anterior leaflet to the posteromedial papillary muscle. Accessory chordae tendineae or a raphe-like fibrous structure constantly extended from the anterior mitral leaflet to the septal or anterior walls of the left ventricle. The valvular origin of the accessory chordal tissue was into that part of the anterior leaflet that lay between the apex of the cleft and the basal attachment of the leaflet (Fig. 3 right, 5 bottom, 6 right, and 7). In only 2 cases were accessory chordae attached to the edges of the cleft (Fig. 7). The insertion of these structures was to the ventricular septum in 16 cases (Fig. 3 right, 5 bottom, 6 right, and 7) and to the anterior wall of the left ventricle in 4 cases, each with d-transposition. When insertion occurred to the ventricular septum it was to the membranous septum or the crest or body of the muscular septum. The sites of ventricular insertion with respect to the position of the above-lying aortic sinuses were as follows (Fig. 8): (1) insertion of accessory tissue under the commissure between the left and right aortic cusps (position 1), 3 cases; (2) under the right aortic cusp (position 2), 6 cases; (3) under the commissure between the right and posterior aortic cusps (position 3), 5 cases; (4) under the noncoronary aortic cusp (position 4), 1 case; (5) under the left aortic cusp (position 6), 4 cases.
922
CLEFT ANTERIOR LEAFLET OF THE MITRAL VALVE
As will be shown later, the insertion site of the chordal or raphe-like accessory tissue was a determining factor as to whether or not left ventricular outflow tract obstruction was considered present. Associated Anomalies
In some of the cases, anomalies in addition to a cleft mitral valve were present. These are divided into 2 groups: anomalies that are either part of or frequently associated with the endocardial cushion defect, and those that appear unrelated to the endocardial cushion defect. Anomalies related to the endocardial cushion defect: Mitral valve: A double mitral orifice was found in 2 cases. Left ventricle: The ratio between the length of the outflow tract and the inflow tract of the left ventricle
was as in normal hearts in 8 cases. In 12 cases, this ratio was similar to what is found in typical atrioventricular canal defects in which the inflow dimension of the left ventricle is distinctly shorter than the outflow dimem sion. 24 Ventricular septum: The summit of the ventricular septum was deficient in 4 hearts, each in Group I. The muscular septum in these cases resembled the "scooped out" aspect seen in classic endocardial cushion defect (Fig. 7). This deficiency was closed by a membrane which we considered to be tricuspid tissue closing a ventricular septal defect. Tricuspid valve: A cleft in the septal leaflet of the tricuspid valve was present in 4 hearts. Anomalies not related to the endocardial cushion defect: Anomalies that are not considered part of the endocardial cushion defect were found in 12 of the 13
FIGURE 5. Cleft mitral valve from a 74-year-old in whom a mild prolapse of the tricuspid valve was also present, a, opened mitral valve viewed from the atrial aspect. The edges of the cleft are thickened by fibrous tissue, b, mitral valve viewed from its free edge. Accessory chordae tendineae extend from the apex of the cleft to the ventricular septum (arrow). Abbreviations as in Figure 3.
March 15, 1983
THE AMERICAN JOURNAL OF CARDIOLOGY Volume 51
923
specimens without transposition and are listed in Table I. Of the 2 hearts with large ventricular septal defects, in each the defect was not of the so-called atrioventricular canal type. In the first of the 2, the defect was located in the area of the membranous septum. In the second case, the defect was located in the muscular septum. In the latter case, coarctation of the aorta, bicuspid aortic valve, and patent ductus arteriosus were
FIGURE 6. Cleft mitral valve in a 3-year-old boy with severe mitral insufficiency, a, atrial aspect of opened mitral valve. A shallow cleft (arrow) with thickened margins is present in the center of the anterior leaflet, b, ventricular aspect of anterior mitral leaflet from interior of left ventricle. An accessory chorda tendinea (arrow) and, above that, a raphe-like ridge extend from the mitral valve to the membranous septum in a position below the commissure between the right and POsterior aortic cusps (position 3). In this case severe mitral insuffiCiency was present. This was apparently due to the restriction of the motion of the anterior mitral leaflet caused by the abnormal accessory chordae rather than to the extent of the cleft. LA = left atrium; other abbreviations as in Figure 3.
FIGURE 7. Cleft mitral valve in a 41-year-old man with Down's syndrome, a, opened mitral valve from its atrial aspect is shown, a, the ventricular aspect of the mitral valve is shown. Solid arrow in a points to the apex of the cleft. Accessory chordae extend from the anterior margin (broken arrow) and from the posterior margin (open arrow) of the cleft to the margins of the deficient ventricular septum. The "scooped out" appearance of the muscular septum is similar to that seen in classic endocardial cushion defect. The summit of the ventricular septum is closed by a membrane which was judged to be tissue of the tricuspid valve. LA = left atrium; other abbreviations as in Figure 3.
924
CLEFTANTERIOR LEAFLET OF THE MITRAL VALVE
L
o
~
11
o
12 13
15
Subaortic stenosis
}6
(Degree)
I
i
I
i
I--I=o
I
I I
I I
I~J=+
I c~
14
I
gZ~d
Hh i I
R _
to have been present. Three of the patients died from congestive cardiac failure. This functional disturbance was more difficult to evaluate in those cases having significant anomalies in addition to the mitral cleft. Nevertheless, among the 11 cases with additional anomalies, mitral insufficiency had either been demonstrated clinically or interpreted from the specimen as having been present in 6 cases (3 moderate and 3 mild). Among the remaining 5 cases with additional anomalies, mitral insufficiency was considered not to have been present in each, including the I case of cotrected transposition and right-sided mitral valve. In the latter case, ventriculography had demonstrated competence of the valve. Correlations were attempted between the presence or absence of mitral insufficiency and, when present, its degree on one hand, and certain features of the mitral valve on the other (Fig. 9). These were: (1) dimension of the cleft, (2) the width of the base of the anterior leaflet compared with the width of the base of the posterior leaflet, (3) the position of the cleft, and (4) the presence of ectopic chordae. Ratios were determined of the width of the cleft compared with the width of the base of the anterior leaflet. These ranged from 0.1 to 0.5. The wider the cleft, the more likely was the presence of mitral insufficiency. With this ratio, a statistically significant difference (p <0.025) was found between subjects with absent or mild mitral insufficiency on one hand, and subjects with moderate or severe mitral insufficiency on the other (Fig. 10). Ratios were determined for the depth of the cleft compared with the depth of the anterior mitral leaflet. There was no relation between these values and mitral insufficiency. Ratios were obtained of the width of the entire mitral anulus to the width of the base of the anterior mitral leaflet. These ranged from 1.6 to 2.4. No relation between these ratios and mitral insufficiency was noted. The position of the cleft was not always central in the anterior leaflet as judged by the fact that the anterior and posterior halves of the leaflet were not always equal. Mitral regurgitation was always found when the anterior portion of the cleft leaflet was larger than the posterior.
~=+t-
N--+++
-]
FIGURE 8. Various positions of ectopic chordal insertion as defined in Figure 2, according to the degree of subaortic stenosis. 0 = no subaortic stenosis; 4- = mild, 4-4- = moderate, and 4-4-4- = severe subaortic stenosis, respectively. The case with I-transposition of the
great arteries is not included.
also present. In the 1 case with aortic atresia, septal attachment of accessory chordae of the cleft mitral valve caused subaortic obstruction, in addition. Functional Consequences
As stated, the principal basis for interpreting functional effects of the anomaly of the mitral valve was the appearance of the specimen. The 2 major consequences of the cleft in the anterior mitral valve appeared to be mitral insufficiency and subaortic stenosis. The principal factors favoring an opinion that mitral insufficiency had been present were left atrial enlargement, right ventricular hypertrophy, and, to some extent, left ventricular enlargement. Subaortic stenosis was judged to have been present when associated anomalous attachment of the anterior leaflet of the mitral valve to either the ventricular septurn or anterior wall of the right ventricle had restricted significant movement of the anterior mitral leaflet from the septal wall of the left ventricle. Mitral insufficiency: In each of the 9 cases in which the mitral cleft was the only significant anomaly (Group I), some degree of mitral insufficiency was considered
•kk. ~ o
R
114~
11 I I I
d z
i
I
12
j~
)~
/I\ p i - , ~
/!\ .I-I ~ ~
13
i4
,I
15
o
J Mitral /Insuffic ency (Degree)
]CO
,
I-1--0
I
I I
I
zl
I
m[
[]
=4-+
Ill]m--,,, ]I
m
I,Group I II, Group ]]
FIGURE 9. Various positions of ectopic chordal insertion as defined in Figure 2, according to the degree of mitral insufficiency. 0 = no mitral insufficiency; 4- = mild, 4-4= moderate, and + 4 - + = severe mitral insufficiency, respectively. The case with I-transposition of the great arteries and a case in which evaluation of mitral insufficiency was not possible are not included.
March 15, 1983
Symmetrically cleft leaflets or leaflets With a larger posterior component varied as to the presence of mitral sufficiency. There was no obvious correlation between the site of insertion of accessory chordae on one hand, and mitral insufficiency on the other. This lack of correlation may result from the fact that the presence of the cleft is the primary determinant of mitral insufficiency. Nevertheless, some influence of chordal insertion may have played a role in favoring mitral insufficiency. For example, in Case 3 as shown in Figure 6, a small cleft with anterior insertion of ectopic chordae beneath the commissure between the right and posterior aortic cusps was associated with severe mitral insufficiency. Left ventricular outflow stenosis: From pathologic examination, narrowing of the left ventricular outflow tract was considered to have been present in 10 cases. This abnormality, among the most severe forms of subaortic stenosis, had been diagnosed clinically in some. Based on our interpretation of the presence or absence of subaortic stenosis, in both Groups I and IIA, left ventricular outflow tract stenosis was determined to be clearly related to the site of septal insertion of accessory chordae, namely into the ventricular septum beneath the right aortic cusp (Fig. 8). In 3 cases, relatively long accessory chordae appeared to have caused a degree of subaortic stenosis which was less than that expected from the position of their septal insertion. In cases with d-transposition of the great arteries (IIB), left ventricular outflow stenosis was rare. In the case with 1-transposition of the great arteries (IIC), the narrowing of the outflow tract of the right-sided morphologic left ventricle was caused by accessory tissue of the mitral valve and not by the insertion of accessory chordae. Discussion The anomaly described in this communication consists of a cleft of the anterior mitral leaflet. The cleft may involve a variable length on the anterior mitral leaflet and is usually shaped like an inverted V. As a result of the cleft, the anterior mitral leaflet is divided in anterior and posterior components. Accessory tissue taking the form of chordae, a raphe structure, or both extends from the ventricular aspect of the intactoportion of the cleft leaflet to the ventricular septum or the anterior wall of the left ventricle. The latter process may cause left ventricular outflow tract stenosis. The question might be raised as to whether the cleft is acquired or congenital. Acquired disease giving rise to a defect would, of necessity, be a destructive inflammatory process such as bacterial endocarditis. Militating against this possible cause is the fact that no torn chordae were seen in any of the hearts examined. An important factor favoring a congenital origin is the presence of accessory tissue that attaches to the cleft, either at its apex or along the tissue edging the cleft. The cleft is of the same type as seen in classic examples of persistent common atrioventricular canal or endocardial cushion defect. 1,4 Thus, the condition of cleft anterior mitral leaflet may be considered a forme fruste of the endocardial cushion defect in which the septal defects that characterize the full picture of the
THE AMERICAN JOURNAL OF CARDIOLOGY Volume 51
925
0.~ "6 "$ 0.4
0.3
"-
0.2
:.
t
p< 0.025
"5 o ._o
s~
rr
0.1
:Absent o r m i l d mitral insufficiency
Moderate or severe mitral insufficiency
FIGURE 10. Correlation between the ratio of width of the cleft to width of the base of the anterior mitral leaflet and the degree of mitral insufficiency. In subjects with absent or mild mitral insufficiency, the ratio was 0.19 4- 0.8 (standard deviation) and in subjects with moderate or severe mitral insufficiency, the ratio was 0.31 4- 0.12 (p <0.025). Two of the cases in the study are not represented,
malformation are absent. Additional features related to the endocardial cushion defect may be found in hearts with a cleft in the anterior mitral leaflet. These include abnormally increased ratio of length of left ventricular outflow to inflow tract, "scooped out" deficiency of the ventricular septal summit, cleft of the septal tricuspid leaflet, and double mitral orifice. The association with Down's syndrome in 4 of our 20 cases, a condition frequently associated with the endocardial cushion defect, further stresses the embryologic relation of the isolated cleft mitral valve with endocardial cushion defect. As far as we are aware, isolated cleft of the mitral valve was first described by one of us (JEE) in 1954.1 A few reports of examples of this condition have since been reported. We were able to find only 36 cases, 1-21 9 of which correspond to 9 of our 20 cases. 1,4,10,16-19 Eleven of our cases have not previously been reported. Associated cardiac anomalies were found in 27 of the 36 reported cases to which reference has been made. 4-16,1s-21 The most frequent of such anomalies was a fossa ovalis (secundum)-type atrial septal defect (15 cases). 4-9,~1-14,2° The unusual association of a secundum-type atrial septal defect with a cleft mitral valve was the source of diagnostic errors, since this defect of the mitral valve is classically associated with an ostium primum atrial septal defect. Other associated anomalies reported were transposition of great arteries, 16-1s tri~ cuspid atresia, is pouches of the tricuspid valve, 19 left ventricular-right atrial communication, 19 coarctation of aorta, 7 ventricular septal defect, 7-14 partial anomalous pulmonary venous connection,~5 and double-outlet right ventricle. 21 The tendency of a cleft of the anterior mitrat leaflet to be associated with other cardiac malformations is emphasized by the present series. The scarcity of the reported cases appears to be due to the rarity of the syndrome, as well as to difficulty of the clinical differentiation from other causes of mitral
926
CLEFT ANTERIOR LEAFLET OF THE MITRAL VALVE
insufficiency and subaortic stenosis. Most of the reported cases were correctly recognized at Operation or at autopsy. The diagnostic value of the electrovectorcardiogram was suggested in the past. 5,632,13 A left-axis deviation with counterclockwise rotation of the initial vector on the frontal plane, such as that seen in atrioventricular canal defect, 25,26 was considered a useful sign of mitral valve cleft; but, judging from limited electrocardiographic data in our material, this sign is infrequent in our series. Angiographic diagnosis of the mitral valve cleft is usually possible in atrioventricular canal defect. However, as far as the isolated mitral valve cleft is concerned, the angiographic demonstration of the cleft was unsuccessful according to the experience of others and in the cases in our material, v,11-1~,15,16 The usefulness of angiography lies in its ability to quantify the mitral insufficiency rather than in its ability to identify its cause. It has been recently shown that the mitral valve cleft can be precisely imaged by 2-dimensional echocardiography. 22 The finding of a cleft mitral valve is a cardinal echocardiographic sign of atrioventricular canal defect. The echocardiographic diagnosis of cleft of the anterior mitral leaflet in 2 cases associated with double-outlet right ventricle has been reported. 21 We have personal experience with 2 living patients having severe mitral insufficiency and no septal defects as shown by cardiac catheterization whose echocardiograms showed a typical mitral valve cleft and intact atrial and ventricular septa. Various degrees of left ventricular outflow tract stenosis were interpreted as having been present in about half of our cases. The condition appears to result from restraint of the anterior mitral leaflet by accessory chordae that attach to the ventricular septum. This phenomenon was described by Sellers et a117 in 1964. Our cases emphasize the point that cleft mitral valve may simultaneously cause subaortic stenosis and mitral insufficiency. In this way the anomaly described herein must be distinguished from hypertrophic muscular subaortic stenosis. While the condition represents a "minor" lesion from the embryologic point of view compared with the usual picture of the endocardial cushion defect, in many cases it represents a severe clinical disease which requires surgery early in childhood. The problem of mitral valve surgery in children is obviously avoiding replacement of the valve. Plastic repair of the affected leaflet has been reported in 18 cases of isolated mitral valve cleft. 2,5-8,11-15,2° In the majority of these cases, the results of operation were evidently successful. This experience on a limited number of cases matches the larger experience of repair of cleft valves of atrioventricular canal defects. 27 The rationale for reparative surgery seems well based. Our data show that potentially correctable factors causing mitral insufficiency may be
identified. These factors are the width of the cleft and perhaps the septal insertion of ectopic chordae. In the past, the role of these elements was recognized in the cleft mitral valve of persistent common atrioventricular canal. 28 Suture of the cleft and resection of the accessory chordae are probably both necessary for a complete correction of the altered function of the mitral valve.
References 1. Edwards JE, Dry TJ, Parker RL, Burchell HS, Wood EH, Bulbulian AH. An Atlas of Congenital Anomalies of the Heart and Great Vessels. Springfield, IL: Charles C Thomas, 1954:41-42. 2. Talner NS, Stern AM, Sloan HE Jr. Congenital mitral insufficiency. Circu. lation 1961;23:339-349. 3. Berghuis J, Klrklin JW, Edwards JE, Titus JL. The surgical anatomy of isolated congenital mitral insufficiency. J Thorac Cardiovasc Surg 1974; 47:791-798. 4. Edwards JE, Carey LS, Neufeld HN, Lester RG. Congenital Heart Disease. Correlation of Pathologic Anatomy and Angiocardiography. Philadelphia: WB Saunders, 1965: 784. 5. Hara M, Char F. Partial cleft of septal mitral leaflet associated with atrial septal defect of the secundum type. Am J Cardiol 1966; 17:282-285. 6. Pifarre R, Dieter RA, Hoffman FG, Neville WE. Atrial secundum septal defect and cleft mitral valve. Ann Thorac Surg 1968;6:373-376. 7. Messmer BJ, Hallman GL, Cooley DA. Congenital mitral insufficiency. Results in unusual lesions. Ann Thorac Surg 1970;10:450-~461. 8. Salomon J, Aygen M, Levy MJ. Secundum type atrial septal defect with cleft mitral valve. Chest 1970;58:540-542. 9. Cohn LH, Hancock EW, Griepp RB, Shumway NE. Congenital cleft mitral valve associated with ostium secundum atrial septal defect (abstr). Circulation 1971;43,44:Suppt Ih11-152. 10. Davachi F, Moiler JH, Edwards JE. Diseases of the mitral valve in infancy. An anatomic analysis of 55 cases. Circulation 1971 ;43:565-579. 11. Goodman DJ, Hancock EW. Secundum atrial septal defect associated with a cleft mitral valve. Br Heart J 1973;35:1315-1320. 12. Murray GF, Wilcox BR. Secundum atrial septal defect and mitral valve incompetence. Ann Thorac Surg 1975;20:136-143. 13. Snow NJ, Ankeney JL. Congenitally cleft atrioventricular valves associated with secandum atrial septal defect. J Thorac Cardiovasc Sur9 1976;72: 925-928. 14. 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 malformations of the mitral valve in children. Pathology and surgical treatment. J Thorae Cardiovasc Surg 1976;72:854-866. 15. Pritchard DA, Tajik AJ, Rutherford HD, Harrison CE Jr, Pluth JR, Danielson GK. Partial anomalous pulmonary venous connection (intact atrial septum) associated with mitral regurgitation. Am Heart J 1977;94:209-216. 16. Levy MJ, Lillehei CW, Elliott LP, Carey LS, Adams P Jr, Edwards JE. Accessory valvular tissue causing subpulmonary stencsis in corrected transposition of great vessels. Circulation 1963;27:494-502. 17. Sellers RD, Lillehei CW, Edwards JE. Subaortic stenosis caused by anomalies of the atrioventricular valves. J Thorac Cardiovasc Surg 1964;48:289-302. 18. Layman TE, Edwards JE. Anomalies of the cardiac valves associated with complete transposition of the great vessels. Am J Cardiol 1967; 19:247255. 19. Chesler E, Korns ME, Edwards JE. Anomalies of the tricuspid valve, including pouches, resembling aneurysms of the membranous ventricular septum. Am J Cardiol 1968;21:661-668. 20. Billig DM, Hallman GL, Bloodwell RD, Cooley DA. Surgical treatment of atrial septal defects in patients with angina pectoris. Ann Thorac Surg 1968;5:566-568. 21. Hagler DJ, Tajik AJ, Seward JB, Mair DD, Rifler DG. Double-outlet right ventricle: wide-angle two-dimensional echoeardiographic observatiOnS. Circulation 1981;63:419-428. 22. Hagler DJ, Tajik AJ, Seward JB, Mair DD, Ritter DG. Real-time wide-angle sector echocardiography: atrioventricular canal defects. Circulation 1979;59:140-150. 23. Du Plessis LA, Marchand P. The anatomy of the mitral valve and its asSOciated structures. Thorax 1964;19:221-227. 24. Goor D, Lillehei CW, Edwards JE. Further observations on the pathology of the atrioventricular canal malformation. Arch Surg 1968"97"954-962' 25. Lev M. Conduction system in congenital heart disease. Am J Cardiol 1968;21:619-627. 26. Feldt RH, DuShane JW, Tilus JL. The atrioventricular conduction syste~ in persistent common atrioventricular canal defect. Correlations wun electrocardiogram. Circulation 1970;42:437-444. 27. McGoon DC, Puga FJ. Atrioventricular canal. Cardiovasc Clin 1981;11: 311-322. 28. Edwards JE. The problem of mitral insufficiency caused by accessory chordae tendineae in persistent common atrioventricular canal. Proc Mayo Clin 1960;35:299-305.
The American
, J o u r n a l of C A R D I O L O G Y
®
VOLUME 51 NUMBER 6
CONGENITAL HEART DISEASE
Cleft Anterior Leaflet of the Mitral Valve With Intact Septa A Study of 20 Cases ELIO DI SEGNI, MD and JESSE E. EDWARDS, MD
Twenty pathologic specimens of heart, each with a cleft in the anterior leaflet of the mitral valve not associated with septal defects of persistent common atrioventricular canal (isolated cleft of the mitral valve), were studied. In 9 cases, there were either no associated anomalies or ones not of functional significance. In each of the other 11 cases there were other significant associated cardiac anomalies, including ventricular septal defect and d-transpo-
sition of the great arteries. Functional consequences of the mitral anomaly were mitral insufficiency, subaortic stenosis, or both. Mitral insufficiency was related principally to the width of the cleft. Subaortic stenosis, when present, was due to the position of insertion of accessory chordae in the ventricular septum in a position under the commissure, between the left and right aortic cusps or under the right aortic cusp.
Cleft anterior leaflet of the mitral valve, when not associated with septal defect of p e r s i s t e n t c o m m o n atrioventricular canal (so-called endocardial cushion defect) is rare. T w e n t y such cases observed in autopsy-derived specimens are described. A review of this material seems a p p r o p r i a t e in t h a t the condition is not well known, and only a few reports have dealt with its clinical and pathologic featuresi-2i; the clinical recognition of this a n o m a l y is now potentially possible with characteristics of 2-dimensional echocardiograpby.2i, 22
syndrome was present in 4 cases. The ages ranged from stillborn to 74 years. The mean age at death was about 4 years. Situs solitus was present in each subject. The specimens were derived from numerous sources over a period exceeding 22 years. The clinical data supplied to us varied. To some extent this was related to the time when any given specimen was received. Therefore, interpretation of functional consequences of the anomaly, whether mitral insufficiency, subaortic stenosis, or both were present or absent, was judged primarily from the details observed in the pathologic specimens. Our evaluation of the anatomy of the mitral valve included measurements of the dimensions of the mitral valve and of the cleft as shown in Figure 1. Certain terms were derived from these measurements: (1) width of cleft, (2) depth of cleft, (3) width of base of anterior leaflet, and (4) depth of anterior leaflet. Certain ratios were derived from these absolute measurements. The presence and the insertion of ectopic chordae were recorded. The position of ventricular insertion of such chordae was related to the specific bverlying aortic cusps, as shown in Figure 2.
Methods Twenty specimens of heart with a cleft in the center of the anterior mitral leaflet were available for restudy. There was an equal distribution among males and females. Down's From the Departments of Pediatric Cardiology and Pathology, University of Minnesota, Minneapolis, and the Department of Pathology, United
Hospitals, St. Paul, Minnesota. This study was supported in part by Public Health Service Research Grant 5 R01 HL05694 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland. Manuscript received July 2, 1982; revised manuscript received October 21, 1982, accepted October 28, 1982. Address for reprints: Jesse E. Edwards, MD, Department of Pathology, United Hospitals, 333 North Smith Avenue, St. Paul, Minnesota 55102.
Results T h e 20 cases could be classified into 2 groups as defined later (Table I). G r o u p I consisted of 9 cases in which the cleft of the anterior mitral leaflet was asso919
920
CLEFTANTERIOR LEAFLET OF THE MITRAL VALVE
A L
I
I
I ~'~
',
FI
2
-C
C_
FIGURE 1. Schematic drawing of the anterior mitral leaflet showing the measurements taken. A = width of the base of anterior leaflet; B and B 1 = distance from the commissural chorda to the respective edge of the cleft; C = commissural chordae; D = width of the cleft (this width was calculated according to the formula D = A - [B + B1]); E = depth of the anterior leaflet; F = depth of the cleft.
ciated either with no anomalies or anomalies of minor significance. In Group I, additional anomalies were present in 4 cases. These were fossa ovalis type (secundum) atrial septal defect in 2 cases, and small left ventricular-right atrial communication and floppy tricuspid valve in 1 case each. In each of the 11 cases in Group II, a cleft in the anterior mitral leaflet was associated with other cardiac anomalies, each of significant nature. These cases were further subdivided according to whether transposition was absent or present. Thus, in our cases transposition was absent (Group IIA). Some form of transposition was present in 7 cases (6 with dtransposition, Group IIB) and 1 with classical corrected transposition (1-transposition, Gro(lp IIC). In the latter case, the cleft was in the right-sided mitral valve.
5
4
I I I t
5
6
FIGURE 2. Schematic drawing showing the different positions (1 to 6) of ventricular insertion of ectopic chordae in relation to the aortic cusps, R = right, P = posterior, and L = left aortic cusps, respectively, The circles in R and L represent corresponding coronary arterial ostia,
Anatomic
TABLE I
I I
I I I I
Features
of the Mitral Valve
I n the normal case, the w i d t h of the base of the anterior leaflet is less than that of the posterior leaflet by
a ratio of about 1:2.23 In 13 of our 20 cases this ratio was different, the width of the anterior leaflet at its base being equal to or greater •than the corresponding part of the posterior leaflet. This discrepancy from the usual was about equally distributed among cases of Groups I and II. The leaflets of the mitral valve and the papillary muscles were normally oriented in 8 cases and rotated clockwise in 12 cases. This rotation appeared to have resulted from the abnormally posterior position of the anterolateral papillary muscle. This phenomenon was seen in 12 cases (4 of Group I, 3 of Group IIA, and 5 of Group IIB). The cleft of the anterior mitral leaflet was usually shaped like an inverted V, with the apex pointing toward the valve ring. In 2 cases the cleft had a rectangular shape. The cleft extended for from 30 to 90% of the distance between the free margin and the base of the anterior mitral leaflet. The anterior leaflet was divided into halves except at its base, where the halves of the cleft leaflet were continuous. In 8 specimens, the cleft was located exactly in the center of the anterior mitral leaflet (Fig. 3). In the remaining cases, the cleft was
Classification and Associated Lesions in 20 Cases of Isolated Mitral Valve Cleft Group
I
The isolated cleft of the mitral valve is the predominant lesion
II
The associated defects are predominant
Associated Defects
Cases (n)
None Atrial septal defect secundum Left ventricular-right atrial communication Floppy tricuspid valve Total IIA Ventricular septal defect Ventricular septal defect and coarctation Aortic atresia Tricuspid atresia Total liB D-transposition of great arteries D-transposition of great arteries and tricuspid atresia Total IIC L-transposition of great arteries Total
5 2 1 1 9 1 1 1 1 4 4 2 6 1 11
March 15, 1983 THE AMERICAN JOURNAL OF CARDIOLOGY Volume 51
921
FIGURE 3. Cleft mitral valve from a stillborn infant in whom an atrial septal defect at the fossa ovalis was also present, a, opened mitral valve and related chambers. The cleft is in the center of the anterior mitral leaflet. The edges of the cleft are thin and smooth, b, left ventricle, aortic valve, and ventricular aspect of anterior mitral leaflet. A raphe-like fibrous ridge extends (arrow) from the anterior mitral leaflet to the ventricular septum. In both views A = anterior portion of the anterior mitral leaflet; AL = anterolateral papillary muscle; Ao = aorta; LV = left ventricle; P = posterior portion of the anterior mitral leaflet; PM -- posteromedial papillary muscle.
eccentric. In 5 cases (4 of Group I) the anterior portion of the cleft leaflet was wider than the posterior. The posterior portion of the anterior leaflet was wider than the anterior in 7 cases, 4 being among the cases with d-transposition of the great arteries (Fig. 4).
FIGURE 4. From a 2-year-old child with d-transposition of the great arteries. The atrial aspect of the cieft anterior mitral leaflet is shown. The POsterior portion of the leaflet is wider than the anterior. The edges of the cleft are thin. Abbreviations as in Figure 3.
The edges of the cleft were thin and smooth in 8 specimens (Fig. 3 and 4). In the other 12 cases, the edges of the defect were thickened by nodular fibrous tissue, while elsewhere the leaflet remained thin (Fig. 5 to 7). The thickness of the edges was 2 to 4 mm in these cases. A clear positive relation existed between the ages of the subjects and the thickness of the edges of the cleft. Normal chordae tendineae extended from the anterior portion Of the anterior leaflet to the anterolateral papillary muscle and from the posterior portion of the anterior leaflet to the posteromedial papillary muscle. Accessory chordae tendineae or a raphe-like fibrous structure constantly extended from the anterior mitral leaflet to the septal or anterior walls of the left ventricle. The valvular origin of the accessory chordal tissue was into that part of the anterior leaflet that lay between the apex of the cleft and the basal attachment of the leaflet (Fig. 3 right, 5 bottom, 6 right, and 7). In only 2 cases were accessory chordae attached to the edges of the cleft (Fig. 7). The insertion of these structures was to the ventricular septum in 16 cases (Fig. 3 right, 5 bottom, 6 right, and 7) and to the anterior wall of the left ventricle in 4 cases, each with d-transposition. When insertion occurred to the ventricular septum it was to the membranous septum or the crest or body of the muscular septum. The sites of ventricular insertion with respect to the position of the above-lying aortic sinuses were as follows (Fig. 8): (1) insertion of accessory tissue under the commissure between the left and right aortic cusps (position 1), 3 cases; (2) under the right aortic cusp (position 2), 6 cases; (3) under the commissure between the right and posterior aortic cusps (position 3), 5 cases; (4) under the noncoronary aortic cusp (position 4), 1 case; (5) under the left aortic cusp (position 6), 4 cases.
922
CLEFT ANTERIOR LEAFLET OF THE MITRAL VALVE
As will be shown later, the insertion site of the chordal or raphe-like accessory tissue was a determining factor as to whether or not left ventricular outflow tract obstruction was considered present. Associated Anomalies
In some of the cases, anomalies in addition to a cleft mitral valve were present. These are divided into 2 groups: anomalies that are either part of or frequently associated with the endocardial cushion defect, and those that appear unrelated to the endocardial cushion defect. Anomalies related to the endocardial cushion defect: Mitral valve: A double mitral orifice was found in 2 cases. Left ventricle: The ratio between the length of the outflow tract and the inflow tract of the left ventricle
was as in normal hearts in 8 cases. In 12 cases, this ratio was similar to what is found in typical atrioventricular canal defects in which the inflow dimension of the left ventricle is distinctly shorter than the outflow dimem sion. 24 Ventricular septum: The summit of the ventricular septum was deficient in 4 hearts, each in Group I. The muscular septum in these cases resembled the "scooped out" aspect seen in classic endocardial cushion defect (Fig. 7). This deficiency was closed by a membrane which we considered to be tricuspid tissue closing a ventricular septal defect. Tricuspid valve: A cleft in the septal leaflet of the tricuspid valve was present in 4 hearts. Anomalies not related to the endocardial cushion defect: Anomalies that are not considered part of the endocardial cushion defect were found in 12 of the 13
FIGURE 5. Cleft mitral valve from a 74-year-old in whom a mild prolapse of the tricuspid valve was also present, a, opened mitral valve viewed from the atrial aspect. The edges of the cleft are thickened by fibrous tissue, b, mitral valve viewed from its free edge. Accessory chordae tendineae extend from the apex of the cleft to the ventricular septum (arrow). Abbreviations as in Figure 3.
March 15, 1983
THE AMERICAN JOURNAL OF CARDIOLOGY Volume 51
923
specimens without transposition and are listed in Table I. Of the 2 hearts with large ventricular septal defects, in each the defect was not of the so-called atrioventricular canal type. In the first of the 2, the defect was located in the area of the membranous septum. In the second case, the defect was located in the muscular septum. In the latter case, coarctation of the aorta, bicuspid aortic valve, and patent ductus arteriosus were
FIGURE 6. Cleft mitral valve in a 3-year-old boy with severe mitral insufficiency, a, atrial aspect of opened mitral valve. A shallow cleft (arrow) with thickened margins is present in the center of the anterior leaflet, b, ventricular aspect of anterior mitral leaflet from interior of left ventricle. An accessory chorda tendinea (arrow) and, above that, a raphe-like ridge extend from the mitral valve to the membranous septum in a position below the commissure between the right and POsterior aortic cusps (position 3). In this case severe mitral insuffiCiency was present. This was apparently due to the restriction of the motion of the anterior mitral leaflet caused by the abnormal accessory chordae rather than to the extent of the cleft. LA = left atrium; other abbreviations as in Figure 3.
FIGURE 7. Cleft mitral valve in a 41-year-old man with Down's syndrome, a, opened mitral valve from its atrial aspect is shown, a, the ventricular aspect of the mitral valve is shown. Solid arrow in a points to the apex of the cleft. Accessory chordae extend from the anterior margin (broken arrow) and from the posterior margin (open arrow) of the cleft to the margins of the deficient ventricular septum. The "scooped out" appearance of the muscular septum is similar to that seen in classic endocardial cushion defect. The summit of the ventricular septum is closed by a membrane which was judged to be tissue of the tricuspid valve. LA = left atrium; other abbreviations as in Figure 3.
924
CLEFTANTERIOR LEAFLET OF THE MITRAL VALVE
L
o
~
11
o
12 13
15
Subaortic stenosis
}6
(Degree)
I
i
I
i
I--I=o
I
I I
I I
I~J=+
I c~
14
I
gZ~d
Hh i I
R _
to have been present. Three of the patients died from congestive cardiac failure. This functional disturbance was more difficult to evaluate in those cases having significant anomalies in addition to the mitral cleft. Nevertheless, among the 11 cases with additional anomalies, mitral insufficiency had either been demonstrated clinically or interpreted from the specimen as having been present in 6 cases (3 moderate and 3 mild). Among the remaining 5 cases with additional anomalies, mitral insufficiency was considered not to have been present in each, including the I case of cotrected transposition and right-sided mitral valve. In the latter case, ventriculography had demonstrated competence of the valve. Correlations were attempted between the presence or absence of mitral insufficiency and, when present, its degree on one hand, and certain features of the mitral valve on the other (Fig. 9). These were: (1) dimension of the cleft, (2) the width of the base of the anterior leaflet compared with the width of the base of the posterior leaflet, (3) the position of the cleft, and (4) the presence of ectopic chordae. Ratios were determined of the width of the cleft compared with the width of the base of the anterior leaflet. These ranged from 0.1 to 0.5. The wider the cleft, the more likely was the presence of mitral insufficiency. With this ratio, a statistically significant difference (p <0.025) was found between subjects with absent or mild mitral insufficiency on one hand, and subjects with moderate or severe mitral insufficiency on the other (Fig. 10). Ratios were determined for the depth of the cleft compared with the depth of the anterior mitral leaflet. There was no relation between these values and mitral insufficiency. Ratios were obtained of the width of the entire mitral anulus to the width of the base of the anterior mitral leaflet. These ranged from 1.6 to 2.4. No relation between these ratios and mitral insufficiency was noted. The position of the cleft was not always central in the anterior leaflet as judged by the fact that the anterior and posterior halves of the leaflet were not always equal. Mitral regurgitation was always found when the anterior portion of the cleft leaflet was larger than the posterior.
~=+t-
N--+++
-]
FIGURE 8. Various positions of ectopic chordal insertion as defined in Figure 2, according to the degree of subaortic stenosis. 0 = no subaortic stenosis; 4- = mild, 4-4- = moderate, and 4-4-4- = severe subaortic stenosis, respectively. The case with I-transposition of the
great arteries is not included.
also present. In the 1 case with aortic atresia, septal attachment of accessory chordae of the cleft mitral valve caused subaortic obstruction, in addition. Functional Consequences
As stated, the principal basis for interpreting functional effects of the anomaly of the mitral valve was the appearance of the specimen. The 2 major consequences of the cleft in the anterior mitral valve appeared to be mitral insufficiency and subaortic stenosis. The principal factors favoring an opinion that mitral insufficiency had been present were left atrial enlargement, right ventricular hypertrophy, and, to some extent, left ventricular enlargement. Subaortic stenosis was judged to have been present when associated anomalous attachment of the anterior leaflet of the mitral valve to either the ventricular septurn or anterior wall of the right ventricle had restricted significant movement of the anterior mitral leaflet from the septal wall of the left ventricle. Mitral insufficiency: In each of the 9 cases in which the mitral cleft was the only significant anomaly (Group I), some degree of mitral insufficiency was considered
•kk. ~ o
R
114~
11 I I I
d z
i
I
12
j~
)~
/I\ p i - , ~
/!\ .I-I ~ ~
13
i4
,I
15
o
J Mitral /Insuffic ency (Degree)
]CO
,
I-1--0
I
I I
I
zl
I
m[
[]
=4-+
Ill]m--,,, ]I
m
I,Group I II, Group ]]
FIGURE 9. Various positions of ectopic chordal insertion as defined in Figure 2, according to the degree of mitral insufficiency. 0 = no mitral insufficiency; 4- = mild, 4-4= moderate, and + 4 - + = severe mitral insufficiency, respectively. The case with I-transposition of the great arteries and a case in which evaluation of mitral insufficiency was not possible are not included.
March 15, 1983
Symmetrically cleft leaflets or leaflets With a larger posterior component varied as to the presence of mitral sufficiency. There was no obvious correlation between the site of insertion of accessory chordae on one hand, and mitral insufficiency on the other. This lack of correlation may result from the fact that the presence of the cleft is the primary determinant of mitral insufficiency. Nevertheless, some influence of chordal insertion may have played a role in favoring mitral insufficiency. For example, in Case 3 as shown in Figure 6, a small cleft with anterior insertion of ectopic chordae beneath the commissure between the right and posterior aortic cusps was associated with severe mitral insufficiency. Left ventricular outflow stenosis: From pathologic examination, narrowing of the left ventricular outflow tract was considered to have been present in 10 cases. This abnormality, among the most severe forms of subaortic stenosis, had been diagnosed clinically in some. Based on our interpretation of the presence or absence of subaortic stenosis, in both Groups I and IIA, left ventricular outflow tract stenosis was determined to be clearly related to the site of septal insertion of accessory chordae, namely into the ventricular septum beneath the right aortic cusp (Fig. 8). In 3 cases, relatively long accessory chordae appeared to have caused a degree of subaortic stenosis which was less than that expected from the position of their septal insertion. In cases with d-transposition of the great arteries (IIB), left ventricular outflow stenosis was rare. In the case with 1-transposition of the great arteries (IIC), the narrowing of the outflow tract of the right-sided morphologic left ventricle was caused by accessory tissue of the mitral valve and not by the insertion of accessory chordae. Discussion The anomaly described in this communication consists of a cleft of the anterior mitral leaflet. The cleft may involve a variable length on the anterior mitral leaflet and is usually shaped like an inverted V. As a result of the cleft, the anterior mitral leaflet is divided in anterior and posterior components. Accessory tissue taking the form of chordae, a raphe structure, or both extends from the ventricular aspect of the intactoportion of the cleft leaflet to the ventricular septum or the anterior wall of the left ventricle. The latter process may cause left ventricular outflow tract stenosis. The question might be raised as to whether the cleft is acquired or congenital. Acquired disease giving rise to a defect would, of necessity, be a destructive inflammatory process such as bacterial endocarditis. Militating against this possible cause is the fact that no torn chordae were seen in any of the hearts examined. An important factor favoring a congenital origin is the presence of accessory tissue that attaches to the cleft, either at its apex or along the tissue edging the cleft. The cleft is of the same type as seen in classic examples of persistent common atrioventricular canal or endocardial cushion defect. 1,4 Thus, the condition of cleft anterior mitral leaflet may be considered a forme fruste of the endocardial cushion defect in which the septal defects that characterize the full picture of the
THE AMERICAN JOURNAL OF CARDIOLOGY Volume 51
925
0.~ "6 "$ 0.4
0.3
"-
0.2
:.
t
p< 0.025
"5 o ._o
s~
rr
0.1
:Absent o r m i l d mitral insufficiency
Moderate or severe mitral insufficiency
FIGURE 10. Correlation between the ratio of width of the cleft to width of the base of the anterior mitral leaflet and the degree of mitral insufficiency. In subjects with absent or mild mitral insufficiency, the ratio was 0.19 4- 0.8 (standard deviation) and in subjects with moderate or severe mitral insufficiency, the ratio was 0.31 4- 0.12 (p <0.025). Two of the cases in the study are not represented,
malformation are absent. Additional features related to the endocardial cushion defect may be found in hearts with a cleft in the anterior mitral leaflet. These include abnormally increased ratio of length of left ventricular outflow to inflow tract, "scooped out" deficiency of the ventricular septal summit, cleft of the septal tricuspid leaflet, and double mitral orifice. The association with Down's syndrome in 4 of our 20 cases, a condition frequently associated with the endocardial cushion defect, further stresses the embryologic relation of the isolated cleft mitral valve with endocardial cushion defect. As far as we are aware, isolated cleft of the mitral valve was first described by one of us (JEE) in 1954.1 A few reports of examples of this condition have since been reported. We were able to find only 36 cases, 1-21 9 of which correspond to 9 of our 20 cases. 1,4,10,16-19 Eleven of our cases have not previously been reported. Associated cardiac anomalies were found in 27 of the 36 reported cases to which reference has been made. 4-16,1s-21 The most frequent of such anomalies was a fossa ovalis (secundum)-type atrial septal defect (15 cases). 4-9,~1-14,2° The unusual association of a secundum-type atrial septal defect with a cleft mitral valve was the source of diagnostic errors, since this defect of the mitral valve is classically associated with an ostium primum atrial septal defect. Other associated anomalies reported were transposition of great arteries, 16-1s tri~ cuspid atresia, is pouches of the tricuspid valve, 19 left ventricular-right atrial communication, 19 coarctation of aorta, 7 ventricular septal defect, 7-14 partial anomalous pulmonary venous connection,~5 and double-outlet right ventricle. 21 The tendency of a cleft of the anterior mitrat leaflet to be associated with other cardiac malformations is emphasized by the present series. The scarcity of the reported cases appears to be due to the rarity of the syndrome, as well as to difficulty of the clinical differentiation from other causes of mitral
926
CLEFT ANTERIOR LEAFLET OF THE MITRAL VALVE
insufficiency and subaortic stenosis. Most of the reported cases were correctly recognized at Operation or at autopsy. The diagnostic value of the electrovectorcardiogram was suggested in the past. 5,632,13 A left-axis deviation with counterclockwise rotation of the initial vector on the frontal plane, such as that seen in atrioventricular canal defect, 25,26 was considered a useful sign of mitral valve cleft; but, judging from limited electrocardiographic data in our material, this sign is infrequent in our series. Angiographic diagnosis of the mitral valve cleft is usually possible in atrioventricular canal defect. However, as far as the isolated mitral valve cleft is concerned, the angiographic demonstration of the cleft was unsuccessful according to the experience of others and in the cases in our material, v,11-1~,15,16 The usefulness of angiography lies in its ability to quantify the mitral insufficiency rather than in its ability to identify its cause. It has been recently shown that the mitral valve cleft can be precisely imaged by 2-dimensional echocardiography. 22 The finding of a cleft mitral valve is a cardinal echocardiographic sign of atrioventricular canal defect. The echocardiographic diagnosis of cleft of the anterior mitral leaflet in 2 cases associated with double-outlet right ventricle has been reported. 21 We have personal experience with 2 living patients having severe mitral insufficiency and no septal defects as shown by cardiac catheterization whose echocardiograms showed a typical mitral valve cleft and intact atrial and ventricular septa. Various degrees of left ventricular outflow tract stenosis were interpreted as having been present in about half of our cases. The condition appears to result from restraint of the anterior mitral leaflet by accessory chordae that attach to the ventricular septum. This phenomenon was described by Sellers et a117 in 1964. Our cases emphasize the point that cleft mitral valve may simultaneously cause subaortic stenosis and mitral insufficiency. In this way the anomaly described herein must be distinguished from hypertrophic muscular subaortic stenosis. While the condition represents a "minor" lesion from the embryologic point of view compared with the usual picture of the endocardial cushion defect, in many cases it represents a severe clinical disease which requires surgery early in childhood. The problem of mitral valve surgery in children is obviously avoiding replacement of the valve. Plastic repair of the affected leaflet has been reported in 18 cases of isolated mitral valve cleft. 2,5-8,11-15,2° In the majority of these cases, the results of operation were evidently successful. This experience on a limited number of cases matches the larger experience of repair of cleft valves of atrioventricular canal defects. 27 The rationale for reparative surgery seems well based. Our data show that potentially correctable factors causing mitral insufficiency may be
identified. These factors are the width of the cleft and perhaps the septal insertion of ectopic chordae. In the past, the role of these elements was recognized in the cleft mitral valve of persistent common atrioventricular canal. 28 Suture of the cleft and resection of the accessory chordae are probably both necessary for a complete correction of the altered function of the mitral valve.
References 1. Edwards JE, Dry TJ, Parker RL, Burchell HS, Wood EH, Bulbulian AH. An Atlas of Congenital Anomalies of the Heart and Great Vessels. Springfield, IL: Charles C Thomas, 1954:41-42. 2. Talner NS, Stern AM, Sloan HE Jr. Congenital mitral insufficiency. Circu. lation 1961;23:339-349. 3. Berghuis J, Klrklin JW, Edwards JE, Titus JL. The surgical anatomy of isolated congenital mitral insufficiency. J Thorac Cardiovasc Surg 1974; 47:791-798. 4. Edwards JE, Carey LS, Neufeld HN, Lester RG. Congenital Heart Disease. Correlation of Pathologic Anatomy and Angiocardiography. Philadelphia: WB Saunders, 1965: 784. 5. Hara M, Char F. Partial cleft of septal mitral leaflet associated with atrial septal defect of the secundum type. Am J Cardiol 1966; 17:282-285. 6. Pifarre R, Dieter RA, Hoffman FG, Neville WE. Atrial secundum septal defect and cleft mitral valve. Ann Thorac Surg 1968;6:373-376. 7. Messmer BJ, Hallman GL, Cooley DA. Congenital mitral insufficiency. Results in unusual lesions. Ann Thorac Surg 1970;10:450-~461. 8. Salomon J, Aygen M, Levy MJ. Secundum type atrial septal defect with cleft mitral valve. Chest 1970;58:540-542. 9. Cohn LH, Hancock EW, Griepp RB, Shumway NE. Congenital cleft mitral valve associated with ostium secundum atrial septal defect (abstr). Circulation 1971;43,44:Suppt Ih11-152. 10. Davachi F, Moiler JH, Edwards JE. Diseases of the mitral valve in infancy. An anatomic analysis of 55 cases. Circulation 1971 ;43:565-579. 11. Goodman DJ, Hancock EW. Secundum atrial septal defect associated with a cleft mitral valve. Br Heart J 1973;35:1315-1320. 12. Murray GF, Wilcox BR. Secundum atrial septal defect and mitral valve incompetence. Ann Thorac Surg 1975;20:136-143. 13. Snow NJ, Ankeney JL. Congenitally cleft atrioventricular valves associated with secandum atrial septal defect. J Thorac Cardiovasc Sur9 1976;72: 925-928. 14. 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 malformations of the mitral valve in children. Pathology and surgical treatment. J Thorae Cardiovasc Surg 1976;72:854-866. 15. Pritchard DA, Tajik AJ, Rutherford HD, Harrison CE Jr, Pluth JR, Danielson GK. Partial anomalous pulmonary venous connection (intact atrial septum) associated with mitral regurgitation. Am Heart J 1977;94:209-216. 16. Levy MJ, Lillehei CW, Elliott LP, Carey LS, Adams P Jr, Edwards JE. Accessory valvular tissue causing subpulmonary stencsis in corrected transposition of great vessels. Circulation 1963;27:494-502. 17. Sellers RD, Lillehei CW, Edwards JE. Subaortic stenosis caused by anomalies of the atrioventricular valves. J Thorac Cardiovasc Surg 1964;48:289-302. 18. Layman TE, Edwards JE. Anomalies of the cardiac valves associated with complete transposition of the great vessels. Am J Cardiol 1967; 19:247255. 19. Chesler E, Korns ME, Edwards JE. Anomalies of the tricuspid valve, including pouches, resembling aneurysms of the membranous ventricular septum. Am J Cardiol 1968;21:661-668. 20. Billig DM, Hallman GL, Bloodwell RD, Cooley DA. Surgical treatment of atrial septal defects in patients with angina pectoris. Ann Thorac Surg 1968;5:566-568. 21. Hagler DJ, Tajik AJ, Seward JB, Mair DD, Rifler DG. Double-outlet right ventricle: wide-angle two-dimensional echoeardiographic observatiOnS. Circulation 1981;63:419-428. 22. Hagler DJ, Tajik AJ, Seward JB, Mair DD, Ritter DG. Real-time wide-angle sector echocardiography: atrioventricular canal defects. Circulation 1979;59:140-150. 23. Du Plessis LA, Marchand P. The anatomy of the mitral valve and its asSOciated structures. Thorax 1964;19:221-227. 24. Goor D, Lillehei CW, Edwards JE. Further observations on the pathology of the atrioventricular canal malformation. Arch Surg 1968"97"954-962' 25. Lev M. Conduction system in congenital heart disease. Am J Cardiol 1968;21:619-627. 26. Feldt RH, DuShane JW, Tilus JL. The atrioventricular conduction syste~ in persistent common atrioventricular canal defect. Correlations wun electrocardiogram. Circulation 1970;42:437-444. 27. McGoon DC, Puga FJ. Atrioventricular canal. Cardiovasc Clin 1981;11: 311-322. 28. Edwards JE. The problem of mitral insufficiency caused by accessory chordae tendineae in persistent common atrioventricular canal. Proc Mayo Clin 1960;35:299-305.