Congenital mitral stenosis resulting from anomalous arcade and obstructing papillary muscles

Case Reports Congenital

Mitral

Anomalous

Stenosis Resulting

Arcade

Papillary Report ALDO

of Correction

from

and Obstructing Muscles

by Use of Ball Valve Prosthesis*

R. CASTANEDA, M.D.,F.A.c.c., RAY C. ANDERSON, M.D.,F.A.C.C.and JESSE E. EDWARDS M.D.,F.A.C.C. Minneapolis

and St. Paul, Minnesota

Successful replacement of a mitral valve with a ball valve prosthesis in a 10 month old male infant is described. The resected congenitally stenotic mitral valve showed the obstructing mechanism to be related to (1) an arcade-like thickening of the line of closure of the anterior mitral leaflet, extending between the apexes of the anterolateral and the posteromedial papillary muscles, and (2) prominent papillary muscles that crowded the subvalvar area in the left ventricular inflow tract. Neither closed mitral commissurotomy nor open valvuloplasty seemed adequate to relieve this obstruction. As a consequence, replacement of the mitral valve by a ball valve prosthesis was carried out. Thirteen months after operation the patient was well. It is recognized that progressively larger prosthetic replacements may be needed as the infant grows.

C

ONGENITAL MITRAL STENOSIS iS a rare condition which has been described in one of two forms. It may present as a funnelshaped structure with shortened chordae tendineae, fibrotic leaflets and fused commissures,‘-3 or it may be characterized by the so-called “parachute mitral valve complex” in which the chordae tendineae of both leaflets converge to insert into a single papillary muscle.4 Either of these forms may occur as a single pathologic entity, but more commonly the second type forms part of a developmental complex with other malformations such as a supravalvar ring of the left atrium, subaortic stenosis, or coarctation of the aorta.5 Since diverse surgical operations have been employed congenital mitral for the treatment of stenosis,6-g a detailed knowledge of other anatomic variations of congenital mitral stenosis is of more than purely academic interest.

The purpose of this report is to present an unusual case of congenital mitral stenosis in which the obstructing mechanism was related mainly to (1) an arcade-like thickening of the line of closure of the anterior mitral leaflet extending between the apexes of the anterolateral and posteromedial papillary muscles and (2) prominent papillary muscles that crowded the subvalvar area and the left ventricular inflow tract. This hitherto unreported form of congenital mitral stenosis required complete removal of the mitral valve and substitution by prosthesis in a 10 month old infant. CASE REPORT This infant was referred to the University of Minnesota Hospitals on January 26, 1967, at age 10 months because of recurrent cough and frequent upper respiratory infections since age 3 months. The infant had always seemed irritable to the parents.

* From the Departments of Surgery and Pediatrics, University of Minnesota, Minneapolis, Minn. and the Department of Pathology, The Charles T. Miller Hospital, St. Paul, Minn. Manuscript received May 13, 1968. Address for reprints: Aldo R. Castaneda, M.D., Department of Surgery, University of Minnesota Medical School, Minneapolis, Minn. 55455. VOLUME24, AUGUST1969

237

Castaneda

238 Table I.

Cardiac

Catheterization

et al.

Data

02 Site Right atrium Right ventricle Pulmonary artery Pulmonary artery wedge Left ventricle i\orta Cardiac

index

Pulmonary vascular resistance Figures in parentheses

Pressure (mm. Hg)

(10) 95/o-10 90/40(70) (28); a = 38, U = 34 100/o-10 100/70(80)

Sat. (%) 65 65 65

98

3 7 L. /min. per M.2 3,700 dynes sec. cm.3

indicate

mean pressures.

Moderate enlargement of the heart and prominence of the pulmonary vessels had been noted radiographitally at age 9 months. A cardiac murmur was first noted at that time. Examination revealed a relatively well developed male infant with mild dyspnea. He weighed 8.5 kg. and measured 74 cm. in length. Fine rales were heard over both lung fields. Heart rate was lbO/min. and regular. The first heart sound was considerably accentuated at the apex, and the second heart sound was split, with prominence of both components. There was a long, low pitched grade 2/4 diastolic murmur at the apex, with presystolic accentuation. The liver edge was palpable 5 cm. below the right costal margin. Normal femoral’ pulses were present. Thora& roentgenograms showed mild cardiomegaly with prominent left atria1 enlargement and pulmonary venous congestion. The electrocardiogram demonstrated tall but broad P waves and right ventricular hypertrophy. Cardiac catheterization findings supported the clinical diagnosis of congenital mitral stenosis. They revealed a right ventricular pressure of 95/O-10 mm. Hg, a pulmonary arterial pressure of 90/40 (mean 70), and a mean left pulmonary arterial wedge pressure of 28 mm. Hg (a wave 38 and u wave 34; Table I). Total calculated pulmonary resistance was 3,700 dynes sec. cm.?. The cardiac index was 3.7 L./min. per M.2. Pulmonary arteriography demonstrated a very large left atrium which emptied slowly. The left ventricular pressure was 100/O-10 mm. Hg and the aortic pressure was 100/70 (mean 80), with no pressure difference across the left ventricular outflow tract and aortic valve, nor between the ascending or descending aorta. A left ventriculogram showed a questionable ventricular filling defect which was interpreted as being possibly related to a parachute mitral valve deformity. Surgical Findings and Treatment: In view of the continuing and increasing pulmonary difficulties and the markedly abnormal laboratory findings, the infant

7‘11~rrsrr~rd rnrflal t.ul~ as virwcd frown above, 1. measures 2.5 by 2.2 cm. Both the anterior and posterior leaflets are conlposed of translucent, glistening white tissue. The principal orifice is located centrally and does not exceed 1 cm. in its greatest dilnrnsion.

Figure

underwent operation on February 24, 1967. The heart was exposed through a right anterolateral thoracotomy. The left atrium as well as the right atrium and the pulmonary arterial trunk were found to be markedly enlarged. After cannulation of the left femoral artery and both superior and inferior venae cavae, cardiopulmonary bypass was instituted, utilizing a roller pump and a bubble type oxygenator. Perfusion was maintained at 900 ml./min. throughout the procedure. When total cardiac bypass was established, the heart was stopped by induced electrical fibrillatory arrest. The left atrium was then opened. The mitral valve, although funnel-shaped with a somewhat stenotic central orifice, was obstructed by a central crowding of several heavy papillary muscles rather than by fused commissures. The possibility of achieving a satisfactory valvuloplasty had to be discarded. The entire mitral valvar apparatus was therefore removed by incising each leaflet near its basal attachment and by severing each papillary muscle near its attachment to the ventricular wall. Thus, part of the annulus and all of the mitral valve leaflets, chordae tendineae and papillary muscles were resected in continuity to allow for a detailed pathologic examination. A StarrEdwards ball valve prosthesis (No. 00) was inserted. Total pump time was 45 minutes. The lowest degree of esophageal temperature during the procedure was 28O C. The postoperative period was uneventful, and the infant was discharged from the hospital 12 days after the operation. PATHOLOGIC

FEATURES

As viewed from above, the dimension of the resected mitral valve was 2.5 by 2.2 cm. Both the anterior and posterior leaflets were composed of translucent, glistening white tissue which was partly gelatinous. The principal orifice of the valve was THE

AMERICAN

JOURNAL

OF

CARDIOLOGY

Congenital

Mitral

Stenosis

239

Figure 3. Arcade-lil;e /hicXrning &n,g of the anterior mitral lq%t. This arcade

Figure 2. Thr papillary muscles. Some do not halve a discrete apex. Although each set of muscles is located beneath its appropriate commissure, all of the chordae are shortened. Several units of the papillary muscles attach directly to the inferior surface of the valvar tissue.

thr lim

(I/ rlo~urr

esrrnds betwren the apex of the antwAater;d to thr ‘rpex of the posteromedial papillary muscles. In addition, thrrc is an anomalow transverse chorda connecting thr antcrolateral papillary r~~usclrs to thr postrrollwtiiwl papillary muscle sroup.

located centrally

and did not exceed 1 cm. in its greatest dimension (Fig. 1). Some of the papillary muscles did not have a discrete apex (Fig. 2). Each set of papillary muscles, however, was located beneath its appropriate commissure, but all of the chordae were shortened, none exceeding 0.6 cm. in length and the majority being shorter. Several units of the papillary muscles attached directly to the inferior surface of the valvar tissue. A prominent finding was an arcade-like thickening along the line of closure of the anterior mitral leaflet (Fig. 3). This arcade extended between the apex of the anterolateral papillary muscles to the apex of the posteromedial papillary muscles. The apex of each group of papillary muscles had multiple attachments to the valve. A few of the chordae were translucent and delicate, but the majority were thick and bulbous in nature. Beneath the anterior leaflet of the mitral valve was an anomalous transverse chorda connecting the anteroIatera1 papillary muscles to the posteromedial group of papillary muscles. An additional feature was the subvalvar crowding by these groups of heavy papillary muscles (Fig. 4 and 5). There was considerable variation in the size of the muscles. The largest solitary papillary muscle located beneath the posteromedial commissure measured 1.2 cm. in its greatest dimension. There was a cluster of papillary muscles beneath the anterolateral commissure, and the largest of these did not exceed 0.8 cm. in its greatest dimension.

Figure 4. Vmtricular vim of thP subualvar crowding by papillary muscles which appear to contribute groups of heavy significantly

to mitral

stenosis.

COMMENT Several forms of congenital anomalies of the mitral valvar apparatus which cause either mitral insufficiency or mitral stenosis have been described. Recently, Layman and EdwardslO introduced the term “anomalous mitral arcade” VOLUME

24,

AUGUST

1969

Figure 5.

The mitral valve, although funnel-shaped with a somewhat stenotic orifice, is obstructed by a central crowding of several heavy papillary muscles rather than by fused commissures.

240

Castaneda

for an anomaly that caused mitral insufficiency in 3 infants who died at the ages of 2 and 6 weeks and 455 months, respectively. The mitral valves they described resemble in some aspects the resected mitral valve in our case. In their cases, both papillary muscles of the left ventricle participated in the formation of an arcade that passed through the anterior mitral leaflet, and the chordae tendineae were unusually short and thickened. This peculiar configuration of the valve was interpreted as causing mitral insufficiency since there was no interposition of chordae tendineae between the anterior leaflet and the papillary muscles. This lack may have caused undue restraint upon motion of the leaflet, thus preventing adequate valvar closure during ventricular systole. The evidence for mitral insufficiency was supported by the history of a systolic murmur heard early in life in their cases and by biventricular and biatrial enlargement of the pathologic specimen. Unfortunately, cardiac of the patients underwent none catheterization studies during life. In the present case, the clinical diagnosis of mitral stenosis was confirmed by catheterization studies. The arcade-like structure and the shortening and thickening of the chordae tendineae were essentially identical to those in In our case an additional the cases quoted. feature was the subvalvar crowding by groups of heavy papillary muscles. The latter phenomenon appears to have been the major basis for mitral stenosis. Whatever the mechanisms responsible for the mitral stenosis in this infant, neither closed mitral commissurotomy nor open valvuloplasty seemed to be an appropriate procedure to alleviate the condition. Resection of the entire mitral valvar apparatus and prosthetic replacement was therefore considered necessary and was carried out. Prosthetic valvar replacement has been utilized with increasing frequency in the and Robinson9 were the young. i1,12 Young first to succeed in replacing the mitral valve in a 10 month old infant suffering from the conventional form of congenital mitral stenosis. Although this valve had to be replaced with a larger one 22 months later, the feasibility of prosthetic valvar replacement in infants was well demonstrated by these authors. Our operative experience with prosthetic valvar replacement in this 10 month old infant and the uneventful postoperative course substantiates this finding. Since the area of the orifice in the

et al. No. 00 Starr-Edwards ball valve prosthesis is only 1.27 c~rt.~, it is probable that at least one or more prosthetic replacements will later need to be carried out as the patient grows. Anticoagulant medication is not being used in this patient because of difficulties in controlling dosage of these drugs in children and because of the inherent dangers related to their use in this age group. Heparin neutralization after cardiopulmonary bypass was also avoided in an effort to curb excessive fibrin formation and therefore to minimize the possibility of thromboembolism.i3 No thromboembolic complications have occurred in this child in the 13 months since operation. REFERENCES 1. DAY H. B. A case of mitral stenosis fatal at two years of age. Lamt, 1:1144, 1932. 2. EMERY, J. L. and ILLINGWORTH, R. S. Congenital mitral stenosis. Arch. Dis. Child., 26:304, 1951. 3. VAN DER HORST, R. L. and HASTREITER, A. E. Congenital mitral stenosis. Am. J. Cardiol., 20:773, 1967. 4. SCHIEBLER, G. L., EDWARDS,J. E., BURCHELL, H. B., DUSHANE, J. W., ONGLEY, P. A. and WOOD, E. H. Congenital corrected transposition of the great vessels. A study of 33 cases. Pediatrics, 27 (Suppl.) : 851, 1961. 5. SHONE, J. D., SELLERS, R. D., ANDERSON,R. C., ADAMS, P., JR., LILLEHEI, C. W. and EDWARDS, J. E. The developmental complex of “parachute mitral valve,” supravalvular ring of left atrium, subaortic stenosis and coarctation of the aorta. Am. J. Cardiol., 11:714, 1963. 6. BOXER, B. D., GERARD, J. W., D’ABREN, A. L. and PARSONS, C. G. Two cases of congenital mitral stenosis treated by valvotomy. Arch. Dir. Child., 28:91, 1953. 7. MAXCVELL,G. M. and YOUNG, W. P. Isolated mitral stenosis in an infant of three months: Report of a case treated surgically. Am. Heart. J., 48:787, 1954. 8. BRAVDO, J. L., JAVETT, F. N., ADLER, D. I. and KESSEL, I. Isolated congenital mitral stenosis: Report of two cases with mitral valvulotomy in one. Circulation, 15:358, 1957. 9. YOUNG, D. and ROBINSON, G. Successful valve rcplacement in an infant with congenital mitral stenosis. New England J. Med., 270:660, 1964. 10. LAYMAN, T. E. and EDWARDS, J. E. Anomalous mitral arcade. A type of congenital mitral insufficiency. Circulation, 35:389, 1967. 11. SDAELOFF,E. A., CAYLEER,G. G. and SNEIK, D. F. The use of valve prosthesis in childhood. J. Thorncic & Cardiovas. Sure.. 51~839. 1966. 12. BLOODWELL, R. D., HALL&N, A. L. and COOLEY, D. A. Cardiac valve replacement in children. Surgery, 63 177, 1968. 13. CASTANEDA,A. R., GANS, H., WEBER, K. C. and Fox J. Heparin neutralization: Experimental and clinical studies. Surgery, 62:686, 1967.

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