Subvalvar Congenital Mitral Stenosis

Brit. Heart J., 1966, 28, 808.

Subvalvar Congenital Mitral StenosisA. SANCHEZ CASCOS, P. RABAGO, M. SOKOLOWSKI, AND J. R. VARELA DE SEIJAS

From the Cardiac Department, Fundacion Jimenez Diaz, Madrid, Spain

The recent rapid development of cardiac surgerynow demands accurate diagnosis of the rarer typesof congenital heart disease; the exact anatomy ofcongenital valve stenosis, for example, must bedetermined. The occurrence of valvar, subvalvar,and supravalvar forms of either aortic or pulmonarystenosis is well known.With respect to congenital mitral stenosis, a rarer

cardiac anomaly, we are now beginning to dis-tinguish the valvar type, of which we have previouslyreported two examples (Varela de Seijas et al., 1960),and the supravalvar form (Rogers et al., 1955; John-son and Dodd, 1957; Manubens, Krovetz, andAdams 1960): this latter is to be distinguished fromcor triatriatum in which an aberrant septum dividesthe left atrium into two different chambers, whereasin supramitral stenosis a fibrous stenosing ring isplaced immediately above the valve. More recently,Shone et al. (1963) have defined a developmentalcomplex comprising four successive obstructions toleft heart flow: supravalvular mitral ring, "para-chute" submitral anomaly, subaortic stenosis, andcoarctation of the aorta; all or only some of thesefour being present in each of the eight cases theyreported. The so-called "parachute" mitral valvewas present in half. The term "parachute" is usedby these authors by analogy with a parachute whosecanopy is represented by the valve leaflets, its stringsby the chordw, and its harness by the papillarymuscle. The fused leaflets and chordm converge ona single papillary muscle and the subvalvar obstruc-tion is formed by the small orifices between thechorde and papillary muscle.

In rarer cases subvalvar mitral obstruction can bedue to the existence of fibrous bands, or abnormal,shortened, and fused chords tendinee (Daoudet al., 1963). In this connexion Moller et al. (1964),studying cases of congenital endocardial fibro-elastosis, either "primary" or "secondary" (i.e.

Received October 8, 1965.

associated with aortic stenosis, aortic coarctation, oraberrant coronary artery), found a typical abnor-mality of the mitral valve, generally causing mitralincompetence; the leaflets are small and the pap-illary muscles arise higher than usual on the wall ofthe left ventricle. This position of the papillarymuscles, as well as the shortening of the leaflets,chordae, and even of the papillary muscles, pro-duces the mitral incompetence, but it is clear thatthis mitral anomaly can sometimes be obstructive,giving a new form of subvalvar mitral obstruction.We report here three cases of submitral stenosis,

all of them associated with other cardiac anomalies.One is an example of the "parachute" type ofvalve; in the second the valve was involved bycongenital endocardial fibro-elastosis; the thirdpresented chordal obstruction.

CASE REPORTSCase 1. This 5-year-old girl was born after a normal

full-term pregnancy. The family history was withoutinterest. She had previously been asymptomatic exceptfor frequent respiratory episodes, during which she hadmild dyspncea and cyanosis. Recently she also com-plained of mild dyspnoea on effort.

Physical examination revealed a well-nourished girlwithout cyanosis or clubbing. The chest showed pectuscarinatum; the apex beat was felt in the 6th left inter-costal space. There was physiological splitting of thesecond sound, but neither an ejection click nor anopening snap was heard. A grade 5 (out of 6) pansystolicmurmur was best heard at the left sternal border and agrade 4 murmur in the mitral area filled diastole. Thefemoral pul3es were present. The electrocardiogram(Fig. 1) showed sinus rhythm at 110 a minute, a clearmitral P wave with a normal P-R interval, QRS of0-11 sec., with a slow end-phase, negative in I andaVL, positive in II, III, and aVF; pr2ecordial leadsrevealed big isodiphasic complexes in V3-5. Theelectrocardiogram was interpreted as indicating leftatrial enlargement with possible biventricular over-loading.

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Case 2

Case 3

I II III aVR aVL aVF VI V2 V3 V4 V5 V6FIG. 1.-The electrocardiograms from the three cases.

The chest radiograph (Fig. 2) showed increased lungvascularity, hilar dance, and a globular-shaped heartsuggestive of biventricular hypertrophy; the left atriumwas found to be dilated in the right anterior obliqueposition. Blood examination revealed mild polycythmmia(5 3 million).A clinical diagnosis of ventricular septal defect with

mitral obstruction (possibly cor triatriatum) was made.Right heart catheterization (Table I) revealed severe

pulmonary hypertension at near systemic levels; thepulmonary wedge pressure was high (21/13, mean19 mm. Hg). The blood oxygen saturation was increasedin the right ventricle and a left-to-right shunt at ven-tricular level of 43 per cent of the total pulmonary bloodflow was calculated. A persistent left superior vena cavawas also found. The final heemodynamic diagnosis wasventricular septal defect with left atrial hypertension.

TABLE ICASE 1: CATHETERIZATION DATA

Pressures (mm. Hg)Chamber

Systolic Diastolic Mean

Right atrium .. 3 (8) - 1 (2) 0 (6)Right ventricle .. 74 (80) 2 (6)Pulmonary artery 73 37 55Pulmonary wedge.. 21 13 19Left atrium .. (22) (14) (18)Left ventricle .. (85) (12)Femoral artery .. 87 (88) 48 (45) 70

Figures in parentheses indicate pressures at operation.

The presence of an important ventricular septal defectbeing recognized, cine-angiocardiography was performedin an attempt to obtain information about the state of themitral valve. The injection was made into the pulmonary

FIG. 2.-Chest radiograph of Case 1.

Case I

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FIG. 3.-View of the dissected ventricle in Case 1. Both atrio-ventricular valves (M=mitral andT=tricuspid) are seen in continuity. The single bifid papillary muscle (P) of the mitral valve producing

the "parachute" deformity is well shown.

trunk. Passage of the opaque medium across the mitralvalve appeared to be slow, but mitral stenosis was notconclusively demonstrated.

It was decided to operate to close the septal defect andto explore the mitral valve. At operation no mitral valveobstruction was found, though a clear mitral diastolicgradient was again demonstrated (Table I). When theventricle was opened no ventricular septum was found,and banding of the pulmonary artery was then per-formed. The patient died a few hours after the operation.

Necropsy. The extemal shape of the heart was tri-angular, with both great vessels coming out from theleft side. Three caval veins drained into the rightatrium, the left superior vena cava doing so through thecoronary sinus. The right atrium and interatrial septumwere normal and so was the tricuspid valve. There was a

common ventricle with no evidence of a septum. Thegreat vessels arose from it without transposition or in-version; both aortic and pulmonary valves were normal.The left atrium was externally normal but its wall wasthick and the endocardium was white and fibrous. Themitral valve appeared normal when viewed from theatrium, but from the ventricle it was seen to be funnel-shaped with fusion of the leaflets. There was a singlebifid papillary muscle and from its apices short partiallyfused chorde tendine&e extended towards the leaflets(Fig. 3), only small orifices allowed blood flow from thissubvalvar cul-de-sac to the ventricular cavity: the widerof these orifices was a longitudinal slit placed against theleft myocardial wall, while on the internal aspect bothapices of the papillary muscle were partially fused by a

fibrous membrane. The coronary arteries were normal

in course and distribution. No ductus arteriosus wasfound.The final diagnosis was persistent left superior vena

cava, common ventricle, and subvalvar "parachute"-type mitral stenosis.

Case 2. This 7-year-old boy was born a month pre-maturely after an otherwise normal pregnancy. Therewas no significant family history. Congenital heartdisease was recognized shortly. after birth. He startedwalking at 2 years and the parents noted then that hewas dyspnoeic on effort. At 5 years, he developed pro-gressive heart failure that did not respond to the treat-ment given.When we saw the patient he was undernourished with

severe ascites and cedema. The apex beat was in the 6thleft intercostal space and the apical thrust suggested leftventricular hypertrophy. A parasternal right ventricularlift was also felt. On auscultation there was a triplerhythm, due to a third sound, and a pansystolic, grade 4,murmur in the mitral as well as in the tricuspid areaswith muffled heart sounds. The remainder of the exami-nation was normal, and the femoral pulses were feltnormally.The electrocardiogram (Fig. 1) showed atrial fibril-

lation with low voltage complexes (not seen in the Figurewhich is taken from a later record), and signs of pre-dominant right ventricular hypertrophy, possiblyassociated with left ventricular hypertrophy; big Qwaves were present over the right prxcordium.

Chest radiographs (Fig. 4) showed an enlargedglobular heart with pulmonary congestion.

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TABLE IICASE 2: CATHETERIZATION DATA

Pressures (mm. Hg)Chamber


Right atrium .. 14 8 13Right ventricle .. 47 6Pulmonary artery 33 33 15Pulmonary wedge .. 17 12Left atrium 17 9 13Left ventricle .. 85 4


A diagnosis of endocardial fibro-elastosis with mitralincompetence was made.The patient had been previously catheterized at

another hospital and some data had been obtained. Theseshowed (Table II) moderate pulmonary hypertensionand high pressure in both atria with a significant leftatrial to left ventricular diastolic gradient. The left

atrium had been reached from the right through a pre-sumed atrial septal defect or patent foramen ovale.These data were incomplete in so far as no blood oxygensaturations had been obtained and atrial pressure curveshad not been analysed to get evidence of either mitralincompetence or stenosis. It was decided to repeat thecardiac catheterization when the patient's cardiac failurehad been controlled by treatment. He had a gooddiuresis and after a month was without ascites or cedema.Cardiac catheterization was about to be performed whenthe patient suddenly died.

Necropsy. Only the heart was examined; its externalappearance was normal. The right atrium was enlargedand hypertrophied. There was a large ostium secundumatrial septal defect. The right ventricle and pulmonaryartery were normal. The left atrium was also normal.The mitral valve was thick and deformed, but the

area of its orifice was normal. Short chordee tendinescrossed under it fusing the papillary muscles, producingan obvious subvalvar stenosis (Fig. 5). Thespapillary

FIG. 5.-The atrial aspect of the mitral valve in Case 2, showing fused chorde below it.




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FIG. 6.-The opened cavity of the left ventricle in Case 2, showing the white colour of the endocardiumand the anomalous high implantation of the papillary muscles.

i'FIG. 7.-The histology of the endocardium in Case 2.

E, elastic fibres; C, collagenous fibres; M, myocardium.

muscles were both rudimentary arising from the ventri-cular wall close to the mitral valve in a very high position(Fig. 6) so that a large part of the ventricular chamberlay between their insertion and the apex.The endocardium was white and fibrous in all cham-

bers particularly in the left ventricle. Microscopically(Dr. Oliva) the endocardium was found to be thickenedin all chambers and a great amount of elastic fibre waslocated in its superficial layers, while collagenous fibrespredominated in the deep ones; the myocardium wasnot involved (Fig. 7).The final diagnosis was endocardial fibro-elastosis,

atrial septal defect, and congenital deformity of themitral valve producing both mitral incompetence andsubmitral obstruction.

Case 3. This 1 1-year-old girl was born after a normalfull-term pregnancy, and congenital heart disease wasdiagnosed shortly after birth. The family history waswithout interest. Physical development was normal,whereas she was mentally retarded because of severecongenital deafness. She had been asymptomatic exceptfor the presence of mild cyanosis with respiratoryepisodes.At 7 years she was catheterized at another hospital

and a 100 mm. Hg pulmonary valvular gradient wasfound. A pulmonary valvotomy was then performed, theresult being apparently good. When we saw the patientshe complained of repeated melena; there had beendyspncea and cedema. She showed severe mental im-pairment and bilateral hypacusia.The apex beat was normal and a systolic thrill was

felt at the pulmonary area. A grade 5/6 systolic murmurwas best heard high on the left sternal border; heart

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sounds were normal. Blood pressure was normal andfemoral pulses were present. The electrocardiogram(Fig. 1) showed sinus rhythm at 90 a minute, right atrialoverloading of diastolic type, and diastolic overloadingof the right ventricle with an extreme deviation of theAQRS presenting negative complexes in all leadsexcept aVR and V1-2. The chest radiograph (Fig. 8)presented increased lung vascularity and right ventric-ular hypertrophy. The patient had anemia (2-5 million)and positive liver function tests, suggesting cirrhosis.

FIG. 9.-Appearance of the mitral valve in

Right ventricular catheterization (Table III) revealedmoderate right ventricular hypertension with a 22 mm.Hg systolic transpulmonary gradient with normal pul-monary pressures; the pulmonary wedge pressure wasnormal (9/5, mean 7 mm. Hg). The blood oxygensaturation was increased in the right atrium and a left-to-right shunt at atrial level of 37 per cent of the totalpulmonary blood was calculated.The final hamodynamic diagnosis was atrial septal

defect with mild pulmonary gradient probably due to theincreased pulmonary flow. Twenty-four hours aftercardiac catheterization the patient died following anepisode of ventricular fibrillation.

TABLE IIICASE 3: CATHETERIZATION DATA

Pressures (mm. Hg)Chsmber


Right atrium .. 3 - 3 0Right ventricle .. 42 2Pulmonary artery .. 20 12 15Pulmonary wedge.. 9 5 7Brachial artery .. 123 74 95

Necropsy. Only the heart was examined. The externalshape was normal; the right atrium was normal except forthe presence of an ostium secundum type atrial septaldefect. The tricuspid valve was normal and the rightventricle presented only moderate hypertrophy of theparietal band of the crista supraventricularis. On theanterior wall of the right ventricle there was a fibrouscircular patch, 1 cm. in diameter. The pulmonary valve

ase 3. The arrow points to the fused chordx under the posteriorcommissure.

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was normal having only two small perforations, prob-ably relics of the previous blind valvotomy. The leftatrium and ventricle and aortic valve were normal.The mitral valve was apparently normal when viewedfrom the atrium, but both commissures presented acentral raphe towards the papillary muscles, from whichparallel chordte emerged towards the leaflets, resemblinga strap (Fig. 9); only small peripheral orifices and a2 cm. central one allowed the blood flow through thissubvalvar mitral obstruction. Coronary arteries werenormal. The ductus arteriosus was not found.The final diagnosis was ostium secundum atrial septal

defect with mild infundibular obstruction and sub-valvar mitral stenosis.

DISCUSSIONThese three patients have in common only the

presence of submitral stenosis. They are reportedin order to emphasize the possibility of this type ofcongenital mitral obstruction and to discuss itsanatomical forms.The first patient had the typical "parachute"

mitral valve, as described by Shone and his col-leagues (1963), but it lacked the other elements ofthe syndrome they described (i.e. supramitralstenosis, subaortic stenosis, and coarctation of theaorta). The association in this case with a singleventricle perhaps explains the development of the"parachute" anomaly in this instance and possiblyin others. We think that the lack of formation of theseptum could account for the anomaly of thepapillary muscles; the other examples of "para-chute" valve with a complete septum could perhapsbe due to a failure of the formation of the septalcontribution to the papillary muscles.The second patient demonstrates that the typical

mitral deformity that occurs in endocardial fibro-elastosis can also give rise to submitral obstructionof a different anatomical type.

Finally, the third case is an example of anotherform of submitral stenosis, the obstruction beingnot critical from the haemodynamic point of view.

Details of three patients who had mitral sub-valvar obstruction are reported. In one there was a"parachute" deformity of the valve associated withabsence of the ventricular septum; the second had amitral valve deformed by congenital endocardialfibro-elastosis; the third presented fusion of chordttendineae.

We wish to express our indebtedness to Dr. DennisDeuchar, of Guy's Hospital, London, who has kindlyrevised the text, and to Dr. Oliva, of our PathologyDepartment, for his microscopical study of the secondcase.

REFERENCES

Daoud, G., Kaplan, S., Perrin, E. V., Dorst, J. P., andEdwards, F. K. (1963). Congenital mitral stenosis.Circulation, 27, 185.

Johnson, N. J., and Dodd, K. (1957). Obstruction to leftatrial outflow by a supravalvular stenosing ring. J.Pediat., 51, 190.

Manubens, R., Krovetz, L. J., and Adams, P. (1960). Supra-valvular stenosing ring of the left atrium. Amer. HeartJ.,60,286.

Moller, J. H., Lucas, R. V., Adams, P., Anderson, R. C.,Jorgens, J., and Edwards, J. E. (1964). Endocardialfibroelastosis: A clinical and anatomic study of 47patients with emphasis on its relationship to mitralinsufficiency. Circulation, 30, 759.

Rogers, H. M., Waldron, B. R., Murphey, D. F. H., andEdwards, J. E. (1955). Supravalvular stenosing ring ofleft atrium in association with endocardial sclerosis(endocardial fibroelastosis) and mitral insufficiency.Amer. Heart_J., 50, 777.

Shone, J. D., Sellers, R. D., Anderson, R. C., Adams, P.,Lillehei, C. W., and Edwards, J. E. (1963). The de-velopmental complex of "parachute mitral valve",supravalvular ring of left atrium, subaortic stenosis, andcoarctation of aorta. Amer.3J. Cardiol., 11, 714.

Varela de Seijas, J., Rabago-Gonzalez, P. de, Rabago-Pardo,G. de, Rey-Baltar, E., Esquivel, A., Sokolowski, M.,and Sanchez-Cascos, A. (1960). Estenosis mitralcongenita. Presentaci6n de dos casos comisurotomi-zados. Rev. clin. esp., 77, 85.

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Subvalvar Congenital Mitral Stenosis