Download Straddling mitral valve with hypoplastic right ventricle

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PEDIATRIC
CARDIOLOGY
Straddling Mitral Valve With ilypoplastic Right Ventricle, Crisscross
Atrioventrirular Relations, Double Outlet Right Ventricle and
Dextrocardia: Morphologic, Diagnostic and Surgical Considerations
TAL
GEVA,
MD,
JOHN E. MAYER,
STELLA
VAN
PRAAGH.
JR.. MD, RICHARD
MD, STEPHEN
VAN PRAAGH,
P. SANDERS.
MD,
MD. FACC
The clinical. sureical and muruholonic ti*din”s in five cuw of u
rare fnrm nf
mitral &e ire preset&d. Three patients
were dl@nnsed by two-dimensbmal wzfuxardiognphy, cardiac
catbeterhattmi and angiocardttphy
and two had diagnostic
cu&rmatfon at autupsy. At1 tlve casesshared a didoctive and
cm&tent cumbimtiun of armmalteszI) dextruoxdia: 2) vtscerastrtll situs solihts, enncnrdant ventricular D-loop and double
outlet right veatrictertth the aurta positionedto the left ef and
anteriur to the putntnnary artery; 3) hypoplasia&right venhirulsr Mow (sin”3J with trtcusptd valve stenusfra hypoptaria; 4)
huge right vmtrfcular infuodlbutum (outdow): 5) mdnlignment
cuoo~lw
septat defect; 6) straddling aitrat valve wi:h
churdal attachments to the letl ventricle and right ventricular
inlundibufum; 7) were subpulmunary stenusiswith welt devet.
uped pdmmary tieiieq and 8) rupemtnfert”r ventrittes sith
crisscrmsstrblvmmc”lar (Av) relPtio.6.
The degrer of
betweenthe atrial and ventricular
septawasstudiedquantitatively by memsurfngthe .A\1septt aogle
projected an the frontal plane. The AV septal angle in the two
pustmurtem ciwr wus IsOq retlectbegmarked malslignment of
the ventrtc!?~relativeto the atria. This AY m&t@ment appears
to pta) an impwtant *
in tie morpbugeoesisd saddllllg
mitral valve. As judged by P companionstudy of sew,, p&mar.
tern oases.the more MRUW(Lfnrm of straddling ndhnl valvewith
a hypertrophied and e&r@ right vmtrfcuta sinus he-! fess
severeventrkular nlatpmttian than did the five rare StuLycases
with hjpoptwtic right vmtiulpr sinus.
A rompetent ndbat vslve. low pulmmary vascularre&tam~
and low left ventrtcutnr md.di&otfc nwmwe were found at
cardiaccatheteriratim in the thre- livini
rho utierwent
a moditled Funtun pmcedure and are Liw welt 1.2 to 5.8 years
Straddling of the mitral valve is an uncommon congenital
cardiac malformation that does not occur in isolation (I-3).
Despite extensive published studies (I-I?) devoted to the
pathologic anatomy. embryology. diagnosis and surgical
management ofthis anomaly, its etiology and morphogenesis
remain poorly understood. It is widely accepted that the
mitral valve straddles the anterior portion of the interventricular septum (2.3.7-12) through a maialignment conoventricular type of ventricular septal defect (13). Almost always.
there is an associated conotruncal anomaly: transposition of
the great atWies or doubie nutlet right ventricle, ofren of Ihe
Taussig-Bing variety (7-12). Freedom et al. (3) observed that
when the mitral valve straddles. the covdition is often
associated with some degree of left ventricular hypoplasia.
yet in some cases the left ventricle is of normal size. The
rwht vetnrtcle is most commonly enlarged and uften hypcrtrophied (3.7.9.12). Cases of straddling mitral vaive with
hypoplasia of the right ventricle and tricuspid valve appear
to be rare 19.14).
We prewn tie clinical. surgical and pathologic findings in
five CBPES
of this rare type of straddling mitral valve with
marked underdevelopment of the right ventricular sinus. AU
live patievs had the following combination of
malformations: dextmcardia. tricuspid stenosis or hypaplasia. hypoplastic right venrricular inflow (sinils). large right ventricular
outflow (infundibulum). subpulmonnry stenosis.conovcntricular type of ventricular septal defect. superoinferior ventricles,
cricscroii atrioventricular (AV) relations and double outlet
right ventricle ofthe infrequent 1S.D.L) type, that is. visccmatrial situs sohtus (Sl. ventricular D-loop (DJ and L-maloasition
of the great arteries tLJ (151. Despite their compkx~cardiac
anatomy, these patients are surgically treatable; hence, the
importance of accuratediagnostic understanding.
straddling
malalignroeot
patients
ptopratirely.
N Am Cuff Cardief 199I;17:1603-12)
cardiac
Study patients. Five patients from the Children’s Hospital, Boston with a straddling mitral valve and hypoplastic
right ventricle form the basis of this study. Three patients
(Cases
3) are alive and were studied by clinical evrduation. two-dlmensianal and Doppler echocardiography, cardiac catheterization and angiocardiography. Several of the
analomic findings in these patients were confirmed during
open heart surgery. The anatomic findings in Cases 4 and 5
wcrc studied at autopsy. Although these two cases were
included in previous publications (16.17) concer?ir.k superoinferior ventricles and double outlet right ventricle, the
findings concerning straddling mitral valve have not been
previously presented in detail.
Echwrdiography.
A complete examination, including
subxiphoid. apical. parasternal and supraslernal views, was
performed in Patients I to 3. The techmque of echocardiographic examination and certain features in these patients
were published previously (I).
Pathology. A detailed study of the heart specimens from
the two patients studied at autopsy was undertaken. The
degree of malalignment between the ventricles and the atria
was quantltated by measuring the angle between the atrial
and the ventricular sepia projected on the frontal plane. The
AV septal angle was measured as described by Van Praagh
et al. (18). Corresponding control measurements were oh.
tained from seven patients with straddling mitral valve and
large right ventricle and nine normal heart specimens from
age-matched patient
Definitions: Straddling mitral v&e was diagnosed when
the mitral valve had chordal attachments on both sides of the
ventricular septum (2.3.7.10). The right ventricular sinus, or
the inflow portion of the right ventricle, is bordered pmximally by the tricuspid valve anulus and distally by the
muscular ring formed by the parietal band. sepral band and
moderator hand (13). The infundibulum or outflow tract
extends between the muscular ring proximally and the
semilunar valve or valves distally (!3).
Statistical analysis. The significance of differences in AV
seplal angles between hearts with a straddling mitral valve
and normal control hearts was determined using the two.
tailed Student’s t test. Values are presented as mcan values
+ SD; a p value < 0.05 was considered significant.
I to
RWSlt.9
Clinicalcharscteristies(Tabte 1). The salient clinical findings, surgical procedures and follow-up data are summarized
in Table
The male/female ratio was 4: I. Cyanosis was
noted at presentation in all. Congestive heart failure was
present initially in one patient (Case 2). who subsequently
developed subpulmonary stenosis. As this patient’s heart
failure resolved, cyanosis became apparent.
Morohoheie characteristiu (Table 21. A diieram of the
relation’ b&en
the atrial and‘the ventricular iepla in the
normal heart and in Cases4 and 5 is shown in r~gure I. The
two-dimensional echacardiographic features from Cases 2
and 3 are presented in Figure 1. Representative angioeardiograms from the same cases are shown in Figures 3 and 4.
Portmonem morphologic findings in the two autopsy eases
are summarized in Table 2. Photographs of the heart specimen from Case 5 are presented in Figure 5. and a diagram of
the heart specimen from Case 6 is shown in Figure 6. Five
cases had similar anatomic features.
1. The heart was in the right chesr with the apex poinfing
10 rhe riphr (thrd is, dextmcardia was present in all) (Fig.
SA).
2. Double mfler right ventricle (&DA}, that is, visceroatrial Sims solitus (9. ventricular D-loop (D) and L-malwshion ofthe great arteries (L) (15) with the aortic valve to;he
left, anterior and superior relative to the pulmonary valve
was found in all. Each patient also had a well developed
subaortic infundibulum (Fig. ZA, 3A. 4A. 5A and C and 6).
The right-sided location of the inferior vena cave and morphologically right atrium confirmed the presence of situs
solilus of the viscera and atria (Fie. 3A and BI.
3. Deficiency of the subpu~mn~ery infu~dibubm. seen
best echocardiaaraphicallv in the subxiohoid views. resulted
in approximation oilhe p&onary and@ieuspid valves (Fig.
2A). Subpulmonary stenosis resulted from “crowding” of
the subpulmonary region between the conal septum anteriorly and the tricuspid valve posteriorly (Fig. SC and 6). This
was best demonstrated echocardiographically in the subxiphoid short- and long-axis views and by selective right and
I,
left ventricular injeciions (Fig. 2A and 43). The main pulmonary artery and branches were well developed (Fig. 4A).
4. Severe hypoplasia of the tricuspid valre and righr
ventricufrrr sinus finjkw) (Fig. 28.3A. 56 and C and 61was
present in all. Selective right atrial injection (Fig. 3A)
showed a right-sided, suuerior and hvw&tic
tricusuid
valve. a smali sinus comp&nt of the &&logically
right
ventricle that was right-sided and superior and a large
left-sided infundibulum (autflw tract). The right ventricle
was right-sided (Fig. 50 (19); hence. D-loop ventricles were
pESe”t.
5. Srmddling o.f the mitral wlve into u lar.w left-sided
subaorric infundibtdwn could be seen in multiple echocardiographic views (Fig. ZCI and by selective left atrial and left
ventricular injections (Fig. 38 and 4AI. The mitral valve
straddled the ventricular septum through 8 malalignment
Figure 1. Diagram illustrating the angle
between the atrial septum (ASI and the
ventricular septum IVS). projected on the
frontal plane (short-axis view of the
heart). Note in Cases 4 tb) and 5 tc) the
marked ctackvnre rotation at the vmtriCkP and ventricular repturn ttw clockwise rotation compared with the normal
heart shown ina). Theoutflow pal oflhe
ventricutw septum (“S, (that is. the reptat band) underlies the mitral valve (MY).
which straddles the venrricular septum
and inserts mm the infundlbulum (In%
LV = left ventricle: RV = right ventricle:
RV In = right ventricular i&w
lsinwl:
TV = tricuspid vatvc.
conoventricular
with
swtum
postenor
(Fit.
type of ventricular
and rightward
septal defect wocisted
malalignment
of the conal
2C. 4A and SC and LX. The anterolatera!
p&lary
m&k
of the left ventricle was absent in two
patients at postmartem examination, with only the postem.
medial papillary muscle grcup being present (Table 2). The
anterolateral commissure of the mitral valve had chordal
attachmenrs 10an infundibular papillary muxle (Fig. 5D). In
Case 5. a third mitral valve commissurc was present and the
mitral valve had three leaflets (Fig. 6). This accessory
commirsure should not be confused with a cleft in the
anterior leaflet of the mitral valve. The chordae tendineae of
this commissure converged into a single focus of insertion on
the ventricular septal crest. In contrast, in a cleft mitral
valve. the churdae ieddineae 8; each anterior leaflet comimnent typically attach to a different papillary muscle.
CGG
m7.m
As
Figure 2. Two-dmlcnrionid cch”c.mrdi”gnqhic
U,l.lr*E,E”l,lC~
of5trad-
dlinp mimal valve wh hypoplwic r~pbf ve~riclc. A. Palirnl ?.
Subriphoid rhort&
view ?hnwmp were narmwmg of the rubpul.
monary ani brluecn the hypnpbwc fncuwd valve (TV1 posteriorly
and tbc eonill \cptum ,armwbcad, anrenorly Now the double oude!
neht vemnclc wh a well developed wbaortic infundihulumOnll and
absent rubpulmonary infund~hulum.permitting Pulmonary valve lo
tricurpid valve contmvity. A _ amenor: A0 _ aona: PA = pulmonary
anery: S = wpcrior. 8, Patient 3. Subxiphoid long-ax< view showing
the markedly hypopla<lic rncurpid valve and righI ventricular WI
sinus onented from right IKi ruperiody 10 lcn inferiorly The large
left.rided infundlbulum (InO is wpamtec8 from the right ventricular
sinusby Ihe septalband lopensrrowbwdadl
and the infundihvlarseptum
kiangle). The left venfncle ILW is righladed and inferior. Aona (Ao)
is l&sided with a well dcvsloped rubaonic cows, PIS = pslerosup&r. RA = nsht atrium. C. Same padem Subniphoid long-axis
view. scanningpo~lenorly rhowng the mitral valve (MY) straddling
the ventricular nepmm 6) and inserting into the large leWded
infundihulum (Inf) throwh a conovenldcular malalignment type of
venbicular septal defect (between the vcntrieular septum below and
Ihe cnnal septum Iarrowhead] above).
Figure 3. Angiocardiagramfrom Case 3. A, Selective right atrial
(RAI injection. postemanterior projection. Note the hypaplanic
tricuspid valve (TV1 and right ventricular sinus (RV In) and large
IeWided infundibulum IInD. The tricuspid valve is oriented from
right superiorly to lefi inferiorly. 8, Selective left atrial (LA)
injection. posteroanterior projection. The mitral valve (MV) straddles the ventricular seplum through the ventricular septal defect
WSDI inlo the len-sided infundibulum. AO = aorta; Inf Apcx =
apex of the infundibulum: LV = left ventricle; PV = pulmonary
vein: WC = superior vena cave.
6. B~pcroinferiorvenrricles
wirh crisscrossAV relations
~twe prominenr featrrres in allfivecam. Echacardiographically, these findings could be seen by scanning in an apical
or subxiphoid four-chamber view. The left-sided and posterior mitral valve was oriented from left pustem~upen~rly to
right anteroinferiorly (Fig. ZC). The hypoplastic right-sided
and anterior tricuspid valve was oriented from right to left
(Fig. 281. Selective left ventricular injection showed the
semihorizontal position of the ventricular septum. with the
left ventricle being inferior (Fig. 4A and B). The right atrial
to right ventricular inflow axis pointed anteriorly, inferiorly
Figure 4. Angiocardiogmm from Case 2. A, SelectiveIen
ventricular itiection. left anterior abbque projection. diastolic frame. The mitral valve WV) opens mm both the
infundibulum (In0 and left ventricle.The a~rticvalve IAo V)
is anteriorand has a well-developed subaanic infundibulum.
Note the normal size of the main pulmonary artery ,MPA,.
VSD = venwicular septal defect. B, Same projrcrion 8s A.
synolic frame. The wntricular peplumIVSI 1ssemihorizontal
andthe left ventricle,I-“, is inferior. Nate the subpulmonary
stenosis(Sub PSI.
and leftward (Fig. 3A); the lefl atriai IO left ventriculer axis
pointed anteriorly. inferiorly and rightward IFig. 39). This
created the appearance of crisscross AV relations (16.1921). The AV septal angle in Cases 5 and 6 was 150”(Table 2).
reflecting major clockwise rotation (viewed from the apex) of
the ventricular septum relative to the normally positioned
atrial septum (Fig. I).
Hemedynamic data. Severe subvalvular pulmonary ctenosis was associated with well developed pulmonary arferies. normal pulmonary anery pressure and low pulmonary
vascular resistance in a:1three living patients. Left ventricular end-diastolic ~ressurc xx 8 and I2 mm HP m Cases 2
and 3. respectively. and a competent mitral valve wa*
documented in all. On the basis of the aforementioned
anatomic and hemodynamic data. all three patients were
considered 10 be approprnte candidates for a modified
Fontan operation.
Surgical management. A systemic to pulmonary aflery
shunt was performed in four of the five patients LOimprove
pulmonary blood Row and relieve cyanosis (Table I). The
three living patients ICases I to 3) underwent a modified
Fcmtan operation at 2. 5 and 8.5 years of age. respectively.
In Caser I and 2. an atriopulmonary anastomcsis was
performed I??). In Case 3. the modified Fontan procedure
cunristed uf a cavopulmonary anastomosis (23). All three
pwn~s had an uncomplicated postoperative course and are
acyanohc and doing well 2.2 to 5.R years postoperatively.
Discussion
Morphologic eonsidet’ations. The cases described in lhir
wdy xhere a distinctive and cofisntem pattern of congenital
cardiac malformation,. Tbc hallmarks of this entity are
\rraddling of the mitral valve associated with severe hypoplari;, of the right ventricular sinus and tricuspid valve,
with a large infwdibulum (outflow chamber) and marked
malposnion ofthe ventricles r&live to Lheatria. Ventricular
malposmon ts associwed with extreme AV septal malalignmcnt rewldng in superoinferiar ventricles. crisscross AV
rel&ms and dexlrocardia.
Co,u,mrr;.ro,rwith rhe ~umtew~~ rype of srraddli% mitral
wlw. This type of mitral valve straddling with hypoplastic
right ventricular sinus is quite different from the more
common and better known form of slrdddlinp mitral valve. in
Flpre 5. Heart and lung specimen from
Case 4. A, External view as seen from the
front. The ventricular apex points rightward. indicating dextrocardia. The rightsided morphologically right atrium MA)
signifies atrial rims sol&us. The right YCP
tcicular infundibulum W in0 is left-sided
and the morphologically left ventricle (LV)
is righl.sidcd. The a-ma (Aol is l&sided
and aaerior relaive to the righl-sided and
posterior main pulmonary artery (PAI. Note
the well developed left pulmonary artery
(LPA). B, Opened right atrium IRA) rhowiw the hypaplastis and superior tricuspid
valve (TV). 1VC = inferior vena cave. WC
= superior “ena cava.
Figure 5. C. Opened right venlricle. The rricuspid valve (TV) is hypoplastic. right-sided
and superior and opens into the markedly
hypop,ar,ic ri&* “enlricular &;““I ,R”,. The
mitral valve (WI rrmddles into the large
left-sided infundibulum IRV inn. The pulmo.
nary valve WI is “wueezcd” be~vcen the
“\‘u,
Figure 6. Diagram illustrating Ihc heart specimen from Care 5.
Arrowhead = conal septum: LAA = left atrial appendage: RAA =
right ntrial appendage:
other abbreviations
8s in Figure 5.
which the right ventricle is well developed and often hypertrophied. indeed. th majority of previously published stttdies (2,3,7.9,11,12.24.25)
of slraddline mitral valve belonp: to
this anatomic type. To compare and contrast the anat&tttc
and the AV reptal angles in the cases of straddling
mitral valve having a hypoplsstic right ventricular sinus with
those having a well developed right ventricle, we summarized the anatomic fealures of sevw heart specimens with
straddling mitral valve and large right ventricle in Table 3.
The degree of AV neptal malaliinment in the compatison
group (straddling mitral valve with large right ventricle) was
smaller (44.3” t 25.6”; range 0 to 75”) than that in our two
autopsy eases (150’1 but significantly greater than that in the
nomtal control heart specimens (4” e 3”) (p < 0.005) (Table
3). These data suggest that the degree of ventricular malpzsition in cases with straddlise mitral valve with hypoplastic
right venlricle, dexlrocardia and ctisscross AV relations is
much greater than in cases wilh the common type of straddling mitral valve with a well daveloped right ventricle and
levocardia.
Crisxross AV rPlarions. The appearance of crirscross
AV relations in our cases is a chsracteristic and prominent
feature. There ewes. in tact, constitute a specific type of
crisscross AV relation. as oointed out bv Marina et al. 01
(their type 2). The import&e
of venttic~lar ma;posit&in
the morphogenesis of crisscross AV relations is ehetttplit%d
by Case 4 (Fig. SC); the right anterior surface of the
ventricles is the surface that normally is inferior or diaphragmatic. The inferior or diaphragmatic surface ofthe ventriclcr
in Case 4 is the surtace that normally is left and anterior. If
one rotates Fiaure SC W counterclockwise, the right ventticular sinus a; influ tract and the infundibulum o~outtlow
findings
tract look much more normal. Note that 90” countcruluckwise rotation results in a leftward-pointmg apex Ilevocxdral.
thus “curing” the patient’s dextracardia. The infundlbuioventricular part of the heart has undergone approximately
90’ of abnormal dextrorotation (compared with normal
D-loop ventricles).
T/w marked ventricrrlnr malpo,iriun I.> rhu P>IYI<Y of
so-called crisscross AV relod>“s ,211 mJ has scvcml rmportam seqwlae: the heart sit9 on what normvtty IS its amenor
surface; the tricuspid valve and right ventricular smus are
very superior: the infundibulum is very inferior. reaching
down to the diaphragm and underlying the mitral valve.
making possible straddling of the mitral valve mto lhe
infundibulum; what looks like the anterior descending cownary artery on the right and aaterior ventricular surface is m
fact the posterior descending coronary anew emerging
between or close to the AV valve-: and what loakc like the
posterior dewending coronary arwy coursin; on the dlaphragmalic surface of the ventricler IS really the anierw
descending coronary artery. which emerges between or
close to the semilunar valves.
Several cases with straddlinp mimd wdw nnd small righr
wnrricle were previously idcntijcd (7.9./0./4.22~.
but they
were not distinguished from other fwss of straddling mitral
valve. Patient in the series of Muster et al. (9) had tricuspid
stenosis. small right ventricle and subpulmonary slenosis
without dextrocardia or suwoinferior
ventricles. Nakada et
al. (14) described a aucces~ful modified Fontan operatton m
a 5 year old girl with the same anatomic features as in our
cases. This iE probably the first repan of this entity and 11s
successful surgical repair. Several cases with tricuspid
atresia and mitral valve straddling were previously reported
(7.10.26). but there patients did not have dextrocardia.
sttperoittferior ventricles or crisscross AY relation% as did
our patients.
De~erOptttenIal consider&ions. Our data suggest tlut major malposition of the highly mobile infundibuloventricular
-part of-the heart retative IC rhe campantivety
fined atria
plays a major role in the morphogenerir of straddling mitral
valve (27). Hypoplasia of the right ventricular sinus is
certainly associated with ventricular mdlposition and dextrocardia in our caseS and may even play a ;ole in the causation
of these anomalies. It should be recalled that the straight
heart robe starts to loop 10 the right tD_toaping) during
Streeter’s horizon to I20 to ?? days of gestationI. During lhat
period, the left ventricle develops earlier and fater than the
right ventricle. When D-looping is completed (horizon I I.
days 22 to 24). the ventricular apex paints to the right lthat
is. dextrocardia is a normal developmental ytagel 1281.
Subsequent growth and development uithe right ventricular
sinus are associated with leftward movcmcnt of xhe ventricular apex until levocardia is achieved by horizon 18 (36 to 38
days) (281. Hence. underdevelopment ofthe right ventricular
sinus between horizons I I and I8 may result in dextrocardra
and ventricular malalignment relatwe to the atria. When the
malposed infttndibulum underlies the developing mitral
I
YBIVC. the antenor mitral leaRet can waddle the venoicular
siplum through the opeq bulbovcntricular foramen and
insert into the infundihulum. as is seen in our study case,.
The origin of right ventricular sinus hypoplasia in OUT CB~P
remains unknown.
Diagnortieconsideratiom.
Yoshida et al. (4) were the first
10 dexribe the M-mode echwxdiographx
daagnosls of
straddling mitral YIIY~. Although the mitral valve and it?
tensor apparatus can be visualized by cineangiocardiography
(3.9.29l. adequate films may he difficult to achieve in some
cares (3). Two-dimensional echocardiography appears IO be
the optimal diagnostic technique for imaging the anatomic
details of a straddling AV valve. permitting excellent visuabzetion of the l&err
and tensor apparatus tt.?.X-32).
Mitral and tricuspid valve funnian can he assessed by
Doppler echacardiapphy
with color Row mapping. which
is highly sensitive for detection of valvular rtenos~s or
regurgitation. Cardiac whetrri?;ltinn.
however. IS imporrant to the preoperative assessment of tiiese patierds before
o modified Fontsn operation is performed.
Surgirdl considerations. Clinical presenraucm with cyanocis and decreased pulmonary blood Row was a common
fezturc in our study casec (Table I). Hence. an early
systemic to pulmonary artery shunt may be necessary in
some patients with markedly decreasedpulmonary blood
Row, When both ventticlcsare well &eloped.
biventncolar
repair 15 sometimes feeastble (5.61. However. in our three
patients who were diagnosed after 1978. the right ventricular
binus was considered to he too small to allow bivemricular
repair. The combination of low pulmonary artery pressure
and rcsistancc, good-sized and undistorted pulmonary arterie$. a competent mitral valve (despite straddling) and normal
left ventricular end-diastolic pressure renders there patients
good candidates
a modified Fontan operation. Because of
the encouraging surgical results in our three patients. we
bclicve that a modified Fontan operation is currently the
treatment of cnoice far this complex form ofcongenital heart
disease.
for
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inversion {S,D.l): a newly recognized form of congenital heart disease.
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