Download Uncommon Conal Pathology in Complete Dextrotransposition of the

Uncommon Conal Pathology in Complete
Dextrotransposition of the Great Arteries
with Ventricular Septal Defect*
M . Quero l i d n e z , M.D., and V . Pdrez Martinez, M.D.
The anatomic and clinical findings are reported in five
cases of complete dextrotrausposition of the great arteries with an uncommon and varied c o d pathology, different from the usual conal architecture of classic complete dextrotranspositionof the great arteries. The following points summarize the most important findings: (1)
The ventricular septal defect was due to a positional
anomaly or a deficiency of the conal septum in all of
these cases. (2) The conal free wall distribution was different from that designated as characteristic of clansic
complete dextrotraqmWon of the great arteries, ie, in
three cases, a persistence of the subpulmonary conal free
wan preventing the pulmonary-mitral fibrous continuity.
(3) A positional deviation of the conal septum inside the
conus resulted in obstructive anomalies of the subpuE
monary outtlow tract in two cases and of the subaortic
in another. (4) There was overriding of the conal septum
of the ventricular septum in two case& (5) In keeping with
item 4, the observation of the pulmonary outflow tract of
three additional cases of classic complete dextrotransposition of the great arteries with intact ventricular septum
sqggesb a possible origin of the fibromuscular subpulmonary sten& in these patients: the abnormal fusion
line between the ventricular septum and a malorientated
conal septum. Some important angiocardiographic characteristica of these cases are also shown. The surgical impHcations of these particular anatomic characteMc8 are
disc&
he conus cordis has long been a cardiac structure
Tin which cardiologists and pathologists have
shown a great interest, and alterations in its morphology and/or position have been recognized in
various forms of congenital cardiac defe~ts."~
Among the main alterations reported are: (1) a
malalignment between the conal and the ventricular septa giving rise, in certain malformative
c o m p l e x e ~ , ~ "a~ ventricular septal defect and an
ovemding of one of the great arteries of the ventricular septum; (2) an unequal partitioning of the
conus by an eccentrically located conal septum resulting in a narrowing of one of the outflow tracts as
may occur in some cardiac malformation^;^^ and
(3) an abnormal reabsorption or persistence of certain areas of the conal free wall, a fact that, for many
authors and for a long time, has been considered of
utmost importance in explaining the changes in the
conal morphology and position found in certain
forms of congenital heart di~ease.'-~-'~'~"'
In this report we consider as complete dextrotransposition of the great arteries only those cases in
which two-thirds or more of the aortic and pulmonary orifices originated in the morphologically and
topographically right and left ventricle, respectively.
The term "conus cordisn applies to the outflow
tracts of both ventricles situated under the semilunar
valves. It derives from the primitive conus cordis
once it has been partitioned by the conal septum and
the portion pertaining to the left ventricle has been
reabsorbed.
The "conal septumn is a muscular septum that
divides the primitive conus cordis in the definitive
aortic and pulmonary outflow tracts. When viewed
from the subaortic outflow tract in cases of complete
dextrotransposition of the great arteries. the conal
septum lies beneath the right and left coronary
leaflets of the aortic valve. For descriptive purposes,
the conal septum may be said to be delimited by
imaginary lines running vertically through the midpoints of the right and left coronary leaflets of the
aortic valve. The subaortic conal free wall is composed of the remainder of the subaortic conus that
lies outside the two imaginary lines.
In most cases of complete dextrotransposition of
the great arteries the conal septum divides the primitive conus cordis in a subaortic and a subpulmonary
conus located over the right and left ventricle, respectively. The subaortic conus is generally well
developed, being muscular all around, as much in
the area of the conal septum as in that of the conal
free wall. Located between an anterior and rightsided aortic valve and the tricuspid leaflets, it prevents the fibrous continuity between them. The subpulmonary conus has been reabsorbed during the
expansion of the conus cordis toward the left ventricle, being muscular only at the region of the conal
septum. A subpulmonary conal free wall is, therefore, absent in the majority of the cases of complete
dextrotransposition of the great arteries, a fact accounting for the fibrous continuity that is found in
most cases between the posterior and left-sided
pulmonary valve and the mitral leaflets. Nevertheless, in some cases of transposition of the great
arteries, a subpulmonary conal f.ree wall may persist,
preventing the mitral-pulmonary fibrous continuity
'From the Servicio de Cardiologia PediAtrica, Clinica Infantil
La Paz, Madrid, S ain.
Manuscript r e c e i v s September 4, 1973; revision accepted
March 26.
Reprint requests: Dr. Quero Jimenez, Clinics Znfantil LA Paz,
Madrid,Spain
CHEST, 66: 4, OCTOBER, 1974
UNCOMMON CONAL PATHOLOGY 411
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which characterizes the cases with classic complete
dextrotransposition of the great arteries. In them,
the subpulmonary conal free wall is composed of the
subpulmonary muscular conus, with the exception of
the region of the conal septum.
In this paper, the term "septal band" has been
used to describe a morphologic feature of the right
ventricular aspect of the ventricular septum characterized by: (1) smooth appearance; (2) a superior
concave border, the posterior end of which receives
the attachment of the papillary muscle of the conus;
and (3) an inferior extremity receiving the medial
end of the moderator band.
In most cases of complete dextrotransposition of
the great arteries there is a normal junction between
the conal septum and the superior concave extremity
of the septal band, the line of fusion between both
structures being sometimes recognizable in heart
tissue of young patients. When a ventricular septal
defect is present, it is most often subpulmonary and
involves the membranous ventricular septum.
In this report, the term "classic complete dextrotransposition of the great arteries" will be reserved
for those cases with the morphologic characteristics
described above, including the spatial relationships
between the ventricles and both great arteries as
stated in the above definitions.
The morphologic characteristics used to define classic
complete dextroh-anspositionof the great arteries were found
in 61 cases (88.4 percent) of a total of 69 cases of this
malformation examined at necropsy in our hospital. They
were lacking in the remaining eight cases (11.6 percent).
The study of five cases of this last group is the main object of
this remrt.
In all five patients an uncommon and varied conal pathology was found, very Werent from the morphologic charae
teristics of classic complete dextrotranspmition of the great
arteries described above.
For the purpose of understanding the specific type of amal
alteration present in every case the following data were
studied: ( 1 ) position and ventricular origin of the great
arteries; ( 2 ) the conal septum and conal free wall; (3) the
septal band; ( 4 ) associated obstructive lesions; and (5)
position and boundaries of the ventricular septal defect.
Particular attention was paid to the relationship between
the septal band and the papillary muscle of the conus, the
moderator band and the anterior papillary muscle. The morphology of the superior, concave, bifid border of the septal
band was considered useful for its recognition. The papillary
muscle of the conus, usually situated on the posterior division
of the superior end of the septal band, was considered a
useful and reliable structure in locating the septal band.
Nevertheless, in some cases, chordae tendinae similar to the
papillary muscle of the conus may be found on the conal
septum, or certain muscular portions of it.
Such a malformation is frequently found in dextmposition
of the anterior extremity of the conal septum which, in these
circumstances, is often prolonged in an anomalous muscle
bundle that extends to the right of the septal band, ending in
the anterior free wall of the right ventricle.17
In these cases with anomalous muscle bundle which may
receive some short chordae tendinae similar to those of the
papillary musde of the wnus and conceal the septal band for
which it may be mistaken, impotCant e m may be made in
the interpretation of the anatomic nature of the ventricular
septal defect.
To avoid mistakes it is necessary to identify the septal
band, looking for it in the right aspect of the ventdcdar
septum of which the septal band is a component, unlike the
above-mentioned anomalous musde bundle, which is more
related to the anterior right ventricular free wall (Fig la).
The pulmonary outeow tracts of three additional cases of
classic complete tramposition of the great arteries with intact
ventricular septa were also studied in order to illustrate a
hypothetic origin of the fibromuscu1a.r subpulmonary stenwis.
subaortic muscular conus (SACFW) separating fibrous tissue
of aortic ( AV ) and tricuspid valves ( TV ) . Obserue anterior
extremity of conal septum ( CS ) ending in anomalous muscle
bundle ( AMB) located anteriorly and to right of septal band
( SB). Note ventricular septal defect (VSD) between conal
septum above and septal band below. APM: anterior papillary
muscle; MB: moderator band; SACFW: subaortic conal free
wall. ( l b lower). Left ventricular cavity showing subpulmonary conal free wall (SPCFW) separating fibrous tissue
of pulmonary ( W ) and mitral valves (MV). Note conal
septum ( CS ) ovemding ventricular septum through ventricular septal defect (VSD). Posterior portion of this defect (mrow 1 ) is subaortic, anterior defect ( a m 2 ) being apparently subpulmonary. There is, however, no direct connection between right ventricle and pulmonary artery due to
interposition of anomalous muscle band (Fig la: AMB)
between. Apparent cleft in anterior mitral leaflet ( ) is only
d a c t u a l tear.
412 QUERO JIMENEZ, PERU MARTINEZ
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CHEST, 66: 4, OCTOBER, 1974
The patient is a four-month-old boy. The external view
discloses the aorta located to the right and slightly posterior
to the pulmonary artery. There is a persistence of the conal
free wall, both below the aorta and the pulmonary artery
preventing fibrous continuity between both semilunar valves
and the atriwentricular fibrous tissue. The conal septum
wemdes the ventricular septum as m case 1, and divides the
conus into two different sized parts: one, a narrower subpulmonary in the anterior and left area of the conus, and the
other, a larger subaortic corresponding to the remaining area
of the amus. The ventricular s e ~ t adefect
l
is limited bv the
superior concave border of the-septal band below, a& the
conal septum and both semilunar valves above. As in case 1,
the anterior end of the conal septum ends in an anomalous
muscle band situated anteriorly and to the right of the septal
band.
FIGURE 1 ( c , upper). General arrangement of great arteries, conal free wall (CFW), canal septum (CS) and superior
border of septal band (SBSB) of case 1. Aorta (Ao) arises
almost entirely from right ventricle located to right and
slightly posterior to pulmonary artery (PA), which originates
from left ventricle. Posterior conal free wall (CFW) prevents
fibrous continuity between great arteries and atrioventricular
valves (TV and MV). C o d septum ovemdes superior
border of septal band, crossing ventricular septal defect (dark
shadowed) from right ventricle, where anterior extremity
ends in anterior conal free wall, to left ventricle, fusing with
posterior conal free wall. Note how hole between two branches
of septal band is divided by conal septum into two ventricular
septal defects, posterior one in relation to aorta and an anterior one to pulmonary artery. A: anterior, P: posterior, R:
right, L: left. (Fig l a and b reproduced with permission of
Coeur ).
The patient is a two-month-old boy. In the external examination, the aorta is to the right and slightly posterior to the
pulmonary artery. The internal findings reveal both the entire
subaortic and subpulmonary conal free wall and the conal
septum and there is a lack of fibrous continuity between the
aorta and the tricuspid and the pulmonary and mitral valves
measuring 2 and 4 mm, respectively ( Fig la, l b ) The conal
septum ovemdes the interventricular septum ( Fig lc), with
its posterior and anterior junctions with the conal free wall m
the left and right ventricle, reqectively. The anterior end of
the conal septum terminates in a muscular bundle located to
the right of the septal band, for which it might be mistaken.
The ventricular septal defect, partially obstructed by the
ovemding conal septum (Fig lb), is situated above the
superior concave border of the septal band and below the
conal septum ( Fig l c ) .
.
CHEST, 66: 4, OCTOBER, 1974
The patient is a three-and-one-half-month-oldboy. The
aorta is anterior and slightly to the left of the pulmonary
artery, and there is a persistence of subaortic and subpulmaary conus (Fig 2u. 2b). The canal septum has developed
rather posteriorly in the conus, its left end joining the
posterior division of the septal band (Fig 20, 2b). The
posteriorly developed conal septum divides the conus into
two infundibula very different in size, the ro(subpulmonary) portion being mu& smaller than the levoanterior ( subaortic) ( Fig 2b). The limits of the ventricular
septal defect are: the superior border of the septal band
below, the anterior aspect of the conal septum behind, the
aortic semilunar valves (the anterior part of the left coronary
and the posterior part of the noncoronary l e h ) together
with the free wall of the left ventricle above (Fig 2u, 2b).
CASE4
The patient is a one-month-old boy. The aorta originates
anteriorly and to the right of the pulmonary artery. There is a
persistence of the subaortic conal free wall which preventa
the fibrous continuity between the aortic and tricuspid
leaflets. The posterior subpulmonary conal free wall has
disappeared, which allows the fibrous continuity between the
pulmonary and mitral valvular tissue. The conal septum is
incompletely developed, with the superior part of the posterior conal ridge absent. The resulting infundibular ventricular septal defect is small, being limited by the posterior
aspect of the anterior conal ridge in front, the anterior aspect
of the subaortic conal free wall behind, the anterior part of
the coronary aortic leaflet above, and the inferior normally
developed part of the posterior conal ridge below.
The patient is a four-month-old boy. The aorta is anterior
to the pulmonary artery,the subaortic conal free wall is well
developed (Fig 3), and the subpulmonary c o d free wall is
nonexistent, allowing fibrous contact between the pulmonary
and mitral valves. The conal septum is well developed and,
instead of joining the superior extremity of the septal band,
ends anteriorly, in the anterior right ventricular free wall
(Fig 3). The ventricular septal defect is limited by the
superior border of the septal band below and the pulmonary
semilunar valves above (Fig 3). Viewed from the left ventricle, it occupies the region of the anterior smooth component of the ventricular septum. The aortic o u t h v tract is
n a ~ ~ ~and
~ ea dpreductal
,
aortic coarctation exists.
UNCOMMON COWL PATHOLOGY 413
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BSB
FIGURE
3. Right ventricular view of case 5. In this case aorta
(Ao) originated entirely from right ventricleand approximately
two thirds of pulmonary artery orifice connectedJeft ventricle.
Note ventricular septal defect (VSD) locatedbtween the two
branches of superior border of septal band (SB). Note how
conal septum (CS), instead of 6lling hole between two divisions of septal band, ends in anterior wall of' right ventricle,
resulting in a narrowed aortic outflow tract. In case this
dextroposition of conal septum coexisted with subaortic narrowing and aortic isthmus hypoplasia. ( R e p r o d u d with permission of Coeur).
cases 1, 2, 4, and 5 revealed cardiomegaly and increased pulmonary circulation, with a narrow vascular pedicle in cases 1,4, and 5; the heart size and the
pulmonary circulation were normal in case 3, and
the vascular pedicle was not strikingly narrow in
cases 2 and 3.
The electrocardiogram showed an AQRS ranging
between 100' and - 135". There was biventricular
enlargement in cases 1,2,4 and 5. Isolated enlarge
ment of the right atrium and ventricle characterized
case 3. In case 1, "q" waves existed in leads 1 and
aVL.
The cardiac catheterization and angiocardiog-
+
A
FIGURE
2. ( a upper). Note conal septum (CS) joining posterior
division (arrow) of septal band (SB). Posterior conal free wall
(PCFW) prevents fibrous continuity between aortic (AV)and
bicuspid (TV)valves. Boundaries of ventricular septal defect
(VSD) are superior border of septal band below, anterior
aspect of conal septum behind, and aortic valves above. (2b
lower). Note position of aorta (Ao), anterior and somewhat
to left of pulmonary artery (PA). Obseroe, also, how conal
septum (CS), very posteriorly situated, joins posterior division of superior border of septal band (SBSB). Result of posterior location of a n a l septum is narrowing of pulmonary outflow tract in comparison with aortic. Posterior canal free wall
(CFW) persists both beneath aortic and pulmonary valves,
preventing fibrous continuity between semilunar and atrioventricular valves (TV and MV). Observe aorta overriding
ventricular septum (SB). A: anterior, P: posterior, R: right,
L: left.
CLINICAL
FINDINGS
The clinical &dings in the five cases are shown in
Table 1. A brief report of the most outstanding
features follows:
All patients were infant boys, with the age of
death ranging between one and four months. Heart
failure and hypoxemia were present in cases 1, 2,4,
and 5. In case 3, with pulmonary stenosis, hypoxemia was the dominant feature in the clinical
picture.
The plain radiologic examination of patients in
Table I-Main Clinical Findinga i n Five Carer of
Complete Dextrotranapdtion of the Great Arterier,
d t h Ventricular S e p t d Defect
Cam. Age, Sex Clinical
No. Mo.
1
2
Picture
m
X-Ray
ECG
Position of
Great Arteries in
Film
Fin-
~
HF+++ HS+++ AQRS
H+
PC+ + + CVH
-A
7
~
~
p
b
AofromRV:PAfrom
LV; P A and Ao more
pasterior than
nornul: subpulmo-
2
3
4
3
m
m
HF+++ HS++
H++
PC++
VP-HF HS H+ ++ PC I
VP--
4
1
m
6
4
m
nary
mnun
AQRS~OOOAO~IO~RVW~~II
d v u l u plane lowthan normd
&QRB13n0 Ao from both
RAH RVH ventricles. overti*
V8. PA from
LV; Ao anterior
and to left of PA
HF+++ HS+++ A ~ ~ s i i o ~ ~ ~ f ~ ~ m ~ v w i t h
antenor position
H+
PC+ ++ CVH
vp&
PA is not viaruli.sd
HF+++ HS+++ AQRS 1000
H+
PC+++ CVH
VPl
'HF: h e u t failure: H: hypoxemia; HS: h e u t sin:PC: pulmonary cimub
tion: VP: vrrscular pedicle; CVH: combined ventricular hypertrophy;
RAE: right atrial hypertrophy; RVH: right ventricular hypertrophy;
Ao: .art.; PA: pulmonary artery; RV: &ht ventride; LV: ldt ventricle;
VS: ventricular nptum; 1 : decnased or numwed;
:n o d .
414 QUERO JIMENEZ, PEREZ MARTINEZ
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--
CHEST, 66: 4, OCTOBER, 1974
FIGURE6. Left ventricular view of a case with transposition
of the great arteries and intact ventricular septum. Observe
how the overriding conal septum (CS) ends rather posteriorly
in the left aspect of the ventricular septum (VS) instead of
forming the smooth anterior portion of this latter structure.
Note the pronounced fusion line (arrows) between this malorientated conal septum and the ventricular septum. The
continuous deposition of fibrin in this irregularity of the left
septal surface could be the origin of the fibro-muscular subpulmonary stenosis present in some cases of transposition of
the great arteries with intact ventricular septum.
septal defect in cases 3 and 5 was the same as in
cases 1 and 2, with the superior limit the aortic
semilunar leaflets in case 3 and the pulmonary valve
in case 5.
The posterior location of the aortic in relation to
the pulmonary valve (Fig 1 ) in cases 1 and 2 is in
perfect accordance with the smaller dimension of
the subaortic muscle (posterior conal free wall) as
compared with the subpulmonary musculature in
both cases.
The posteriorly situated aortic valve and the lack
of fibrous continuity between the pulmonary and
mitral leaflets in transposition of the great arteries,
are anatomic peculiarities already reported.'"18
Our contribution to previous studies1518 was not
included in the present report.
The angiocardiographic demonstration of a posteriorly located aortic valve, as reported previously,18 and a subpulmonary muscle bundle (Fig 4),
was possible in case 1. However, they do not invalidate the diagnosis of transposition of the great arteries provided that two-thirds or more of the aortic
and pulmonary orifices originate from the right and
left ventricle, respectively.
The peculiar location of the conal septum in case 3
(Fig 2) accounts, in our opinion, for the most striking origin and position of the great arteries. In fact,
it is interesting to note that in the complete dextrotransposition of the great arteries (the pulmonary
artery originated entirely from the left ventricle and
the aorta, although ovemding the ventricular s e p
tum, emerged predominantly from the right ventricle) the aortic valve was anterior and somewhat
to the left of the pulmonary valve.
Considering the angiocardiographic features of
case 3, one could suspect that both great arteries
originated predominantly from the left ventricle
(Fig 5b). This was a false impression obtained by
examining only this angiocardiographic projection,
but a careful observation of the frontal view and the
heart specimen showed that the aorta, although
overriding the ventricular septum, originated p r e
dominantly from the right ventricle.
It is'worthwhile to note how the conal septum has
developed eccentrically inside the conus, its growth
more anterior and posterior than normal in cases 2
and 3, respectively. Considering the different location of the pulmonary artery in case 2 (anterior)
and case 3 (posterior), it is easily understood how
the eccentric growth of the conal septum resulted in
pulmonary stenosis in both cases.
Unlike the common forms of classic complete
dextrotranspositionof the great arteries in which the
ventricular septal defect is subpulmonary, the latter
lesion was simultaneously subpulmonary and subaortic in cases 1and 2 ( Fig 1), and only subaortic in
case 3 (Fig 2). We wonder whether in these cases
the surgical techniques aiming to re-establish the
continuity between the left ventricle and the aorta1@mwould be more appropriate than the Mustard procedure.
An enlargement of the ventricular septal defect
enabling the re-establishment of the left ventricularaortic continuity by removing the conal septum
musculature, probably should be made in patients
with the anatomic characteristics of cases 1and 2, in
which the conal septum overrode the ventricular
septum obstructing the ventricular septal defect
(Fig 1). The ventricular septal defect in case 4 was
not due to a malalignrnent between the conal and
ventricular septa, but to defective development of
the superior part of the posterior conal ridge.
It is noteworthy that in case 5 a dextroposed
conal septum (Fig 3), resulting in subaortic stenosis,
was associated with a preductal aortic hypoplasia as
happens more frequently in other forms of congenital heart lesions with dextroposition of the conal
septum (double outlet right ventricle, etc). The ventricular septal defect of this patient viewed from the
left ventricle involved, as expected, the anterior
smooth regi0n'O.l' of the ventricular septum.
For years we have been searching for the anatomic basis supporting the statement that the conus in
transposition of the great arteries with an anterior
and right-sided aorta is the mirror-image of the
normal ~onus.~l
By the same reasoning, it would
seem perfectly logical that the orientation of the
conal septum in such cases would also be inverted,
with respect to the normal ones. Although infrequently, in some cases we have observed how the
conal septum overrides the ventricular septum extending from the right ventricle (in which it is
416 QUERO JIMENU, PERU MARTINU
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CHEST, 66: 4, OCTOBER, 1974
FIGURE6. Left ventricular view of a case with transposition
of the great arteries and intact ventricular septum. Observe
how the overriding conal septum (CS) ends rather posteriorly
in the left aspect of the ventricular septum (VS) instead of
forming the smooth anterior portion of this latter structure.
Note the pronounced fusion line (arrows) between this malorientated conal septum and the ventricular septum. The
continuous deposition of fibrin in this irregularity of the left
septal surface could be the origin of the fibro-muscular subpulmonary stenosis present in some cases of transposition of
the great arteries with intact ventricular septum.
septal defect in cases 3 and 5 was the same as in
cases 1 and 2, with the superior limit the aortic
semilunar leaflets in case 3 and the pulmonary valve
in case 5.
The posterior location of the aortic in relation to
the pulmonary valve (Fig 1 ) in cases 1 and 2 is in
perfect accordance with the smaller dimension of
the subaortic muscle (posterior conal free wall) as
compared with the subpulmonary musculature in
both cases.
The posteriorly situated aortic valve and the lack
of fibrous continuity between the pulmonary and
mitral leaflets in transposition of the great arteries,
are anatomic peculiarities already reported.'"18
Our contribution to previous studies1518 was not
included in the present report.
The angiocardiographic demonstration of a posteriorly located aortic valve, as reported previously,18 and a subpulmonary muscle bundle (Fig 4),
was possible in case 1. However, they do not invalidate the diagnosis of transposition of the great arteries provided that two-thirds or more of the aortic
and pulmonary orifices originate from the right and
left ventricle, respectively.
The peculiar location of the conal septum in case 3
(Fig 2) accounts, in our opinion, for the most striking origin and position of the great arteries. In fact,
it is interesting to note that in the complete dextrotransposition of the great arteries (the pulmonary
artery originated entirely from the left ventricle and
the aorta, although ovemding the ventricular s e p
tum, emerged predominantly from the right ventricle) the aortic valve was anterior and somewhat
to the left of the pulmonary valve.
Considering the angiocardiographic features of
case 3, one could suspect that both great arteries
originated predominantly from the left ventricle
(Fig 5b). This was a false impression obtained by
examining only this angiocardiographic projection,
but a careful observation of the frontal view and the
heart specimen showed that the aorta, although
overriding the ventricular septum, originated p r e
dominantly from the right ventricle.
It is'worthwhile to note how the conal septum has
developed eccentrically inside the conus, its growth
more anterior and posterior than normal in cases 2
and 3, respectively. Considering the different location of the pulmonary artery in case 2 (anterior)
and case 3 (posterior), it is easily understood how
the eccentric growth of the conal septum resulted in
pulmonary stenosis in both cases.
Unlike the common forms of classic complete
dextrotranspositionof the great arteries in which the
ventricular septal defect is subpulmonary, the latter
lesion was simultaneously subpulmonary and subaortic in cases 1and 2 ( Fig 1), and only subaortic in
case 3 (Fig 2). We wonder whether in these cases
the surgical techniques aiming to re-establish the
continuity between the left ventricle and the aorta1@mwould be more appropriate than the Mustard procedure.
An enlargement of the ventricular septal defect
enabling the re-establishment of the left ventricularaortic continuity by removing the conal septum
musculature, probably should be made in patients
with the anatomic characteristics of cases 1and 2, in
which the conal septum overrode the ventricular
septum obstructing the ventricular septal defect
(Fig 1). The ventricular septal defect in case 4 was
not due to a malalignrnent between the conal and
ventricular septa, but to defective development of
the superior part of the posterior conal ridge.
It is noteworthy that in case 5 a dextroposed
conal septum (Fig 3), resulting in subaortic stenosis,
was associated with a preductal aortic hypoplasia as
happens more frequently in other forms of congenital heart lesions with dextroposition of the conal
septum (double outlet right ventricle, etc). The ventricular septal defect of this patient viewed from the
left ventricle involved, as expected, the anterior
smooth regi0n'O.l' of the ventricular septum.
For years we have been searching for the anatomic basis supporting the statement that the conus in
transposition of the great arteries with an anterior
and right-sided aorta is the mirror-image of the
normal ~onus.~l
By the same reasoning, it would
seem perfectly logical that the orientation of the
conal septum in such cases would also be inverted,
with respect to the normal ones. Although infrequently, in some cases we have observed how the
conal septum overrides the ventricular septum extending from the right ventricle (in which it is
416 QUERO JIMENU, PERU MARTINU
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CHEST, 66: 4, OCTOBER, 1974
possible to recognize its anterior end) to the left
ventricle in which its posterior end abnormally fills
the hole between the two divisions of the septal
band. This filling is accomplished with the conal
septum extending in a different direction as it normally does, resulting in certain irregularities in the
left ventricular aspect of the ventricular septum
(Fig 1, 6 ) that might well correspond to abnormal
fusion lines between the ventricular septum and the
abnormally orientated conal septum.
It is our tentative supposition that the continuous
deposition of fibrin in these irregularities" could be
the origin of some fibromuscular subpulmonary
stenosis observed in cases of transposition of the
great arteries with intact ventricular septum (Fig
6 ).*
1 Keith A: The Hunterian Lectures. Lancet 2:433, 1909
2 De la Cruz MV, Da Rocha JP: An ontogenic theory for
the explanation of congenital malformations involving the
truncus and the conus. Am Heart J 51 :782, 1956
3 Van Mierop LHA, Alley RD, Kansel HW, et al: Pathogenesis of transposition complexes. 1. Embryology of the
ventricles and great arteries. Am J Cardiol 12:216, 1963
4 Van Mierop LHS, Wiglesworth FW: Pathogenesis of
transposition complexes. 2. Anomalies due to faulty transfer of the posterior great artery. Am J Cardiol 12:226,
1963
5 Van Mierop LHS, Wiglesworth FW: Pathogenesis of
transposition complexes. 3. True transposition of the great
vessels. Am J Cardiol 12:233, 1963
6 Van Praagh R, Van Praagh S: The anatomy of common
aortico-pulmonary trunk ( truncus arteriosus mmunis )
and its embryologic implications. A study of 57 necropsy
cases. Am J Cardiol 16:445, 1965
7 Van Praagh R: What is the Taussig-Bing malformation?
Circulation 38:445, 1968
8 Van Praagh R, Van Praagh S, Nebesar RA, et al: Tetralogy of Fallot: Underdevelopment of the pulmonary infundibulurn and its sequelae. Report of a case with cor
triatriatum and pulmonary sequestration. Am J Cardid
26:25, 1970
9 Van Praagh R, Bemhard WF, Rosenthal A, et al: Interrupted aortic arch: Surgical treatment. Am J Cardid
27:200, 1971
CHEST, 66: 4, OCTOBER, 1974
10 Goor DA, Edwards JE, Lillehei CW:The development of
the interventricular septum of the human heart. Correlative morphogenetic study. Chest 58:453,1970
11 Goor DA, Lillehei CW, Rees R, et al: Isolated ventricular
septal defect. Developmental basis for various types and
presentation of classifucation. Chest 98:482, 1970
12 GOO; DA, Dische R, Lillehei CW: The cono-truncus. 1.
Its normal inversion and conus absorption. Circulation
46:375, 1972
13 Van Praagh R, Van Praagh S: Isolated ventricular inversion. A consideration of the morphogenesis, definition and
diagnosis of nontransposed and transposed great arteries.
Am J Cardiol 17:395, 1966
14 Van Praagh R, Vlad P, Keith JD: Complete transposition
of the great arteries. In Heart Disease in Infancy and
Childhood (Keith JD, Rowe RD, Vlad P eds) (ed 2 ) .
New York, M a d a n , 1967
15 Quero-Jim6nez M, Pkrez-Martinez V, Moreno-Grandos F:
Variantes de D-transposicibn de las grandes arterias
s e g h el tipo y la localizacibn del cono muscular. Descripcibn de 2 casos. Ref Pediatr 9:63, 1969
16 Van Praagh R, P6rez Treviiio C, Mpez Cdllar M, et al:
Transposition of the great arteries with posterior aorta,
anterior pulmonary artery, subpulmonary conus and fibrous continuity between aortic and atrioventricular
valves. Am J Cardiol28:621,,1971
17 Quero Jhdnez M, Castro Gussoni MC, Moreno Granado
F, et al: Transposition des gros vaisseaux. Anatomie
pathologique. Coeur ( No Special) : 177, 1973
18 Moreno Granado F, P6ra Diaz L, Quero J M n e z M, et
al: Hallazgos anathicos en la transposici6n de las
grandes arterias. Irnplicaciones clinicas y embriol6gicas.
Proceedings of the sixth European Congress of Cardiology, Madrid 1972 (in press)
19 Inamura ES, Morikawa T, Tatsuno K, et al: Surgical
considerations of ventricular septal defect associated with
complete transposition of the great arteries and pulmonary stenosis. Circulation 44:914, 1971
20 McGoon DC: Intraventricular repair of transposition of
the great arteries. J Thorac Cardiovasc Surg &1:433,
1972
21 Paul MH, Van Praagh Ft, Van Praagh S: Transposition of
the great arteries. In Pediatric Cardiology (Watson H,
ed ) . Saint Louis, CV Mosby, 1968
22 Shaher RM, Puddu GC, Khoury G, et al: Complete
transposition of the great arteries with anatomic obstruction of the oudow tract of the left ventricle. Surgical
implications of the anatomic -&dings. Am J Cardiol
19:858, 1967
UNCOMMON CONAL PATHOLOGY 417
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