Cardiology in the Young (2011), 21, 299–302
r Cambridge University Press, 2011
doi:10.1017/S104795111000199X
Original Article
Atrioventricular septal defect with coexisting tricuspid atresia
Vera Demarchi Aiello,1 Jorge Yussef Afiune,1 Samuel Menahem,2 Robert H. Anderson3
Heart Institute, University of São Paulo Medical School, São Paulo, Brazil; 2Monash Heart, Monash Medical
Centre, Monash University, Melbourne, Australia; 3Institute of Child Health, Great Ormond Street Hospital,
London
1
Abstract We describe two infants having an atrioventricular septal defect in the setting of a double inlet
atrioventricular connection, but with patency of the left-sided valvar orifice and an imperforate right-sided
valvar component, and a further case with atrioventricular septal defect and an imperforate Ebstein’s
malformation, all producing the haemodynamic effect of tricuspid atresia. We make comparisons with
the arrangement in trisomy 16 mice, in whom deficient atrioventricular septation is seen at times with the
common atrioventricular junction exclusively connected to the left ventricle, a situation similar to that seen in
two of our infants. We also review previous reports emphasising the important theoretical implication of the
findings despite their rarity.
Keywords: Double inlet left ventricle; imperforate atrioventricular valve; ostium primum
Received: 15 September 2010; Accepted: 1 December 2010; First published online: 25 January 2011
P
ATIENTS
WITH
DEFICIENT
ATRIOVENTRICULAR
septation and common atrioventricular junction
typically have the common junction shared
between the ventricles, although the junction can
be guarded by a common valvar orifice, or separate
orifices for the two ventricles. Occasionally, nonetheless, such a common atrioventricular junction may
be exclusively connected to one or another ventricle.
When the junction is exclusively connected to the left
ventricle, the right atrium can be blind-ending, as
with typical tricuspid atresia, but yet communicating
with the left atrium through an ostium primum
defect.1 Such cases raise interesting questions concerning the morphology of the patent left atrioventricular valve. We describe two infants having this
combination in the setting of a trifoliate left-sided
atrioventricular valvar orifice, comparing the situation
with the findings reported in mice with trisomy 162
and a third case with deficient atrioventricular
septation and imperforate Ebstein’s anomaly.
Correspondence to: Dr V. D. Aiello, Laboratory of Pathology, Av. Dr Enéas C.
Aguiar, 44, São Paulo 05403-000, Brazil. Tel: 155 11 3069-5252; Fax: 155
11 3069-5279; E-mail: vera.aiello@incor.usp.br
Case reports
Case I: A male infant aged 2 months was admitted
with a history of cyanosis since birth. The echocardiographic diagnosis was a double inlet left
ventricle, concordant ventriculo-arterial connections, and a restrictive ventricular septal defect
(Fig 1a). The gradient between the ventricles was
measured at 76 millimetres of mercury. The infant
was referred for construction of a Blalock–Taussig
shunt, which produced an immediate improvement
in the saturations of oxygen, but he died on the first
post-operative day having developed bradycardia
followed by cardiorespiratory arrest.
Autopsy examination revealed the usual atrial
arrangement and relatively normal venous connections, albeit with a persistent left superior caval vein
draining to the right atrium through a dilated
coronary sinus. There was an additional separate
connection of one hepatic vein to the right atrium.
A rhabdomyoma, 0.4 centimetre in diameter, was
also seen in the right atrium, protruding on its
epicardial surface lateral to the orifice of the inferior
caval vein. When examining the inferior aspect of
the heart, the inferior interventricular artery was
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Figure 2.
The outflow tract of the left ventricle (a) shows the anterior aorta
(Ao) and restrictive ventricular septal defect (VSD). The
incomplete right ventricle (b) gives rise to the pulmonary trunk
(PT). There is a small rhabdomyoma (arrow heads) on the
endocardial surface, in a sub-pulmonary position.
Figure 1.
The four-chamber view of our first case (a) shows malalignment
between the atrial and ventricular septa (asterisks), with an effective
double inlet left ventricle. LA 5 left atrium; RA 5 right atrium;
RV 5right ventricle; LV 5 left ventricle. The right and inferior
view of the heart (b) shows the inferior caval vein (ICV) and the
adjacent rhabdomyoma (arrow heads), the dilated right atrium,
and the origin of the displaced posterior descending coronary artery
(*). Opening the right atrium (c) shows the dilated orifice of the
coronary sinus (CS) and mostly the muscular floor. The opened left
atrium (d) shows the ‘‘primum’’ defect and patency of the oval
foramen (arrow heads). The inlet of the left ventricle shows the
‘‘cleft’’ of the left-sided atrioventricular valve (arrow).
noted to be displaced laterally, marking the
boundary of an incomplete right ventricle (Fig 1b).
The atrioventricular junction was common, but due
to the marked malalignment between the atrial and
ventricular septa, the right atrium was connected
mainly to the left ventricle. Its floor was mostly
muscular, a small anterior area floored by a valvar
membrane separating the atrial cavity from the
cavity of the left ventricle. (Fig 1c) The atrial
septum itself was defective, having a large ostium
primum defect in addition to a patent oval foramen.
The left-sided atrioventricular valve was made up of
three leaflets, with one of its commissures pointing
to the top of the inlet component of the muscular
ventricular septum (Fig 1d). The inferior leaflet was
firmly adhered to the ventricular septum, whereas
the superior one was attached to the septal crest at
the level of the septal commissure, but floated
anteriorly, straddling a restrictive ventricular septal
defect, and opening in part in an incomplete right
ventricle. The aorta, which arose from the left
ventricle, was unwedged relative to the atrioventricular junction. The pulmonary trunk arose from
the incomplete right ventricle (Fig 2b). We
identified two additional small rhabdomyomas, one
bulging in the sub-pulmonary region (Fig 2b), and
the other on the epicardial surface of the left
ventricular free wall. The arterial duct was patent
but restrictive. A patent modified Blalock–Taussig
was present between the right subclavian and right
pulmonary arteries.
Case II: An antenatal diagnosis of complex
congenital cardiac disease had been made in a foetus
conceived via an in vitro fertilisation. Delivery was by
caesarean section under spinal anaesthesia because of
failure to progress and meconium staining of the
liquor. The infant was satisfactory at birth, weighing
nearly 4 kilograms, and registering Apgar scores
of 9 at 1 minute and 5 minutes.
On examination, the infant was found to be well,
with normal pulses, but a soft precordial systolic
murmur. The electrocardiogram showed sinus
rhythm, a frontal axis of 1808, probable biventricular hypertrophy, and widespread inversion of
the ST segments and T-waves over the precordial
leads. The initial chest X-ray showed a heart of
normal size, and with normal pulmonary vasculature. Transthoracic cross-sectional echocardiography
confirmed the prenatal diagnosis. An atrioventricular septal defect was observed, with a large
primum component (Fig 3a and b), and the atrial
septum was malaligned relative to the ventricular
septum, being deviated to the left. The right-sided
component of the common atrioventricular valve
was imperforate, while the left-sided component
was trifoliate, a zone of apposition being noted
between its bridging leaflets, but with only mild
incompetence. The pulmonary trunk arose from
the dominant left ventricle and was unobstructed.
The aorta arose from the small and incomplete
right ventricle. It narrowed significantly when
traced to the transverse and distal arches, but the
descending aorta was of normal size, being fed
Vol. 21, No. 3
Aiello: Ostium primum with tricuspid atresia
301
Figure 3.
The apical four-chamber view in our second case (a) shows
‘‘normal’’ left-sided component of the common AV valve, with the
arrow pointing to the imperforate right-sided component of the
common AV valve. LA 5 left atrium; RA 5 right atrium;
RV 5right ventricle; LV 5 left ventricle; AVSD 5 atrioventricular septal defect; LAVV 5 left-sided component of common AV
valve. The subcostal view (b) confirms the findings.
through an arterial duct of moderate size, which
permitted bidirectional shunting. A left superior
caval vein drained to the right atrium through the
coronary sinus.
The infant was transferred to a tertiary surgical
centre on the second day of life, having been
maintained on an infusion of Prostaglandin. On her
third day of life, the proximal pulmonary trunk was
connected to the aorta and the aortic arch repaired.
The atrial septum was resected and a modified
right-sided Blalock–Taussig shunt constructed.
After the initial surgery to the aorta, a significant
gradient persisted, and therefore the connections
were reconstructed a second time. Post-operatively,
the infant was troubled by excessive pulmonary
flow, and required a prolonged period of continuous
positive airway pressure, also requiring ongoing
diuretics and an inhibitor of angiotensin converting
enzyme. She developed paralysis of the left vocal
cord, and initially was fed via gavage. She eventually
settled, and was able to be discharged home,
gaining weight satisfactorily. On review, increasing
cardiomegaly led to the discovery of increasing
atrioventricular valvar regurgitation. Further surgery, performed in two stages, consisted of initial
repair of the incompetent atrioventricular valve and
further revision of the aortic arch. After a further
2 months, she underwent a successful bidirectional
cavopulmonary connection.
Case III: A 3-year-old female patient previously
palliated by construction of a modified Blalock–
Taussig shunt in the neonatal period was referred to
hospital with fever and bronchospasm. Despite
therapy with antibiotics, she developed septicaemia
and died three days after admission. A previous
echocardiographic study had revealed isomerism of
the right atrial appendages with mixed biventricular
Figure 4.
The right-sided cardiac chambers in our third case (a) show a
huge atrial primum defect and an imperforate Ebstein’s malformation
of the right-sided component of the atrioventricular septal defect
(asterisk). There is complete fusion of the bridging leaflets on the crest
of the ventricular septum (open rectangle). The left atrioventricular
valve is trifoliate, with the zone of apposition between the left
ventricular components of the bridging leaflets pointing towards the
outlet (‘‘cleft’’- white arrow). Further examination of the left-sided
cardiac chambers (b) reveals that the left atrioventricular valve has
two orifices. The arrow shows the zone of apposition between the
superior and inferior bridging leaflets, whereas the arrowheads show
the opening of the second orifice, located between the superior bridging
leaflet and the mural leaflet. Opening the right ventricle (c) shows a
double outlet with a right-sided aorta (Ao). The pulmonary trunk
(PT) is supported by a complete muscular infundibulum. The asterisk
shows the outlet septum.
atrioventricular connections, right-handed ventricular topology, atrioventricular septal defect with
Ebstein’s anomaly of the right-sided valvar component, and double outlet right ventricle.
At necropsy, we confirmed the diagnosis of
right isomerism of the atrial appendages, with the
right pulmonary veins connected to the right-sided
atrium. The atrial septum was deficient, showing
a huge primum defect (Fig 4a). There was an
atrioventricular septal defect with separate valves
and complete plastering of the right-sided component of the inferior bridging leaflet against the right
ventricular inlet. The right-sided component of the
superior bridging leaflet lacked tendinous cords,
and was fused with the inferior bridging leaflet
to produce an imperforate Ebstein’s malformation (Fig 4b). The left atrioventricular valve was
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trifoliate, albeit with dual orifices (Fig 4b). A small
interventricular communication was found below
the superior bridging leaflet. Both arterial trunks
emerged exclusively from the right ventricle (Fig 4c),
the aortic valve being in fibrous continuity with the
superior bridging leaflet, and the pulmonary valve
supported by a muscular infundibulum. The atrial
and ventricular septa were aligned.
Discussion
The morphology of atrioventricular septal defects
with a common atrioventricular junction has been
extensively studied in humans. The phenotypic
feature is now recognised as the commonality of the
atrioventricular junction, with variation depending
on the presence of a common or separate valvar
orifices, variation in the level of shunting across the
atrioventricular septal defect, and the balance
between the atrial and ventricular chambers. The
presence of malalignment between the atrial and
ventricular septa can also provide the potential for
a spectrum from biventricular to univentricular
atrioventricular connections.
In infants born with Down’s syndrome, the most
frequent presentation is that of a common valve
with interatrial and interventricular communications and balanced ventricles.
Owing to the homology between the trisomic
chromosomes, the mouse with trisomy 16 has long
been recognised as a potential genetic model for
humans with trisomy 21. The cardiac malformations
typically seen in the mice, however, are markedly
different from this typical morphology seen in man.
A frequent arrangement in the mice, nonetheless,
with a common atrioventricular junction exclusively
connected to the left ventricle, is comparable to the
anatomy observed in two of our patients.
This anatomy, although unexpected in the global
sense, was observed in a relatively large series of
13 human cases reported by Van Praagh et al.1
In nine of their cases, the arrangement of the
atrioventricular junction was as described in our
first two patients, and in the mouse hearts. Of the
remaining cases, three had an imperforate Ebstein’s
malformation of the right component of the
common atrioventricular valve, as in our third case.
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The final case showed severe stenosis of the right
atrioventricular valvar orifice. At least one of their
cases could be seen to exhibit malalignment of the
atrial septum, thus resulting in a double inlet left
ventricle. Other series of hearts exhibiting tricuspid
atresia are reported to show coexistence of ‘‘ostium
primum’’ atrial septal defects. In one such series,3 all
six cases were reported to show a ‘‘cleft’’ in the left
atrioventricular valve. Nonetheless, in one of the
cases reported by Williams et al,4 and in one from
the series reported by Van Praagh and colleagues,1
the mitral valve was described as being ‘‘normal’’.
An examination of the photographic documentation
in the article by Anderson et al3 demonstrates in at
least one case the presence of a double inlet left
ventricle, as in our first case.
It is the use of ‘‘tricuspid atresia’’ in the
description of these anomalies that creates potential
problems. The common atrioventricular junction
lacks a definitive mitral component, although the
right half of the common valve is more akin to the
normal tricuspid valve. As is shown in one of our
cases, and in those reported by Van Praagh et al,1
nonetheless, the right side of the common valve can
exhibit Ebstein’s malformation. The haemodynamic
effect of the imperforate valve, furthermore, produces the clinical picture of tricuspid atresia. It is
the term ‘‘absence of the right atrioventricular
connection’’ that is inapplicable. The atrioventricular connection is certainly univentricular, but
with a double inlet via a patent left valve and an
imperforate right valvar component.
References
1. Van Praagh S, Vangi V, Sul JH, et al. Tricuspid atresia or severe
stenosis with partial common atrioventricular canal: anatomic
data, clinical profile and surgical considerations. JACC 1991; 17:
932–943.
2. Webb S, Brown NA, Anderson RH. Cardiac morphology at
lat fetal stages in the mouse with trisomy 16: consequences
for different formation of the atrioventricular junction when
compared to humans with trisomy 21. Cardiovasc Res 2007; 34:
515–524.
3. Anderson RH, Wilkinson JL, Gerlis LM, Smith A, Becker AE.
Atresia of the right atrioventricular orifice. Br Heart J 1977; 39:
414–428.
4. Williams HJ, Tandon R, Edwards JE. Persistent ostium primum
coexisting with mitral or tricuspid atresia. Chest 1974; 66:
39–43.
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