European Heart Journal (1993) 14, 1717-1718

Aneurysm of the interventricular membranous septum with
thrombo-embolism — an indication for surgical repair?
D. THOMAS*, J. SALLOUM* AND G. RANCURELt

* Department of Cardiology, fDepartment of Neurology, Groupe Hospitalier Pitie-Salpetriere, 47 bdde VHopital 75651
Paris Cedex 13 France
KEY WORDS: Aneurysm of the interventricular membranous septum, thrombo-embolism, surgery.
A 40-year-old woman with a significant neurological history presented with right hemiparesia, paraesthesia of the right
upper member and of the hemiface. Computer tomography scanning revealed hypodensity along the right lateral ventricle
which corresponded to the left hemiplegia which had developed when she was 20 years old. Arteriography of the four
cervical axes was normal. Eclwcardiography visualized an aneurysm of the membranous septum free of thrombosis without
ventricular septal defect. The embolism was thought to be ofcardiac origin and a decision was taken to correct it by surgery.
Ten years after surgical repair no other neurological event has occurred.
Introduction
Aneurysm of the interventricular membranous septum
can spontaneously close a ventricular septal defect1'-21.
Complications such as rupture, endocarditis or thrombosis
are unusual'1"1. We report the occurrence of repetitive brain
embolism in a patient with aneurysm of the membranous
septum. Ten years after surgical repair no further occurrence
of embolism has been observed.
Case report
A 40-year-old woman was admitted to our hospital for
right hemiparesia, paresthaesia of the right upper member
and of the right side of the face. Clinical examination
revealed a blood pressure of 110/80 mmHg, a heart rate
of 80 beats. min~' and a respiratory rate of 15min~'.
Cardiac examination was normal, as were chest X-ray and
electrocardiogram. Motor function of the right side was
diminished. Paresthaesia of the left upper member with
reduced power was also noted; it probably consisted of
sequelae as a result of a previous neurological accident.
This patient already had a long neurological history:
regressive right hemiplegia and aphasia at the age of 3
months; an episode of vertigo, diplopia with occipital
headaches at 19 years of age; left hemiplegia, anosognosia, left lateral homonymous hemianopsia and decreased
sensitivity at 20 years of age. Occlusion of the right sylvian
artery was revealed by arteriography. Cardiovascular
examination, cerebro-spinal fluid (CSF) and coagulation
tests were normal. Recovery of the left upper member
function was only partial. Multiple episodes of transient
right hemiparesia occurred at the age of 20. Despite anticoagulant therapy, using acenocoumarol with the dosage
titrated to maintain a prothrombin time 1-5 to 2-5 the
normal control times, she presented another neurological
event with central vertigo, diplopia, right paresthaesia,
Submitted for publication on 22 March 1993, and in revised form 7 July 1993.
Correspondence: Pr Daniel Thomas, Department of Cardiology Groupe
Hospitalier Pitie-Salpelriere, 47 bdde I'Hopital 75651 Paris cedex 13 France.
0195-668X/93/I2I717 + O2 $08.00,0

Figure I Left ventricular angiography in left anterior oblique view:
a pouch-like structure bulges into the right ventricle during the
systole (arrows).

right thermoalgesic hypoaesthesia and left lateral
nystagmus at the age of 35. CSF and coagulation tests
were normal. Transmitral echocardiography revealed a
lack of continuity between the aorta and the interventricular septum. Angiography revealed a pouch-like structure with distinct margins bulging into the right ventricle
during systole and indicated the diagnosis of aneurysm of
the membranous interventricular septum (AMS) (Fig. 1).
Computed tomographic scanning was performed and
revealed a hypodensity along the right lateral ventricle
which was dilated and corresponded to the previous left
hemiplegia at 20 years of age. Cervical echo-Doppler was
normal, as was arteriography of the four cervical axes.
Two-dimensional echocardiography showed the AMS to
be free of thrombus. The cardiac origin of the embolism
was confirmed and it was decided to proceed to surgery.
A spherical aneurysmal pouch 1 cm in diameter was
visualized protruding into the right ventricular outflow
© 1993 The European Society of Cardiology

1718 D. Thomas et al.

tract. There was no ventricular septal defect and the
aneurysm was free of thrombus. Obliterating endoaneurysmorraphy was performed. After surgery, anticoagulant therapy was instituted for 6 months and
then stopped. Ten years after surgical repair no other
neurological events have been observed.
Discussion

Aneurysm of the membranous septum is almost always
associated with a ventricular septal defect (VSD) and may
be a marker for a defect that is likely to become smaller
and close in the future'1-21. Diagnosis is made by twodimensional echocardiography and by angiography'31.
Thrombo-embolic complications are very rare.
Bush et al.li] reported the case of a 57-year-old
patient presenting symptoms of congestive heart failure.
Echocardiogram, magnetic resonance imaging, cardiac
catheterization and cardiac surgery demonstrated an
AMS containing a large thrombus associated with aortic
stenosis. Pernot et a/.'21 reported right hemiplegia in a
3-year-old child known to have a VSD. The diagnosis of a
large VSD was made at 5 months of age; it then became
smaller. Repeat catheterization revealed AMS with a
small VSD; at cardiac surgery the AMS was free of
thrombosis. Soyer et a/.'4' reported syncope and regressive
right hemiplegia in a 10-year-old boy who had a VSD
diagnosed at 10 months of age. Echocardiogram, catheterization and surgery revealed an AMS free of thrombosis without any shunt. In our patient, the AMS was
small and was not associated with VSD and repetitive
cerebro-vascular embolism occurred.
Thrombo-embolic complications in AMS are very rare
but may be underestimated, as in the past with aneurysm
of the interatrial septum which was not considered to be a
potential cause of thrombo-embolism'51. In previously

reported cases of AMS with thrombo-embolism, there
was no VSD in one case'"1 and a small VSD in two cases'231;
in our case there was no VSD. In large VSDs the blood
flow through the AMS is important and blood stasis does
not occur. Conversely, in cases with small or no VSDs,
conditions are favourable for blood stasis and thrombosis. The size of the AMS does not seem to be a risk
factor for thrombo-embolism; it was small in two cases'23'
(as in our case) and large in one case'4'.
Rhythm disturbances have been reported in association
with AMS'61 but there were no cardiac arrhythmias in any
of the reported cases of AMS with thromboembolism.
The history of our patient was suggestive of repetitive
cerebral embolism. Ten years after surgical repair no
other neurological event had occurred. We believe that
surgical repair for AMS is indicated when cerebral
embolism occurs despite anticoagulant therapy in order
to prevent other neurological accidents.
References
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[3] Bush HS, Perin E, Massumi A, Klima T, Hall RJ. Detection
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