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Re: Linear insertion of the AV valves without defect exists and was already described and published

Dear Editor,

In the article “Can atrioventricular septal defects exist with intact structures?”, the authors seem not to know that a similar case was described on a fetus and published in 2002[1].

This case was diagnosed through the prenatal ultrasound screening of a supposed partial AVSD which led to the discovery of a Down Syndrome (DS). The parents asked for a termination of pregnancy and a fetal pathological examination. The standardized examination of the heart[2] showed no defect (neither atrial nor ventricular) and a normal mitral left atrioventricular valve. The pathologist, who also practised fetal ultrasonography (US), thought of sectioning this heart in the plane of the US four chamber view. There, instead of the normal offsetting, the septal leaflets of the atrioventricular valves were found to be at the same level of the crux of the heart. This we called: the Linear insertion of the atrioventricular valves (LIAVV) without defect[1].

This case became the index case of an anatomical series of 52 hearts of DS fetuses. 23 out of 41 examinable hearts were “supposed normal” because without any associated defect. After a standardized complementary four chamber view section[3], 16 out of these 23 DS fetal hearts (70%) showed a LIAVV. This result was highly significant (p<10-6) compared with the controls showing a 100% normal offsetting.

A further anatomical series of 213 fetal hearts confirmed these data[4]. 63% LIAVV without defect were found among 113 “supposed normal” DS hearts None of our “supposed normal”DS hearts ever showed any trileaflet left atrioventricular valve, unlike the 4 DS postnatal cases described in the article. Moreover, we noticed[4] some ballooning of the septal tricuspid leaflet and/or a particular aspect of the membranous septum. This one was more often losangic than triangular, and in a few cases, it was so thin that it looked like a spontaneously prenatally closed VSD.

We previously defined the apex and the two inferior pulmonary veins as the most reliable hallmarks of an “optimal” fetal four chamber view through echo-anatomical correlations. These hallmarks are reproducible in the Fetal pathology complementary section[3] and in the routine US screening as well[4]. The histological study enabled us to find the best US incidence and settings able to emphasize the crux of the heart in order to search for LIAVV without defect cases[4,5].

Further studies were required to establish the feasibility of the US screening of this marker and its diagnostic value for the detection of DS. So, we induced a prospective ultrasonographic study. Previously trained physicians studied the crux of the heart in all the routine 2nd and 3rd trimester prenatal screening they practised on low risk pregnancies. Reliable results will be soon submitted for publication.

References

1. Fredouille C, Piercecchi-Marti M-D, Liprandi A et al.
Linear insertion of atrioventricular valves without septal defect; a new anatomical landmark for Down’s syndrome?
Fetal Diagn Ther 2002 ; 17 : 188-92. Erratum in: Fetal Diagn Ther. 2002 ;17(5):292.

2. Fredouille C.
Diagnosis of a fetal cardiac malformation. Fetal heart.
Ann Pathol.1997. Sep; 17(4):300-5.

3. Fredouille C, Morice JE, Delbecque K, et al.
New foetopathological section of the heart. Correlated to the ultrasonographic 4 Chamber view in fetuses.
Ann Pathol. 2006 Feb;26(1):60-5.

4. Fredouille C, Baschet N, Morice JE, et al.
Linear insertion of the atrioventricular valves without defect
Arch Mal Coeur Vaiss. 2005 May;98(5):549-55.