PhD thesis of B. L. TRUONG on 05/30/2017

PhD thesis of B. L. TRUONG on 05/30/2017 at 2 pm :

« Three-dimensional organization of myocardial cells during foetal and postnatal ventricular development »

Place : Amphithéatre de l’IAB, Institut pour l’Avancée des Biosciences, Site Santé, Allée des Alpes, 38700 La Tronche.

Direction : Pierre-Simon JOUK (TIMC-IMAG) and Yves Usson (TIMC-IMAG)

Jury :

  • M. Damien BONNET, Professeur des Universités-Praticien hospitalier, Hôpital Necker-Enfants malades de Paris, Rapporteur
  • M. Patrick PLADYS, Professeur des Universités-Praticien hospitalier, CHU Rennes, Rapporteur
  • M. Gilles BARONE ROCHETTE,Professeur des Universités-Praticien hospitalier, CHU Grenoble Alpes, Examinateur
  • Mme Magalie VIALLON-CROISILLE, Physicien médical, CHU Saint-Étienne, Examinateur
  • M. Pierre-Simon JOUK, Professeur des Universités-Praticien hospitalier, CHU Grenoble Alpes, Examinateur

Abstract :
The 3D architecture of the ventricular mass is poorly known, although in vivo imaging techniques show the physiological inhomogeneity of transmural myocardial mechanics. Polarized light imaging makes it possible to quantitatively analyse the myocardial cell orientation to study the regional isotropy of myosin filaments (a new parameter) and to provide virtual dissection (a new tool) of the myocardial ventricular mesh. This deep inside is complementary of superficial anatomical description.
Sixteen normal hearts of human term stillbirths, newborns and infants were studied. During the first months of postnatal age, the median regional isotropy values decreased in the ventricular three-dimensional mesh. There was a progressive appearance of a particularly inhomogeneous secondary arrangement of myocardial cells with alternation of thick low-RI and thin high-RI areas. The topology of Torrent-Guasp’ cleavage plans and intercalated high RI areas were identical. The outlet septum was constantly identified.
Eleven malformed hearts were studied. The deep components of the ventriculo-infundibular fold, the outlet septum and the latitudinal fibres of the ventricular walls were described and 3 different patterns could be portrayed :
1) a normal aligned pattern ;
2) a parallel pattern of the ventriculo-infundibular fold and the outlet septum in Tetralogy of Fallot ;
3) a V pattern of the ventriculo-infundibular fold in heart with mitro-arterial muscular discontinuity.
To conclude, we uncover new elements to understand the onset of the myocardial architecture in normal and pathological hearts. However, this new data need to be statistically consolidated by studying a greater numbers of cases. As a perspective, these observations will be confronted to physiological data provided by functional imaging technique.

Key words : cardiac development, polarized light microscopy, anatomy, regional isotrophy, virtual dissection