The differential and linear insertion of the atrioventricular valves: a useful tool?

Abstract

INTRODUCTION

The differential insertion of the atrioventricular valves is the ultrasonographic representation of the more apical attachment of the tricuspid valve to the septum with respect to the mitral valve. A linear insertion is present when both valves form a linear continuum and is suggested as a marker for atrioventricular septal defects (AVSDs). The objective is to evaluate the anatomical substratum of differential and linear insertion of the atrioventricular valves in normal fetal hearts and fetal hearts with an AVSD.

METHODS

The extent and position of the fibrous skeleton and attachment of atrioventricular valves to the septum were studied in histological sections of 17 normal hearts and 4 hearts with an AVSD (10 + 0 weeks gestation - 3 days postpartum) with various immunohistochemical tissue markers. In addition, STIC volumes of 10 normal hearts and STIC volumes of 8 hearts with AVSD (13 + 6 - 35 + 5 weeks gestational age) were examined. RESULTS The differential insertion of the atrioventricular valves was visible in normal hearts in the four-chamber plane immediately beneath the aorta. More towards the diaphragm, a linear insertion was found. In hearts with an AVSD, a linear appearance was observed in the four-chamber plane immediately beneath the aorta. Towards the diaphragm, however, first a differential and more caudal, a linear insertion was found. CONCLUSION Both differential and linear insertion can be found in normal fetal hearts and fetal hearts with AVSD, dependent on the plane in which the four-chamber view is visualised. Therefore, measurement of the differential insertion is probably only useful in experienced hands.