Obstetrical and Gynecological Department, San Bassiano Hospital, Bassano del Grappa, Italy.

Synonym: Transitional common atrioventricular canal

Definition

Atrioventricular septal defects (AVSDs) refer to a broad spectrum of malformations characterized by a deficiency of the atrioventricular septum. These malformations are presumed to result from abnormal or inadequate fusion of the anterior and posterior endocardial cushions with the mid portion of the atrial septum and the muscular (trabecular) portion of the ventricular septum.
The term intermediate atrioventricular septal defect is an infrequent form of AVSD. It refers to the combination of a partial AVSD with a interventricular communication. A single valvar annulus is usually present where the anterior and posterior bridging leaflets fuse overlying the ventricular septum. Because of the leaflet"s fusion, two distinct valvar components are observed, mitral and tricuspid. This is different from the complete AVSD were anterior and posterior leaflets are not fused.

Image 1: Image shows a schematic drawing of the single valve annulus, anterior and posterior bridging leaflets are fused. Tricuspid and mitral component of the atrioventricular valve is present.

Case Report

The following images and video shows a case of a 32-year-old woman G2P1, with non contributive personal history. She presented to our unit at 21 weeks of gestation. Her pregnancy was uncomplicated. Her partner had surgery as a child for a ventricular septal defect. Her ultrasonographic examination revealed following finding.
We performed a cordocentesis. The karyotype was normal 46 XX.

Images 1,2: Images show a AVSD and communication between left and right heart.

Images 3,4: Image 3 shows a AVSD; Image 4 shows color Doppler demonstrating the defect in the atrioventricular septum.

Images 5,6: Image 5 shows a tricuspid and mitral part of the single valve annulus; Image 6 shows a AVSD and left outflow tract.

Videos 1,2,3: Videos show the valve movement with apparent AVSD.