Determinants of early and late results of repair of atrioventricular septal (canal) defects

Atrioventricular septal defects: What's in a name?

• The atrioventricular canal is the "classic" congenital heart anomaly in Down syndrome. We may learn more of the nature of this disorder by careful study of the anatomic characteristics of the cardiac lesions and by comparing these lesions in patients with and patients without Down syndrome. We reviewed the clinical characteristics (echocardiographic and angiocardiographic) of 220 patients with atrioventricular canal and compared the prevalence of anatomic types and associated cardiac malformations in children with (105) and without (115) Down syndrome. In patients with Down syndrome, the complete form of atrioventricular canal was prevalent, with a high frequency of associated Fallot's tetralogy. Partial atrioventricular canal and left-sided anomalies were more common in patients without Down syndrome. Down syndrome is associated with a simpler type of atrioventricular canal when compared with patients with a normal chromosome configuration. ( AJDC . 1990;144:1120-1122)

Atrioventricular canal in Down syndrome. Prevalence of associated cardiac malformations compared with patients without Down syndrome.

Further observations on the morphology of atrioventricular septal defects.

Surgical anatomy and pathology of the conduction tissues in atrioventricular defects

Anatomical studies were made on 114 necropsy specimens of atrioventricular defects with atrioventricular concordance. The malformation is characterised by disproportion between the ventricular inlet and outlet dimensions and a malorientation of the aortic valve relative to the atrioventricular valve or valves. Associated with this there is a characteristic 'scopped-out' appearance of the muscular ventricular septum, gross abnormalities of the membranous components of the septum as compared with the normal heart, and narrowing of the aortic outflow tract. Hearts with these anatomical features can be divided into partial and complete forms depending on the morphology of the atrioventricular annuli. In the partial form the septal leaflets are conjoined to give separate mitral and tricuspid orifices, the conjoined leaflets being displaced into the ventricles and usually attached to the crest of the septum. In the complete form, anterior and posterior components of the 'septal' leaflets are separate, so that a single valve orifice connects the atrial to the ventricular chambers. Further subdivision of the complete form, apart from the morphology of the anterior leaflet, is dependent upon the presence or absence of an ostium primum atrial septal defect.

https://heart.bmj.com/content/heartjnl/42/6/621.full.pdf

K Lozsadi

Papers

Morphology and classification of atrioventricular defects.