Hearts with one ventricle: current concepts and management.

Nature of the problem Many congenital cardiac malformations result in a heart with only one effective ventricle. In most of these there is a second ventricle present, but it is too small to sustain cardiac output making construction of a biventricular circulation impossible. These hearts may be classified according to the atrioven-tricular connection. There are two possibilities: the atria are each connected to a separate ventricle, or the atria are connected to only one ventricle. When each of the atria is connected separately to one of two ventricles, either ventricle may be too small. The right ventricular cavity is small in almost all cases of pulmonary atresia with intact ventricular septum, and in some hearts in which the tricuspid valve straddles a ventricular septal defect. A small left ventricular cavity is the hallmark of the hypo-plastic left heart syndrome. When the atria are connected to only one ventricle (irrespective of the possible presence of another rudimentary ventricle) there is a 'univen-tricular atrioventricular connection'.1 2 If both atria are connected to one ventricle, it is termed 'double inlet' ventricle. There are usually two atrioventricu-lar valves under these circumstances but sometimes a common atrioventricular orifice drains both atria. Alternatively, one atrioventricular connection may be absent (fig 1). In tricuspid atresia the right atrioventricular connection is absent. Systemic venous return to the right atrium has an obligatory flow across the atrial septum into the left atrium and together with pulmonary venous blood passes to the left ventricle through the mitral valve. There is obligatory transatrial flow of pulmonary venous blood in the opposite direction (from left atrium to right atrium) in hearts in which the mitral valve is atretic or the left atrioventricular connection absent. A valve is atretic if it is formed but imperforate; the atrioventricular connection is absent if there is no valve tissue at all. Although these malformations are comparatively rare, tricuspid atresia, double inlet ventricle, and hypoplastic left heart syndrome each accounted for nearly 5% of the total number of symptomatic infants with congenital heart disease in a British survey of the decade preceding 1982.3 In addition, about a third of those patients with double inlet ventricle will present after infancy (Franklin RCG, Deanfield JE, Anderson RH, et al, unpublished observations). Presentation The nature of the ventriculoarterial connection and the degree of obstruction to pulmonary or systemic outflow will determine the clinical presentation. Symptoms of heart failure caused by …