FIG 26.2 Essence of the usual body arrangement (left) and its mirror image (right) Individuals with these arrangements would exhibit enantiomerism relative to each other LAA, Left atrial appendage; RAA, right atrial appendage FIG 26.3 Short-axis view of the base of the heart illustrating an unbalanced common atrioventricular junction with a common atrioventricular valve and right dominance The interventricular septum (yellow dots) is easily appreciated The pectinate muscles extend around both atrioventricular junctions to the crux of the heart (star) in this patient with isomerism of the right atrial appendages FIG 26.4 Triangular appendages (stars) on the right (A) and left (B) sides in a patient with right isomerism Note the bilateral superior caval veins and the pulmonary veins coming together in a midline confluence The yellow dots show the bilateral terminal grooves FIG 26.5 Short-axis view of the base of the heart illustrating a common atrioventricular junction with a common atrioventricular valve that has separate right and left orifices The bridging leaflets are adherent to the interventricular septum and to one another The atrial appendages are bilaterally morphologically left with the characteristic tubular appearance and the narrow or constricted junction (arrows) to the smooth-walled vestibules Note the left-sided persistent left superior caval vein (LSCV) FIG 26.6 Atrial appendages (stars) to the right (A) and left (B) sides of a patient with visceral heterotaxy It is easy in this instance to recognize that both are morphologically left simply from their external appearance Note the bilateral superior caval veins FIG 26.7 Typical bodily arrangements in the setting of visceral heterotaxy In each instance, insofar as the thoracic structures are