instances, there is disharmony between the connections of the segments and the topologic arrangement of the ventricular mass.26,27 These hearts produce a different variant of the criss-cross heart, which cannot simply be explained on the basis of rotation of the ventricular mass In the examples we have seen, the atrial chambers were arranged in the usual fashion The right atrium connected to the morphologically right ventricle, which was left-sided relative to the morphologically left ventricle (Fig 49.21) The left ventricle was connected to the left atrium However, despite the concordant atrioventricular connections there was left hand ventricular topology In addition, there was double outlet from the morphologically right ventricle and left-sided juxtaposition of the atrial appendages It is in these particularly rare instances that it is necessary to specify the topology of the cardiac segments in addition to the identified atrioventricular connections Provided that all these features are recognized, and accounted for separately, there should be little room for confusion or misunderstanding, irrespective of the specific words used for their description However, the term “criss-cross” itself describes a particular relationship of the ventricular inlets Indeed, the atrioventricular valvar planes can cross each other even when both valves open to the same ventricle (Fig 49.22).28 Simply describing the twisted atrioventricular connections does not account for the morphology of the entire heart Full sequential segmental description is needed for that purpose FIG 49.21 Heart with a very rare form of criss-cross malformation (A) The atriums are connected to morphologically appropriate ventricles; in other words, the atrioventricular connections are concordant, with the pink probe passing from the usually arranged right atrium to the morphologically right ventricle (B) The morphologically right ventricle is left-sided, and gives rise to both arterial trunks in the setting of bilateral infundibulums There is left-hand ventricular topology, despite the presence of usual atrial arrangement and concordant atrioventricular connections Providing that the segmental connections are described separately from the ventricular topology, this arrangement should not cause confusion LA, Left atrium; LV, left ventricle; PT, pulmonary trunk; RV, right ventricle FIG 49.22 Magnetic resonance images from a patient with double-inlet right ventricle showing how the atrioventricular valves cross each other as they enter the dominant right ventricle (arrows), producing twisted doubleinlet atrioventricular connection LA, Left atrium; RA, right atrium; RV, dominant right ventricle In comparison with the potential problems encountered with criss-cross hearts, few difficulties should be posed by ventricles that are arranged in the superoinferior or the upstairs-downstairs manner This finding simply reflects a tilting of the ventricular mass along its long axis (see Fig 49.16) Superoinferior ventricles are usually described in the setting of congenitally corrected transposition, where in most instances the ventricles are arranged in side-by-side fashion Tilting of the ventricular mass to either side produces a stacking effect of the ventricles one on top of the other As with twisted atrioventricular connections, superoinferior ventricles are often seen in the presence of straddling and/or overriding atrioventricular valves As was also the case with the twisted arrangement, noting an upstairs–downstairs or superoinferior arrangement does not describe the complete heart, but only a particular ventricular relationship Sequential segmental description is mandatory for full categorization of the hearts showing this abnormality There is a further variation to be noted in the setting of these unusual ventricular relationships First described by Freedom and his colleagues in their textbook of angiography, the entity has now been diagnosed during fetal life, and in a familial setting.29 Called the topsy-turvy arrangement, the essential feature is rotation of the whole heart around its long axis, with superoinferior relationships of the atriums and ventricles (see Fig 49.17), but without twisting of the axes of the atrioventricular connections As the arterial roots, as well as the aortic arch and arterial duct, are displaced downward as a consequence of rotation of the whole heart, the branches of the aortic arch and the superior caval vein are elongated (Figs 49.23 and 49.24) More importantly, the trachea is elongated and the left bronchus is severely compressed by the low-lying aortic arch and arterial duct (Fig 49.25) The group from Toronto initially described two cases of the topsy-turvy heart, and subsequently encountered an additional example There have now been five additional cases described in the literature, all of Middle Eastern or South Asian origin, which suggests a genetic background for this rare malformation.30,32 FIG 49.23 Magnetic resonance images showing the essence of the