FIG 49.15 Essence of the criss-cross heart, better described in terms of twisted atrioventricular connections The spatial relationship of the cardiac chambers and arterial trunks can best be understood by imagining that the heart is twisted clockwise or anticlockwise by the right hand of the observer placed on the cardiac apex, with the left hand holding the posterior aspect of the atriums The direction of twisting is in such a way to place the right ventricular inlet upward and forward With a greater degree of twisting, the entirety of the axes of the atrioventricular connections seem to be crisscrossing The upper panel shows the arrangement in transposition with concordant atrioventricular connections, while the lower panel shows the situation in the setting of the usual arrangement and congenitally corrected transposition In both instances, if the ventricular mass becomes twisted, the morphologically right ventricle (RV) assumes an anterior location In the setting of regular transposition, the aortic valve is positioned anterior and to the left, rather than to the right as is expected The reverse arrangement is seen in the setting of congenitally corrected transposition The twisting, in most instances, does not change the segmental connections Ao, Aorta; LV, left ventricle; LA, left atrium; PT, pulmonary trunk; RA, right atrium FIG 49.16 Mechanism producing superoinferior ventricles in the setting of congenitally corrected transposition There is tilting of the ventricular mass to either the right or the left, with the drawing showing tilting to the left Often such tilting is combined with a twisting abnormality The arrangement is also described as “upstairs-downstairs” heart Ao, Aorta; LA, morphologically left atrial appendage; LV, morphologically left ventricle; PT, pulmonary trunk; RA, morphologically right atrium; RV, morphologically right ventricle FIG 49.17 Rotation of the heart along its long axis produces the “topsyturvy” arrangement Ao, Aorta; LA, morphologically left atrial appendage; LV, morphologically left ventricle; PT, pulmonary trunk; RA, morphologically right atrium; RV, morphologically right ventricle; SVC, superior caval vein It is twisting that is the essential feature of the so-called criss-cross heart (Figs 49.18 to 49.20) The common characteristics of the twisted heart include loss of normal parallel axes of ventricular inlets There is also angulation of the