Positional anomalies of the heart

Summary

The surgical problems posed by cardiac malformations may be considerably increased when the heart itself is in an abnormal position. This is, in part, due to the unusual anatomical perspective presented to the surgeon because of the malposition, and also to the abnormal locations of the cardiac chambers, which may necessitate approaches other than those already discussed. Cardiac malposition itself, nonetheless, does not constitute a diagnosis. Any normal or abnormal segmental combination can be found in a heart that, itself, is abnormally located. The heart may be normal, despite its abnormal location, but extremely complex anomalies are frequently present. Consequently, the very presence of an abnormal cardiac position emphasises the need for a full and detailed segmental analysis of the heart. All the rules enunciated in Chapter 6 apply should the heart not be in its anticipated position. In this chapter, we confine ourselves to a description of abnormally positioned hearts, giving a more detailed discussion for specific types of malposition. We conclude with a review of the surgical significance of isomerism of the atrial appendages, which is generally agreed to be one of the major harbingers of abnormal cardiac position. We emphasise the need to segregate the syndromes, preferably into the subsets of right versus left isomerism, as the prognosis is markedly different for the two variants.