Evaluation of the morphology of the oval fossa for placement of devices

Objectives. First, to examine the morphology of heart specimens with defect s of the oval fossa so as to define the factors that facilitate appropriate selection of the size of devices used for inteventional closure. Second, t o examine the relationship between morphology and transthoracic and transes ophageal echocardiography. Background The success of transcatheter closure is influenced by the variable morphology of deficiencies with the oval foss a. and of the relationship of the fossa itself to adjacent structures. More appropriate selection could reduce the incidence of failures. Methods: Fro m over 100 specimens in the cardiac registry at the University of Californi a, San Francisco, we judged IG hearts with atrial septal defects within the oval fossa, either in isolation or associated with other cardiac malformat ion, to be suitable for this study. We measured the dimensions of the defec t and the surrounding rims of the fossa. AII values were normalized to the diameter of the aortic root. Results: A fenestrated defect was present in 9 specimens (56%). The shape defect itself was oval in all specimens, With a ratio of major to minor axes of 1.70 +/- 0.63. The major axis took one of three main directions with respect to the vertical plane: in 11 specimens ( 69%) it was at horizontal; in 3 (19%) it was at oblique at an angle of 45 d egrees; and in 2 (12%) it was vertical. Discordance was noted in some heart s between the major axis of the defect and that of the oval fossa. Structur es closest to the rim of the fossa were the aortic mound, the coronary sinu s, and the hinge point of the aortic leaflet of the mitral valve. Conclusio ns. Extrapolating from these specimens permitted identification of the majo r and minor axes iii the atrial septal defect by transthoracic and transeso phageal echocardiography. Our study has identified landmarks and dimensions that may be employed to improve effectiveness of selection of patients for transcatheter closure of defects within the oval fossa.