3-DIMENSIONAL RECONSTRUCTION OF VENTRICULAR SEPTAL-DEFECTS - VALIDATION STUDIES AND IN-VIVO FEASIBILITY

Objectives. The purpose of this study was to demonstrate the feasibili ty of in vivo three-dimensional reconstruction of ventricular septal d efects and to validate its quantitative accuracy for defect localizati on in excised hearts (used to permit comparison of three-dimensional a nd direct measurements without cardiac contraction). Background. Appre ciating the three-dimensional spatial relations of ventricular septal defects could be useful in planning surgical and catheter approaches. Currently, however, echocardiography provides only two-dimensional vie ws, requiring mental integration. A recently developed system automati cally combines two-dimensional echocardiographic images with their spa tial locations to produce a three-dimensional construct. Methods. Surg ically created ventricular septal defects of varying size and location were imaged and reconstructed, along with the left and right ventride s, in the beating heart of six dogs to demonstrate the in vivo feasibi lity of producing a coherent image of the defect that portrays its rel ation to surrounding structures. Two additional gel-filled excised hea rts with defects were completely reconstructed. Quantitative localizat ion of the defects relative to other structures (ventricular apexes an d valve insertions) was then validated for seven defects in excised he arts. The right septal margins of the exposed defects were also traced and compared with their reconstructed areas and circumferences. Resul ts. The three-dimensional images provided coherent images and correct spatial appreciation of the defects (two inlet, two trabecular, one ou tlet and one membranous Gerbode in vivo; one inlet and one apical in e xcised hearts). The distances between defects and other structures in the excised hearts agreed well with direct measures (y = 1.05x - 0.18, r = 0.98, SEE = 0.30 cm), as did reconstructed areas (y = 1.0x - 0.23 , r = 0.98, SEE = 0.21 cm2) and circumferences (y = 0.97x + 0.13, r = 0.97, SEE = 0.3 cm). Conclusions. Three-dimensional reconstruction of ventricular septal defects can be achieved in the beating heart and pr ovides an accurate appreciation of defect size and location that could be of value in planning interventions.