INTRACARDIAC ULTRASONOGRAPHIC ASSESSMENT OF ATRIAL SEPTAL-DEFECT AREA- IN-VITRO VALIDATION AND TECHNICAL CONSIDERATIONS

Assessment of atrial septal defect (ASD) size and shape is important f or planning and guiding its transcatheter occlusion and can potentiall y be achieved by intracardiac ultrasonography (ICUS). ICUS accuracy, h owever, must first be established against stable standards and technic al imaging requirements defined. We therefore used 10, 20, and 30 MHz ICUS catheters to examine 17 ASDs that were 0.16 to 6.7 cm(2) in area and were surgically created in excised ovine hearts with 10, 20, and 3 0 MHz ICUS catheters. ASD shape and area by ICUS were compared with di rect video images of the actual ASD. In all instances minimal area by ICUS pullback agreed well with actual values (y = 1.04x + 0.2, SEE = 0 .23 cm(2), r = 0.99) and corresponded well with defect shapes. The max imum angle between ultrasonography beam and septal plane allowing for complete ASD visualization was 20 degrees. The angle depended on trans ducer frequency and septal thickness. This new technique has potential value for the accurate assessment of ASD shape and size and may be es pecially useful in the setting of transcatheter occlusion.