Assessment of atrial septal defect size during systole and diastole using 4D CT: a case series

The size of atrial septal defects (ASDs) is typically measured using echocardiography. In contrast, computed tomography (CT) images offer superior spatial resolution, and four-dimensional (4D) CT enables visualization of the defect hole during various cardiac phases. In this study, we compared the results of 4D CT measurements of defect sizes during atrial systole (As) and atrial diastole (Ad) in 7 of 18 cases of robot-assisted ASD closure (Robotic ASD closure) with measurements obtained by other methods.

Robotic ASD closure was performed in 18 patients between December 2019 and April 2025. Surgery was performed under general anesthesia, with a venous line from the right internal jugular vein and right femoral vein, and an arterial line on the right femoral artery to establish extracorporeal circulation. The procedure was conducted using the DaVinci Xi^® surgical system. Image analysis was performed using VINCENT^®, and the size of the defect was measured during As and Ad, and calculated using the formula: long radius × short radius × π. The mean age was 60.9 years (range, 34-82 years), and 10 (55.6%) patients were male. No residual shunt flow was detected on intraoperative or postoperative echocardiography. The defect size was measurable using 4D CT in 7 cases. The area of the defect was significantly different between As [65.9-207.2 mm², mean 134.1 mm², interquartile range (IQR) 58.9] and Ad (113.0-490.6 mm², mean 226.1 mm², IQR 94.2) (P=0.04).

Using 4D CT, it was possible to determine the morphology and area of ASD defects in As/Ad before surgery. This is useful for selecting surgical procedures and determining patch size and may contribute to reducing cardiac arrest and surgical time. To prove that 4D CT can accurately predict the size and morphology of the defects in As/Ad, further accumulation of cases and analyses are required.