Stretching of the ductus: an important factor in determining the outcome of coil occlusion

The present study measured the minimal diameter of the ductus (minimal D), the stretched minimal diameter (stretched D), and the stretch index (SI) before coil occlusion in 25 patients with a patent arterial duct. The following factors were compared in the success group (22 cases, coil successfully placed after initial deployment) versus the failure group (3 cases): minimal D, stretched D, SI, the sum of the loop diameter of coils (the loop diameter), the sum of the product of the loop diameter and the number of loops (the loop diameter and number), the loop diameter/minimal D, the loop diameter/stretched D, the loop diameter and number/minimal D, and the loop diameter and number/stretched D. In the failure group, minimal D, stretched D, SI, the loop diameter, and the loop diameter and number were larger than in the success group. The loop diameter/stretched D, and the loop diameter and number/stretched D were smaller in the failure group. Although the loop diameter and number/minimal D was slightly smaller in the failure group, the loop diameter/minimal D was comparable. It is concluded that the stretched D is more reliable than minimal D to determine the appropriate size of coil for successful initial deployment.