Preoperative loop length determination for mitral valve repair by 4-dimensional computed tomography.

Objective: In the loop technique for mitral valve repair, the loop bundles are usually created during cardiac arrest after chordal length measurements, which seems time-consuming and less reproducible. To address this issue, we determined the loop length preoperatively using 4-dimensional computed tomography. Methods: The loop length was determined on the basis of the distance from the papillary muscle head to the free margin of nonprolapsing leaflet corresponding to the prolapsed leaflet, to which the loops would be secured. Measurements were made on the commissural and long-axis views created by a medical image post-processor in the late systolic phase. This technique was used in consecutive 45 patients undergoing mitral valve repair with the loop technique since April 2021. Results: A total of 55 loop bundles were created in 45 patients; in 10 cases loop bundles were fixed to both anterior and posterior papillary muscles. There were 31 posterior, 6 anterior, and 8 bileaflet prolapse. The loop length was set at 16 to 26 mm (median 19 mm). Mitral valve repair was successfully completed in all patients, and the loop bundles of predetermined length were used successfully in 42 patients (93.3%). Postoperative echocardiography revealed none/trace regurgitation in 41 and mild regurgitation in 4. There was no hospital mortality or major postoperative complication. During 4 to 35 months follow-up (median 10 months), no case required reintervention for the mitral valve. Conclusions: Preoperative measurements using 4-dimensional computed tomography can accurately and reproducibly predict the required loop length for mitral valve repair.