A new method for intraoperative quantification of mitral leaflet segment prolapse

During mitral valve reconstruction, intraoperative valve analysis is carried out by the cardiac surgeon for assessing location and extent of leaflet defects. The analysis of each leaflet segment is usually examined using two nerve hooks, as proposed by Carpentier. Qualitative comparison between the possible displacement of the segments is done in order to evaluate motion restriction or prolapse. However, this comparison depends on the subjective assessment and the experience of the surgeon. We propose a new computer-based approach which allows for a quantitative measurement of the segment displacement in relation to the annulus plane. Infrared reflecting markers are attached to the instruments for optical tracking. The segments are examined as proposed in the Carpentier method using either a single or two nerve hooks. Evaluation was carried out by repeating measurements three times on an excised porcine heart. Mean chordae were cut to induce a prolapse iatrogenically. The single-hook procedure turned out to be less time-consuming and easier to perform and showed a high reproducibility (mean standard deviation: 1.51 mm) in comparison to the hook-pair approach (3.35 mm). Our method overcomes the limitations of actual subjective analysis, enables to get quantitative and highly reproducible measurements of leaflet prolapse and may provide valuable decision support during surgery.