N. Dobrilovic1 1Northshore University Health System, Surgery, Evanston, IL, USA
Introduction:
Proof-of-concept of a novel ‘two-ring’ mitral (tricuspid) annular sizing device and technique was introduced at AATS Mitral Conclave 2023. This technique has the potential to dramatically improve ring selection during valve repair procedures. Figures 1a/1b provide a visual reference to orient the reader with the general concept. This technology has recently been approved for first-in-human trial at our institution. In preparation for in-human use, the current study aims to validate the manufacturing precision of each of 9 custom sizers designed to correspond specifically to Physio 2 (Edwards Lifesciences, Irvine, CA) annuloplasty rings.
Methods:
For each available Physio 2 ring (sizes #24-40), caliper (Mitutoyo 505-732, Kanagawa, Japan) measurements were obtained to evaluate correspondence between implantable commercial ring and our manufactured sizer. A total of 1,080 measurements was conducted to a level of 1/100th of a mm. Antero-posterior (AP) and width (horizontal) dimensions were measured, comparing each ring sizer with its corresponding Physio 2 ring across all sizes. This was performed 30 times for each unique measurement to validate design accuracy and ability of each sizer to perform (precisely control placement of sutures in the desired position). Bland-Altman analysis with plots was performed to evaluate correspondence of paired sets of measurements. Mean difference with a 95% confidence interval (CI), as well as 95% limits of agreement, are reported.
Results:
Mean difference [95% CI] between sizer and ring measurements indicated that measurements differed by negligible amounts across all 9 pairs. All 9 sets of statistical analyses yielded similar outcomes. Given limited abstract space, a sample, complete statistical analysis is provided for a single (#36) sizer (Figure 1c/1d) where mean differences were 20/100ths mm in the AP dimension (-0.20 [-0.37, -0.04]) and 13/100ths in the width dimension (-0.13 [-0.29, 0.02]). Limits of agreement were from -1.08 to 0.68 for AP and -0.95 to 0.69 for width. Differences do not show heteroscedasticity.
Conclusion:
Novel two-ring sizers designed for use with Physio 2 annuloplasty rings performed as expected. Validation measurements were extremely close and do not suggest any pattern of error. It is anticipated that this novel sizing technique will provide surgeons with precise, intraoperative anatomic (ink test coaptation length) and physiologic ring sizing information as we now enter human trials.