Predictors of operative time in multicenter port-access valve registry: Institutional differences in learning

Background: The predictors of operative time and the effects of learning in isolated valve operations using port-access techniques have not been defin ed. Methods: Analysis of covariance was used to examine the determinants of pro cedure time, pump time, and aortic clamp time. In the largest prospective, registry of patients undergoing isolated aortic valve replacement (AVR, N=1 99), mitral repair (MVP, N=307), or mitral replacement (MVR, N=232) using p ort-access techniques 1997-1999 at 27 institutions. Results: Institutional case volume ranged from one to 214 (median 6). Opera tive time was longer in redo procedures (5.3 +/- 1.6 vs. 4.4 +/- 1.3 hr, p = 0.0001), longer with MVP or MVR vs. AVR (4.8 +/- 1.2 vs. 5.0 +/- 1.5 vs. 3.8 +/- 1.2 hr, p = 0.0001), and decreased with case number (mean decrease 1.00 + 0.19 min/case, p = 0.04). Operative time also varied between institu tions (p = 0.001). Rate of learning (decrease in time per case) varied sign ificantly between institutions only for MVP (p = 0.03). Similar analysis sh owed that pump time and clamp times did not significantly change over time (p > 0.17) but varied significantly between institutions. Institutional vol ume did not affect operative, pump, or clamp times or rate of learning (dec rease in operative time/case). Conclusions: These prospective registry data demonstrate that, for port-acc ess valve procedures, procedure times continue to improve (learning) even a fter 100 cases. Procedure time and learning are affected by institutional d ifferences and by the type of procedure, but are little affected by institu tional volume. This data provides a model to understand learning of new sur gical procedures, and this data suggests that port-access valve procedures can be mastered by a variety of institutions.