Background-Learning curves are vigorously discussed and viewed as a negative aspect of adopting new procedures.However, very few publications have methodically examined learning curves in cardiac surgery, which could lead to a better understanding and a more meaningful discussion of their consequences. The purpose of this study was to assess the learning process involved in the performance of minimally invasive surgery of the mitral valve using data from a large, single-center experience. Methods and Results-All mitral (including tricuspid, or atrial fibrillation ablation) operations performed over a 17-year period through a right lateral mini-thoracotomy with peripheral cannulation for cardiopulmonary bypass (n=3907) were analyzed. Data were obtained from a prospective database. Individual learning curves for operation time and complication rates (using sequential probability cumulative sum failure analysis) and average results were calculated. A total of 3895 operations by 17 surgeons performing their first minimally invasive surgery of the mitral valve operation at our institution could be evaluated. The typical number of operations to overcome the learning curve was between 75 and 125. Furthermore, >1 such operation per week was necessary to maintain good results. Individual learning curves varied markedly, proving the need for good monitoring or mentoring in the initial phase. Data were drawn from a prospectively gathered database for MIS-MV housed at our institution. The study was approved for anonymous analysis by the institutional review board, with additional patient consent waived.
Conclusions
Patient Selection and Surgical TechniqueIt is the policy at our institution to use the MIS-MV approach whenever possible. The main reasons for not using minimally invasive procedures were previous right thoracotomy with expected lung adhesions, difficulties with femoral vessel cannulation, and in the case or urgent or emergent surgery, the unavailability of a surgeon versed in the MIS-MV approach. Other possible reasons for preferring the sternotomy approach were a very low ejection fraction (to achieve the shortest possible cross-clamp time) and expected difficulties with valve replacement because of extremely severe annular calcification or deep annular abscess. Such decisions were made at the surgeon's discretion.In all patients who underwent an MIS-MV, a right-lateral minithoracotomy and femoral cannulation for cardiopulmonary bypass with mild to moderate hypothermia were performed. In the vast majority of patients, a transthoracic aortic clamp as introduced by Chitwood et al 8 was used. Details on the MIS-MV operative approach are described more thoroughly elsewhere. 2,9 Patients who underwent robotic mitral valve surgery were excluded.
Data AnalysisCategorical variables are expressed as proportions and continuous variables as mean±SD throughout this study. Patients were divided into groups of 50 consecutive operations to evaluate the influence of growing surgical experience on adverse outcomes. Testing for ...