Minimising The Learning Curve For Minimally Invasive Surgery With An Intra-aortic Occlusion Device
Bilal H. Kirmani, Andrew Knowles, Palanikumar Saravanan, Joseph Zacharias.
Blackpool Victoria Hospital, Blackpool, United Kingdom.
Background The majority of centres that offer minimally invasive cardiac surgery (MICS) are low-volume centres. Publications on learning curves for mitral MICS, by contrast, have come from expert “pioneer” institutions with historical and high volume experience. They recommend that around 100 cases per year are required in order to safely navigate the learning curve. We sought to demonstrate the learning curve, with an intra-aortic occlusion device, in our low-volume centre.
Methods We undertook an analysis of our prospective database of minimally invasive surgery on the mitral, tricuspid, atrial septum and atrial fibrillation surgery. Data was analysed using cumulative sum sequential probability analyses (CUSUM) for various complications, using reference ranges from the literature.
Results A total of 316 patients were identified for inclusion in the study. Age: 64.5 years [interquartile range (IQR): 51 - 71]; Male: 193 (61.1%); Body Mass Index 26.2 [IQR: 22.7 - 29.6]; Known history of stroke: 33 (10.4%); Known history of peripheral vascular disease: 17 (5.4%); Logistic EuroSCORE 6.98 ± 8.51
Bypass and aortic occlusion times (median 163 and 111 minutes, respectively) showed a decreasing trend over time. There were no intra-operative aortic dissections or malperfusion complications. Post-operative stroke was seen in 8 (2.6%) patients. In-hospital mortality was 7/316 (2.2%) and conversion to sternotomy was 12 (3.8%) during the study. There was no correlation between increased extra-corporeal circulation times and either conversion or death. Mean length of stay decreased from 8.5 to 6.9 days, with 93.7% of patients returning home. Patients requiring additional convalescence had a mean age of 72y compared to 61y for those returning home. CUSUM analyses demonstrated an accelerated learning curve for composite complications including conversion (Figure 1).
Conclusion Adequate pre-operative planning and an integrated team approach to device deployment and monitoring in theatre have been fundamental to our institutional implementation of MICS with the endovascular aortic clamp. Our series included patients with high EuroSCOREs, peripheral vascular disease and previous stroke and had excellent results. We have demonstrated that a learning curve, even when using modern technology such as the endo-aortic occlusion device, can be navigated safely in low volume centres.
Legend CUSUM curve for composite outcomes
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