Renal function after port access and median sternotomy mitral valve surgery

Background. Acute renal injury is an important postoperative complication of mitral valve surgery. We tested the hypothesis that minimally invasive port access (PA) surgery is linked to a smaller postoperative renal injury compared to the standard median sternotomy (MS) technique. Methods. Ninety-six patients in the PA group and 102 patients in the MS group were compared regarding postoperative renal dysfunction. Preoperative and maximal postoperative serum creatinine levels were used to calculate creatinine clearance which was implemented for the renal function assessment. Additionally, the new RIFLE classification for acute renal injury was used for the comparison of the postoperative kidney function. This classification is divided into 3 levels and in addition to the glomerular filtration rate, it is also based on urine output. Results. The analysis of preoperative renal function did not demonstrate any significant differences between the two groups in any of the creatinine-based renal function markers. However, the comparison of the minimal postoperative creatinine clearance showed significantly lower values in the median sternotomy group. The conventional MS approach was confirmed as an independent renal risk factor in the multivariate analysis. The postoperative RIFLE classification comparison also showed higher postoperative renal impairment in the MS group. Conclusion. With the limitations of a retrospective study, our results suggest that for mitral valve surgery the minimally invasive PA approach might be associated with lower postoperative renal injury compared to the conventional surgical technique.