僧帽弁狭窄症の術後左心機能と運動耐容能よりみた至適術式の選択

There are two major surgical procedures for pure or predominant mitral stenosis, open mitral commissurotomy (OMC) and mitral valve replacement (MVR). The purpose of this study was to assess the left ventricular (LV) function and exercise tolerance after mitral surgery by these procedures. Forty-eight patients underwent mitral valve surgery, and were divided into 3 groups, namely, Sellors type I+II (OMC, 18 patients), Sellors type III (OMC, 13 patients) and Sellors type III (MVR, 17 patients). Bjork-Shiley disc prosthetic valves were used in most of the MVR cases. Although the incidences of the NYHA Class (III+IV) in the Sellors type I+II, Sellors type III and MVR groups were 44.4% , 76.9% and 64.7%, respectively, before surgery, they improved to 0%, 15.4% and 5.9% postoperatively. No remarkable changes in the CI of the Sellors type I+II and Sellors type III groups were recognized through the entire postoperative period, but in the MVR group, both the CI and SVI increased significantly 6 months after the operation compared to preoperative values. The postoperative LV function at rest was best in the Sellors type I+II group (OMC), moderate in the MVR group and worst in the OMC patients of the Sellors type III group. The same results were recognized when scored using the NYHA functional classification. Six months after the operation, both the CI and SVI during exercise markedly decreased in the Sellors type III and MVR groups, and no improvement in the exercise tolerance of either group was recognized. Also, the Heather index increased significantly in comparison with preoperative values. Therefore, improvement in LV contractility and exercise tolerance hoped for in valvular reconstructive surgery was not realized. On the contrary, there was a tendency to become worse at the 6th postoperative month. It is difficult to decide whether to reconstruct or to replace a severely distored mitral valve. Considering the above results, we conclude that OMC of a remarkably distored valve was not necessarily indicated since the possibility of postoperative restenosis and regurgitation is rather high. In light of postoperative LV function and exercise tolerance, MVR seems preferable to OMC.