新型弹性二尖瓣环与仿Carpentier硬环矫治小牛急性二尖瓣反流的研究

EXPERIMENTAL STUDY ON ANNULOPLASTY FOR ACUTE MITRAL REGURGITATION IN CALVES BY NEW FLEXIBLE RING AND IMITATIVE CARPENTIER RIGID RING

本实验是将两种新型弹性二尖瓣环(FWⅡ、FWⅢ环)和仿制的Carpentier硬环分别随机植入3组小牛体内(每组5头),通过应用术中超声多普勒比较3种瓣环对矫治小牛急性二尖瓣反流模型的血液动力学效果。本文还着重讨论其产生机制及临床应用前景。

The Carpentier mitral annuloplasty ring had been used in cardiac valve surgery for more than 20 years since the first application in 1968. Now, it has been widely used in the clinic and the effects are satisfactory. However, certain problems such as residual mitral stenosis (MS) and mitral regurgitation (MR) still remain. And postoperative obstruction of left ventricular outflow tract (LVOT) was found in about 9% of the patients. Therefore, a flexible ring expected to be more suitable for the physiological change of mitral annulus from systolic to diastolic period has been investigated.Based on the measurement of the systolic and diastolic force of the mitral annulus of normal dogs, Two kinds of new flexible rings named FW Ⅱ and FW Ⅲ (with a valve) were designed and were implanted together with the Carpentier rigid ring randomly in three groups of calves, 5 in each group. The hemodynamic efficiency of these rings used for correction of acute MR has been compared by using two-dimensional contrast echocardiography and Doppler at operation. The results were as follows: (1) The new flexible mitral rings, FW Ⅱ and FW Ⅲ, could change synchronously with the cardiac cycle, tbe perimeter change rates of which were 7.2% and 9.0%, respectively, while the area change rates were 18.5% and 18.7%, respectively. The differences between rigid ring and flexible rings were statistically significant (p<0.05) ; (2) As compared with the pre-operative measurements, the rigid ring resisted mitral flow in the diastolic period, especially during increased volume load and myocardial contractility, significant differences of the absolute increase between rigid ring and flexible rings were found (p<0.05, p=0.057); (3) Similarly, the rigid ring resisted LVOT markedly in the diastolic period, especially during increased myocardial contractility. This effect could not be resolved completely by increasing resistance and volume load. The differences of absolute increase between rigid ring and flexible rings were statistically significant (p<0.001); (4) The FW Ⅲ ring could be selectively used to correct acute MR.In conclusion, the new flexible mitral ring is superior to the rigid ring in being able to change synchronously with the systolic and diastolic force and is expected to have wide clinical application.