Hansen D E, Cahill P D, DeCampli W M, Harrison D C, Derby G C, Mitchell R S, Miller D C
Circulation. 1986 Jun;73(6):1310-20. doi: 10.1161/01.cir.73.6.1310.
As the mitral valvular apparatus tenses during systole, forces transmitted along the chordae tendineae to the left ventricular chamber may influence left ventricular performance. To test this hypothesis, 10 dogs anesthetized with fentanyl were studied during cardiopulmonary bypass. The importance of the mitral apparatus in left ventricular systolic function was assessed independent of load by means of the slope of the contractile state-dependent left ventricular peak isovolumetric pressure-volume relationship (Emax), which was measured at constant heart rate and aortic pressure with a micromanometer inside a left ventricular intracavitary balloon before and immediately after all chordae tendineae were severed. Herniation of the balloon was prevented by a disk secured to the mitral anulus. Emax decreased from 11.97 +/- 3.35 (+/- SD) to 6.38 +/- 0.96 mm Hg/ml (p less than .001) with chordal severing. The volume intercept (Vo) was unchanged. Fluoroscopic studies of the balloon contour in eight additional dogs revealed dyskinesia in the area of the papillary muscle insertion and substantial alterations in chamber geometry during systole after the chordae were severed. Accordingly, we conclude that global left ventricular systolic performance is impaired when chordal attachments of the mitral valve are disrupted. Changes in left ventricular geometry or loss of inward force normally transmitted to the left ventricular wall as the valve tense may underlie these changes. These findings suggest that postoperative left ventricular dysfunction after mitral valve replacement may be attributable, in part, to excision of the native mitral apparatus at the time of surgery and support efforts to spare chordae during mitral valve surgery.
在收缩期二尖瓣装置绷紧时，沿腱索传递至左心室腔的力可能会影响左心室功能。为验证这一假设，对10只接受芬太尼麻醉的犬在体外循环期间进行了研究。通过收缩状态依赖性左心室等容收缩期峰值压力 - 容积关系（Emax）的斜率来评估二尖瓣装置在左心室收缩功能中的重要性，该斜率在恒定心率和主动脉压力下，于所有腱索切断前后，通过左心室内球囊内的微压计进行测量。通过固定在二尖瓣环上的圆盘防止球囊疝出。切断腱索后，Emax从11.97±3.35（±标准差）降至6.38±0.96mmHg/ml（p＜0.001）。容积截距（Vo）未改变。对另外8只犬的球囊轮廓进行荧光透视研究发现，腱索切断后，乳头肌附着区域出现运动障碍，收缩期心室几何形状发生显著改变。因此，我们得出结论，当二尖瓣的腱索附着被破坏时，整体左心室收缩功能受损。左心室几何形状的改变或瓣膜绷紧时通常传递至左心室壁的内向力丧失可能是这些变化的基础。这些发现表明，二尖瓣置换术后的左心室功能障碍可能部分归因于手术时切除了天然二尖瓣装置，并支持在二尖瓣手术中保留腱索的努力。
