Nakano K, Swindle M M, Spinale F, Ishihara K, Kanazawa S, Smith A, Biederman R W, Clamp L, Hamada Y, Zile M R
Division of Cardiology, Medical University of South Carolina 29425.
J Clin Invest. 1991 Jun;87(6):2077-86. doi: 10.1172/JCI115238.
It is known that long-standing volume overload on the left ventricle due to mitral regurgitation eventually leads to contractile dysfunction. However, it is unknown whether or not correction of the volume overload can lead to recovery of contractility. In this study we tested the hypothesis that depressed contractile function due to volume overload in mitral regurgitation could return toward normal after mitral valve replacement. Using a canine model of mitral regurgitation which is known to produce contractile dysfunction, we examined contractile function longitudinally in seven dogs at baseline, after 3 mo of mitral regurgitation, 1 mo after mitral valve replacement, and 3 mo after mitral valve replacement. After 3 mo of mitral regurgitation (regurgitant fraction 0.62 +/- 0.04), end-diastolic volume had nearly doubled from 68 +/- 6.8 to 123 +/- 12.1 ml (P less than 0.05). All five indices of contractile function which we examined were depressed. For instance, maximum fiber elastance (EmaxF) obtained by assessment of time-varying elastance decreased from 5.95 +/- 0.71 to 2.25 +/- 0.18 (P less than 0.05). The end-systolic stiffness constant (k) was also depressed from 4.2 +/- 0.4 to 2.1 +/- 0.3. 3 mo after mitral valve replacement all indexes of contractile function had returned to or toward normal (e.g., EmaxF 3.65 +/- 0.21 and k 4.2 +/- 0.3). We conclude that previously depressed contractile function due to volume overload can improve after correction of the overload.
已知由于二尖瓣反流导致的左心室长期容量超负荷最终会导致收缩功能障碍。然而，容量超负荷的纠正是否能导致收缩力恢复尚不清楚。在本研究中，我们检验了这样一个假设：二尖瓣反流中因容量超负荷导致的收缩功能降低在二尖瓣置换术后可恢复正常。使用一种已知会产生收缩功能障碍的二尖瓣反流犬模型，我们在基线、二尖瓣反流3个月后、二尖瓣置换术后1个月以及二尖瓣置换术后3个月对7只犬的收缩功能进行了纵向研究。二尖瓣反流3个月后（反流分数0.62±0.04），舒张末期容积从68±6.8 ml几乎增加了一倍，达到123±12.1 ml（P<0.05）。我们检测的所有五项收缩功能指标均降低。例如，通过评估时变弹性获得的最大纤维弹性（EmaxF）从5.95±0.71降至2.25±0.18（P<0.05）。收缩末期硬度常数（k）也从4.2±0.4降至2.1±0.3。二尖瓣置换术后3个月，所有收缩功能指标均恢复到或接近正常（例如，EmaxF为3.65±0.21，k为4.2±0.3）。我们得出结论，先前因容量超负荷而降低的收缩功能在超负荷纠正后可以改善。
