Goto Y, Futaki S, Kawaguchi O, Hata K, Takasago T, Saeki A, Nishioka T, Taylor T W, Suga H
Department of Medicine, National Cardiovascular Center, Osaka, Japan.
J Am Coll Cardiol. 1993 May;21(6):1522-31. doi: 10.1016/0735-1097(93)90333-v.
This study was designed to assess the relation between left ventricular regional myocardial oxygen consumption (VO2) and variables of regional myocardial contractile function under various loading conditions.
Although the relation between global VO2 and global ventricular function has been extensively studied, the relation between regional VO2 and regional myocardial contraction is not fully understood.
Myocardial shortening (regional area shrinkage), regional work, regional total mechanical energy index and regional VO2 were measured under variously altered loading conditions in the isolated, blood-perfused dog left ventricle. Regional total mechanical energy per beat was quantified by wall tension-regional area area (TAA) by the analogy of left ventricular pressure-volume area. Left ventricular loading conditions were altered by changing end-diastolic volume and stroke volume with a servo pump as follows: 1) increased preload (increased end-diastolic volume and stroke volume at a constant ejection fraction), 2) decreased afterload (increased stroke volume at a constant end-diastolic volume), 3) increased preload and afterload (increased end-diastolic volume at a constant stroke volume), and 4) altered mode of contraction (ejecting vs. isovolumetric contractions).
During increased preload, all three variables correlated positively with regional VO2 (r = 0.78 to 1.00). During decreased afterload, the correlation was negative for area shrinkage (r = -0.65 to -0.91) and variable for regional work (r = -0.55 to 0.98) but positive and highly linear for TAA (r = 0.80 to 0.99). During increased preload and afterload, the correlation was again negative for area shrinkage (r = -0.77 to -0.97) but positive for regional work (r = 0.83 to 0.93) and TAA (r = 0.95 to 0.99). During altered mode of contraction, the correlation was insignificant for area shrinkage (r = 0.24 to 0.57) and moderate for regional work (r = 0.50 to 0.79), whereas again highly linear for TAA (r = 0.95 to 0.98). Thus, only TAA correlated closely with regional VO2 under any loading conditions. Furthermore, the slope and regional VO2 intercept of the regional VO2-TAA relation was remarkably consistent among the different hearts and loading conditions.
We conclude that there is a tight coupling between regional VO2 and regional total mechanical energy represented by TAA regardless of left ventricular afterload and preload conditions.
本研究旨在评估不同负荷条件下左心室局部心肌耗氧量（VO2）与局部心肌收缩功能变量之间的关系。
尽管整体VO2与整体心室功能之间的关系已得到广泛研究，但局部VO2与局部心肌收缩之间的关系尚未完全明确。
在离体、血液灌注的犬左心室中，于多种改变的负荷条件下测量心肌缩短（局部面积缩小）、局部功、局部总机械能指数和局部VO2。通过将左心室压力-容积面积类比为壁张力-局部面积面积（TAA）来量化每搏局部总机械能。使用伺服泵通过改变舒张末期容积和每搏输出量来改变左心室负荷条件，如下：1）增加前负荷（在恒定射血分数下增加舒张末期容积和每搏输出量），2）降低后负荷（在恒定舒张末期容积下增加每搏输出量），3）增加前负荷和后负荷（在恒定每搏输出量下增加舒张末期容积），以及4）改变收缩模式（射血与等容收缩）。
在前负荷增加期间，所有三个变量均与局部VO2呈正相关（r = 0.78至1.00）。在后负荷降低期间，面积缩小的相关性为负（r = -0.65至-0.91），局部功的相关性变化不定（r = -0.55至0.98），但TAA的相关性为正且呈高度线性（r = 0.80至0.99）。在前负荷和后负荷增加期间，面积缩小的相关性再次为负（r = -0.77至-0.97），但局部功的相关性为正（r = 0.83至0.93），TAA的相关性为正（r = 0.95至0.99）。在收缩模式改变期间，面积缩小的相关性不显著（r = 0.24至0.57），局部功的相关性中等（r = 0.50至0.79），而TAA的相关性再次呈高度线性（r = 0.95至0.98）。因此，在任何负荷条件下，只有TAA与局部VO2密切相关。此外，不同心脏和负荷条件下局部VO2-TAA关系的斜率和局部VO2截距显著一致。
我们得出结论，无论左心室后负荷和前负荷条件如何，局部VO2与以TAA表示的局部总机械能之间存在紧密耦合。
