University of Ottawa Heart Institute, 40 Ruskin St, Ottawa, ON K1Y4W7, Canada.
Circ Cardiovasc Imaging. 2010 May;3(3):308-13. doi: 10.1161/CIRCIMAGING.109.859843. Epub 2010 Mar 1.
Hemodynamically significant mitral regurgitation (MR) may alter left ventricular (LV) myocardial energy requirements. The effects of MR and subsequent corrective mitral valve (MV) surgery on myocardial energetics are not well understood. A better understanding of myocardial energetics and the LV responses to changes in preload and afterload may assist with the understanding of mitral regurgitation and its effect on the LV. We sought to determine the effects of MV surgery on forward stroke work, myocardial oxidative metabolism, and myocardial efficiency.
Prospectively enrolled patients with chronic, severe, nonischemic mitral regurgitation underwent echocardiography, radionuclide angiography, and C-11 acetate positron emission tomography to measure LV volumes, ejection fraction, and oxidative metabolism before and 1 year after MV surgery. Forward and total stroke work corrected for oxidative metabolism was used to estimate efficiency using the work metabolic index. Fourteen patients (age, 59+/- 8 years) with myxomatous MV were enrolled. One year after MV surgery, there was a reduction in LV end-diastolic and end-systolic volumes (231+/-86 to 131+/-21 mL; P<0.01 and 98+/-53 to 55+/-17 mL; P<0.01). Forward stroke volume increased (58.1+/-15.0 to 75.5+/-23 mL; P<0.01), LV ejection fraction was preserved without a significant change in oxidative metabolism. Forward work metabolic index improved (4.99+/-1.32 x 10(6) to 6.59+/-2.45 x 10(6) mm Hg x mL/m(2); P=0.02). This was not at the expense of total work metabolic index, which was preserved.
MV surgery has a beneficial effect on forward stroke volume and forward work metabolic index without adverse effects on oxidative metabolism or total work metabolic index.
血流动力学意义重大的二尖瓣反流（MR）可能改变左心室（LV）心肌的能量需求。二尖瓣反流及随后的二尖瓣修复手术对心肌能量学的影响尚未得到很好的理解。更好地了解心肌能量学以及 LV 对前负荷和后负荷变化的反应，可能有助于理解二尖瓣反流及其对 LV 的影响。我们试图确定二尖瓣修复手术对前向stroke work、心肌氧化代谢和心肌效率的影响。
前瞻性纳入 14 例患有慢性、严重非缺血性二尖瓣反流的患者，分别在二尖瓣修复术前和术后 1 年进行超声心动图、放射性核素血管造影和 C-11 乙酸正电子发射断层扫描，以测量 LV 容积、射血分数和氧化代谢。使用工作代谢指数，通过校正氧化代谢的前向和总 stroke work 来估计效率。14 例患者（年龄 59+/-8 岁）为黏液样二尖瓣。二尖瓣修复术后 1 年，LV 舒张末期和收缩末期容积减少（231+/-86 至 131+/-21 毫升；P<0.01 和 98+/-53 至 55+/-17 毫升；P<0.01）。前向 stroke volume 增加（58.1+/-15.0 至 75.5+/-23 毫升；P<0.01），LV 射血分数保持不变，氧化代谢无显著变化。前向工作代谢指数改善（4.99+/-1.32 x 10(6) 至 6.59+/-2.45 x 10(6) mm Hg x mL/m(2)；P=0.02）。这并没有以氧化代谢或总工作代谢指数为代价，后者得到了保持。
二尖瓣修复手术对前向 stroke volume 和前向工作代谢指数有有益的影响，而对氧化代谢或总工作代谢指数没有不良影响。
