Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn 55905, USA.
J Thorac Cardiovasc Surg. 2010 Dec;140(6):1300-5. doi: 10.1016/j.jtcvs.2009.12.031. Epub 2010 Mar 11.
Mitral valve repair for mitral regurgitation is followed by left ventricle adjustment to new preload and afterload. We evaluated left ventricular geometry and function immediately after mitral valve repair for degenerative prolapse.
We prospectively studied 25 patients undergoing mitral valve repair; 15 patients undergoing a coronary artery bypass graft served as controls to determine the impact of cardiopulmonary bypass and cardioplegic arrest on left ventricular function. Intraoperative transesophageal echocardiography was conducted after sternotomy before initiation of cardiopulmonary bypass and after termination of cardiopulmonary bypass and protamine infusion. Simultaneous pulmonary catheter data ensured that the images were obtained under similar hemodynamic conditions.
Immediately after mitral valve repair, left ventricular fractional area change decreased significantly from 65% ± 7% to 52% ± 8% (P < .001). Left ventricular end-diastolic area decreased minimally (21.3 ± 5.3 cm(2) vs 19.4 ± 4.5 cm(2); P = .005), whereas left ventricular end-systolic area increased significantly (7.5 ± 2.3 cm(2) vs 9.3 ± 2.5 cm(2); P < .001). Notably, forward stroke volume (thermodilution) remained similar (63 ± 24 mL vs 66 ± 19 mL; P = .5). No significant difference was found in controls between pre- cardiopulmonary bypass and post-cardiopulmonary bypass fractional area change (54% ± 12% vs 57% ± 10%; P = .19), left ventricular end-diastolic area (16.6 ± 6.2 cm(2) vs 15.7 ± 5.0 cm(2); P = .32), and stroke volume (72 ± 29 mL vs 65 ± 19 mL; P = .15); they had a slight decrease in left ventricular end-systolic area (7.9 ± 4.4 cm(2) vs 6.9 ± 3.2 cm(2); P = .03).
Early after correction of mitral regurgitation, left ventricular fractional area change decreases significantly, primarily as the result of a larger end-systolic dimension. This may be a compensatory mechanism to prevent augmentation of forward stroke volume after mitral valve repair.
二尖瓣修复术后左心室会根据新的前负荷和后负荷进行调整。我们评估了退行性二尖瓣脱垂患者行二尖瓣修复术后即刻的左心室几何形状和功能。
我们前瞻性研究了 25 例行二尖瓣修复术的患者；15 例行冠状动脉旁路移植术的患者作为对照组，以确定体外循环和心脏停搏对左心室功能的影响。在体外循环开始前和体外循环结束及鱼精蛋白输注后经胸食管超声心动图检查。同时进行肺动脉导管数据监测，以确保在类似的血液动力学条件下获取图像。
二尖瓣修复术后即刻，左室射血分数从 65%±7%显著下降至 52%±8%（P<0.001）。左心室舒张末期面积仅略有减少（21.3±5.3cm2 比 19.4±4.5cm2；P=0.005），而左心室收缩末期面积显著增加（7.5±2.3cm2 比 9.3±2.5cm2；P<0.001）。值得注意的是，经热稀释法测量的前向每搏量（stroke volume）仍相似（63±24mL 比 66±19mL；P=0.5）。对照组在体外循环前与体外循环后射血分数（54%±12%比 57%±10%；P=0.19）、左心室舒张末期面积（16.6±6.2cm2 比 15.7±5.0cm2；P=0.32）和每搏量（72±29mL 比 65±19mL；P=0.15）无显著差异，左心室收缩末期面积有轻度减少（7.9±4.4cm2 比 6.9±3.2cm2；P=0.03）。
二尖瓣反流矫正后早期，左室射血分数明显下降，主要是由于收缩末期直径增大所致。这可能是一种代偿机制，以防止二尖瓣修复后前向每搏量的增加。
