Anesthesia Service, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI 53295, USA.
J Cardiothorac Vasc Anesth. 2013 Aug;27(4):660-4. doi: 10.1053/j.jvca.2013.01.007. Epub 2013 May 30.
Transmitral blood flow produces a vortex ring that enhances the hydraulic efficiency of early left ventricular (LV) filling. The effect of pressure-overload hypertrophy on the duration of LV vortex ring formation (vortex formation time [VFT]) is unknown. The current investigation tested the hypothesis that chronic LV pressure-overload hypertrophy produced by severe aortic stenosis (AS) reduces VFT in patients with preserved LV systolic function undergoing aortic valve replacement.
Observational study.
Veterans Affairs Medical Center.
After the Institutional Review Board's approval, 8 patients (7 men and 1 woman; age, 62±5 y; and ejection fraction, 59%±5%) with AS (peak pressure gradient, 81±22 mmHg; aortic valve area, 0.78±0.25 cm(2)) scheduled for aortic valve replacement were compared with 8 patients (all men; age, 63±3 y; and ejection fraction, 60%±7%) without AS undergoing coronary artery bypass graft surgery.
None.
Under general anesthesia, peak early LV filling (E) and atrial systole (A) blood flow velocities and their corresponding velocity-time integrals were obtained using pulse-wave Doppler echocardiography to determine E/A and atrial filling fraction (β). Mitral valve diameter (D) was calculated as the average of minor and major axis lengths obtained in the midesophageal bicommissural and long-axis transesophageal echocardiography imaging planes, respectively. Posterior wall thickness (PWT) was measured at end-diastole using M-mode echocardiography. VFT was calculated as 4×(1-β)×SV/πD(3), where SV = stroke volume measured using thermodilution. Systemic and pulmonary hemodynamics, LV diastolic function, PWT, and VFT were determined during steady-state conditions 30 minutes before cardiopulmonary bypass. Early LV filling was attenuated in patients with AS (eg, E/A, 0.77±0.11 compared with 1.23±0.13; β, 0.43±0.09 compared with 0.35±0.02; p<0.05 for each). LV hypertrophy was observed (PWT, 1.4±0.1 cm compared with 1.1±0.2 cm; p<0.05) and VFT was lower (3.0±0.9 v 4.3±0.5; p<0.05) in patients with versus without AS. Linear regression analysis showed a significant correlation between VFT and PWT (VFT = -2.57 ×PWT + 6.81; r(2) = 0.345; p = 0.017).
The results indicated that pressure-overload hypertrophy produced by AS reduced VFT in patients with normal LV systolic function undergoing aortic valve replacement.
二尖瓣血流产生的涡流环增强了左心室（LV）早期充盈的水力效率。压力超负荷肥厚对 LV 涡流环形成时间（VFT）的持续时间的影响尚不清楚。目前的研究检验了这样一个假设，即严重主动脉瓣狭窄（AS）引起的慢性 LV 压力超负荷肥厚会降低接受主动脉瓣置换术的左心室收缩功能正常的患者的 VFT。
观察性研究。
退伍军人事务医疗中心。
在机构审查委员会批准后，将 8 名患者（7 名男性和 1 名女性；年龄 62±5 岁；射血分数 59%±5%）与 8 名无 AS 接受冠状动脉旁路移植术的患者（均为男性；年龄 63±3 岁；射血分数 60%±7%）进行比较。这些患者均患有 AS（峰值压力梯度为 81±22mmHg；主动脉瓣面积为 0.78±0.25cm²），计划进行主动脉瓣置换术。
无。
在全身麻醉下，使用脉冲波多普勒超声心动图获得左心室早期充盈（E）和心房收缩（A）血流速度及其相应的速度时间积分，以确定 E/A 和心房充盈分数（β）。二尖瓣直径（D）通过测量中食管双腔和长轴经食管超声心动图成像平面的小轴和大轴长度的平均值来计算。使用 M 型超声心动图在舒张末期测量后壁厚度（PWT）。VFT 通过以下公式计算：4×（1-β）×SV/πD（3），其中 SV 通过热稀释法测量。在体外循环前 30 分钟稳定状态下，测定全身和肺血流动力学、LV 舒张功能、PWT 和 VFT。AS 患者的早期 LV 充盈减弱（例如，E/A，0.77±0.11 比 1.23±0.13；β，0.43±0.09 比 0.35±0.02；p<0.05 ）。观察到 LV 肥厚（PWT，1.4±0.1cm 比 1.1±0.2cm；p<0.05），并且 VFT 较低（3.0±0.9v 4.3±0.5；p<0.05），与无 AS 的患者相比。线性回归分析显示 VFT 与 PWT 之间存在显著相关性（VFT = -2.57×PWT + 6.81；r²=0.345；p=0.017）。
结果表明，接受主动脉瓣置换术的左心室收缩功能正常的 AS 患者的压力超负荷肥厚降低了 VFT。
