Harrison M R, Clifton G D, Berk M R, DeMaria A N
Division of Cardiology, College of Medicine, University of Kentucky, Lexington.
Am J Cardiol. 1989 Oct 15;64(14):905-8. doi: 10.1016/0002-9149(89)90840-0.
Doppler echocardiographic measurements of blood flow velocity and acceleration in the ascending aorta have been shown to be useful descriptors of left ventricular (LV) systolic function. Few data exist, however, regarding the influence of loading conditions, particularly afterload, on these Doppler measurements in human subjects. Therefore, 14 normal volunteers (mean age 28 years) were studied using continuous wave Doppler echocardiography performed from the suprasternal notch both at baseline and during a controlled infusion of methoxamine. LV peak systolic (delta pk) and end-systolic (delta ES) wall stresses were calculated noninvasively using blood pressure and echocardiographic dimensions. Heart rate was kept constant by transesophageal atrial pacing. Methoxamine resulted in significant increases in mean systolic (163 +/- 8 vs 129 +/- 10 mm Hg) and diastolic (93 +/- 7 vs 71 +/- 12 mm Hg) blood pressure, as well as delta pk (277 +/- 25 vs 222 +/- 40 g/cm2 x 10(3] and delta ES (97 +/- 26 vs 77 +/- 19 g/cm2 x 10(3] (p less than or equal to 0.0004 for all). Conversely, peak velocity decreased from 0.91 +/- 0.18 m/s at baseline to 0.8 +/- 0.18 m/s (p less than or equal to 0.002) and peak acceleration decreased from 22 +/- 5 m/s2 at baseline to 19 +/- 5 m/s2 (p less than or equal to 0.006) during methoxamine infusion. Flow velocity integral and LV end-diastolic dimension remained unchanged. Thus, aortic flow velocity and peak acceleration are inversely related to afterload. This relation should be considered when using serial determinations of these Doppler parameters for patients in whom changing levels of afterload might occur.
经证明，利用多普勒超声心动图测量升主动脉内的血流速度和加速度，是描述左心室（LV）收缩功能的有效方法。然而，关于负荷条件，尤其是后负荷，对人体这些多普勒测量值的影响，相关数据很少。因此，对14名正常志愿者（平均年龄28岁）进行了研究，在基线状态以及在控制性输注甲氧明期间，从胸骨上切迹进行连续波多普勒超声心动图检查。利用血压和超声心动图测量值无创计算左心室收缩期峰值（δpk）和收缩末期（δES）壁应力。通过经食管心房起搏使心率保持恒定。甲氧明使平均收缩压（163±8 vs 129±10 mmHg）和舒张压（93±7 vs 71±12 mmHg）显著升高，同时δpk（277±25 vs 222±40 g/cm2×10³）和δES（97±26 vs 77±19 g/cm2×10³）也显著升高（所有p均≤0.0004）。相反，在输注甲氧明期间，峰值速度从基线时的0.91±0.18 m/s降至0.8±0.18 m/s（p≤0.002），峰值加速度从基线时的22±5 m/s²降至19±5 m/s²（p≤0.006）。流速积分和左心室舒张末期内径保持不变。因此，主动脉流速和峰值加速度与后负荷呈负相关。对于可能出现后负荷水平变化的患者，在连续测定这些多普勒参数时应考虑这种关系。
