Gorcsan J, Denault A, Gasior T A, Mandarino W A, Kancel M J, Deneault L G, Hattler B G, Pinsky M R
Division of Cardiology, University of Pittsburgh Medical Center, Pennsylvania 15261.
Anesthesiology. 1994 Sep;81(3):553-62; discussion 27A. doi: 10.1097/00000542-199409000-00006.
Automated echocardiographic measures of left ventricular (LV) cavity area are closely correlated with changes in volume and can be coupled with LV pressure to construct pressure-area loops in real time. The objective was to rapidly estimate LV contractility from the end-systolic relations of cavity area (as a surrogate for LV volume) and femoral arterial pressure (as a surrogate for LV pressure) in patients undergoing cardiac surgery.
Studies were attempted on 18 consecutive patients with recordings of LV pressure, LV area, and femoral arterial pressure on a computer workstation interfaced with the ultrasound system. End-systolic pressure-area relations (in terms of pressure-area elastance [E'es]) from pressure-area loops during inferior vena caval occlusions were determined before and immediately after cardiopulmonary bypass using both LV and arterial pressure by semiautomated and automated iterative linear regression methods.
Data sets were available for 13 patients before and 8 patients after bypass (21 studies in 14 patients). E'es by arterial pressure was closely correlated with E'es by LV pressure: r = 0.96, standard error of the estimate = 2 mmHg/cm2, y = 1.01 x -0.7 by the semiautomated method and r = 0.94, standard error of the estimate = 3 mmHg/cm2, y = 1.02 x -0.5 by the automated method. Analysis of semiautomated and automated estimates of E'es from arterial pressure and E'es using LV pressure by the Bland-Altman method showed no systematic measurement bias and calculated limits of agreement of 8 and 9 mmHg/cm2, respectively. Similar decreases in E'es by arterial and LV pressure occurred from before to after bypass in 7 patients with paired data sets: 32 +/- 12 to 15 +/- 6 mmHg/cm2 and 32 +/- 15 to 15 +/- 7 mmHg/cm2, respectively (P < 0.05 for both).
On-line femoral arterial pressure and LV area data by echocardiographic automated border detection may be used to rapidly calculate E'es as a means to estimate LV contractility in selected patients.
左心室（LV）腔面积的超声心动图自动测量与容积变化密切相关，并且可以与左心室压力相结合以实时构建压力-面积环。目的是在接受心脏手术的患者中，根据收缩末期腔面积（作为左心室容积的替代指标）和股动脉压力（作为左心室压力的替代指标）的关系快速评估左心室收缩力。
对连续18例患者进行研究，在与超声系统相连的计算机工作站上记录左心室压力、左心室面积和股动脉压力。在下腔静脉阻塞期间，通过半自动和自动迭代线性回归方法，使用左心室和动脉压力，在体外循环前和体外循环后立即确定压力-面积环的收缩末期压力-面积关系（以压力-面积弹性[E'es]表示）。
有13例患者体外循环前和8例患者体外循环后的数据集（14例患者共21项研究）。通过动脉压力得出的E'es与通过左心室压力得出的E'es密切相关：半自动方法的r = 0.96，估计标准误差 = 2 mmHg/cm2，y = 1.01x - 0.7；自动方法的r = 0.94，估计标准误差 = 3 mmHg/cm2，y = 1.02x - 0.5。采用Bland-Altman方法分析从动脉压力得出的E'es的半自动和自动估计值以及使用左心室压力得出的E'es，结果显示无系统测量偏差，计算得出的一致性界限分别为8和9 mmHg/cm2。在7例有配对数据集的患者中，从体外循环前到体外循环后，通过动脉压力和左心室压力得出的E'es均出现类似下降：分别从32±12降至15±6 mmHg/cm2和从32±15降至15±7 mmHg/cm2（两者P均<0.05）。
通过超声心动图自动边界检测获得的在线股动脉压力和左心室面积数据可用于快速计算E'es，作为评估特定患者左心室收缩力的一种方法。
