Evangelista A, Garcia-Dorado D, Garcia del Castillo H, Gonzalez-Alujas T, Soler-Soler J
Servei de Cardiología, Hospital General Universitari Vall d'Hebron, Barcelona, Spain.
J Am Coll Cardiol. 1995 Mar 1;25(3):710-6. doi: 10.1016/0735-1097(94)00456-z.
We attempted to ascertain whether cardiac index can be directly estimated from Doppler mean velocity.
Although diverse Doppler echocardiographic methods have been described for cardiac output quantification, they are not widely used in clinical practice. Cross-sectional area measurement has been identified as the main source of error in flow volume quantification.
A three-phase study by Doppler echocardiography was conducted in 306 patients. In phase I, the normal mean velocity ratio of the left and right ventricular outflow tracts was established in 170 normal subjects. In phase II, cardiac index, calculated as the product of aortic annular area index by mean velocity (conventional method), and mean velocity determined in the left ventricular outflow tract and ascending aorta by pulsed and continuous wave Doppler, respectively, were correlated with thermodilution cardiac index in 66 patients. In phase III, the accuracy of the regression equations obtained was prospectively assessed in an additional 70 patients.
The normal left/right ventricular outflow tract mean velocity ratio by pulsed wave Doppler was 1.1 +/- 0.1. Cardiac index (CI) calculated by the conventional method and thermodilution (TD) showed acceptable correlation (r = 0.90, CITD = 1.20 CIPWD + 357; r = 0.86, CITD = 0.90 CICWD + 262) for pulsed (PWD) and continuous wave (CWD) Doppler, respectively, but with systematic underestimation (-28 +/- 13%, p < 0.01) by pulsed wave Doppler. Mean velocity (MV) showed excellent correlation with the thermodilution cardiac index (r = 0.97, CITD = 172 MVPWD - 172; r = 0.93, CITD = 129 MVCWD - 255). When these regression equations were prospectively applied, better agreement with the thermodilution cardiac index was obtained by pulsed wave Doppler directly from mean velocity (SD 240 ml/min per m2) than when aortic annular area was considered in the calculation (SD 428 ml/min per m2). Similar results were obtained by continuous wave Doppler (SD 433 vs. 599 ml/min per m2) but with less accuracy.
Left ventricular outflow tract mean velocity determined by pulsed wave Doppler permits easy, accurate cardiac index quantification in the absence of left ventricular outflow abnormalities. The simplicity of this method enhances its clinical applicability in noninvasive monitoring of cardiac index.
我们试图确定是否可以从多普勒平均速度直接估算心脏指数。
尽管已经描述了多种用于心输出量定量的多普勒超声心动图方法，但它们在临床实践中并未得到广泛应用。横截面积测量已被确定为流量定量误差的主要来源。
对306例患者进行了一项多普勒超声心动图的三阶段研究。在第一阶段，在170名正常受试者中确定左、右心室流出道的正常平均速度比值。在第二阶段，在66例患者中，将以主动脉环面积指数乘以平均速度计算的心脏指数（传统方法），以及分别通过脉冲波和连续波多普勒在左心室流出道和升主动脉中测定的平均速度，与热稀释法心脏指数进行相关性分析。在第三阶段，在另外70例患者中前瞻性评估所获得回归方程的准确性。
脉冲波多普勒测得的正常左/右心室流出道平均速度比值为1.1±0.1。传统方法计算的心脏指数（CI）与热稀释法（TD）的心脏指数，对于脉冲波（PWD）和连续波（CWD）多普勒分别显示出可接受的相关性（r = 0.90，CITD = 1.20 CIPWD + 357；r = 0.86，CITD = 0.90 CICWD + 262），但脉冲波多普勒存在系统性低估（-28±13%，p < 0.01）。平均速度（MV）与热稀释法心脏指数显示出极好的相关性（r = 0.97，CITD = 172 MVPWD - 172；r = 0.93，CITD = 129 MVCWD - 255）。当前瞻性应用这些回归方程时，直接根据平均速度通过脉冲波多普勒获得的结果与热稀释法心脏指数的一致性更好（标准差为每平方米240 ml/min），优于在计算中考虑主动脉环面积时的结果（标准差为每平方米428 ml/min）。连续波多普勒也得到了类似的结果（标准差分别为433和599 ml/min每平方米），但准确性较低。
在没有左心室流出道异常的情况下，通过脉冲波多普勒测定的左心室流出道平均速度可实现简便、准确的心指数定量。该方法的简单性增强了其在心脏指数无创监测中的临床适用性。
