Automated echocardiographic analysis. Examination of serial intraoperative measurements

Although transesophageal echocardiography allows continuous intraoperative cardiac monitoring, the technique has been limited by the lack of a method for realtime, quantitative assessment of cardiac chamber size and systolic function. Automated border detection (ABD), based on an analysis of integrated backscatter, is a new technique that is purported to provide real-time, quantitative assessment of left ventricular (LV) areas and fractional area change (FAC). A prospective investigation was designed to assess the accuracy and trending capability of ABD during continuous intraoperative monitoring.

In 16 patients monitored throughout noncardiac surgical procedures, serial real-time estimates of LV end-diastolic area (EDA), end-systolic area (ESA), and FAC by ABD were compared with paired off-line manual measurements made by two experiences echocardiographers.

There was a high correlation between real-time ABD estimates of LV ESA (r = 0.93), EDA (r = 0.89), and FAC (r = 0.90) to those of the off-line technique. The automated technique systematically underestimated both EDA and ESA, resulting in a small underestimation of FAC. The automated technique demonstrated an accuracy rate of 96% in tracking serial changes in LV area. The technique performed with an 83% sensitivity and 85% specificity for detecting acute changes in LV area.

This analysis of serial intraoperative echocardiograms demonstrates the accuracy of ABD to estimate LV area in real time and to track serial changes in cardiac area during surgery. Although ABD is an automated technique, application by personnel experienced in its operation and an echocardiographic system that includes lateral-gain adjustment controls are recommended for its optimal performance.