Evaluation of echocardiography indices of systolic function: a comparative study using pressure‐volume loops in patients undergoing coronary artery bypass surgery*

Transoesophageal echocardiography measures of systolic left ventricular function obtained during coronary artery bypass surgery are heavily influenced by alterations in loading conditions. No validation of these measurements against load independent indices obtained by pressure-volume loop analysis has been undertaken in humans. Ten patients undergoing coronary artery bypass surgery underwent simultaneous transoesophageal echocardiography and pressure-volume loop analysis of cardiac function at different loading conditions (reduced preload, increased afterload and atrial pacing). Fractional area change, afterload corrected fractional area change, and lateral basal wall peak systolic myocardial velocity, along with dP/dt, were compared to the preload recruitable stroke work relationship. There were no significant differences between the echocardiography measures when compared to the preload recruitable stroke work relationship; however, dP/dt varied significantly across loading conditions (p<0.001). Transoesophageal echocardiography adequately assesses systolic function across loading conditions commonly seen during coronary artery bypass surgery.