Left ventricular pressure-area relations as assessed by transoesophageal echocardiographic automated border detection: comparison with conductance catheter technique in cardiac surgical patients

The aim of this study was to validate measurements of intraoperative left v entricular (LV) area by transoesophageal echocardiography against simultane ous measurements of LV volume by conductance catheter (CC) in cardiac surgi cal patients with normal systolic LV function. Echo area was compared with CC volume during steady state and during acute changes of pre- and afterloa d by partial clamping of the inferior vena cava and the ascending aorta in eight patients scheduled for coronary artery bypass grafting. At steady sta te, Bland-Altman analysis of 32 recordings revealed a bias (SD) of 0.6% (2. 5%) between echo area and CC volume. related to the initial values of end-d iastolic area (100% area) and volume (100% volume), respectively During loa ding interventions, bias between the two methods, as assessed by 112 measur ement sequences, was 0.5% (3.7%) during aortic occlusion and -3.9% (4.4%) d uring cava occlusion at end-systole (P<0.0001); at end-diastole, this bias was 1.3% (4%) during aortic occlusion and 0.2% (5.7%) during cava occlusion (P<0.0001). Intraoperative area measurements with transoesophageal echocar diography in cardiac surgical patients with normal systolic LV function sho w good correlation with CC volume measurements under steady-state condition s. During acute unloading by vena cava occlusion, the resulting small end-s ystolic echo area measurements differ significantly more from CC volume mea surements than during acute increase in afterload by aortic occlusion.