Shape and movement of the interatrial septum predicts change in pulmonary capillary wedge pressure

We aimed to assess whether movement of the interatrial septum predicts change in pulmonary capillary wedge pressure (PCWP). In 71 patients undergoing cardiac surgery, the interatrial septum was categorised by its shape and movement using transesophageal echocardiography. Fixed curvature (FC) was identified by bowing of the interatrial septum from left to right throughout the cardiac cycle, mid-systolic reversal (MSR) by minimal septal movement and transient reversal (right to left) during mid-systole, and mid-systolic buckling (MSB) by marked movement and buckling of the septum during mid-systole. These were compared with PCWP. Sensitivity and interobserver reliability was studied with continuous PCWP and TEE measurement during a period of acute volume alteration in 10 additional patients. Interatrial septal movement predicted PCWP, with mean PCWP (95% confidence intervals) for FC, 18.1 mmHg (16.7 to 19.6), MSR 13.2 mmHg (12.5 to 13.8) and MSB, 9.9 mmHg (9.0 to 10.7) mmHg. The mean PCWP at which a change in pattern occurred was 8.9 mmHg (8.3 to 9.6) for MSR to MSB, and 10.9 mmHg (10.1 to 11.8) for MSR to FC (p<0.001). There was no significant difference in mean values for all three observers. Movement of the interatrial septum predicts change in PCWP.