Left atrial inflow propagation rate: a new transesophageal echocardiographic index of preload

We postulated that the rate of blood propagating into the left atrium from the left upper pulmonic vein would be a useful measure of pulmonary capillary wedge pressure (PCWP). In 23 adult patients who were critically ill (ie, study group) and receiving mechanical ventilation, color M-mode multiplane transesophageal echocardiography was used to measure left atrial inflow propagation rate (LAIF-PR) as a potential index of PCWP measured by right heart catheterization. LAIF-PR was measured in systole and diastole as the slope of the color M-mode signal entering the left atrium from the left upper pulmonic vein. Correlation with PCWP was good for systolic (r = -0.847, P < .0001) and diastolic (r = -0.78, P < .0001) LAIF-PR. The reliability of univariate linear regression equations derived from the study group was tested in 29 subsequent patients (ie, testing group). Measured PCWP was accurately estimated within 5 mm Hg in 85% (22 of 26 patients) and 68% (17 of 25 patients) of the testing group by systolic and diastolic LAIF-PR, respectively. Color M-mode transesophageal echocardiography-derived LAIF-PR, particularly in systole, is a promising new index to estimate PCWP in patients who are critically ill.