Left Ventricular Filling Pressure

Surprisingly, TEE provides practical ways to estimate LV filling pressure. By placing the Doppler cursor at the junction of the left atrium and left superior pulmonary vein, Kuecherer and coworkers demonstrated that a systolic fraction of flow of less than 55% was a specific and sensitive sign of left atrial pressure greater than 15 mm Hg. This sign is easily detected as predominance of flow during diastole ( Fig. 33-11 and Fig. 33-12 ).^[42] Significant mitral regurgitation, the presence of non-sinus rhythm, and extremes of cardiac output affect pulmonary venous flow and therefore limit this application of TEE. Alternative methods have been described that obviate these limitations. ^{[43] [44] [45] [46]} Accordingly, TEE cannot estimate left atrial pressure precisely, but it can reliably identify clinically significant elevations.