Figure 33-12 High left atrial pressure produces diastolic predominance in the pulmonary venous flow pattern. Pulsed-wave Doppler measurement of blood flow velocities in the left upper pulmonary vein (LUPV) in a patient with abnormally high left atrial pressure is shown. At the top of the figure is a still-frame image of the two-dimensional cross section used to position the Doppler sample volume (the round white sphere). On the bottom two thirds of the figure is the display in white of the instantaneous blood flow velocities (vertical axis) versus time (horizontal axis) occurring in that sample volume. The electrocardiogram provides timing, and the bold horizontal line is the baseline (zero flow) for the flow velocities. Flow velocities above the red line are positive (i.e., toward the transducer) to a maximum of 80 cm/sec. Flow below the red line is negative (i.e., away from the transducer) to a maximum of -44 cm/sec. In this patient with abnormally high left atrial pressure, diastolic predominance of flow is evident; that is, more flow enters the atrium during the period of ventricular diastole than during ventricular systole as evidenced by the greater peak and average flow velocities during diastole than during systole. The negative flow velocities are due to atrial contraction pushing blood back into the pulmonary vein. LA, left atrium. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)