Figure 33-11 Normal pulmonary venous flow pattern. Pulsed-wave Doppler measurement of normal blood flow velocities in the left upper pulmonary vein (LUPV) 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 69 cm/sec. Flow below the red line is negative (i.e., away from the transducer) to a maximum of -32 cm/sec. In this patient with normal left atrial pressure, systolic predominance of flow is evident; that is, more flow enters the atrium during the period of ventricular systole than during ventricular diastole as evidenced by the greater peak and average flow velocities during systole than during diastole. LA, left atrium. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)