Pulmonary venous flow velocities recorded by transthoracic Doppler ultrasound: relation to left ventricular diastolic pressures.

OBJECTIVES: This study was conducted to investigate whether pulmonary venous flow variables measured by transthoracic Doppler ultrasound can help identify patients with elevated left ventricular end-diastolic or filling pressures, or both.
BACKGROUND: A widened left atrial pressure A wave occurs when left ventricular end-diastolic pressure is increased. Increased duration of pulmonary venous flow reversal at atrial systole might therefore be a marker for elevated end-diastolic pressure. Decreased systolic pulmonary venous flow is shown to be related to increased left ventricular filling pressure in studies using transesophageal Doppler echocardiography.
METHODS: Left ventricular pressures at late diastole were measured by fluid-filled catheters in 50 consecutive patients undergoing diagnostic cardiac catheterization. Pulmonary venous and mitral flow velocities were recorded by transthoracic pulsed Doppler ultrasound.
RESULTS: Adequate recordings were obtained in 45 patients. Pulmonary venous flow reversal exceeding the duration of the mitral A wave predicted left ventricular end-diastolic pressure > 15 mm Hg with a sensitivity of 0.85 and a specificity of 0.79. This difference in flow duration correlated well with the increase in ventricular pressure (r = 0.70, p < 0.001) at atrial systole and the end-diastolic pressure (r = 0.68, p < 0.001). The systolic fraction of pulmonary venous flow was markedly decreased (< 0.4) in all patients with a pre-A pressure (left ventricular pressure before atrial systole) > 18 mm Hg.
CONCLUSIONS: Pulmonary venous flow reversal exceeding the duration of the mitral A wave indicates an exaggerated increase in left ventricular late diastolic pressure. Pulmonary venous systolic fraction < 0.4 suggests markedly increased ventricular filling pressure.