Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography
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J Am Soc Echocardiogr · May 1994
Relationship of left atrial pressure and pulmonary venous flow velocities: importance of baseline mitral and pulmonary venous flow velocity patterns studied in lightly sedated dogs.
Prior clinical and animal studies have shown a markedly different relationship between left atrial pressure and the systolic fraction of pulmonary venous flow but have not discussed possible reasons for this discrepancy. To examine the possibility that these disparate results are due to differences in baseline mitral and pulmonary venous flow velocities, we recorded both velocities with left atrial and left ventricular pressure under different loading conditions in eight lightly sedated normal dogs. With constant atrial pacing at 85 beats/min, mean left atrial pressure was increased from 5.3 +/- 1.1 mm Hg at baseline to 16.1 +/- 1.7 mm Hg with volume and methoxamine infusion (p < 0.05). ⋯ These results are consistent with previous animal and clinical results that indicate pulmonary venous diastolic flow is closely related to early mitral flow velocity, whereas systolic flow is determined primarily by left atrial systolic function. The markedly different relationships observed between left atrial pressure and pulmonary venous systolic flow in animal and clinical studies are most likely due to different baseline flow velocity patterns and differences in left atrial systolic reserve. Future studies investigating these relationships should include data on mitral and pulmonary venous flow velocities as well as left atrial size and systolic function.