Assessment of Pulmonary Venous and Transmitral Flow in Closed-Chest Dogs Under Various Loading Conditions by Transesophageal Doppler Echocardiography

: Pulmonary venous flow velocity (PVFVe), pulmonary venous dimension (PVD) and transmitral flow (TMF) velocity were examined under various loading conditions in 15 anesthetized closed-chest dogs by transesophageal Doppler echocardiography (TEE). We also compared PVFVe with pulmonary venous flow volume (PVFVo) simultaneously in open-chest dogs using an ultrasonic flow probe. PVFVo decreased by more than 50% and PVD also decreased significantly during preload reduction, while there was no change in PVFVe. This discrepancy between PVFVo and PVFVe was apparently due to the collapse of pulmonary veins. TMF consisted of both rapid-filling flow velocity and atrial flow velocity components (R and A), while PVF consisted of systolic and diastolic forward flow velocity components (S and D). The peak values of R,A,S and D and the time-velocity integrals of each wave (RI, AI, SI and DI, respectively) were measured. There was a significant correlation between the changes in RI and SI/DI during preload reduction (r = 0.82, p < 0.001) and during after-load increase (r = -0.59, p < 0.05). These results suggest that changes in RI with different loading conditions might be attributable to changes in atrial reservoir volume and conduit volume.