Background: Mechanisms of the pseudonormalization (PN) of the transmitral flow (TMF) velocity pattern have been mainly attributed to left ventricular diastolic function. Purpose: To assess the influence of left atrial (LA) function on the PN with two-dimensional tissue tracking technique. Methods: The subjects consisted of 21 healthy volunteers and 70 patients with various cardiac diseases. Images of one cardiac cycle in the apical four-chamber view were stored by the HIVISION 900 (Hitachi Medico, Chiba, Japan). The LA volume (LAV) loop was created using two-dimensional tissue tracking technique and LAV index (LAVI) at a given cardiac phase was calculated. A preload of 90. mmHg was applied using a customized lower body positive pressure (LBPP) system. Patients were divided into the PN group (n= 18) with their early diastolic TMF velocity (E) increased and late diastolic TMF velocity (A) decreased, and the non-(N)-PN group (n= 52) with both E and A wave velocities increased by BPP. Results: (1) During LBPP, the LAVImax in both the groups increased significantly. (2) In the N-PN group, the LAVIpass (p<0.001), LAVIact (p<0.01), and LAVItotal (p<0.0001) increased significantly. The dV/dts (p<0.0001) and dV/dtE (p<0.0001) increased significantly with an increase in the dV/dtA. On the other hand, there was no change in those parameters except LAVIpass (p<0.05) and dV/dtE (p<0.05) significantly increased in the PN group. (3) As a result, the LAVImin was significantly greater in the PN group than in the N-PN group (p<0.0001) during LBPP. The ratio of E velocity to early diastolic mitral annular velocity (E/E') during LBPP was significantly greater in the PN group than in the N-PN group (p<0.0001). Conclusions: The lack of an increase in active LA emptying volume in response to an increase of preload leads to elevated LA pressure and the pseudonormalization of the TMF velocity pattern in patients with various cardiac diseases.
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