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Figure 2 The relation between transmitral flow and PV venous flow and changes of LA and LV pressures with or without DOB. Representative simultaneous recordings of the transmitral flow velocity and PV flow volume and tracings of LV pressure and magnified LV and LA pressures (arrows in right lower panel). With Aoc during MI, the pressure increase is larger and more rapid in the LV than it is in the LA at atrial systole (lower mid panel), resulting in a reduced late diastolic transmitral flow velocity and an increased PV reverse flow volume (upper mid panel). Thus, in the presence of an LA afterload mismatch, a substantial blood volume was ejected from the LA backward into the PV with atrial contraction. Dobutamine infusion markedly corrected this mismatch (upper right panel). Aoc = aortic constriction; DOB = dobutamine infusion; LA = left atrial; LV = left ventricular; MI = myocardial ischemia; PV = pulmonary vein.