Example of a patient with a reduced acoustic window. A) TSI in the apical two-chamber view. The inferior segment is color-coded in orange. Therefore, S' must be within the middle third of the transaortal flow. This information serves as an intrinsic plausibility control and helps to identify the correct S' in the subsequent TDI measurements - especially under impaired ultrasound conditions as depicted in here. B) TDI in the apical two-chamber view. The interval between the aortic valve opening (AVO) and the peak systolic velocity (S') is 140 ms. In agreement with the TSI data, S' can be found within the middle third of the transaortal flow.