All data will be tabulated case-wise and pair-wise (i.e. PAC and TEE measurements) Quantitative data will be expressed as mean +/- SD if normally distributed or as medians and interquartile ranges (IQRs) if not normally distributed. Qualitative variables will be presented as absolute and relative frequencies. Measurement from the best obtainable of the three TEE views will be used for analysis. According to the method described by Bland and Altman we will assess agreement between measurements: The mean difference (bias, d) as a metric for the systematic measurement error, the SD of the differences (precision, s), and the limits of agreement (d±2s) as metrics for scatter will be calculated. Bland-Altman plots will be used for graphical representation.