The primary outcome of the study is the bias and precision of calculated RVSP with TEE compared to measured systolic pulmonary artery pressure with PAC. The current literature provides no information on possible differences in bias and precision of the measurement between patients with normal, and elevated mean PAP, and those with severe TI, so our sample size considerations are based on the whole cohort. Based on currently published RVSP-distributions to show a clinical significant difference of more than 10% with a power of 80% we will have to include 33 patients in total. This estimation is based on a one-tailed comparison and a probability of error of first kind of 0.05, and was calculated using G*Power 3.1.9.2. To allow for dropouts and uncertainty in this calculation, we will include 39 patients in total. Based on clinical considerations and feasibility, this will include 13 with mild to moderate TI and normal mean PAP, 13 with mild to moderate TI and elevated mean PAP, and 13 with severe TI.