X-ray of the thorax to assess correct positions of catheters. A conventional pulmonary artery (Swan-Ganz) catheter was placed in the pulmonary artery for gold standard measurement of pulmonary artery pressure (circle). The sensors of two Millar Mikro-Tip catheters are located in a proximal (filled triangles) and a distal branch of the (open triangles) pulmonary artery (, X-ray taken with the C-Arm Ziehm Vision, Ziehm Imaging, Nuremberg, Germany).