The use of pulmonary artery catheter can be helpful in managing patients after cardiac surgery. Nevertheless, there is a risk of serious complications, such as knotting. A 61 year old man underwent tricuspid valve replacement under cardiopulmonary bypass (GPB). After implantation of a stented tissue valve in the tricuspid valve, repositioning of the catheter was performed. After weaning from GPB, an abnormal pattern of pulmonary artery pressure was suddenly observed on the monitor. Resistance was met when removing the catheter with the balloon defiated, at a 20 cm distance from the tip of the catheter. Ghest radiography showed a ktiot in the catheter within the right brachiocephalic vein. Superior vena cava opened and the distal part of the catheter with the knot was successfully removed.