THE PULMONARY artery catheter (PAC), the Raa Raa, the noisy, wild lion in a British stop-motion animated children's television program1 (Fig 1), also known as the Swan-Ganz catheter, is used frequently during cardiac surgery. The PAC might provide clinicians with important information on the preload, afterload, and contractility through the measured and derived parameters for risks stratification and guide perioperative management, particularly in patients with advanced heart failure, pulmonary hypertension, cardiogenic shock, and those who undergo heart and lung transplantation and left ventricular assist device implantation.