[Low output syndrome; prevention and treatment]

Cardiac surgery has advanced remarkably in a sense by overcoming perioperative low output syndrome (LOS). Improvement of surgical results and postoperative quality of life has expanded the range of treatment to patients with higher risk and/or advanced age. LOS is still a major concern in cardiac surgery. Of upmost importance are proper myocardial protection and precise surgery. Transesophageal echocardiography is the best perioperative monitor to prevent, and if necessary to treat, LOS. Cardiac tamponade is the most frequent cause of LOS, and should be diagnosed and resolved without delay. Spasm of the coronary artery or the bypass graft is rare complication which may bring on LOS. LOS may be caused by right heart failure, for which open-chest management is useful in case of unsuccessful inotropic support. Careful check-up of blood gas and electrolytes is also important to maintain good hemodynamics and to prevent arrhythmias. Pacing is very useful, particularly atrial or AV seguential pacing, to obtain reasonable output and to prevent arrhythmias. Mechanical circulatory support is considered when other strategies are not effective. Which support modality is to be chosen among intraaortic balloon pumping, percutaneous cardiopulmonary support and ventricular assist device is based on required strength and duration of support.