Post-operative cardiac function generally is monitored by electrocardiography, invasive measurement of blood pressure, and determination of hemodynamic variables, such as pulmonary pressures and cardiac output with a Swan-Ganz catheter. In recent years, transesophageal echocardiography has been introduced into clinical use, but it is not a popular method of monitoring for various reasons, including the difficulty of application to unconscious post-operative patients. Since 1991, we have been developing a small implantable echocardiography probe. This probe was tested in 15 patients who underwent open heart surgery for severe left ventricular hypofunction, and its clinical utility was demonstrated. No deaths occurred in this series. The implantable echocardiography probe allowed post-operative cardiac function to be monitored in real-time. The ejection fraction, the cardiac output, the status of valves after valvuloplasty, the presence of cardiac tamponade, and other variables could be assessed. The echocardiography probe can be positioned at any site where specific information is desired during surgery. It can be inserted as easily as a pericardial drain tube and is removed in the same manner when no longer necessary. This probe has the potential to be useful for monitoring patients on assisted circulation after cardiac surgery.
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