['To evaluate right ventricular dimensions and function by echocardiography in anesthetized patients during superimposed high-frequency jet ventilation (HFJV).', 'Prospective clinical study.', 'University hospital operating room.', '20 ASA physical status I patients undergoing elective minor otorhinolaryngological surgery, and undergoing conventional mechanical ventilation with subsequent superimposed HFJV.', 'Two-dimensional transesophageal echocardiography with a 5-MHz multiplane transducer to determine right ventricular dimensions and function from a mid-esophageal view. Insertion of a radial artery catheter for monitoring blood pressure and blood gases.', 'Heart rate, mean arterial blood pressure, and right ventricular end-diastolic and end-systolic volumes determined by echocardiography, stroke volume, and ejection fraction. Measurements were performed after 10 minutes of conventional positive pressure ventilation (control) and after 10 minutes of subsequent superimposed HFJV at similar peak and positive end-expiratory airway pressures. Right ventricular systolic and diastolic volumes, stroke volume, and ejection fraction did not reveal statistical significant differences after transition to HFJV. Interventricular septum did not show any abnormalities in motion. In contrast, interatrial septum demonstrated momentary mid-systolic bows toward the left atrium in 9 of 17 patients (53%) during conventional ventilation, but in 15 of 17 patients (88%) during jet ventilation. Heart rate and mean arterial blood pressure remained unchanged, but arterial oxygen tension values were higher and arterial carbon dioxide tension values lower during HFJV.'] Do transesophageal echocardiographic assessment of right heart hemodynamics during high-frequency jet ventilation?