Currently undergoing a clinical trial a new miniaturized monoplane ultrasound probe potentially enhances the practicability of perioperative transesophageal echocardiography(TEE) without loss of echocardiographic quality. Methods: In the present prospective study, the nasally inserted miniaturized TEE probe was tested in 12 ventilated patients and compared with a conventional TEE probe. Echocardiographic quality was tested by two independent investigators by analyzing the percentage of the endocardium contour detection (<50%, 50-75%, 75-100%) in the left ventricular short- and long-axis views. Results: In 11 patients, more than 50% of endocardium were visualized continuously with both probes. Although the nasal TEE probe was inferior to conventional TEE in detecting lateral endocardium,automated endocardium detection compared well with both methods. Inter- and intraobserver variability in manual measurements of the left ventricular cross-sectional area was below 5% on average and differed non-significantly with regard to the method. In 2 patients, continuous monitoring was aggravated by repeated loss of contact between the miniaturized TEE probe and mucosa. Conclusions: In comparison with conventional TEE, the miniaturized TEE probe provides practicability advantages without significant loss of information for cardiovascular monitoring.