New miniaturized versus conventional biplane transesophageal transducers: recent clinical experience in adults

A subset of patients have substantial discomfort on examination with transesophageal echocardiography with the conventional probe, whereby the dimensions of the probe play a decisive role. Miniaturized biplane transducers have recently become available (2 x 32 channels, dimensions 9.5 x 8.7 mm, and circumference approximately 30% less than the conventional echoscope) and allow ultrasound examination at 3.5, 5.0 and 7.0 MHz. A prospective study was carried out in 90 patients to compare difficulties on insertion of the probe, subjective evaluation by the patient during examination, and the two-dimensional image, as well as Doppler and color-coded Doppler quality of the miniaturized biplane versus the conventional probe. In 62 patients, intubation of the esophagus proved less difficult with the smaller instrument and more difficult in nine cases. Seventy-six patients reported that they suffered less discomfort on use of the narrow instrument. Concomitant parasympatholytic medication was needed with the smaller probe in seven cases and 17 times with the conventional probe. As anticipated, quality of the two-dimensional image attained by the miniaturized probe was lower. With transmit/receive frequency of 7.0 MHz, however, image resolution was excellent in the near field of 5 cm and nearly equivalent to that of the conventional probe (5.0 MHz). Pulsed-wave and continuous wave Doppler and color-coded Doppler information from both probes was similar in quality. Whenever examination with a conventional transesophageal transducer promises to be difficult, or when sedation is contraindicated because of a severe illness or respiratory insufficiency, transesophageal echocardiography should be considered with a smaller biplane probe at higher transmit-receive frequencies.