Feasibility study: Transesophageal echocardiography with a 10F (3.2-mm), multifrequency (5.5-to 10-MHz) ultrasound catheter in a small rabbit model

Transesophageal echocardiography (TEE) is useful in children with congenita l heart defects. However because of available probe size (greater than or e qual to 7 mm diameter), its use Its limited to patients weighing more than 3 kg. The aim of this study was to determine the feasibility of TEE in a sm all animal model by using a 10F (3.2-mm) intravascular ultrasound tipped ca theter with a monoplane (longitudinal) 5.5- to 10-MHz phased vector array t ransducer. Ten New Zealand White rabbits (400 to 3400 g; mean 1580 g) under went TEE. With animals under general sedation, the probe was blindly introd uced into the esophagus. All intracardiac and extracardiac structures were examined, and the images were stored and independently reviewed. All pertin ent intracardiac and extracardiac structures were identified except in the 3 smallest rabbits (400 to 600 g). Doppler hemodynamics and color Doppler w ere possible in each animal. frequency agility (5.5 to 10 MHz) facilitated optimization of image resolution and penetration. Certain transgastric, 4- chamber, and short-axis views were limited because of the monoplane array. No overt adverse effects were associated with the procedure. Diagnostic TEE can be performed in a small animal model with a 10F, 5.5- to 10-MHz phased vector array ultrasound catheter. Our study suggests that this system has potential In performing diagnostic TEE safely in small, even premature, neo nates.