Accurate knowledge of the anatomy of intracardiac structures is essential for the efficiency and safety of performing interventional procedures. Although fluoroscopy is an important aid while advancing catheters in the heart, it is not sufficient to supply accurate anatomical information on the position of veins, ridges, and septa in the heart. Furthermore radiation exposure forms a risk to both the patient and the operator.

Intracardiac echocardiography (ICE) is a promising technique for imaging of intracardiac structures, and may serve as an alternative for the transoesophageal approach,¹ which is semi-invasive and requires anaesthesiology. The introduction of ICE catheters with low frequencies allows accurate visualisation of intracardiac anatomical structures with an ultrasound catheter placed exclusively in the right side of the heart. This report focuses on the use of ICE in guiding percutaneous interventional procedures.

BASICS OF INTRACARDIAC ECHOCARDIOGRAPHY

History of two dimensional intracardiac ultrasound systems

The first application of ICE was done using mechanical ultrasound systems, which were introduced in the 1980s. These systems provided high resolution imaging, but because of the high frequency of the transducers (20–40 MHz), tissue penetration was only limited and anatomic intracardiac overviews could not be obtained. The subsequent development of lower frequency transducers allowed imaging of intracardiac structures, but these systems were still limited by the low steerability and over-the-wire design of the catheters.² The clinical use was improved by the development of flexible lower frequency transducers (9 MHz), but depth control of these catheters still was not sufficient to allow visualisation of the whole heart from the right side of the heart. In the 1990s, systems modified after transoesophageal echocardiographic probes were introduced. In these systems depth was improved by the use of lower frequencies (5 MHz). However, the large size of these transducers limited the clinical use. In recent years the development of steerable phased array ultrasound catheter systems with low frequency …