INTRODUCTION
One of the major limitations of percutaneous catheter ablation is the inability to image the cardiac tissue thus providing real-time information on wall thickness and on acute tissue changes produced by energy delivery during ablation. Due to the unpredictable variability of the wall thickness in the areas targeted for ablation1,2, choosing appropriate ablation settings for creation of effective lesions is often challenging. Insufficient ablation will translate into non-transmural and non-durable lesions, while excessive ablation could lead to steam pops, cardiac perforation and damage to surrounding anatomical structures (e.g. the esophagus). Moreover, very little is known about acute tissue changes produced by catheter ablation and the role they might play in lesion failure. Acute development of tissue oedema has been reported when using radiofrequency (RF) energy for ablation3-5 and it has been advocated as a possible mechanism accounting for lesion failure6,7. The presence and degree of acute tissue oedema when using cryoenergy or laser energy for ablation is not known.
Ultrasound imaging has previously been used in animal studies for assessment of atrial wall thickness and lesion formation during catheter ablation8-10. Preliminary data in human also suggest that ultrasound imaging modalities such as intracardiac echocardiography (ICE) and intravascular ultrasound (IVUS) can be used for left atrial (LA) wall thickness measurements and detection of acute changes produced by ablation11-13.
This pilot study was conducted to compare ICE and IVUS for real-time LA wall imaging and assessment of acute tissue changes produced by different ablation energies during pulmonary vein isolation (PVI).