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).