Cardiac Rhythm Management
Articles Articles 2015 August

Letter from the Editor in Chief

DOI: 10.19102/icrm.2015.060801


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Dear Readers,

The field of cardiac ablation has been rapidly progressing. The evolution has been attained by understanding the mechanisms of arrhythmias such as atrial fibrillation and ventricular tachycardia, combined with advances in technology which provided the therapeutic tools. Despite all the advances in this field, some unmet needs remain. One of the major unmet needs is the assessment of adequate lesion formation during radiofrequency (RF) ablation. Lesions that are deep can carry the risk of injury to adjacent structures such as the esophagus and the phrenic nerve. On the other hand, lesions that are superficial can result in gap formation and arrhythmia recurrence. Most operators currently use impedance drop, electrogram amplitude reduction, and contact force to estimate adequate lesion formation. However none of these markers have been shown to provide accurate assessment of lesion formation. More recently tools that integrate inputs from difference sources have been developed. These inputs include power, duration, contact force, and catheter stability. The combined information from these sources provides an “index” aiming to estimate lesion formation. Such indices are available in some mapping systems such as the “Lesion Size Index (LSI)” system and the VisiTag system. While these surrogate indices have improved our ability to estimate the formation of adequate RF lesions significantly, they remain limited in their ability to provide exact information on lesion depth.

As a result significant effort has been concentrated on the development of tools aiming at direct imaging of the myocardium during RF energy delivery. These imaging technologies include magnetic resonance imaging, microwave thermal imaging, and ultrasound. All these imaging technologies have been shown to be effective in visualizing real-time lesion formation in preclinical studies and in small preliminary clinical studies. However their widespread adoption has been limited by the complexity of the tools and the inability to fit them in our daily EP workflow.

This issue of the Journal contains an article by Herranz et al. describing another promising technology for real time imaging of ablation lesions. The system consists of an integrated catheter design capable of simultaneous RF ablation and imaging using polarization sensitive optical coherence reflectometry. The feasibility of the system was tested in vivo on right ventricular muscle wedge preparation as well as in vivo in swine. This technology detects changes in tissue optical properties during ablation resulting from protein denaturation in the extracellular matrix of muscular fibers upon heating. In addition, this technology also allows the detection of adequate tissue-catheter contact. While this study is very preliminary and the described catheter is an early prototype, this technology certainly appears to have the potential to provide accurate real-time lesion assessment. The findings observed in this animal study will need to be replicated in large-scale animal and later human studies.

In addition to the study highlighted above, this issue contains many other important articles which I hope you will enjoy reading. Best wishes for a relaxing summer.

Warm regards,


Moussa Mansour, MD, FHRS, FACC
The Journal of Innovations in Cardiac Rhythm Management
Director, Cardiac Electrophysiology Laboratory,
Director, Atrial Fibrillation Program
Massachusetts General Hospital
Boston, MA