Characterization of cardiac tissue using optical coherence tomography.

摘要

Radiofrequency ablation (RFA) therapy is the standard of care for the treatment of cardiac arrhythmias. Current techniques to guide ablation therapy utilize low resolution two dimensional fluoroscopic images and functional measurements from the RFA catheter, temperature, impedance and electrograms. High resolution, depth resolved imaging is needed to characterize early structural changes in the myocardium due to disease and therapy. Optical coherence tomography (OCT) is a noninvasive imaging modality that provides high resolution, depth resolved imaging of tissue microstructure in real time. OCT provides subsurface imaging of depths 1-2 mm in cardiac tissue with high spatial resolution (~10 mum) in three dimensions and high sensitivity in vivo. An automated algorithm for fiber orientation quantification in the plane parallel to the wall surface was developed. The algorithm was applied to volumetric image sets of wild type mouse ventricles, and normal and infarctions within rabbit ventricles. Using an ex vivo wedge swine model, we demonstrated that OCT can distinguish necrotic ablation lesions from untreated tissue and identify precursors to overtreatment. OCT image features were observed that clearly distinguish untreated myocardium, ablation lesions, epicardial fat, and coronary vessels and assess tissue contact with catheter based imaging, potential critical structures for real-time guidance of epicardial RFA therapy. A forward scanning OCT catheter was prototyped that provides contact, cone scanning with no metal was used to visualization of real time increase in intensity and decrease in gradient strength and imaging ex vivo of the endocardial surface of the right ventricle submerged in heparinized blood, where an image of the myocardium was obtained when the catheter was in direct contact with the tissue, displacing the blood. Using the forward imaging probe, we demonstrated the first use of OCT to image the endocaridum and visualize dynamics due to RF energy delivery in a living animal. OCT can provide real-time direct visualization of RFA treatment to confirm energy delivery and visualize lesion formation, image in the presence of blood, visualize critical structures and potentially identify arrhythmogenic substrates. This feedback may increase RFA therapy procedural success, reduce procedural time, and reduce complication rates.