Atrial fibrillation is a common and potentially lethal arrhythmia, yet catheter radiofrequency ablation (RFA), a mainstay of treatment, frequently fails to provide long-term remission. We present a catheter capable of near-infrared diffuse reflectance spectroscopy, with a source fiber delivering broadband light and a detection fiber whose light is sent to a spectrometer. Separate catheters have been fabricated with different source-detection separations, yielding spectra sensitive to different optical properties of the underlying tissue. Optical indices have been developed from benchtop measurements to distinguish the spectral signatures of different cardiac substrates. These measurements will equip clinicians with intraprocedural feedback to improve RFA effectiveness.
SignificanceRadiofrequency ablation (RFA) procedures for atrial fibrillation frequently fail to prevent recurrence, partially due to limitations in assessing extent of ablation. Optical spectroscopy shows promise in assessing RFA lesion formation but has not been validated in conditions resembling those in vivo.AimCatheter-based near-infrared spectroscopy (NIRS) was applied to porcine hearts to demonstrate that spectrally derived optical indices remain accurate in blood and at oblique incidence angles.ApproachPorcine left atria were ablated and mapped using a custom-fabricated NIRS catheter. Each atrium was mapped first in phosphate-buffered saline (PBS) then in porcine blood.ResultsNIRS measurements showed little angle dependence up to 60 deg. A trained random forest model predicted lesions with a sensitivity of 81.7%, a specificity of 86.1%, and a receiver operating characteristic curve area of 0.921. Predicted lesion maps achieved a mean structural similarity index of 0.749 and a mean normalized inner product of 0.867 when comparing maps obtained in PBS and blood.ConclusionsCatheter-based NIRS can precisely detect RFA lesions on left atria submerged in blood. Optical parameters are reliable in blood and without perpendicular contact, confirming their ability to provide useful feedback during in vivo RFA procedures.
Patients with atrial fibrillation (AF) require detailed mapping of the left atrium (LA) during radiofrequency ablation (RFA) procedures. Identifying the lesion gaps can provide helpful guidance for complete conduction blocks, reducing the probability of recurrence. We implement anatomical mapping using an integrated optical probe with a combined modality of near-infrared spectroscopy (NIRS) and optical coherence tomography (OCT). Both spectral signatures are captured simultaneously, with the sample-sites located by a magnetic tracking sensor. With increased sampling density and speed, we are able to recognize small gaps between lesions LA, and reconstruct atrial substrate and lesion maps with the tissue underneath PBS and blood.
An intraoperative tool that accurately provides detailed structural information and classifies endocardial substrates could help improve guidance during ablation therapy. With our custom near infrared spectroscopy-integrated radiofrequency catheter, here we demonstrate atrial substrate mapping on ex vivo swine and human left atria. Optical contrast indices and classification algorithms were developed, which classified pulmonary vein, lesion, and fibrosis using optically derived parameters based on endogenous tissue spectral signatures with high accuracy. Predicted lesion depth percentage linearly corresponded with ground truth measurements from trichrome histology. These results suggest near infrared-integrated mapping catheters can serve as a complementary tool to currently-available electroanatomical mapping systems to improve treatment efficacy.
Radiofrequency ablation procedures, such as pulmonary vein isolation for patients with atrial fibrillation, require detailed anatomical mapping of atrial structural substrate to identify AF substrate. Identification of structural substrates, such as scar tissue, pulmonary vein, collagen and adipose tissue can provide helpful guidance of RFA procedures. We demonstrate mapping of atrial substrates using optical spectral signatures from near-infrared spectroscopy. Using position tracking and interpolation algorithm, we assess the capability of NIRS to distinguish various tissue structures on a reconstructed 3D spatial maps of ex-vivo swine and human atriums.
Patients with cardiac arrythmia most commonly require radiofrequency ablation to destroy arrhythmogenic electrical pathways and restore normal heart rhythm. However, arrhythmia resurgence exists from limited means to directly confirm the extent of lesion progression during RFA procedure. Optical spectroscopy is sensitive to tissue optical properties and changes in biomolecular composition. We propose a simplified optical spectroscopy through a single fiber integrated catheter to predict irrigated endocardial lesion progression using deep neural network model on ex-vivo model.
Radiofrequency ablation is the most common procedure to treat cardiac arrythmias, such as atrial fibrillation. Catheter ablation isolates or eradicates abnormal electrical activity to maintain sinus rhythm. However, inadequate lesion formation permits arrhythmia resurgence. Optical spectroscopic signatures can detect biomolecular and tissue structural changes and can potentially serve as a tool to evaluate lesion quality. In this work, we introduce a near-infrared spectroscopy through fiber-optic integrated catheter to assess contact and predict lesion size using artificial neural network model on both ex-vivo porcine model and non-survival in-vivo pilot experiments in pigs.
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