Near-infrared spectroscopy integrated catheter for characterization of myocardial tissues: preliminary demonstrations to radiofrequency ablation therapy for atrial fibrillation

Abstract

Effects of radiofrequency ablation (RFA) treatment of atrial fibrillation can be limited by the ability to characterize the tissue in contact. Parameters obtained by conventional catheters, such as impedance and temperature can be insufficient in providing physiological information pertaining to effective treatment. In this report, we present a near-infrared spectroscopy (NIRS)-integrated catheter capable of extracting tissue optical properties. Validation experiments were first performed in tissue phantoms with known optical properties. We then apply the technique for characterization of myocardial tissues in swine and human hearts, ex vivo. Additionally, we demonstrate the recovery of critical parameters relevant to RFA therapy including contact verification, and lesion transmurality. These findings support the application of NIRS for improved guidance in RFA therapeutic interventions.

Spectroscopic photoacoustic imaging of radiofrequency ablation in the left atrium

“…We expect our proposed method to work on human tissue; indeed as reported by [10] the optical changes in porcine and human tissue due to ablation are similar with the human tissue being slightly more scattering. AF is often associated with an underlying disease called atrial fibrosis [29].…”

“…Optical methods which were explored for lesion imaging include Optical Coherence Tomography (OCT) [9], Near Infrared Spectroscopy (NIRS) [10] and auto-Fluorescence Hyperspectral Imaging (aHSI) [11]. These methods are based on scattered, reflected and emitted light from the tissue.…”

Autofluorescence hyperspectral imaging of radiofrequency ablation lesions in porcine cardiac tissue

“…Another interesting approach is the use of Stokes‐Müeller polarimetry to reveal RFA lesions by assessing changes in the scattering coefficient and anisotropy . Near infrared reflectance spectroscopy (NIRS) has been also explored for atrial lesion identification . Notably, with very few exceptions, all of the above techniques have been tested in porcine ventricles where RFA lesions can be readily identified with the naked eye.…”

Real‐time optical spectroscopic monitoring of nonirrigated lesion progression within atrial and ventricular tissues

“…A custom LabVIEW program was used to facilitate data acquisition. Wavelength dependent NIR measurements were converted to relative reflectance spectra, R Rel , using a similar process as described in ; which included dark subtraction, removal of instrument response and normalization at 650 nm from TiO 2 ‐based, silicone phantom measurement of known optical properties.…”

“…Fiber optical geometries could be adjusted to balance the relative sensitivity of diffuse reflectance (DR) measurements to absorption verses scattering changes . Recently our group has demonstrated a strong relationship between near‐infrared spectroscopy (NIRS) derived absorption and chromophore concentrations and endocardial lesion size within porcine atrial specimens . However, this technique requires the computationally intensive step of solving an inverse problem to recover tissue optical properties for feature extraction, which may limit its applicability for real‐time lesion assessment.…”