Intraoperative localization of cardiac conduction tissue regions using real-time fibre-optic confocal microscopy: first in human trial

Abstract

OBJECTIVES The aim of this study was to evaluate the feasibility and safety of fibre-optic confocal microscopy (FCM) using fluorescein sodium dye for the intraoperative location of conduction tissue regions during paediatric heart surgery. METHODS The pilot study included 6 patients undergoing elective surgery for the closure of isolated secundum atrial septal defect aged 30 days to 21 years. FCM imaging was integrated within the normal intraoperative protocol for atrial septal defect repair. Fluorescein sodium dye was applied on the arrested heart. FCM images were acquired at the atrioventricular node region, sinus node region and right ventricle (RV). Total imaging time was limited to 3 min. Any adverse events related to the study were recorded and analysed. Subjects received standard postoperative care. Trained reviewers (n = 9) classified, de-identified and randomized FCM images (n = 60) recorded from the patients as presenting striated, reticulated or indistinguishable microstructures. The reliability of reviewer agreement was assessed using Fleiss’ kappa. RESULTS The FCM imaging instruments were integrated effectively into the cardiac surgery operating room. All adverse events found in the study were deemed expected and not related to FCM imaging. Reticulated myocardial microstructures were found during FCM imaging at atrioventricular node and sinus node regions, while striated microstructures were observed in RV. Reliability of agreement of reviewers classifying the FCM images was high (Fleiss’ kappa: 0.822). CONCLUSIONS FCM using fluorescein sodium dye was found to be safe for use during paediatric heart surgery. The study demonstrates the potential for FCM to be effective in identifying conduction tissue regions during congenital heart surgery. Clinical trial registration number NCT03189134.

Intraoperative characterization of cardiac tissue: the potential of light scattering spectroscopy

“… 38 , 39 Fiber optics confocal microscopy, as one example, has been used during open heart surgery to distinguish tissue regions. 18 However, due to significant financial costs and complexity associated with refining their use and deploying these technologies in the operating room, they have yet to see widespread adoption.…”

“…Though these approaches have shown promise due to their comparatively high imaging resolution and ability to discern different tissue types within the heart, including nodal tissue regions, the significant financial costs, and complexity associated with their use have hindered widespread implementation. 18 – 20 …”

“…Though these approaches have shown promise due to their comparatively high imaging resolution and ability to discern different tissue types within the heart, including nodal tissue regions, the significant financial costs, and complexity associated with their use have hindered widespread implementation. [18][19][20] Optical methods that leverage spectroscopic measurement of light-tissue interactions have the potential to greatly decrease the implementation cost and complexity of FCM and OCT while overcoming the prohibitively small maximum imaging depths of current CCS identification methods. 21,22 Previous research performed by our group has provided proof-of-concept of the imaging capabilities of our custom light-scattering spectroscopy (LSS) probe.…”

Catheter-based optical approaches for cardiovascular medicine: progress, challenges and new directions

“…A focus of our review was on clinical translation of catheterized fiber-optics confocal microscopy. Feasibility of fiber-optics confocal microscopy to image through the endocardial layer in the atrial and ventricular myocardium was demonstrated in in-situ canine [59], neonatal ovine [60], and neonatal human hearts [188]. For myocardial imaging in the adult human heart, the approach must contend with the endocardial thickness.…”

Toward cardiac tissue characterization using machine learning and light-scattering spectroscopy

“… 2 , 6 , 7 Clinical studies and related research with FCM have shown the ability to identify conductive tissue regions during congenital heart surgery, e.g., the sinoatrial and atrioventricular nodes. 8 , 9 Although these technologies have been shown to provide useful information during cardiac procedures, the significant cost and technical complexity associated with their implementation hinder widespread adoption. Additionally, shallow imaging field depths limit the application of these technologies to only a few specific use cases in the heart.…”