Novel catheter enabling simultaneous radiofrequency ablation and optical coherence reflectometry

Abstract

A novel radiofrequency ablation catheter has been developed with integrated custom designed optics, enabling real-time monitoring of radiofrequency ablation procedures through polarization-sensitive optical coherence reflectometry. The optics allow for proper tissue illumination through a view-port machined in the catheter tip, thus providing lesion depth control over the RF ablation treatment. The system was verified in an in-vitro model of swine myocardium. Optical performance and thermal stability was confirmed after more than 25 procedures, without any damage to the optical assembly induced by thermal stress or material degradation. The use of this catheter in RF ablation treatments may make possible to assess lesion depth during therapy, thus translating into a reduction of potential complications on the procedure.

Keywords: (110.4500) Optical coherence tomography; (120.4570) Optical design of instruments; (170.1020) Ablation of tissue; (170.3890) Medical optics instrumentation.

Figures

Fig. 1

Sketch-based modeling used for the focal length calculations.

Fig. 2

(a) Optical simulations using Zemax. (b) and (c) depict the optical assembly by optical microscope featuring 5x magnification (optical fiber with corresponding ferrule, GRIN lens and glass spacer).

Fig. 3

(a) Sketch of the experimental setup. The system consists of a swept laser source (SS), polarizer (P), polarized beam splitter (PBS), fiber coupler (FC), circulator (CIR), collimator (C), variable attenuator (VA) and mirror (M). (b) and (c) show a picture of the in-vitro chamber. and catheter contact with the cardiac swine tissue, respectively.

Fig. 4

(a) Accumulated phase retardation and temperature evolution in time of an in-vitro swine myocardium at tissue surface. (b) A characteristic histology sample collected from ablated tissue, where complete or partial loss of membrane borders is shown. Coagulative necrosis has been denoted by cn.

Fig. 5

Representative OCR images of an in-vitro swine myocardium with the forward imaging catheter probe: (a) and (b) show the structural and accumulated phase retardation evolution in time (M-scan), respectively. The measurement was done applying 40W and the arrow represents the time instant when the RF power start to be applied. (c) and (d) show the recorded structural and polarization sensitive signal for RFA treatment when the tip moves, respectively. Region 1 represents the RFA time interval, in 2 slippage appears and in 3 the contact is lost.

Fig. 6

Figure represents the time dependence of the ablation process at 1 mm below the surface. The insets show the criteria for analyze the time dependence.