Computer simulations of an irrigated radiofrequency cardiac ablation catheter and experimental validation by infrared imaging

Abstract

Purpose

To develop and validate a three-dimensional (3-D) computer model based on accurate geometry of an irrigated cardiac radiofrequency (RF) ablation catheter with microwave radiometry capability, and to test catheter performance.

Methods

A computer model was developed based on CAD geometry of a RF cardiac ablation catheter prototype to simulate electromagnetic heating, heat transfer, and computational fluid dynamics (blood flow, open irrigation, and natural convection). Parametric studies were performed; blood flow velocity (0–25 cm/s) and irrigation flow (0–40 ml/min) varied, both with perpendicular (PE) and parallel (PA) catheter orientations relative to tissue. Tissue Agar phantom studies were performed under similar conditions, and temperature maps were recorded via infrared camera. Computer model simulations were performed with constant voltage and with voltage adjusted to achieve maximum tissue temperatures of 95–105 °C.

Results

Model predicted thermal lesion width at 5 W power was 5.8–6.4 mm (PE)/6.5–6.6 mm (PA), and lesion depth was 4.0–4.3 mm (PE)/4.0–4.1 mm (PA). Compared to phantom studies, the mean errors of the computer model were as follows: 6.2 °C(PE)/4.3 °C (PA) for maximum gel temperature, 0.7 mm (10.9%) (PE)/0.1 mm (0.8%) (PA) for lesion width, and 0.3 mm (7.7%)(PE)/0.7 mm (19.1%) (PA) for lesion depth. For temperature-controlled ablation, model predicted thermal lesion width was 7–9.2 mm (PE)/8.6–9.2 mm (PA), and lesion depth was 4.3–5.5 mm (PE)/3.4–5.4 mm (PA).

Conclusions

Computer models were able to reproduce device performance and to enable device evaluation under varying conditions. Temperature controlled ablation of irrigated catheters enables optimal tissue temperatures independent of patient-specific conditions such as blood flow.

Keywords:

• Radiofrequency/microwave
• thermal ablation
• cardiac catheter ablation
• modeling (i.e.
• heat transfer
• ultrasound
• EM
• integrated
• treatment planning)

Acknowledgments

The authors would like to acknowledge Dr John Dinolfo from the MUSC writing center for his assistance in revising the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Part of this work was conducted in a facility constructed with support from the National Institutes of Health, C06 RR015455 and Grant Number C06 RR018823.