A 3-Dimensional In Silico Test Bed for Radiofrequency Ablation Catheter Design Evaluation and Optimization

Abstract Background Renal denervation with radiofrequency ablation has become an accepted treatment for drug-resistant hypertension. However, there is a continuing need to develop new catheters for high-accuracy, targeted ablation. We therefore developed a radiofrequency bipolar electrode for controlled, targeted ablation through Joule heating induction between 60 and 100 °C. The bipolar design can easily be assembled into a basket catheter for deployment inside the renal artery. Methods Finite element modeling was used to determine the optimum catheter design to deliver a minimum ablation zone of 4 mm (W) × 10 mm (L) × 4 mm (H) within 60 s with a 500 kHz, 60 Vp-p signal, and 3 W maximum. The in silico model was validated with in vitro experiments using a thermochromic phantom tissue prepared with polyacrylamide gel and a thermochromic ink additive that permanently changes from pink to magenta when heated over 60 °C. Results The in vitro ablation zone closely matched the size and shape of the simulated area. The new electrode design directs the current density towards the artery walls and tissue, reducing unwanted blood temperature increases by focusing energy on the ablation zone. In contrast, the basket catheter design does not block renal flow during renal denervation. Conclusions This computational model of radiofrequency ablation can be used to estimate renal artery ablation zones for highly targeted renal denervation in patients with resistant hypertension. Furthermore, this innovative catheter has short ablation times and is one of the lowest power requirements of existing designs to perform the ablation.

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Effects of Open-Irrigated Radiofrequency Ablation Catheter Design on Lesion Formation and Complications: In Vitro Comparison of 6 Different Devices

Journal of Cardiovascular Electrophysiology ◽

10.1111/jce.12175 ◽

2013 ◽

Vol 24 (10) ◽

pp. 1157-1162 ◽

Cited By ~ 14

Author(s):

JOSE M. GUERRA ◽

ESTHER JORGE ◽

SILVIA RAGA ◽

CAROLINA GÁLVEZ-MONTÓN ◽

CONCEPCIÓN ALONSO-MARTÍN ◽

...

Keyword(s):

Radiofrequency Ablation ◽

Ablation Catheter ◽

Lesion Formation ◽

Catheter Design ◽

In Vitro Comparison

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P2842Sequential application of horizontal and vertical orientation on radiofrequency ablation lesions produced by thermocool smarttouch SF catheter

European Heart Journal ◽

10.1093/eurheartj/ehz748.1152 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

K Morgaenko ◽

S Noshin ◽

W Stevenson ◽

N Mehta

Keyword(s):

Radiofrequency Ablation ◽

Surface Area ◽

Lesion Size ◽

Ablation Catheter ◽

Vertical Orientation ◽

Lesion Depth ◽

Catheter Design ◽

Significant Difference ◽

The Impact ◽

Area And Volume

Abstract Background Ablation lesions represent a complex interaction between the ablation catheter configuration and tissue anatomy. An understanding of each variable can assist in determination of the optimal lesion set. One such variable is the catheter orientation. With an irrigated radiofrequency ablation catheter with 6 pores (6P) near the distal tip, lesion surface area and volumes are smaller in the horizontal catheter orientation compared to the vertical catheter orientation. This finding is explained by the 6P irrigation catheter design, where irrigation fluid is discharged from six ports around the circumference of the electrode. Introduced in 2015, the ThermoCool SmartTouch® SF catheter has a 56-pore (56P) distribution to provide high density low volume irrigation settings. Irrigation catheters create smaller lesions in horizontal orientation compared to vertical orientation, however this has not been studied for the 56P irrigated catheter. Purpose Evaluate the impact of catheter orientation with sequential application of 56P catheter. Methods Ablation lesions were created on additive-free chicken model in a saline bath heated to 37°C using the 56P catheter under standard flow rate (8cc/min) conditions. Ablation energy of 20W and 30W was delivered twice for 30 seconds with 3 minutes interval between applications. Contact force (CF) of 5, 10, 15, and 20g was applied with the following conditions: horizontal catheter orientation followed by horizontal (HH), vertical by vertical (VV), horizontal by vertical (HV), and vertical by horizontal catheter orientation (VH). Measurements were obtained by lesion dissection through the midpoint by 3 independent operators. Kruskal-Wallis test was used for comparison of lesion depth, surface area and volume. Results Ninety-six lesions were analyzed. No coagulum or steam pops were included in the analysis. The minimum and maximum lesion depth, surface area and volume were 1.5 & 6.0 mm, 14.1 & 117.7mm2, 47.1 & 471.0 mm3 respectively. There was no significant difference in the lesion depth, surface area or volume in HH, VV, HV or VH orientation at different CF with 20W and 30W. (Fig 1) Figure 1 Conclusion Unlike other irrigated catheters, catheter orientation with sequential application with different CF and power did not impact lesion depth, surface area and volume with 56P catheter. This finding could be considered useful in situations where the catheter orientation could be challenging owing to tissue anatomy to achieve adequate lesion size. Acknowledgement/Funding UVA Health System

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