Comparison of ablation characteristics of three different radiofrequency applicators in renal sympathetic denervation

Figures & data

Figure 1. A 3 D renal artery and surrounding tissue model.

Figure 2. Electrode structure diagrams of three different RF applicators.

Table 1. The electrode sizes with three-electrode configurations [7,24,25].

Size	Balloon-based	Spiral	Monopolar
Electrode length (mm)	2	2	2
Electrode diameter (mm)	1	1.32 (4 Fr)	1.32 (4 Fr)

Table 2. The thermo-electric and fluid properties [17,26,27].

Material	$\rho$ (kg/m^3)	σ (S/m)	C (J/kg$·$ K)	k (W/(m$·$ K)	$\mu \mathrm{ }$(Pa$·$ s)
Blood	1050	0.67	4180	0.517	0.0035
Abdomen cavity	1060	1.69	3600	0.512	–
Balloon-air	1	0	1004	0.03	–
Catheter	2250	0	1045	0.026	–
Electrode-copper	8700	5.998 × 10^7	385	400	–
Renal wall	1150	0.50	3800	0.48	–

Figure 3. Thermal and fluid Boundary conditions.

Figure 4. Temperature-dependent thermal and electrical conductivity.

Figure 5. The tissue-electrode interface temperature curves with a number of mesh cells.

Figure 6. Illustration of lesion size using the different applicators. (a) Balloon-based RDN, (b) spiral RDN, (c) Monopolar-RDN, and (d) Lesion angle.

Figure 7. Schematic diagram in a renal artery phantom ablation.

Figure 8. Schematic diagram of thermocouples arrangement.

Figure 9. Temperature distribution in tissue using different RF applicators. (a) The balloon-based system, (b) spiral system, (c) monopolar system.

Figure 10. Maximum lesion depth and width curves of three applicators with heating time. D: Maximum lesion depth; W: Maximum lesion width. (D1, W1: for balloon-based RDN. D2, W2: for spiral RDN. D3, W3: for monopolar RDN).

Figure 11. Temperature field in the short-cross section after RDN for three applicators (P = 8W) (a) balloon-based system, (b) spiral system, (c) monopolar system.

Table 3. Lesion size after RDN for three different applicators (P = 8W).

	Balloon-based RDN	Spiral-RDN	Monopolar-RDN
Per lesion angle (º)	82.79	59.60	83.02
Coverage rate (%)	91.99	66.23	23.06

Figure 12. Temperature curves of the tissue-electrode interface.

Figure 13. The velocity and lesion zone distribution of renal artery before and after RDN. (a) Before RDN, (b) Balloon-based RDN, (c) Spiral-RDN, (d) Monopolar-RDN.

Figure 14. The blood velocity change after RDN with different electrodes. (a) Peak velocity (b) average velocity.

Table 4. Coagulation zone information for each applicator design.

Applicator	Power (W)	Maximum depth (mm)	Maximum width (mm)	Total area (mm^2)	Coverage rate (%)	Tmax (°C)
Balloon-based	4	1.58	2.22	10.71	41.43	57.06
	6	2.43	4.15	29.66	72.35	67.10
	8	3.11	5.73	55.95	91.99	78.30
Spiral	4	0.90	1.48	2.43	31.71	52.63
	6	1.49	3.04	10.06	61.29	60.87
	8	1.81	3.54	20.54	66.23	68.83
Monopolar	4	1.12	1.93	3.19	9.55	56.50
	6	1.79	4.14	7.54	19.89	66.23
	8	2.38	5.31	10.31	23.06	75.26

Figure 15. Comparison of experimental and simulated temperature curves.

Figure 16. The error curves of the experiment and simulation.

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