Thermal distribution of microwave antenna for atrial fibrillation catheter ablation

Figures & data

Figure 1. Antenna configuration and antenna-myocardium-blood numerical models (A) Antenna configuration (mm), (B) Perpendicular to the myocardium surface (90°), and (C) Parallel to the myocardium surface (0°).

Table I. Dielectric parameters used in antenna model.

Material	ξr	σ (S.m)
Copper	1.0	58,000,000
Teflon	2.1	0

Table II. Dielectric and thermal parameters used in the numerical simulation.

Material	ξr	σ (S/m)	β	ρ (kg/m^3)	c (J/(kg.°C))	k (W/(m°C))
Cardiac muscle	54.8	2.26	0.245	1,064	3,600	0.5
Blood	58.3	2.54	–	1,050	3,900	0.5

Table III. Convective heat transfer coefficient in different applied locations.

Location	Convective heat transfer coefficient
Within 10 mm above the mitral valve  on the lateral wall	1,417 W/(m^2·°C)
CS, ventricular AP	3,350 W/(m^2·°C)
AV node, atrial AP, RV outflow VT	7,100 W/(m^2·°C)

Figure 2. Effect of thermal cooling at the endocardium (A) Antenna temperature, (B) 1417 W/(m²·°C), (C) No blood flow exists, (D) Antenna temperature, (E) 1417 W/(m²·°C), and (F) No blood flow exists.

Figure 3. Thermal distributions with different convective heat transfer coefficient (30 W, 40 s).,(A) 1,417 W/(m²·°C), (B) 3,550 W/(m²·°C), and (C) 7,100 W/(m²·°C).

Figure 4. Lesion area with increasing time (P = 30 W) (A) Perpendicular to the endocardium and (B) Parallel to the endocardium.

Figure 5. Top view of lesion area.

Figure 6. Width changes with increasing heating time (A) Perpendicular to the endocardium and (B) Parallel to the endocardium.

Figure 7. Depth changes with increasing heating time (A) Perpendicular to the endocardium and (B) Parallel to the endocardium.

Table IV. Applied power and ablation time with different requiring lesion depth.

Required depth (mm)	Antenna placement angle	Applied power (W)	Heat duration (s)	Maximum temperature	Depth/ width
2	0°	30	10	58°C	1:3.5
	90°	30	10	71°C	1:2.0
3	0°	40	10	65°C	1:3.0
	90°	30	30	80°C	1:1.8
4	0°	30	24	67°C	1:2.5
	0°	40	16	71°C	1:2.7
	0°	50	13	76°C	1:2.8
	0°	30	40	72°C	1:2.2
5	0°	40	23	77°C	1:2.4
	0°	50	20	84°C	1:2.6
6	0°	30	53	75°C	1:2.1
	0°	40	33	80°C	1:2.2