Temperature controlled short duration ablation
A method, including selecting a first maximum radiofrequency (RF) power to be delivered by an electrode within a range of 70 W-100 W, and selecting a second maximum RF power to be delivered by the electrode within a range of 20 W-60 W. The method also includes selecting an allowable force on the electrode within a range of 5 g-50 g, selecting a maximum allowable temperature, of tissue to be ablated, within a range of 55° C.-65° C., and selecting an irrigation rate for providing irrigation fluid to the electrode within a range of 8-45 ml/min. The method further includes performing an ablation of tissue using the selected values by initially using the first power, switching to the second power after a predefined time between 3 s and 6 s, and terminating the ablation after a total time for the ablation between 10 s and 20 s.
1. A method, comprising:
selecting an initial target maximum radiofrequency (RF) power to be delivered by an electrode within a range of 70 W-100 W;
selecting a subsequent target maximum RF power to be delivered by the electrode within a range of 20 W-60 W;
selecting an allowable force on the electrode within a range of 5 g-50 g;
selecting a maximum allowable temperature, of tissue to be ablated, within a range of 55° C.-65° C.;
selecting an irrigation rate for providing irrigation fluid to the electrode within a range of 8-30 ml/min; and
performing an ablation of the tissue using the selected values for the initial target maximum RF power for an initial time period ranging between 1 s and 6 s and for the subsequent target maximum RF power for a subsequent time period ranging up to 14 s, with an overall time period of ablation between the initial and subsequent time periods ranging between 1 s-20 s.
2. The method according to claim 1 , further comprising measuring at respective times a temperature of the tissue, and, when the temperature of the tissue exceeds the selected maximum allowable temperature, reducing from the initial target maximum RF power to the subsequent target maximum RF power.
3. The method according to claim 1 , wherein the selected values include: initial maximum RF power of 90 W, subsequent maximum RF power of 50 W, allowable force between 10 g and 20 g, maximum allowable temperature 60° C., and irrigation rate 15 ml/min.
4. The method according to claim 3 , wherein the initial maximum RF power of 90 W is delivered for 3 s so as to provide a lesion having a depth between 1 mm and 3 mm.
5. The method according to claim 4 , wherein the subsequent maximum RF power of 50 W is delivered with an overall time period of 6 s so as to provide the lesion with an increased depth between 4 mm and 5 mm.
6. The method according to claim 1 , further comprising measuring an impedance to the initial target maximum RF power delivered by the electrode during the ablation, and, when a change in the impedance exceeds a preset value, halting the ablation of the tissue.
7. The method according to claim 6 , wherein the change is at least 7Ω.
8. The method according to claim 1 , wherein the temperature of the tissue is measured at a frequency of at least 30 Hz.
9. The method according to claim 1 , wherein the initial maximum RF power to the subsequent maximum RF power is reduced according to the following equations:
Δ P =min(Δ P ( T ),Δ P ( p ))
where
Δ
P
(
T
)
=
a
(
T
t
-
1
-
T
t
)
T
+
b
(
T
-
T
t
)
T
and
where
Δ
P
(
p
)
=
(
P
-
P
t
)
P
.
10. The method according to claim 9 , wherein a=10 and b=1.
11. A method, comprising:
selecting an initial target maximum radiofrequency (RF) power to be delivered by an electrode within a range of 70 W-100 W;
selecting a subsequent target maximum RF power to be delivered by the electrode within a range of 20 W-60 W;
selecting an allowable force on the electrode within a range of 5 g-50 g;
selecting a maximum allowable temperature, of tissue to be ablated, within a range of 55° C.-65° C.;
selecting an irrigation rate for providing irrigation fluid to the electrode within a range of 8-30 ml/min; and
performing an ablation of the tissue using the selected values for the initial target maximum RF power and for the subsequent target maximum RF power for an overall time period with both initial and subsequent target maximum RF powers of no more than 10 s.
12. The method according to claim 11 , further comprising measuring at respective times a temperature of the tissue, and, when the temperature of the tissue exceeds the selected maximum allowable temperature, reducing from the initial target maximum RF power to the subsequent target maximum RF power.
13. The method according to claim 11 , wherein the selected values include: initial maximum RF power of 90 W, subsequent maximum RF power of 50 W, allowable force between 10 g and 20 g, maximum allowable temperature 60° C., and irrigation rate 15 ml/min.
14. The method according to claim 13 , wherein the initial maximum RF power of 90 W is delivered for 3 s so as to provide a lesion having a depth between 1 mm and 3 mm.
15. The method according to claim 14 , wherein the subsequent maximum RF power of 50 W is delivered with an overall time period of 6 s so as to provide the lesion with an increased depth between 4 mm and 5 mm.
16. The method according to claim 11 , further comprising measuring an impedance to the initial target maximum RF power delivered by the electrode during the ablation, and, when a change in the impedance exceeds a preset value, halting the ablation of the tissue.
17. The method according to claim 16 , wherein the change is at least 7Ω.
18. The method according to claim 11 , wherein the temperature of the tissue is measured at a frequency of at least 30 Hz.
19. The method according to claim 11 , wherein the initial maximum RF power to the subsequent maximum RF power is reduced according to the following equations:
Δ P =min(Δ P ( T ),Δ P ( p )
where
Δ
P
(
T
)
=
a
(
T
t
-
1
-
T
t
)
T
+
b
(
T
-
T
t
)
T
and
where
Δ
P
(
p
)
=
(
P
-
P
t
)
P
.
20. The method according to claim 19 , wherein a=10 and b=1.