Ultrasonic lesion feedback, antipop monitoring, and force detection
An ablation catheter comprises: an elongated catheter body extending longitudinally between a proximal end and a distal end along a longitudinal axis; a distal member disposed adjacent the distal end, the distal member including an ablation element to ablate a biological member; one or more acoustic transducers disposed in the distal member and each configured to direct an acoustic signal toward a respective target ablation region and receive reflection echoes therefrom; and an acoustic redirection member disposed in the distal member to at least partially redirect the acoustic signal from at least one of the acoustic transducers toward a tissue target. The distal member includes a most-distal portion, a proximal portion, and a deflectable portion between the most-distal portion and proximal portion to permit deflection between the most-distal portion and proximal portion of the distal member. The transducers and redirection member are mounted on opposite sides of the deflectable portion.
1. An method for monitoring a medical procedure, comprising:
providing a catheter comprising:
an elongated catheter body extending longitudinally between a proximal end and a distal end along a longitudinal axis;
a distal member disposed adjacent the distal end and including a most-distal portion, a proximal portion, and a deflectable portion between the most-distal portion and the proximal portion to permit deflection between the most-distal portion and the proximal portion of the distal member, the deflectable portion being more deflectable than at least one of the most-distal portion or the proximal portion;
an acoustic transducer disposed in the distal member and configured to emit acoustic energy toward a biological member and receive reflection echoes therefrom; and
an acoustic redirection member disposed in the distal member to at least partially redirect the acoustic energy emitted from the acoustic transducer toward a tissue target,
wherein one of the acoustic transducer and the acoustic redirection member is mounted to the proximal portion of the distal member and the other of the acoustic transducer and the acoustic redirection member is mounted to the most-distal portion of the distal member;
directing an acoustic signal from the acoustic transducer to the biological member;
receiving reflection echoes of the acoustic signal from the biological member at the acoustic transducer; and
detecting a deflection between the most-distal portion of the distal member and the proximal portion of the distal member based on the received reflection echoes of the acoustic signal.
2. The method according to claim 1 , wherein the detecting comprises detecting the deflection via at least one of an amplitude change, a phase change, or a time-delay change of a reflection of the acoustic signal reflected back from the acoustic redirection member to the acoustic transducer.
3. The method according to claim 1 :
wherein the catheter further comprises an acoustic reflection member mounted to a common portion of the distal member with the acoustic redirection member to partially reflect the acoustic signal back to the acoustic transducer, and
wherein the detecting comprises detecting the deflection at least one of an amplitude change, a phase change, or a time-delay change of a reflection of the acoustic signal back from the acoustic reflection member.
4. The method according to claim 1 , further comprising determining a force acting on the distal member based on the detected deflection and a known relationship between force acting on the distal member and deflection of the deflectable portion of the distal member.
5. The method according to claim 1 , wherein the acoustic signal comprises one of an acoustic beam or an acoustic ping.
6. The method according to claim 1 , wherein the directing comprises at least one of:
directing a first acoustic signal from the acoustic transducer in a direction generally parallel to the longitudinal axis of the elongated catheter body to the acoustic redirection member, which redirects the first acoustic signal in a transverse direction non-parallel to the longitudinal axis of the elongated catheter body; or
directing a second acoustic signal from the acoustic transducer in a direction generally parallel to the longitudinal axis of the elongated catheter body.
7. The method according to claim 1 , wherein directing the acoustic signal to the biological member and receiving the reflection echoes of the acoustic signal from the biological member comprises analyzing at least one of a tissue thickness measurement in the biological member and a tissue proximity to the biological member.
8. The method according to claim 1 , wherein the deflectable portion of the distal member permits at least one of axial deflection along the longitudinal axis of the elongated catheter body or bending deflection between the most-distal portion of the distal member and the proximal portion of the distal member.
9. The method according to claim 8 , wherein the axial deflection is less than 1 mm under an axial force of less than 100 grams-force.
10. The method according to claim 8 , wherein the bending deflection is less than 10 degrees under a bending moment of about 200 grams-force-millimeters.
11. A system for monitoring a medical procedure, comprising:
a catheter comprising:
an elongated catheter body extending longitudinally between a proximal end and a distal end along a longitudinal axis;
a distal member disposed adjacent the distal end and including a most-distal portion, a proximal portion, and a deflectable portion between the most-distal portion and the proximal portion to permit deflection between the most-distal portion and the proximal portion of the distal member, the deflectable portion being more deflectable than at least one of the most-distal portion or the proximal portion;
an acoustic transducer disposed in the distal member and configured to emit acoustic energy toward a biological member and receive reflection echoes therefrom; and
an acoustic redirection member disposed in the distal member to at least partially redirect the acoustic energy emitted from the acoustic transducer toward a tissue target,
wherein one of the acoustic transducer and the acoustic redirection member is mounted to the proximal portion of the distal member and the other of the acoustic transducer and the acoustic redirection member is mounted to the most-distal portion of the distal member;
a transducer pinger configured to:
direct an acoustic signal from the acoustic transducer to the biological member; and
receive reflection echoes of the acoustic signal from the biological member at the acoustic transducer; and
an analyzer configured to detect a deflection between the most-distal portion of the distal member and the proximal portion of the distal member based on the received reflection echoes of the acoustic signal.
12. The system according to claim 11 , wherein the analyzer is configured to detect the deflection via at least one of an amplitude change, a phase change, or a time-delay change of a reflection of the acoustic signal reflected back from the acoustic redirection member to the acoustic transducer.
13. The system according to claim 11 :
wherein the catheter further comprises an acoustic reflection member mounted to a common portion of the distal member with the acoustic redirection member to partially reflect the acoustic signal back to the acoustic transducer, and
wherein the analyzer is configured to detect the deflection via at least one of an amplitude change, a phase change, or a time-delay change of a reflection of the acoustic signal back from the acoustic reflection member.
14. The system according to claim 11 , wherein the analyzer is further configured to determine a force acting on the distal member based on the detected deflection and a known relationship between force acting on the distal member and deflection of the deflectable portion of the distal member.
15. The system according to claim 11 , wherein the acoustic signal comprises one of an acoustic beam or an acoustic ping.
16. The system according to claim 11 , wherein the transducer pinger is configured to at least one of:
direct a first acoustic signal from the acoustic transducer in a direction generally parallel to the longitudinal axis of the elongated catheter body to the acoustic redirection member, which redirects the first acoustic signal in a transverse direction non-parallel to the longitudinal axis of the elongated catheter body; and
direct a second acoustic signal from the acoustic transducer in a direction generally parallel to the longitudinal axis of the elongated catheter body.
17. The system according to claim 11 , wherein the transducer pinger is configured to analyze at least one of a tissue thickness measurement in the biological member and a tissue proximity to the biological member.
18. The system according to claim 11 , wherein the deflectable portion of the distal member permits at least one of axial deflection along the longitudinal axis of the elongated catheter body or bending deflection between the most-distal portion of the distal member and the proximal portion of the distal member.
19. The system according to claim 18 , wherein the axial deflection is less than 1 mm under an axial force of less than 100 grams-force.
20. The system according to claim 18 , wherein the bending deflection is less than 10 degrees under a bending moment of about 200 grams-force-millimeters.