Cardiac motion characterization by strain measurement
View Patent ↗Methods for evaluating motion of a cardiac tissue location, e.g., heart wall, are provided. In the subject methods, timing of a signal obtain from a strain gauge stably associated with the tissue location of interest is employed to evaluate movement of the cardiac tissue location. Also provided are systems, devices and related compositions for practicing the subject methods. The subject methods and devices find use in a variety of different applications, including cardiac resynchronization therapy.
1. A method for evaluating movement of a cardiac tissue location in a subject, the method comprising:
(a) determining timing of a signal obtained from a resistive strain gauge of an implantable device stably associated with the cardiac tissue location, wherein the implantable device comprises:
a lead of a length with a proximal end and a distal end, the lead comprising:
a guide wire core formed within the lead along the length of the lead, wherein the resistive strain gauge is physically attached to the guide wire core; and
at least one insulated conductor spirally wrapping the guide wire core from the proximal end to the distal end, wherein the resistive strain gauge is electrically coupled to an insulated conductor of the at least one insulated conductor; and
(b) evaluating movement of the cardiac tissue location via a signal processing element communicatively coupled to the implantable device based on the timing of the signal obtained from the resistive strain gauge.
2. The method according to claim 1 , wherein said strain gauge comprises multiple strain tranducers.
3. The method according to claim 1 , wherein the resistive strain gauge comprises a substrate.
4. The method according to claim 3 , wherein the substrate is compliant.
5. The method according to claim 1 , wherein said strain gauge does not include a substrate.
6. The method according to claim 1 , wherein said strain gauge comprises a transducer that is hermetically sealed.
7. The method according to claim 1 , wherein the resistive strain gauge is not hermetically sealed.
8. The method according to claim 1 , wherein the resistive strain gauge comprises a transducer in which strain induces an electric signal.
9. The method according to claim 3 , wherein the resistive strain gauge is a fabricated using a resistive material.
10. The method according to claim 9 , wherein the resistive material is platinum.
11. The method according to claim 3 , wherein said strain transducer is fabricated from a piezoelectric material.
12. The method according to claim 1 , wherein said strain gauge comprises a resonant marker band structure.
13. The method according to claim 1 , wherein the lead further comprises a tissue securing element configured to stably associate the resistive strain gauge with the cardiac tissue location.
14. The method according to claim 1 , wherein the resistive strain gauge is stably associated with the cardiac tissue location by a compressive force.
15. The method according to claim 1 , wherein the implantable device is an acute device.
16. The method according to claim 1 , wherein the implantable device is present on a permanently implantable device.
17. The method according to claim 1 , wherein the cardiac tissue location is a septal wall location.
18. The method according to claim 1 , wherein the cardiac tissue location is on a heart wall.
19. The method according to claim 18 , wherein the heart wall is a chamber wall.
20. The method according to claim 19 , wherein the chamber wall is a ventricular wall.
21. The method according to claim 19 , wherein the chamber wall is a septal wall.
22. A system for evaluating movement of a cardiac tissue location, the system comprising:
(a) an implantable device comprising:
a lead of a length with a proximal end and a distal end, the lead comprising:
a guide wire core formed within the lead along the length of the lead;
a resistive strain gauge physically attached to the guide wire core; and
at least one insulated conductor spirally wrapping the guide wire core from the proximal end to the distal end, wherein the resistive strain gauge is electrically coupled to an insulated conductor of the at least one insulated conductor, and the resistive strain gauge stably associated with the cardiac tissue location; and
(b) a signal processing element communicatively coupled to the implantable device and configured to employ timing of a signal obtained from the resistive strain gauge that is induced by movement of the cardiac tissue location to evaluate movement of the cardiac tissue location.
23. An implantable device comprising:
a lead of a length with a proximal end and a distal end, the lead comprising:
a guide wire core formed within the lead along the length of the lead;
a resistive strain gauge physically attached to the guide wire core; and
at least one insulated conductor spirally wrapping the guide wire core from the proximal end to the distal end, wherein the resistive strain gauge is electrically coupled to an insulated conductor of the at least one insulated conductor.
24. The implantable device according to claim 23 , wherein the guide wire core is made of a stainless steel or Ni—Ti.
25. The implantable device according to claim 23 , wherein the insulated conductor comprises:
a silver core;
a stainless steel wire enclosing the silver core; and
an insulation layer coating the stainless steel wire.
26. The implantable device according to claim 23 , further comprising a pacing ring electrode formed at or proximate to the distal end of the lead, wherein the pacing ring electrode is coupled to another insulated conductor of the at least one insulated conductor and is configured to sense an electrical signal and pace a tissue in vicinity.
27. The implantable device according to claim 23 , further comprising a catheter enclosing the lead, and wherein the resistive strain gauge is formed on a flap extending from the catheter.
28. The implantable device according to claim 27 , wherein the resistive strain gauge formed on the flap is configured to measure a blood flow.
29. The implantable device according to claim 23 , wherein the distal end of the lead comprises an umbrella pattern of tines, and wherein the resistive strain gauge is formed at the distal end of the lead.
30. The implantable device according to claim 23 , wherein the distal end of the lead comprises a basket type of structure, and wherein the resistive strain gauge is formed at the distal end of the lead.
31. The implantable device according to claim 23 , wherein the distal end of the lead comprises a coil, and wherein the resistive strain gauge is formed at the distal end of the lead.