The present invention relates to medical devices and methods. More specifically, the present invention relates systems and methods for optimizing the placement of implantable medical leads.
Pacemakers and implantable cardioverter defibrillators (“ICD”) (i.e., pulse generators) are used to provide electrotherapy to a patient's heart via leads extending from the pulse generator to heart tissue of a lead implantation site. To optimize the administration of the electrotherapy, lead placement must be optimized.
There is a need in the art for systems, devices and methods for optimizing lead placement during lead implantation.
Disclosed herein is a method of optimizing the implantation of an implantable medical lead into a patient to optimize electrotherapy administered via the lead. In one embodiment, the method includes: inserting the lead into the patient, the lead including a first electrode; providing a second electrode in the patient, wherein the second electrode is not part of the lead; generating an electrical vector (e.g., constant current) between the first electrode and second electrode, the electrical vector being generated as the lead is being implanted; analyzing the electrical vector (e.g., voltage as a surrogate of impedance) as the lead is being implanted; and optimizing the implantation of the lead based off of the analysis of the electrical vector to optimize electrotherapy administered via the lead.
Also disclosed herein is a method of employing extra-cardiac impedance to intra-operatively optimize lead placement. In one embodiment, the method includes: during the implantation of a lead, generating an electrical vector between a lead electrode supported on the lead and another electrode not supported on the lead but at least partially positioned within a patient; during the implantation of the lead, analyzing the electrical vector; and guiding the implantation of the lead based at least in part off of the analysis of the electrical vector.
Further disclosed herein is a delivery tool for implanting a lead into a patient. In one embodiment, the tool includes a tubular body, a first electrode, and a conductor. The tubular body includes a proximal end, a distal end, and a lumen extending longitudinally through the tubular body between the proximal end and the distal end. The first electrode is supported on the tubular body near the proximal end in such a manner that the first electrode can be displaced longitudinally along the tubular body. The conductor extends proximally from the electrode. In one version of this embodiment, the tubular body is part of an introducer sheath or a catheter. In one version of this embodiment, the tool also includes a system coupled to a proximal end of the conductor and configured to analyze an electrical vector generated between the first electrode and an electrode of a lead delivered via the tool. The electrode of the lead may be positioned in a SVC of a patient. The system may analyze the electrical vector with respect to extra-cardiac impedance.
Also disclosed herein is a method of optimizing an implantation of an implantable medical lead. In one embodiment, the method includes: identifying a characteristic of extra cardiac impedance; and employing the characteristic as a surrogate of cardiac output, wherein the characteristic is monitored during lead implantation so as to position the lead to optimize cardiac output. The characteristic may include at least one of Zarea, slope, max, min, or peak-to-peak. The method may also include optimizing a pulse generator parameter to optimize cardiac output by monitoring the characteristic. The pulse generator parameter may include at least one of AVD, V-V timing, lead configuration, or pacing mode.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
Disclosed herein are systems and methods for determining electrical characteristics during lead implantation to optimize lead placement at the lead implantation site to optimize the electrotherapy to be administered to the heart via the leads. For example, electrical vectors (e.g., constant current) may be generated between various electrodes or coils of the lead and the case of the pulse generator occupying a pocket formed in the patient's chest, temporary electrodes occupying the same type of pocket, or electrodes mounted on an introducer sheath. These electrical vectors can then be analyzed during lead implantation to determine the optimal locations for the implantation of the lead in the patient's cardiovascular system. For example, in analyzing the electrical vectors, voltage may be used as a surrogate of impedance.
Various electrical characteristics may be analyzed during lead implantation to optimize lead placement so as to optimize the electrotherapy to be administered to a patient's heart. For example, extra-cardiac impedance (“ECI”), which is measured between the superior vena cava (“SVC”) coil and the case (i.e., SVC-to-Case) of the pacemaker or ICD (“pulse generator”), provides an impedance signal with features that yield excellent correlation with LV contractility (“LVdp/dt”), cardiac output (“CO”), and systolic blood pressure.
Lead placement may be intra-operatively optimized by computing hemodynamic improvement while performing cardiac resynchronization therapy (“CRT”) to atrial pacing using an identical pacing rate and using a pacing system analyzer (“PSA”) with bi-ventricular (“BiV”) pacing capability. If CRT does not provide acute hemodynamic improvement, the leads may be repositioned or, in the case where a quad-pole left ventricular (“LV”) lead is placed, a different electrode may be selected.
SVC-to-Case impedance measured intra-operatively may be used to optimize lead placement for both LV leads and right ventricular (“RV”) leads. Lead placement optimization can be a mechanism for improving CRT performance in patients and improving the non-responder rate, thereby increasing the number of patients who could potentially benefit from CRT. ECI measurement capability may be provided with a PSA that has been combined with a programmer, such as, for example, the MERLIN™ programmer as marketed by St. Jude Medical, Inc.
As can be understood from Table A provided immediately below, upon collection of an impedance waveform, parameter features such as area, slope, max, min, peak-to-peak, etc. may be used as a surrogate for cardiac output. Based on these parameters, which give max CO, pacemaker parameters such as AVD, V-V timing, lead configuration, and pacing mode may be determined intraoperatively at bed side, at follow-up, or even automatically.
For example, as can be understood from the graphical depiction of CO versus Z Area in
As can be understood from
Where there is an increase in AVD, there will also be an increase in a parameter derived from impedance. For example, as indicated in
As can be understood from
It should be noted that for the plots in the various figures, the mean was subtracted from raw waveform. Consequently, the plots have a mean of zero.
For a discussion of a first method of employing ECI analysis intra-operatively to optimize lead placement, reference is made to
In some embodiments of the first method, other electrical vectors may be generated between the case 22 and the distal lead electrodes 27 or between the distal lead electrodes 27 and the SVC coil 24. These vectors may be analyzed during lead implantation to identify electrical characteristics to optimize lead placement for the optimization of electrotherapy to the heart. In one embodiment, the electrodes 27 may be the electrodes of a quadpolar (multi-polar) lead.
As can be understood from
In one embodiment, the pod 28 may be hardwired to the PSA-programmer 18 as indicated in
In one embodiment, as indicated in
For a discussion of a second method of employing ECI analysis intra-operatively to optimize lead placement, reference is made to
In some embodiments of the second method, other electrical vectors may be generated between the temporary electrodes 32 and the distal lead electrodes 27 or between the distal lead electrodes 27 and the SVC coil 24. These vectors may be analyzed during lead implantation to identify electrical characteristics to optimize lead placement for the optimization of electrotherapy to the heart.
Generally, physicians prefer to perform pocket construction after the leads have been implanted. Therefore, the first and second methods discussed above with respect to
In one embodiment, the pod 28 may be hardwired to the PSA-programmer 18 as indicated in
In one embodiment, as indicated in
In one embodiment, the temporary electrode(s) 32 may be in the form of relatively small single or multiple point or snap electrodes as employed with EKG. Alternatively, the temporary electrode(s) 32 may be in the form of an electrode generally similar in size to the can of a pulse generator.
For a discussion of the features of one embodiment of the electrode-equipped introducer 34 configured for use in the third method, reference is made to
In one embodiment, the pod 28 may be hardwired to the PSA-programmer 18 as indicated in
The electrodes 44, 46 are located near the proximal end 40 of the tubular body. As can be understood from arrow B in
For a discussion of the third method of employing ECI analysis intra-operatively to optimize lead placement, reference is made to
In one embodiment of the third method as indicated in
The proximal end of the lead 8 is electrically coupled to an electrical communication coupler 28 electrically coupled to a PSA-programmer 18 [block 420]. The introducer electrode(s) 44, 46 are electrically coupled to the electrical communication coupler 28 electrically coupled to the PSA-programmer 18 [block 425]. SVC-to-Case vectors are simulated by generating vectors between the introducer electrode(s) 44, 46 and one or more lead SVC coils 24 present in the SVC during implantation of the leads 8 [block 430]. ECI is assessed via the PSA-programmer during implantation of the leads [block 435], the leads being positioned to optimize the electrotherapy to the heart based off the ECI assessment [block 440].
As can be understood from
In some embodiments of the third method, other electrical vectors may be generated between the introducer electrodes 44, 46 and the distal lead electrodes 27 or between the distal lead electrodes 27 and the SVC coil 24. These vectors may be analyzed during lead implantation to identify electrical characteristics to optimize lead placement for the optimization of electrotherapy to the heart.
While first and second methods may be employed to optimize lead implantation for the optimization of electrotherapy to the heart, some physicians may not like forming the pocket 2 prior to lead implantation. Accordingly, the third method addresses the issues with the first and second methods by providing an introducer 34 with electrodes 44, 46. The electrodes provide for a temporary impedance measurement between the SVC coil 24 of the lead 8 to be implanted and introducer electrodes. Hence the introducer electrodes are used as a surrogate for the case 22 of the pulse generator 6 prior to the pulse generator being implanted.
Because the electrodes are incorporated into a lead introducer, the electrodes can be used to provide an anode for pacing, an electrode to emulate the ICD case for common mode grounding of a cardiac electrogram (“EGM”) sensing system or for extra-cardiac impedance measurement. In one embodiment, the electrodes 44, 46 may be in the form of a snap electrode similar to the nipple-like metal electrodes found on an EKG electrode.
As can be understood from
In one embodiment, the pod or electrical communication coupler 28 electrically coupled to the programmer 18 will send a high frequency pulse necessary for ECI measurement. The programmer 18 will display peak-to-peak SVC-Case ECI as a surrogate on the screen to guide optimal placement.
Electrodes being supported on the introducer used in the third method allow for extra-cardiac impedance measurement within the patient while obviating the need for creating a pocket early during the implant surgery as is needed for the first and second methods. The introducer electrodes may alternatively be used to emulate a pulse generator case intraoperatively for any application. The introducer electrodes may also be used for electrogram sensing, as a unipolar pacing anode, or as a common mode electrode for electrogram sensing between implanted electrodes.
Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.