Patent Description:
Implantable medical devices (IMDs), such as cardiac pacemakers or implantable cardioverter defibrillators, deliver therapeutic stimulation to patients' hearts. Patients with a conduction system abnormality, such as poor atrioventricular (AV) node conduction or poor sinoatrial (SA) node function, may receive an IMD, such as a pacemaker, to restore a more normal heart rhythm and AV synchrony. Some types of IMDs, such as cardiac pacemakers, implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices, provide therapeutic electrical stimulation to a heart of a patient via electrodes on one or more implantable endocardial, epicardial, or coronary venous leads that are positioned in or adjacent to the heart. The therapeutic electrical stimulation may be delivered to the heart in the form of pulses or shocks for pacing, cardioversion, or defibrillation. In some cases, an IMD may sense intrinsic depolarizations of the heart and control the delivery of therapeutic stimulation to the heart based on the sensing.

Existing pacing techniques involve pacing one or more of the four chambers of patient's heart <NUM>-left atrium (LA) <NUM>, right atrium (RA) <NUM>, left ventricle (LV) <NUM> and right ventricle (RV) <NUM>, all of which are shown in the anterior view of a frontal section of patient's heart <NUM> illustrated in <FIG>. Some therapeutic pacing techniques involve the cardiac conduction system. The cardiac conduction system, like a "super highway," may be described as quickly conducting electrical pulses whereas pacing cardiac muscle tissue may slowly conduct electrical pulses, like "traveling on a dirt road. " The cardiac conduction system includes SA node <NUM>, atrial internodal tracts <NUM>, <NUM>, <NUM> (i.e., anterior internodal <NUM>, middle internodal <NUM>, and posterior internodal <NUM>), atrioventricular node (AV node) <NUM>, His bundle <NUM> (also known as the atrioventricular bundle or bundle of His), and bundle branches including the left bundle branch (LBB) 8a and the right bundle branch (RBB) 8b. <FIG> also shows the arch of aorta <NUM> and Bachman's bundle <NUM>. The SA node, located at the junction of the superior vena cava and right atrium, is considered to be the natural pacemaker of the heart since it continuously and repeatedly emits electrical impulses. The electrical impulse spreads through the muscles of RA <NUM> to LA <NUM> to cause synchronous contraction of the atria. Electrical impulses are also carried through atrial internodal tracts to AV node <NUM> - the sole connection between the atria and the ventricles.

Conduction through the AV nodal tissue takes longer than through the atrial tissue, resulting in a delay between atrial contraction and the start of ventricular contraction. The AV delay, which is the delay between atrial contraction and ventricular contractor, allows the atria to empty blood into the ventricles. Then, the valves between the atria and ventricles close before causing ventricular contraction via branches of the bundle of His.

His bundle <NUM> is located in the membranous atrioventricular septum near the annulus of the tricuspid valve. His bundle <NUM> splits into right and left bundle branches 8a, 8b and are formed of specialized fibers called "Purkinje fibers" <NUM>. Purkinje fibers <NUM> may be described as rapidly conducting an action potential down the ventricular septum, spreading the depolarization wavefront quickly through the remaining ventricular myocardium, and producing a coordinated contraction of the ventricular muscle mass. <CIT>relates to an integrated lead for applying cardiac resynchronization therapy and neural stimulation.

The techniques of this disclosure generally relate to a lead-in-lead system and methods for cardiac therapy. The lead-in-lead system allows the leads to be translatable or rotatable relative to one another to facilitate capturing desired parts of the patient's heart. In other words, the lead-in-lead system may provide a customized implantation solution for each patient.

In one aspect, the present disclosure provides a system that includes a first implantable lead having a distal portion and a first electrode coupled to the distal portion of the first implantable lead. The first electrode is configured to be implanted at an implantation site on or in a tissue structure of a patient's heart. The system also includes a second implantable lead having a distal portion and a second electrode coupled to the distal portion of the second implantable lead. The second electrode is configured to be implanted at the implantation site distal to the first electrode within the tissue structure of the patient's heart. The distal portion of the second implantable lead is guided by the distal portion of the first implantable lead to the implantation site.

In another aspect, the present disclosure provides an implantable medical device that includes a plurality of electrodes. The plurality of electrodes includes a first electrode configured to be implanted at an implantation site on or in a tissue structure of a patient's heart. The plurality of electrodes also includes a second electrode configured to be implanted at the implantation site distal to the first electrode within the tissue structure of the patient's heart. The second electrode is translatable relative to the first electrode after the first electrode has been implanted to allow the second electrode to be implanted at various depths within the tissue structure of the patient's heart. The implantable medical device also includes a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart, and a sensing circuit operably coupled to the plurality of electrodes to sense electrical activity of the patient's heart. The implantable medical device further includes a controller having processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to provide electrical pulses to at least the second electrode to test one or more depths of the second electrode within the tissue structure of the patient's heart.

The present description relates to a lead-in-lead system and methods for cardiac therapy. The lead-in-lead approach may provide efficient and effective delivery of electrodes to various locations in the patient's heart, including at the triangle of Koch for ventricle-from-atrium (VfA) therapy, at the right ventricular septal wall for dual bundle-branch pacing, and in the coronary vasculature for left side sensing and pacing. VfA therapy may relate to providing an electrode to capture the LV implanted through the AV septum, such as the RA-LV septal wall. The lead-in-lead system includes a first implantable lead and a second implantable lead. One of the leads may be a bipolar lead, while the other lead may be a unipolar lead. The leads may include electrodes that are passive to monitor electrical activity or active to provide pacing pulses. The lead-in-lead system allows the leads to be translatable or rotatable relative to one another to facilitate capturing desired parts of the patient's heart. In other words, the lead-in-lead system may provide a customized implantation solution for each patient.

Reference will now be made to the drawings, which depict one or more aspects described in this disclosure. However, it will be understood that other aspects not depicted in the drawings fall within the scope of this disclosure. Like numbers used in the figures refer to like components, steps, and the like. However, it will be understood that the use of a reference character to refer to an element in a given figure is not intended to limit the element in another figure labeled with the same reference character. In addition, the use of different reference characters to refer to elements in different figures is not intended to indicate that the differently referenced elements cannot be the same or similar.

Various embodiments of this disclosure provide a lead-in-lead system for cardiac or other therapies. <FIG> and <FIG> illustrate different examples of lead-in-lead systems. <FIG> shows a system <NUM> including a first implantable lead <NUM> and a second implantable lead <NUM>, which are operably couplable an IMD <NUM>, and further including a stylet <NUM>. <FIG> shows a system <NUM> also including the first implantable lead <NUM>, the second implantable lead <NUM>, the IMD <NUM>, and a guidewire <NUM> instead of the stylet <NUM>. The system <NUM> and the system <NUM> may be similar in many aspects except where described differently herein.

The IMD <NUM> may be any suitable device known to one of ordinary skill in the art having the benefit of this disclosure that can operably couple to one or more implantable leads and one or more electrodes to sense electrical activity or to deliver therapy. The IMD <NUM> may be, for example, an implantable pacemaker, cardioverter, and/or defibrillator that provides electrical signals to a patient's heart via electrodes coupled to one or more of leads. Further non-limiting examples of the IMD <NUM> include: a pacemaker with a medical lead, an ICD, an intracardiac device, a subcutaneous ICD (S-ICD), and a subcutaneous medical device (e.g., nerve stimulator, inserted monitoring device, etc.). One example of an IMD <NUM> is shown in <FIG>.

Various implantation sites may be targeted using lead-in-lead systems. In one or more embodiments described herein, the systems are configured to be implanted in the triangle of Koch region in the atrioventricular wall of the patient's heart into the tissue structure between the right atrium and left ventricle of the patient's heart. In one or more embodiments described herein, the systems are configured to be implanted in the ventricular septal wall into the tissue structure is between the right ventricle and the left ventricle of the patient's heart. In some embodiments described herein, the systems are configured to be implanted in the coronary sinus or a coronary vein. Further, in some embodiments described herein, the system are configured to be implanted in the LV myocardium.

As can be seen in either <FIG> or <FIG>, the first implantable lead <NUM> may be mechanically coupled to the second implantable lead <NUM> by a lead fixture element <NUM>. In some embodiments, the first implantable lead <NUM> and the second implantable lead <NUM> may be formed separately. In such a configuration, the leads may be advanced one at a time. The second implantable lead <NUM> may be advanced through a lumen of the first implantable lead <NUM> to an implantation site, for example, after the first implantable lead has been fixed at the implantation site. In other embodiments, the first implantable lead <NUM> and the second implantable lead <NUM> may be formed into a single lead assembly or assembled lead configured to concurrently advance toward the implantation site.

The lead fixture element <NUM> may be described as a plug coupled between the leads. The lead fixture element <NUM> may facilitate translation or rotation of the leads relative to one another. In one or more embodiments described herein, the first implantable lead <NUM> is translatable along a longitudinal direction relative to the second implantable lead <NUM>, which may facilitate proper positioning of the leads during implantation to sense electrical activity or to deliver cardiac therapy. The second implantable lead <NUM> may translated to extend, or be advanced, distally from an end of the first implantable lead <NUM> to penetrate further into the tissue structure or to extend distally further into a space than the first implantable lead.

As used herein, the "longitudinal" direction refers to a direction along or parallel to a direction between a proximal part and a distal part of an elongate member, such as an implantable lead.

The system <NUM> may define a proximal portion <NUM> and a distal portion <NUM>, as well as a proximal end and a distal end. As illustrated, the double curve lines between the proximal portion <NUM> and the distal portion <NUM> indicate that the leads may be longer than shown. Each of the first implantable lead <NUM> and the second implantable lead <NUM> may also include a respective proximal portion and a respective distal portion, as well as a respective proximal end and a respective distal end.

The second implantable lead <NUM> may be at least partially received within the first implantable lead <NUM>, for example, to guide the second implantable lead. In some embodiments, the first implantable lead <NUM> may include a lumen <NUM> sized to receive the second implantable lead <NUM>. In some embodiments, an opening of lumen <NUM> may be larger than a cross-section of the second implantable lead <NUM>. A sealing element <NUM> may be coupled between the implantable leads to seal the distal portion of the first implantable lead <NUM> from fluid ingress, for example, at or near the distal end. In other words, the sealing element <NUM> may prevent, or substantially prevent, fluid from entering inside the lumen <NUM> to the space between the implantable leads.

A guidewire or a stylet may be used to advance and guide the lead-in-lead system <NUM> to one or more implantation sites. The guidewire or stylet may be received at least partially into a lumen of the second implantable lead <NUM>. As shown in <FIG>, a stylet <NUM> may be at least partially received within the lumen of the second implantable lead <NUM> from the proximal end of the lead. A distal end of the stylet <NUM> may be retained within the distal portion of the second implantable lead <NUM>, for example, proximal to a closed distal end of the second implantable lead. As shown in <FIG>, a guidewire <NUM> may be at least partially received within the lumen of the second implantable lead <NUM> from the proximal end of the lead and may extend distally from the lead. In one or more embodiments described herein, the guidewire <NUM> may be used to pierce into or through a tissue structure of the patient's heart.

In other embodiments, the second implantable lead <NUM> may not include a lumen. For example, the guidewire <NUM> may extend through the lumen <NUM> of the first implantable lead <NUM>, and the guidewire <NUM> may be exchanged with the second implantable lead <NUM> during an implantation process.

As used herein, a "tissue structure" refers to tissue forming any structures of the heart, such as a heart wall. The tissue structure may define a surface of the heart. Non-limiting examples of tissue structures include an atrioventricular septal wall (such as the RA-LV septum), a ventricular septal wall (such as the RV-LA septum), a wall forming the apex of the patient's heart, and a vessel wall (such as the vessel wall of the coronary sinus or a coronary vein).

The first implantable lead <NUM> may be used to guide the second implantable lead <NUM> to an implantation site or past a first implantation site to a second implantation site. In one or more embodiments described herein, the distal portion of the first implantable lead <NUM> may be used to guide the distal portion of the second implantable lead <NUM>, for example, to the same implantation site. For example, in one or more embodiments described herein, the implantation site may be the triangle of Koch region in the atrioventricular septal wall of the patient's heart or the ventricular septal wall in the basal (e.g., high basal or high septal) region or apical (e.g., low septal or near the apex) region. Implantation in the triangle of Koch region of the atrioventricular septal wall may facilitate pacing of the His bundle or ventricular myocardium. Implantation in the basal region of the ventricular septal wall may facilitate pacing of the His bundle branches. Implantation in the apical region may facilitate pacing of Purkinje fibers.

In other embodiments, the distal portion of the first implantable lead <NUM> may be implanted at a first implantation site, and the distal portion of the second implantable lead <NUM> may be implanted distally at a second implantation site. For example, in one or more embodiments described herein, the first implantation site may be in the coronary sinus or a coronary vein of the patient's heart and the second implantation site may be distal to the first implantation site in the coronary vein or in the myocardium (e.g., left ventricular myocardium) of the patient's heart. In one or more embodiments described herein, the second implantation site may be in the myocardium through the epicardium of the patient's heart outside of the coronary sinus and the coronary veins. In other words, the second implantation site in the myocardium may be accessed using the pericardial cavity.

Implantation leads may be secured, or fixed, for implantation concurrently or independently. For example, the first implantation lead <NUM> may be fixed before, during, or after the second implantation lead <NUM> is fixed. In some embodiments, after one of the implantation leads is fixed for implantation, the other of the implantation leads may be secured. In one example, the second implantation lead <NUM> may be fixed for implantation after the first implantation lead <NUM> is fixed for implantation. In another example, the first implantation lead <NUM> may be fixed for implantation after the second implantation lead <NUM> is fixed for implantation.

The second implantable lead <NUM> may be freely rotatable relative to the first implantable lead <NUM>, or vice versa, which may facilitate certain types of fixation for implantation. For example, a rotating motion may be used to secure the first implantable lead <NUM> or the second implantable lead <NUM> to an implantation site using a fixation element that responds to a rotating motion.

In one or more embodiments described herein, one or both implantation leads may include a fixation element used to secure the respective lead to a tissue structure at a selected implantation site. Non-limiting examples of fixation elements include a drill and a helix. In one or more embodiments, such as shown in <FIG>, the system <NUM> includes a fixation element <NUM> of the first implantable lead <NUM> may include a helix structure, and a fixation element <NUM> of the second implantable lead <NUM> may include a drill structure. In one or more embodiments, such as shown in <FIG>, the system <NUM> includes a fixation element <NUM> of the first implantable lead <NUM> may include a helix structure, and a fixation element <NUM> of the second implantable lead <NUM> may include a helix structure.

In general, any suitable type of drill or helix structure known to one of ordinary skill in the art having the benefit of this disclosure may be used for fixation elements. The fixation elements of the implantable leads may be configured to rotate in the same or opposite directions. For example, one fixation element may be configured to screw into a tissue structure when the respective lead is rotated clockwise and the other fixation element may be configured to screw into the tissue structure when the respective other lead is rotated clockwise (e.g., the same direction) or counterclockwise (e.g., the opposite direction). In addition, or as an alternative, to fixation elements, one or both implantation leads may include a canted lead structure to facilitate fixing the respective implantation lead in a vessel, such as the coronary sinus or a coronary vein.

In one or more embodiments described herein, a puncture element <NUM> may extend distally from the guidewire <NUM>. The puncture element <NUM> may be formed integrally or separately from the guidewire <NUM>. The puncture element <NUM> may have a drill structure that may be used to drill into a tissue structure at an implantation site. In one or more embodiments described herein, when using the puncture element <NUM>, the fixation element <NUM> of the second implantable lead <NUM> may have a helix structure as shown in <FIG>. In one or more embodiments described herein, when not using the guidewire <NUM>, the fixation element <NUM> of the second implantable lead <NUM> may have a drill structure as shown in <FIG>. In one or more other embodiments described herein, the guidewire <NUM> having the puncture element <NUM> may be used with the fixation element <NUM> having a drill structure. For example, the guidewire <NUM> may extend through a lumen of the fixation element <NUM> and extend distally from the fixation element <NUM>. In other words, the guidewire <NUM> may be used with the system <NUM> of <FIG> instead of the stylet <NUM>.

The puncture element <NUM> may be used to provide a micropuncture through a tissue structure, such as a vessel wall, of the patient's heart. For example, the micropuncture into the pericardial cavity of the patient's heart may be formed at a location along the coronary sinus or a coronary vein. In other words, the micropuncture may be formed inferior to the coronal oblique transseptal plane of the patient's heart. In some embodiments, the puncture element <NUM> includes a microneedle configured to provide the micropuncture in the coronary sinus or coronary vein.

As used herein, the term "micropuncture" refers to a puncture through a wall that has a largest dimension, for example, along a major axis or a diameter, of less than about <NUM> millimeter or on the order of about <NUM> micrometers, about <NUM> micrometers, or about <NUM> micrometer.

When forming a puncture in a vessel wall, a structure of the first implantable lead <NUM> may be configured to seal the puncture after implantation. In some embodiments, the structure may include a lead body or sheath of the implantable lead. For example, the first implantable lead <NUM> may be fixed against the vessel wall toward the pericardial cavity. The vessel wall may be sealed by the active fixation, and the second implantable lead <NUM> may extend radially from the first implantable lead <NUM>, through the vessel wall, and into the pericardial cavity. In some embodiments, the structure may include the sealing element <NUM>.

As used herein, the phrase "to seal the puncture" refers to partial sealing, complete sealing, or almost complete sealing of the puncture between a vessel and a space of the patient's heart. For example, the sealing of the puncture may be sufficient to prevent major tamponade (e.g., resulting from fluid buildup in the pericardial cavity).

One or both of the implantable leads includes one or more electrodes. In some embodiments described herein, the first implantable lead <NUM> includes a first electrode <NUM> coupled to the first implantable lead, and the second implantable lead <NUM> includes a second electrode <NUM> coupled to the second implantable lead. Each fixation element may be formed integrally or separately from the respective electrode. In the illustrated embodiments shown in <FIG> and <FIG>, the electrodes are integrally formed with their respective fixation elements. The integrally formed electrodes are configured to pierce into the tissue structure of the patient's heart. In one or more embodiments described herein, the integrally formed electrodes are formed at a distal portion or end of the respective fixation element.

The first electrode <NUM> or the second electrode <NUM> may disposed on the distal portion or at the distal end of the respective implantable lead. In one or more embodiments described herein, the first electrode <NUM> or the second electrode <NUM> may be disposed proximal to a distal end of the respective implantable lead, for example, when a structure of the respective implantable lead is used to seal a puncture in a tissue structure, such as a vessel wall.

The first electrode <NUM> and the second electrode <NUM> may be described as cathode electrodes (or simply cathodes) for pacing or sensing. For example, the electrodes may provide various pacing vectors for different cardiac therapies, such as CRT. The first implantable lead <NUM> or the second implantable lead <NUM> may include a return electrode <NUM>, which may be described as a common anode electrode (or simply an anode). In the illustrated embodiments of <FIG> and <FIG>, the return electrode <NUM> is coupled to the first implantable lead <NUM> and is shown as a ring electrode. The return electrode <NUM> may be proximal or distal to the cathode electrodes. The return electrode <NUM> may be proximal to the first electrode <NUM> and proximal to the second electrode <NUM>. The implantable lead having two electrodes (e.g., cathode and anode electrodes) may be described as a bipolar lead.

In one or more embodiments described herein, the second implantable lead <NUM> includes multiple second electrodes <NUM> (e.g., a plurality of second electrodes), which may be used to provide multiple sensing or pacing sites along the lead. The first electrode <NUM> and the return electrode <NUM> may be proximal to one or more of the multiple second electrodes <NUM>.

In one or more embodiments described herein, the first electrode <NUM> is configured to be implanted on or in a tissue structure of a patient's heart at the implantation site, and the second electrode <NUM> is configured to be implanted at the same implantation site distal to the first electrode within the tissue structure of the patient's heart. After one of the electrodes is implanted, the other electrode may be translatable relative to the implanted electrode. For example, the second electrode <NUM> may be translatable relative to the first electrode <NUM>, even after the first electrode is implanted, to allow the second electrode to be implanted at various depths within the tissue structure of the patient's heart. The translatable coupling of the first implantation lead <NUM> and the second implantation lead <NUM> may facilitate the translatable relationship between the electrodes.

In one or more embodiments described herein, the first electrode <NUM> is configured to be implanted at a first implantation site in the coronary sinus or in a coronary vein of the patient's heart, and the second electrode <NUM> is configured to be implanted at a second implantation site distal to the first electrode in the patient's heart. For example, the second electrode <NUM> may be implanted in a coronary vein.

One or more of the electrodes may be configured to sense electrical activity or to provide pacing pulses (e.g., in delivering cardiac therapy). In one or more embodiments described herein, both the first electrode <NUM> and the second electrode <NUM> are configured to provide pacing pulses. One or both electrodes may also be configured to sense electrical activity. In one or more embodiments described herein, the first electrode <NUM> is configured to only sense electrical activity, and the second electrode <NUM> is configured to provide pacing pulses. The second electrode <NUM> may also be configured to sense electrical activity. In some embodiments, a plurality of second electrodes <NUM> may be configured to deliver cardiac therapy to or sense electrical activity of the left ventricle.

In general, one or more of the electrodes may be configured to deliver electrical pulses to test one or more locations of the respective electrode in the patient's heart. In one or more embodiments described herein, one or more depths of the respective electrode in the tissue structure of the patient's heart may be tested. The test electrical pulses may facilitate identifying an appropriate depth or an appropriate surface location on a tissue structure for the electrode to capture the desired sensing or pacing. In one or more embodiments described herein, the first electrode <NUM> or the second electrode <NUM> may be tested at variable depths or surface locations before being implanted at a selected depth. In one example, an implantation depth or surface location of the first electrode <NUM> may be tested to determine whether the RBB is captured, and the implantation depth of the second electrode <NUM> may be tested to determine whether the LBB is captured. In another example, a surface location of the first electrode <NUM> may be tested to determine whether the RA myocardium is captured, and the implantation depth of the second electrode <NUM> may be tested to determine whether the LV myocardium or His bundle is captured.

In one or more embodiments described herein, one or more locations of the respective electrode in the patient's heart may be tested. In one example, the first electrode <NUM> may be tested to determine whether the LA is captured, and the second electrode <NUM> may be tested to determine whether the LV is captured. The electrodes may be advanced through a vessel, such as the coronary sinus or a coronary vein, of the patient's heart. One or more locations of the first electrode <NUM> in and along the vessel may be tested, for example, to capture the LA. Additionally, or alternatively, one or more locations of the second electrode <NUM> in the vessel or in the myocardium along the vessel may be tested, for example, to capture the LV. Further, one or more of the electrodes may be advanced into a space of the patient's heart, such as the pericardial cavity. One or more locations of the second electrode <NUM> in the myocardium along the pericardial cavity may be tested, for example, to capture the LV.

Although both electrodes may be implanted at the same implantation site, different parts of the patient's heart may be captured by advancing the electrodes to different depths. In one or more embodiments described herein, the first electrode <NUM> is implantable in the RA of the patient's heart to deliver cardiac therapy to or sense electrical activity of the RA of the patient's heart, and the second electrode <NUM> is implantable from the triangle of Koch region of the RA of the patient's heart to deliver cardiac therapy to or sense electrical activity of the LV in the basal region, septal region, or basal-septal region of the left ventricular myocardium of the patient's heart for VfA cardiac therapy.

In one or more embodiments described herein, the first electrode <NUM> is implantable closer to a first bundle branch of the cardiac conduction system of the patient's heart than the second electrode <NUM>, and the second electrode is implantable closer to a second bundle branch of the cardiac conduction system of the patient's heart than the first electrode. For example, the first electrode <NUM> may be implanted closer to the RBB 8b (<FIG>), and the second electrode <NUM> may be implanted closer to the LBB 8a (<FIG>). The implantable leads may be implanted from the RV into the ventricular septal wall toward the LV, which may facilitate placing the first electrode <NUM> in close proximity to the RBB 8b and placing the second electrode <NUM> in close proximity to the LBB 8a. The electrodes may be used to deliver dual-bundle branch cardiac therapy (e.g., using pacing pulses) to or sense electrical activity (e.g., electrical sensing) of the RBB 8b and the LBB 8a.

One or both implantable leads may include a sheath, or lead body, and one or more conductors extending inside the sheath. In one or more embodiments described herein, the systems may include at least three electrodes, including two cathode electrodes and one anode electrode. For example, one of the leads may have two electrodes and the other lead may have one electrode. Each electrode may be operably coupled to a distal portion of a conductor that extends through the sheath of the implantable lead. A proximal portion of the conductor may be operably coupled to one or more electrical connectors at the proximal portion of the lead.

Various types of electrical connectors may be used to provide an operative connection between a medical device, which may be implantable, and one or more conductors. In one or more embodiments described herein, one example of an electrical connector has a bifurcated proximal end. Each branch may include or be described as an IS connector. In some embodiments, a further example of an electrical connector has two separate IS connectors. In one or more embodiments described herein, another example of an electrical connector has an inner conductor and two outer conductors. The inner conductor may be operably coupled to the second electrode <NUM>, and the two outer conductors may be operably coupled to the first electrode <NUM> and the return electrode <NUM>. In some embodiments, such an electrical connector may be described as an IS-<NUM> connector.

<FIG> illustrates a cross-sectional view of one example of the distal portion <NUM> of the lead-in-lead system <NUM> that includes various conductors operably coupled to the electrodes. Any suitable conductors known to one of ordinary skill in the art having the benefit of this disclosure may be used for extending through the implantable leads of the system <NUM>.

The second implantable lead <NUM> may extend through the lumen <NUM> formed by the first implantable lead <NUM>. The second implantable lead <NUM> may also define a lumen <NUM>, and a stylet <NUM> may extend at least partially through the lumen to facilitate control of advancement and direction of the distal portion <NUM> of the system <NUM> during an implantation process.

The first electrode <NUM> is integrally formed with the fixation element <NUM> and coupled to the first implantable lead <NUM>. The first electrode <NUM> is operably coupled to a first conductor <NUM> extending through the first implantable lead <NUM>. The first conductor <NUM> may be disposed in the lumen <NUM> of the first implantable lead <NUM>. The electrode of the conductor may extend through the sealing element <NUM> to establish an electrical connection between the first electrode <NUM> and the first conductor <NUM>.

Also, as illustrated, the second electrode <NUM> is integrally formed with the fixation element <NUM> and coupled to the second implantable lead <NUM>. The second electrode <NUM> is operably coupled to a second conductor <NUM> extending through the second implantable lead <NUM>. The second conductor <NUM> may be disposed in the lumen <NUM> of the second implantable lead <NUM>. Another conductor also may also extend through the first implantable lead <NUM>. As illustrated, the return electrode <NUM> is operably coupled to a third conductor <NUM> extending through the lumen <NUM> of the first implantable lead <NUM>. Any suitable conductor type known to one of ordinary skill in the art having the benefit of this disclosure may be used. In the illustrated embodiment, each of the conductors are coil conductors, which may facilitate flexibility of the respective lead.

In some embodiments, the distal portion of the second implantable lead <NUM> may include a monolithic controlled release device (MCRD). The MCRD may be positioned proximal to the second electrode <NUM>.

<FIG> illustrates a cross-sectional view of one example of the proximal portion <NUM> of the lead-in-lead system <NUM> that includes an electrical connector operably coupled to the conductors. As illustrated, an electrical connector <NUM> includes a first IS connector <NUM> and a second IS connector <NUM>. The first conductor <NUM> and the third conductor <NUM> are operably coupled to the first IS connector <NUM>, for example, using coil joints. The first conductor <NUM> may couple to a proximal contact at a proximal end or tip of the first IS connector <NUM>, and the third conductor <NUM> may couple to a proximal ring contact distal to the proximal end or tip. The second conductor <NUM> is operably coupled to the second IS connector <NUM>, which has at least one proximal contact. The proximal contacts of the IS connectors may be used to operably couple to the IMD <NUM> of <FIG> or <FIG>.

In the illustrated embodiment, the first implantable lead <NUM> and the second implantable lead <NUM> are coupled by the lead fixture element <NUM>. The stylet <NUM> extends through the lumen <NUM> of the second implantable lead <NUM> and through the lead fixture element <NUM> and may be proximally coupled to a stylet driver.

<FIG> illustrates one example of a proximal end of a lead-in-lead system having a bifurcated electrical connector <NUM>. The electrical connector <NUM> has a bifurcated proximal end. Two electrodes, such as the first electrode <NUM> and the return electrode <NUM> of <FIG> or <FIG>, may be operably coupled to conductors extending through one branch <NUM> of the bifurcated proximal end and another electrode, such as the second electrode <NUM> of <FIG> or <FIG>, may be operably coupled to a conductor extending through the other branch <NUM>. Each branch may be described as an IS connector. The electrical connector <NUM> may include a coupling zone <NUM> where the electrical connector <NUM> may interface with the implantable leads. The electrical connector <NUM> may have the same or similar proximal contacts as the electrical connector <NUM> for coupling to the IMD <NUM>.

<FIG> illustrates a cross-sectional view of one example of a coupling zone <NUM> of an electrical connector <NUM> usable in a lead-in-lead system. The coupling zone <NUM> may be coupled to the first implantable lead <NUM> to operably couple to the first conductor <NUM> and the third conductor <NUM>. The second conductor <NUM> of the second implantable lead <NUM> may extend through the coupling zone <NUM> and operably couple to a proximal contact at a proximal end or tip of the electrical connector <NUM>. The first conductor <NUM> and the third conductor <NUM> may each operably couple to a proximal ring contact distal to the proximal end or tip.

Various embodiments of this disclosure provide a method of delivering lead-in-lead systems for cardiac therapy to target various areas within the patient's heart. <FIG> illustrates one example of a method <NUM> for delivering a lead-in-lead system, which includes implanting a first electrode of a first implantable lead at an implantation site on or in a tissue structure of a patient's heart <NUM>. The method <NUM> may also include advancing a second implantable lead having a second electrode guided by a distal portion of the first implantable lead to the same implantation site <NUM>. The method <NUM> may further include implanting the second electrode at the same implantation site distal to the first implantation lead electrode <NUM>.

The first implantable lead and the second implantable lead may be advanced concurrently toward the implantation site. In some embodiments, implanting the second electrode includes translating the second electrode relative to the first electrode after the first electrode has been implanted to allow the second electrode to be implanted at various selectable depths within the tissue structure of the patient's heart. Implanting the second electrode may also include delivering electrical pulses to test one or more depths of the first or second electrode in the tissue structure of the patient's heart.

In some embodiments, implanting the electrode of the first implantable lead may include advancing a guidewire to the implantation site. The guidewire may pierce or puncture the surface of the tissue structure. The first implantable lead may be guided over the guidewire to the implantation site. When the first implantable lead has been appropriately implanted, the guidewire may optionally be removed. The second implantable lead may be guided by a lumen of the first implantable lead or be guided over the guidewire to the implantation site. The second implantable lead may advance (e.g., drill or screw) distally into the tissue structure at the implantation site.

<FIG>, <FIG>, and <FIG> schematically illustrate various stages of one example of carrying out the method <NUM>, in particular, to deliver a lead-in-lead system, such as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), for VfA cardiac therapy. In <FIG>, a deflectable catheter <NUM> is advanced to and placed against the triangle of Koch in the patient's heart. In <FIG>, a bipolar outer lead <NUM> (e.g., first implantable lead) of the system is implanted through the catheter <NUM> and is fixated at the triangle of Koch next to coronary sinus ostium. In <FIG>, once the bipolar outer lead <NUM> of the system is fixed at triangle of Koch next to coronary sinus ostium, the inner lead <NUM> (e.g., second implantable lead) of the system is implanted though the outer lead lumen and fixated into the atrioventricular septal wall by rotating the inner lead body. <FIG> is a flowchart illustrating one example of a particular method <NUM> for carrying out the method <NUM>, in particular, to deliver a lead-in-lead system for VfA cardiac therapy. The method <NUM> may include placing a catheter against the triangle of Koch <NUM> (see <FIG>). The method <NUM> may also include inserting the bipolar outer lead of the system through the catheter and fixing the lead against the triangle of Koch <NUM> (see <FIG>). The method <NUM> may determine whether the bipolar outer lead captures the atrium <NUM>, in particular, the right atrium. If the atrium is not captured, the method <NUM> may return to inserting the bipolar lead <NUM> into a new location in the triangle of Koch. If the atrium is captured, the method <NUM> may include inserting the inner lead of the system into the outer lead lumen and placing the inner lead against the atrioventricular septal wall <NUM> (see <FIG>). The method <NUM> may also include carefully rotating the inner lead into the atrioventricular septal wall toward the left side of the patient's heart while performing test pacing <NUM> (see <FIG>).

The method <NUM> may further determine whether an expected paced ECG or pacing impedance is observed during the inner lead rotating process <NUM>. If the expected ECG or pacing impedance is observed, the method <NUM> may determine that implantation is complete <NUM>. For example, the leads may then be coupled to an IMD. Otherwise, the method <NUM> may continue to rotate the inner lead while test pacing <NUM>.

<FIG> illustrates a system <NUM> that may utilize a lead-in-lead system <NUM>, which may be lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), and a defibrillator lead <NUM> both coupled to the IMD <NUM> to provide cardiac therapy that may include VfA pacing (e.g., DDDR-type pacing) and defibrillation. The defibrillator lead <NUM> may be implanted, for example, in the RV of the patient's heart.

<FIG>, <FIG>, and <FIG> schematically illustrate various stages of one example of carrying out method <NUM>, in particular, to deliver a lead-in-lead system, such as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), for bi-cardiac conduction branch pacing or, in other words, dual bundle-branch cardiac therapy. In <FIG>, a deflectable catheter <NUM> is advanced to and placed against the RV high septal wall under the antero-septal tricuspid commissure, for example, about <NUM> to <NUM> centimeters (cm) below. In <FIG>, a bipolar outer lead <NUM> (e.g., first implantable lead) of the system is implanted through the catheter <NUM> and is fixated at the right ventricular septal wall under the antero-septal tricuspid commissure, for example, about <NUM> to <NUM> below. In <FIG>, once the bipolar outer lead <NUM> of the system is fixed at the right ventricular septal wall, the inner lead <NUM> (e.g., second implantable lead) of the system is implanted though the outer lead lumen and fixated into septal wall to left high septal wall (e.g., at the bundle branches) by rotating the inner lead body.

<FIG> is a flowchart illustrating on example of a particular method <NUM> for carrying out the method <NUM>, in particular, to deliver a lead-in-lead system, such as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), for dual bundle-branch cardiac therapy. The method <NUM> may include placing the catheter against the right ventricular septal wall under the antero-septal tricuspid commissure <NUM> (see <FIG>), for example, about <NUM> to <NUM> below. The method <NUM> may also include inserting the bipolar outer lead of the system through the catheter and fixing the bipolar outer lead at the right ventricular septal wall under the antero-septal tricuspid commissure <NUM> (see <FIG>), for example, about <NUM> to <NUM> below.

The method <NUM> may further include inserting the inner lead of the system into the outer lead lumen and placing the inner lead against the right ventricular septal wall <NUM> (see <FIG>). The method <NUM> may include carefully rotating the inner lead into the right ventricular septal wall toward the left side of the patient's heart while performing test pacing <NUM> (see <FIG>).

The method <NUM> may include determining whether a left bundle Purkinje potential from an EGM using the second electrode or an expected pacing impedance is observed <NUM>. If the left bundle Purkinje potential or pacing impedance is observed, the method <NUM> may determine that implantation is complete <NUM>. For example, the leads may then be coupled to an IMD. Otherwise, the method <NUM> may continue to rotate the inner lead while test pacing <NUM>.

Optionally, the method <NUM> also include rotating the bipolar outer lead and performing test pacing until a right bundle Purkinje-potential, expected EGM, or pacing impedance is observed.

<FIG> illustrates a system <NUM> that may utilize a lead-in-lead system <NUM>, which may be lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), and an atrial lead <NUM> both coupled to the IMD <NUM> to provide cardiac therapy that may include dual bundle-branch pacing (e.g., DDDR-type pacing). The atrial lead <NUM> may be planted in the RA of the patient's heart.

<FIG> illustrates a system <NUM> that may utilize a lead-in-lead system <NUM>, which may be lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), an atrial lead <NUM>, and a defibrillator lead <NUM> each coupled to the IMD <NUM> to provide cardiac therapy that may include dual bundle-branch pacing (e.g., DDDR-type pacing) and defibrillation. The defibrillator lead <NUM> may be implanted, for example, in the RV of the patient's heart.

Various lead-in-lead systems may also be used to access the coronary vasculature, such as the coronary sinus and coronary veins, for left-side cardiac therapy. <FIG> shows one example of a system <NUM>, which may be similar to or the same as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), for left-side cardiac therapy. The system <NUM> includes a first implantable lead <NUM> and a second implantable lead <NUM>. A first electrode <NUM> may be coupled to a distal portion of the first implantable lead <NUM> (e.g., outer lead) and implanted in a coronary vein (e.g., great cardiac vein). The second implantable lead <NUM> (e.g., inner lead) may extend distally from the first implantable lead <NUM>. A second electrode <NUM> may be coupled to a distal portion of the second implantable lead <NUM>. The second electrode <NUM> is positioned distally from the first electrode <NUM> (e.g., further along the great cardiac vein). The first electrode <NUM> may capture the LA of the patient's heart, and the second electrode <NUM> may capture the LV of the patient's heart.

The system <NUM> may be implanted using any suitable technique. One example of an implantation method may include implanting the first implantable lead <NUM> to implant the first electrode <NUM> at a first implantation site in the coronary sinus or a coronary vein of a patient's heart. The method may also include advancing the second implantable lead <NUM> having the second electrode <NUM> guided by a distal portion of the first implantable lead <NUM> to a second implantation site distal to the first electrode <NUM> in a coronary vein of the patient's heart. The method may further include implanting the second electrode <NUM> at the second implantation site.

<FIG> shows one example of a system <NUM>, which may be similar to or the same as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), for left-side cardiac therapy. The system <NUM> includes a first implantable lead <NUM> and a second implantable lead <NUM>. A first electrode <NUM> may be coupled proximal to a distal portion <NUM> of the first implantable lead <NUM> (e.g., outer lead) and implanted in the coronary sinus. The second implantable lead <NUM> (e.g., inner lead) may extend distally from the first implantable lead <NUM> and through a puncture <NUM>, such as a micropuncture, in a coronary vessel wall (e.g., the wall of the middle cardiac vein). A second electrode <NUM> may be coupled to a distal portion of the second implantable lead <NUM> and may extend into the pericardial cavity of the patient's heart and be implanted into the myocardium, such as the LV myocardium, through the epicardium. The first electrode <NUM> may capture the LA of the patient's heart, and the second electrode <NUM> may capture the LV of the patient's heart.

In particular, the second implantable lead <NUM> may extend through the puncture <NUM> from the vessel into the pericardial cavity, which extends between the epicardium and the pericardium of the patient's heart. The distal end of the second implantable lead <NUM> may be positioned at various locations within the pericardial cavity to access different implantation sites in the myocardium, such as the LV myocardium, through the epicardium that are outside of the coronary vasculature.

A guidewire <NUM> may be used to form the puncture in the vessel wall and thereafter retracted from the system <NUM>. A structure of the first implantable lead <NUM>, such as the distal portion <NUM>, may be advanced to the puncture <NUM> and positioned adjacent to the puncture to seal the puncture.

The system <NUM> may be implanted using any suitable technique. One example of an implantation method may include advancing the second electrode <NUM> of the second implantable lead <NUM> guided by the distal portion <NUM> of the first implantable lead <NUM> to a location in the coronary sinus or a coronary vein of a patient's heart. The method may also include implanting the first electrode <NUM> at a first implantation site in the coronary sinus or a coronary vein of the patient's heart. The method may also include puncturing through a vessel wall at the location in the coronary sinus or the coronary vein into the pericardial cavity of the patient's heart, for example, using the guidewire <NUM>. The method may also include advancing the second implantable lead <NUM> through the puncture <NUM> in the vessel wall into the pericardial cavity. Further, the method may include implanting the second electrode <NUM> into the epicardium and myocardium of the patient's heart from the pericardial cavity at a second implantation site distal to the first implantation site. The second implantation site may be in the myocardium of the patient's heart outside of the coronary sinus or the coronary veins. In some embodiments, the first electrode <NUM> is implanted after the second electrode <NUM> is implanted, which may facilitate sealing of the puncture <NUM> by the first implantable lead <NUM>.

<FIG> shows one example of a system <NUM>, which may be similar to or the same as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), for left-side cardiac therapy. The system <NUM> includes a first implantable lead <NUM> and a second implantable lead <NUM>. A first electrode <NUM> may be coupled to a distal portion of the first implantable lead <NUM> (e.g., outer lead) and implanted in the middle cardiac vein (e.g., a coronary vein). The second implantable lead <NUM> (e.g., inner lead) may extend distally from the first implantable lead <NUM>. A second electrode <NUM> may be coupled to a distal portion of the second implantable lead <NUM> and may extend into the myocardium of the patient's heart, such as the LV myocardium. The first electrode <NUM> may capture the LA of the patient's heart, and the second electrode <NUM> may capture the LV of the patient's heart.

<FIG> shows one example of the IMD <NUM> including a connector receptacle <NUM> configured to receive a lead or lead connector from a lead-in-lead system, such as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>), a therapy delivery circuit <NUM> operably coupled to the connector receptacle, a sensing circuit <NUM> operably coupled to the connector receptacle, and a controller <NUM> operably coupled to the therapy delivery circuit and the sensing circuit.

The therapy delivery circuit <NUM> is configured to deliver cardiac therapy to the patient's heart through one or more operably connected electrodes, for example, electrically connected via the connector receptacle <NUM>. The sensing circuit <NUM> is configured to sense electrical activity of the patient's heart using one or more operably connected electrodes, for example electrically connected via the connector receptacle <NUM>. The electrodes operably coupled to the sensing circuit <NUM> may or may not include some or all of the electrodes that are also operably coupled to the therapy delivery circuit <NUM>. The sensing circuit <NUM> may monitor electrical activity of the patient's heart, for example, using electrical signals, such as electrocardiogram (ECG) signals or electrogram (EGM) signals.

The controller <NUM> may have processing circuitry operably coupled to the therapy delivery circuit <NUM> and the sensing circuit <NUM>. The controller <NUM> may be used to carry out various functionality of the IMD <NUM> coupled to the lead-in-lead systems described herein, such as lead-in-lead system <NUM> (<FIG>) or lead-in-lead system <NUM> (<FIG>).

Processing circuitry may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or integrated logic circuitry. In some examples, processing circuitry may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to the processing circuitry of the controller herein may be embodied as software, firmware, hardware or any combination thereof. The controller may control the therapy delivery circuit to deliver stimulation therapy to the patient's heart according to a selected one or more of therapy programs, which may be stored in a memory. Specifically, the controller may control the therapy delivery circuit to deliver electrical pulses with amplitudes, pulse widths, frequency, or electrode polarities specified by the selected one or more therapy programs.

The controller <NUM> may include memory. Non-limiting examples of memory may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random-access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other digital media.

The terms "coupled" or "connected" refer to elements being attached to each other either directly (in direct contact with each other) or indirectly (having one or more elements between and attaching the two elements). Either term may be modified by "operatively" and "operably," which may be used interchangeably, to describe that the coupling or connection is configured to allow the components to interact to carry out functionality.

The term "configured to" refers to an element with suitable structure to carry out a particular function. A suitable structure may be selected by a person having the benefit of this disclosure and at least ordinary skill in the art. As used herein, the term "configured to" may be used interchangeably with the terms "adapted to" or "structured to" unless the content of this disclosure clearly dictates otherwise.

Terms related to orientation, such as "proximal," "distal," "above," or "below," are used to describe relative positions of components and are not meant to limit the orientation of the embodiments contemplated.

As used herein, "have," "having," "include," "including," "comprise," "comprising" or the like are used in their open-ended sense, and generally mean "including, but not limited to. " It will be understood that "consisting essentially of," "consisting of," and the like are subsumed in "comprising," and the like.

The term "and/or" means one or all of the listed elements or a combination of at least two of the listed elements.

Claim 1:
A system comprising:
a first implantable lead (<NUM>) comprising a distal portion and a first electrode (<NUM>) coupled to the distal portion of the first implantable lead, wherein the first electrode is configured to be implanted at an implantation site on or in a tissue structure of a patient's heart; and
a second implantable lead (<NUM>) comprising a distal portion and a second electrode (<NUM>) coupled to the distal portion of the second implantable lead, wherein the second electrode is configured to be implanted at the implantation site distal to the first electrode within the tissue structure of the patient's heart, wherein the distal portion of the second implantable lead is guided by the distal portion of the first implantable lead to the implantation site.