Source: https://patents.google.com/patent/JP5671069B2/en
Timestamp: 2019-10-16 08:23:28
Document Index: 259574451

Matched Legal Cases: ['art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160', 'art 160']

JP5671069B2 - Lead and implantable medical device comprising a conductor configured for reduction of MRI induced current - Google Patents
Lead and implantable medical device comprising a conductor configured for reduction of MRI induced current Download PDF
JP5671069B2
JP5671069B2 JP2012554059A JP2012554059A JP5671069B2 JP 5671069 B2 JP5671069 B2 JP 5671069B2 JP 2012554059 A JP2012554059 A JP 2012554059A JP 2012554059 A JP2012554059 A JP 2012554059A JP 5671069 B2 JP5671069 B2 JP 5671069B2
JP2012554059A
JP2013520238A (en
リー、インボー
アメリ、マスード
レディ、ジー．シャンタヌ
ジー． ベンツェン、ジェイムズ
2010-02-19 Priority to US30637710P priority Critical
2010-02-19 Priority to US61/306,377 priority
2011-02-18 Application filed by カーディアック ペースメイカーズ， インコーポレイテッド, カーディアック ペースメイカーズ， インコーポレイテッド filed Critical カーディアック ペースメイカーズ， インコーポレイテッド
2011-02-18 Priority to PCT/US2011/025457 priority patent/WO2011103444A1/en
2013-06-06 Publication of JP2013520238A publication Critical patent/JP2013520238A/en
2015-02-18 Publication of JP5671069B2 publication Critical patent/JP5671069B2/en
Various embodiments of the present invention generally relate to implantable medical devices. More specifically, embodiments of the present invention relate to conductor configurations for compatibility with magnetic resonance imaging (MRI).
When functioning properly, the human heart maintains its own rhythm and can pump enough blood throughout the body's circulatory system. However, some people have irregular heart rhythms called heart rhythm abnormalities that can lead to decreased blood circulation and cardiac output. One method of treating cardiac rhythm abnormalities involves the use of pulse generators, such as pacemakers, implantable cardioverter defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices. Such devices are typically coupled to a number of conductive leads having one or more electrodes that can be used to deliver pacing therapy or electric shock to the heart. . For example, in atrioventricular (AV) pacing, the lead is typically placed in the heart's ventricle and atria and attached via a lead terminal pin to a pacemaker or defibrillator implanted in the pectoral muscle or abdomen. It is done.
Magnetic resonance imaging (MRI) is a non-invasive imaging technique that utilizes nuclear magnetic resonance technology to obtain an image of the interior of a patient's body. Typically, MRI systems use magnetic coils having a magnetic field strength of about 0.2-3 Tesla. During the procedure, body tissue is temporarily exposed to RF pulses of electromagnetic energy in a plane perpendicular to the magnetic field. The electromagnetic energy resulting from these pulses can be used to image body tissue by measuring the relaxation properties of excited nuclei in the tissue. In some cases, imaging of the patient's chest area may be clinically beneficial. In chest MRI procedures, implanted pulse generators and leads can also be exposed to an applied electromagnetic field.
Various embodiments of the present invention generally relate to implantable lead conductor configurations for compatibility with magnetic resonance imaging (MRI).
In Example 1, the electrical lead comprises a flexible body to provide a connector, an inner conductor coil, and a high voltage multifilar outer coil. The flexible body has a proximal region with a proximal end and a distal region. A connector is coupled to the proximal end of the flexible body of the lead to electrically and mechanically connect the lead to the implantable pulse generator. The low voltage inner conductor coil has one or more filer thicknesses, pitches, and average coil diameters configured such that the inner conductor coil has a first inductance value greater than or equal to 0.0079 μΗ / mm (0.2 μΗ / inch). It is formed from a filer wound in a substantially cylindrical shape. The high voltage multi-filer outer coil has a proximal section, a distal section, and a length, the high voltage multi-filer outer coil having a direct current (DC) resistance of less than approximately 10 ohms and each having a filer thickness. The high-voltage multi-filer outer coil is a second high-voltage multi-filer outer coil having a second high-voltage multi-filer outer coil of 0.0039 μΗ / mm (0.1 μΗ / inch) or more. A pitch and an average coil diameter configured to have an inductance value of The low voltage inner conductor coil and the high voltage outer coil are coaxially arranged so as to be separated from each other.
In Example 2, the electrical lead of Example 1 has an insulator layer disposed around at least a portion of the inner conductor coil.
In Example 3, in at least one of the electrical leads of Example 1 or 2, the inner conductor coil has a single filer structure.
In Example 4, the electrical lead of at least one of Examples 1, 2, or 3 has an inner conductor coil average pitch of approximately 0.13 mm (approximately 0.005 inches).
In Example 5, the electrical lead of Example 4 has an inner conductor coil with a single filer structure and an average coil diameter of 0.58 mm (0.023 inch).
In Example 6, the electrical lead of any one of Examples 1-5 has an inductance that the inner conductor coil is greater than approximately 0.020 μｍｍ / mm (approximately 0.5 μΗ / inch).
In Example 7, the electrical lead wire of any one of Examples 1 to 6 has a first inductance value (L) of the number of filers wound in a cylindrical shape (N), the pitch of the inner conductor coil ( b) and the average coil diameter (a) are defined by the formula L≈μ 0 πa 2 / 4b 2 N 2 (where μ 0 is the permeability of free space).
In Example 8, the electrical lead wire of any of Examples 1-7 has a DC resistance with the inner conductor coil less than 200 ohms.
In Example 9, the electrical lead wire of any of Examples 1 to 8 has a bipolar or unipolar inner conductor coil.
In Example 10, as for the electrical lead wires of Examples 1 to 9, the high-voltage multifilar outer coil is a ribbon-type conductor coil.
In Example 11, the medical lead comprises a flexible body, a connector, a low voltage inner conductor coil, a multifilar high voltage outer conductor coil, and a trifilar shock coil. The flexible body has a proximal end region having a proximal end portion and a distal end region. The connector is coupled to the proximal end of the body configured to electrically and mechanically connect the lead to the implantable pulse generator. The low voltage inner conductor coil is configured to transmit an electrical signal between the distal end region and the proximal end region of the lead wire, and the low voltage inner conductor coil has a low voltage inner conductor coil of 0.0079 μΗ / mm ( Formed of one or more generally cylindrically wound filers having a pitch and an average coil diameter configured to have a first inductance of 0.2 μΗ / inch) or greater. The multifilar high voltage outer conductor coil is a quadfiler spiral-like shape that radially surrounds at least a portion of the low voltage inner conductor coil, a DC resistance of less than 10 ohms, and 0.0039 μΗ / mm (0.1 μΗ / mm). And an outer diameter and an average pitch configured to provide a multifilar high voltage outer conductor coil having a second inductance greater than or equal to inches. The trifiler shock coil has a proximal end, and the proximal end of the trifilar shock coil is connected to the distal end of the multiple filer high voltage outer coil via a coupler. The low voltage inner conductor coil and the multiple filer high voltage outer conductor coil are coaxially arranged so as to be spaced apart from each other.
In Example 12, the medical lead of Example 11 is one in which the lead surrounds one or more of a low voltage inner conductor coil, a multi-filer high voltage outer conductor coil, and a trifilar shock coil. The above insulating material layer is further provided.
In Example 13, at least one of the medical leads of Example 11 or 12 has a multiple filer high voltage outer coil having an outer diameter greater than the outer diameter of the trifilar shock coil.
In Example 14, the medical lead of any one of Examples 11-13 has different pitches for the low voltage inner conductor coil, the multi-filer high voltage outer conductor coil, and the trifilar shock coil.
In Example 15, the medical lead of any of Examples 11-14 has a low voltage inner conductor coil, a multi-filer high voltage outer conductor coil, and a trifilar shock coil of about 0.005 inches ( 0.127 mm) or less.
In Example 16, an implantable medical device comprises a proximal region having a proximal end mechanically and electrically coupled to a pulse generator and a distal region implanted within the patient's heart. A lead having a flexible body configured to transmit electrical signals between the heart and the pulse generator. The lead further comprises a low voltage inner conductor coil configured to conduct an electrical signal between the distal end region and the proximal end region of the lead wire, the low voltage inner conductor coil being one or more wound. It is formed from a filer. The low voltage inner conductor coil has separate turns with pitch, average coil diameter, and the number of one or more wound filers is 0.0079 μΗ / mm (0.2 μΗ / inch) The first inductance value is configured as described above. The lead further comprises a high voltage outer coil with a quad filer spiral-like shape having a DC resistance of less than 10 ohms, the high voltage outer coil radially surrounding at least a portion of the low voltage inner conductor coil. And an outer diameter, a filer diameter, and an average pitch configured to obtain a high-voltage outer coil having a second inductance value of 0.0039 μΗ / mm (0.1 μΗ / inch) or more. . The lead wire further includes a trifilar shock coil having a proximal end, and the proximal end is connected to the distal end of the high voltage outer coil via a coupler. The low voltage inner conductor coil and the high voltage outer coil are coaxially arranged so as to be separated from each other.
In Example 17, the implantable medical device of Example 16 has a DC resistance with a lead wire less than 200 ohms.
In Example 18, the implantable medical device of at least one of Examples 16 or 17 includes a filer in which the low voltage inner conductor coil is made from dft (R) MP35N (TM).
In Example 19, the implantable medical device of any of Examples 16-18, wherein the low voltage inner conductor coil is bipolar or unipolar.
In Example 20, the implantable medical device of any of Examples 16-19, wherein the pitch of the high voltage conductor coil is about 0.25 mm (about 0.010 inch) and the average coil of the high voltage conductor coil The diameter is about 2.3 mm (about 0.090 inch) resulting in a coil inductance value of about 0.0051 μΗ / mm (about 0.13 μΗ / inch) and the inner conductor coil pitch is about 0.13 mm ( The inner conductor coil is formed from one cylindrically wound filer, and the average coil diameter of the inner conductor coil is about 0.58 mm (about 0.023 inch) and about It has a coil inductance value per unit length of 0.020 μΗ / mm (about 0.5 μΗ / inch).
In Example 21, in any of the implantable medical devices of Examples 16-20, the pulse generator is a pacemaker or defibrillator.
In Example 22, the implantable medical lead wire includes a multi-lumen lead wire body, a connector assembly at a proximal end of the lead wire body, a plurality of electrodes coupled to the lead wire body, and an inside of the lead wire body. Having a plurality of conductors extending. The lead wire body includes a tubular member having a plurality of lumens penetrating in the longitudinal direction. Each conductor extends longitudinally within the respective lumen and is electrically coupled to one of the electrodes and also to the electrical contacts of the connector assembly. At least one of the conductors is a coil conductor formed from one or more substantially cylindrically wound filers, and when the lead wire is exposed to a range of high frequencies, the coil conductor is 0.0079 μΗ / It has a filer thickness, a pitch, and an average coil diameter configured to have a first inductance value equal to or greater than mm (0.2 μΗ / inch).
In Example 23, the implantable medical lead of Example 21 is formed from a single cylindrically wound filer having a coil conductor having a thickness of about 0.10 mm (about 0.004 inches). And a coil conductor having a pitch of about 0.13 mm (about 0.005 inches) and an average coil diameter of about 0.58 mm (about 0.023 inches), about 0.020 μΗ / mm (about 0.005 inches). It has a coil inductance per unit length of 5 μΗ / inch).
In Example 24, in the implantable medical lead of Example 21 or 22, the electrode coupled to the coil conductor is a pace / sense electrode.
1 is a schematic diagram of a medical system with an MRI scanner and an implantable cardiac rhythm management system implanted within a human patient's torso according to various embodiments of the invention. FIG. 1 is a schematic diagram of an exemplary pulse generator and lead implanted in a patient's body that can be used in accordance with some embodiments of the present invention. FIG. FIG. 2B is a schematic diagram illustrating a simplified equivalent circuit for the lead of FIG. 2A. FIG. 3 illustrates an exemplary lead that can be used in accordance with one or more embodiments of the present invention. 2 is a cross-sectional view of a high voltage shock coil and a low voltage coil according to various embodiments of the present invention. FIG. FIG. 3 shows various portions of an inner conductor coil, a high voltage conductor coil, and a shock coil according to some embodiments of the present invention. FIG. 3 shows various portions of an inner conductor coil, a high voltage conductor coil, and a shock coil according to some embodiments of the present invention. FIG. 3 shows various portions of an inner conductor coil, a high voltage conductor coil, and a shock coil according to some embodiments of the present invention. FIG. 3 illustrates an example of temperature rise that occurs when a typical lead design and a typical lead designed according to various embodiments of the present invention are exposed to frequencies associated with MRI. 1 is a cross-sectional view of a lead with a multiple lumen structure that can be used in some embodiments of the present invention. FIG.
The drawings are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be scaled up or down to help enhance an understanding of embodiments of the invention. While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. However, it is not intended that the invention be limited to the specific embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION An implantable defibrillator (ICD) is typically implanted in the patient's pectoral muscle. In some cases, one or two electrodes may extend from the ICD and / or into the atrium or ventricle of the patient's heart. In the case of an epicardial lead, the electrodes are attached to the outer surface of the patient's heart. The ICD system can provide at least one of providing a pacing function to the patient's heart or providing a high voltage shock therapy that converts the patient's heart from fibrillation to normal heart function.
As described in further detail below, various embodiments of the present invention relate to new lead designs that are advantageously adapted for operation in a magnetic resonance imaging (MRI) environment. In some embodiments, the lead provides adequate electrical performance for tachycardia therapy and further minimizes the response of the lead to applied electromagnetic energy during the MRI procedure. And a combination of at least one of a unique shock coil and a coil conductor.
In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without some of these specific details.
Further, for convenience, some embodiments are described with respect to an ICD in the presence of an MRI scanner. Embodiments of the present invention apply to a variety of other physiological measurements, procedures, implantable medical devices, and other non-invasive testing techniques in which conductive leads are exposed to time-varying magnetic fields. Could be possible. As such, the applications discussed herein are not intended to be limiting and are exemplary. Other systems, devices and networks to which the embodiments can be applied include, but are not limited to, other types of sensory systems, medical devices, medical procedures, and computer devices and computer systems. In addition, the various embodiments are applicable to any level of sensory device, from a single IMD with sensors to a large network of sensory devices.
FIG. 1 is a schematic of a medical system 100 comprising an MRI scanner 110, an implantable cardiac rhythm management (CRM) system 115 implanted in the torso of a human patient 120, and one or more external devices 130 according to various embodiments. FIG. External device 130 can communicate with CRM system 115 implanted in patient 120. In the embodiment shown in FIG. 1, the CRM system 115 includes a pulse generator (PG) 140 and a lead 150. During normal device operation, the PG 140 is therapeutic to the patient's heart 160 to provide tachycardiac ventricular fibrillation, anti-tachycardia pacing, anti-tachycardia pacing, or at least one other type of therapy. It is configured to deliver electrical stimulation.
Thus, in the illustrated embodiment, PG 140 may be a device such as, for example, an ICD, a cardiac resynchronization therapy device with a defibrillation function (CRT-D device), or an equivalent device. The PG 140 can be implanted into the pectoral muscle within the body, typically at a location such as the patient's chest. In some embodiments, PG 140 may be implanted in or near the abdomen.
The external device 130 may be a local or remote terminal or other device (eg, a computing device or a programming device) operable to communicate with the PG 140 from a location outside the patient's body. According to various embodiments, the external device 130 may be any device external to the patient's body that is remotely measurable and capable of communicating with the PG 140. Examples of external devices include, but are not limited to, a programmer (PRM), a home monitoring device, a personal computer with a telemetry device, an MRI scanner with a telemetry device, a manufacturing inspection facility, or a pen scanner ( wand). In some embodiments, PG 140 communicates with remote terminal 130 via a wireless communication interface. Examples of wireless communication interfaces include, but are not limited to, a radio frequency (RF) interface, an inductive interface, and an acoustic telemetry interface.
FIG. 2A is a more detailed schematic diagram of a CRM system 115 with an exemplary PG 140 equipped with a lead 150 implanted in the patient's body. In the illustrated embodiment, the CRM system 115 includes a PG implanted near the patient's heart 160 and a lead 150 having a distal portion implanted within the patient's heart 160. As seen in FIG. 2A, the heart 160 includes a right atrium 210, a right ventricle 220, a left atrium 230, and a left ventricle 240.
The lead wire 150 has a flexible body 200 with a proximal end region 205 and a distal end region 250. As shown, lead 150 is coupled to PG 140 and tip region 250 of lead body 200 is at least partially implanted at a desired location within right ventricle 220. As further shown, the lead 150 includes at least one electrode 255 along the distal region 250 such that when implanted as shown in FIG. 2A, the electrode is disposed within the right ventricle 220. It has become. As will be described and illustrated in more detail below, the lead 150 is used to transmit an intrinsic heart signal from the heart 160 to the PG 140, and even to the heart 160 via the electrode 255, or an electric shock or low voltage. One or more conductor coils (not visible in FIG. 2A) within the lead body 250 that electrically couple the electrode 255 to the circuitry to transmit the pacing stimulus of the PG 140 and other electrical components within the PG 140 I have.
While the exemplary embodiment shows only a single lead 150 inserted into the patient's heart 160, in other embodiments multiple leads may be used to electrically stimulate other areas of the heart 160. It may be used. In some embodiments, for example, a distal portion of a second lead (not shown) may be implanted in the right atrium 210. In addition or alternatively, another lead may be implanted in the left side of the heart 160 (eg, coronary vein, left ventricle, etc.) to stimulate the left side of the heart 160. Other types of leads, such as epicardial leads, may be utilized in addition to or as an alternative to the lead 150 shown in FIGS.
In operation, lead 150 carries an electrical signal between heart 160 and PG 140. For example, in embodiments where the PG 140 has a pacing function, the lead 150 can be used to deliver electrical therapeutic stimuli for pacing the heart 160. In embodiments where PG 140 is an ICD, lead 150 can be used to deliver a high voltage electric shock to heart 160 via electrode 255 in response to an event such as ventricular fibrillation. In some embodiments, PG 140 includes both pacing and defibrillation functions.
2B is a schematic diagram illustrating a simplified equivalent circuit 260 for the lead 150 of FIG. 2A, representing the RF energy captured on the lead 150 from the RF electromagnetic energy produced by the MRI scanner. As shown in FIG. 2B, voltage (Vi) 265 of circuit 260 represents an equivalent energy source captured by lead 150 from the MRI scanner. During magnetic resonance imaging, the length of the lead 150 functions like an antenna and receives RF energy transmitted from the MRI scanner into the body. The voltage (Vi) 265 in FIG. 2B may represent the resulting voltage received from RF energy by, for example, lead 150. The RF energy captured by the lead 150 can be due to, for example, an RF rotating magnetic field generated by the MRI scanner, which generates an electric field on a plane perpendicular to the rotating magnetic field vector in the conductive tissue. The tangential components of these electric fields along the length of the lead wire 150 are associated with the lead wire 150. Thus, voltage (Vi) 265 is equal to the integral of the tangential electric field along the length of lead 150 (ie, the line integral of the electric field).
The Zl parameter 270 of circuit 260 represents the equivalent impedance indicated by lead 150 at the RF frequency of the MRI scanner. The impedance value Zl 270 may be, for example, the inductance resulting from the parallel inductance shown by the lead 150 and the capacitance per turn of the coil at the 64 MHz RF frequency of the 1.5 Tesla MRI scanner, or the 128 MHz RF frequency of the 3 Tesla MRI scanner. The equivalent impedance can be expressed. The impedance Zl of the lead wire 150 is a complex quantity having a real part (ie, resistance) and an imaginary part (ie, reactance).
Zb 275 of circuit 260 may represent the body tissue impedance at the lead contact point. Zc 280 can then represent capacitive coupling of the lead 150 to the surrounding body tissue along the length of the lead 150, which is the high frequency current (energy) at the RF frequency of the MRI scanner at the surrounding tissue. There is a possibility of providing a route to leak. By minimizing the absorbed energy (represented by energy source Vi265), the energy transferred to the body tissue at the point of contact of the lead with the body tissue is reduced.
As further seen in FIG. 2B, the lead 150 has some amount of leakage to the surrounding tissue at the RF frequency of the MRI scanner. As further indicated by 275, there is also an impedance at the point of contact of the lead electrode 255 to surrounding body tissue within the heart 160. The resulting voltage Vb delivered to the body tissue is:
Vb = Vi Zbe / (Zbe + Zl) (where Zbe = Zb in parallel with Zc)
Typically, the temperature at the tip of the lead 150 that makes contact with the surrounding tissue is related in part to the power dissipated at 275 (ie, “Zb”), which is related to the square of Vb. . In order to minimize the temperature rise due to the power dissipated at 275, therefore, Vi (265) and Zc (280) are minimized while at the same time the impedance Zl (270) of lead 150 is maximized. It is desirable. In some embodiments, impedance Zl (270) of lead 150 may be increased at the RF frequency of the MRI scanner, which helps reduce the energy dissipated into the surrounding body tissue at contact point 275. It becomes.
In various embodiments described in further detail below, the impedance of the lead 150 may be increased by adding inductance to the lead 150 and / or appropriate construction techniques. For example, in various embodiments, the inductance of the lead 150 can increase the average diameter of the conductor coil or reduce the pitch of the conductor coil used to supply electrical energy to the electrode 255. Increased by at least one of them. A decrease in coil pitch can result in an increase in capacitance between successive turns of the coil (ie, capacitance per turn of the coil). The parallel combination of inductance (from the helical shape of the coil) and capacitance per turn constitutes a resonant circuit. For helically wound lead wire construction, the spiral coil acts as an inductor if the resonant frequency of the lead wire exceeds the MRI RF frequency. For the inductor, at least one of an increase in the cross-sectional area of the coil area or a reduction in the coil pitch increases the inductance and, as a result, increases the impedance of the lead wire 150.
FIG. 3 illustrates in greater detail an exemplary lead 150 that may be used in accordance with one or more embodiments of the present invention. In FIG. 3, a portion of the lead body 200 is shown in a partial cutaway view to better illustrate the inner features of the lead 150. As shown in FIG. 3, lead body 200 includes a proximal end 302, and lead 150 further includes a connector assembly 310 coupled to the proximal end 302 of the lead body for high voltage shock. A conductor coil 320, a shock coil 330, an inner conductor coil 340, a coupler 350, and a pace / sense electrode 360 are provided. Depending on the functional requirements of the IMD 140 (see FIG. 1) and the patient's therapeutic needs, the tip region can include additional shock coils (not shown) and / or pace / sense electrodes. . For example, in some embodiments, a pair of coil electrodes can be used to function as a shock electrode to provide a defibrillation shock to the heart 160.
In the illustrated embodiment, the connector assembly 310 includes a connector body 365 and terminal pins 370. Connector assembly 310 may be coupled to the lead body and configured to mechanically and electrically couple the lead to the header of PG 140 (see FIG. 1). In various embodiments, the terminal pins 370 extend proximally from the connector body 365 and in some embodiments, couple to an inner conductor coil 340 that extends longitudinally through the lead body 200 to the pace / sense electrode 360. Is done. In the illustrated embodiment, the pace / sense electrode 360 is the tip electrode at the most distal end of the lead 150 and is fixed with respect to the lead body 200 so that the lead 150 is considered a passive fixed lead. . In other embodiments, the lead 150 may include additional pace / sense electrodes located more proximally along the lead 150. In some embodiments, the terminal pin 370 includes an aperture through the terminal pin that communicates with the lumen defined by the inner conductor coil 340 to accommodate a guidewire or insertion stylet. Can do.
In some embodiments, the pace / sense electrode 360 may be in the form of an electrically active fixed helix at the distal end of the lead 150. In various such embodiments, the pace / sense electrode 360 is an expandable / retractable spiral that is a mechanism that facilitates a longitudinal transition of the spiral relative to the lead body as the spiral rotates. It may be a assisted spiral. In those embodiments, the terminal pin 370 is configured to rotate the terminal pin 370 relative to the lead body 200 with respect to the inner conductor coil 340 and thus the helical pace / sense electrode 360 relative to the lead body 200. It may be rotatable with respect to the connector main body 365 and the lead wire main body 200 so as to move in one longitudinal direction. Various mechanisms and techniques for providing an expandable / retractable stationary helix assembly (electrically active and passive) are known to those skilled in the art and need not be described in further detail herein. .
The pace / sense electrode 360 (whether a solid tip electrode as shown in FIG. 3 or an active fixed helix as described above) can be any suitable conductive material, such as Elgiloy®, MP35N ™. , Tungsten, tantalum, iridium, platinum, titanium, palladium, stainless steel, and alloys of any of these materials.
Inner conductor coil 340 may be a relatively low voltage conductor that carries pacing and sensing signals to and from heart 160. The low voltage inner conductor coil 340 may be formed from one or more substantially cylindrically wound filers according to various embodiments. As described in more detail below, in some embodiments, the low voltage inner conductor coil 340 reduces the RF current induced in the inner conductor coil 340 by an external MRI magnetic field, and even the heart's desires. In order to prevent unexpected high-speed stimulation, it is configured to have an inductance value of 0.0079 μΗ / mm (0.2 μΗ / inch) or more. In some embodiments, the inductance value is approximately 0.020 μΗ / mm (approximately 0.5 μΗ / inch). In addition, the inner conductor coil 340 is configured to have a DC resistance of less than 200 ohms in some embodiments.
In some embodiments, the high voltage conductor coil 320 is a high voltage pathway that can deliver up to 1000 volts and 40 J of energy to the patient's heart 160 as needed to apply an anti-tachycardia electric shock. Can be provided. The high voltage conductor coil 320 is configured in various embodiments to have a high inductance to reduce current induced by RF pulses generated by an MRI device or other system. In some embodiments, the inductance is greater than or equal to 0.0039 μΗ / mm (0.1 μΗ / inch). In some embodiments, the outer diameter may be increased to compensate for the inductance loss. According to one or more embodiments, the high voltage conductor coil 320 may have a multiple filer structure to reduce DC resistance. In some embodiments, the DC resistance is less than approximately 10 ohms (eg, 6 or 7 ohms in some embodiments) so that maximum energy can be delivered to the heart.
In some embodiments, the high voltage coil 320 can be divided into two paths; one path can be connected to a shock coil proximal to the ICD. Another path can be connected to a shock coil located distal to the ICD. The distal shock coil, together with the high voltage coil 320, can serve as a feedback path for pacing pulses in bipolar pacing. As another example, the second high voltage path may be provided via a high voltage coil (not shown) that is separate from the high voltage coil 320.
In some embodiments, the high voltage conductor coil 320 is mechanically and electrically coupled to the shock coil 330 via a coupler 350. This path can also serve as a feedback path for pacing pulses in bipolar pacing. The shock coil 330 can also deliver an appropriate therapy to the patient's heart. Examples of treatments include, but are not limited to, tachycardia ventricular fibrillation, anti-tachycardia pacing, anti-tachycardia pacing, or at least one of other types of treatment.
In some embodiments, the shock coil 330 can have a coating configured to control (ie, promote or prevent) tissue ingrowth. In various embodiments, the lead may comprise only a single coil electrode, such as shock coil 330. In other embodiments, the lead 150 may include one or more ring electrodes (not shown) along the lead body instead of or in addition to the shock coil electrode 330. . When present, the ring electrode can operate as a relatively low voltage pace / sense electrode. It will be appreciated by those skilled in the art that a wide variety of electrode combinations can be incorporated into the lead 150 within the scope of various embodiments of the present invention.
FIG. 4 shows a cross-sectional view 400 of the lead wire 150 taken along line 4A of FIG. As shown in FIG. 4, in the embodiment in the figure, the high voltage conductor coil 320 and the low voltage inner conductor coil 340 are coaxially arranged inside the lead wire body 200. As further shown, in the illustrated embodiment, the lead 150 has an insulator layer between the high voltage conductor coil 320 and the low voltage inner conductor coil 340 to electrically isolate the coils from each other. 410. In various embodiments, the individual filer of at least one of the high voltage conductor coil 320 or the low voltage inner conductor coil 340 may be in addition to or in place of using the insulator layer 410. It may be individually insulated. Thus, in the embodiment shown in FIG. 4, the high voltage conductor coil 320 and low voltage inner conductor coil 340 filers each have a thin layer of insulator. In other embodiments, the filer of at least one of the high voltage conductor coil 320 or the low voltage inner conductor coil 340 is not individually isolated and spaced to avoid contact with adjacent filers. Is done.
Examples of types of insulation that can be used in various embodiments of the present invention include, but are not limited to, silicone, polytetrafluoroethylene, expanded polytetrafluoroethylene, ethylene-tetrafluoroethylene, and And copolymers of these. In some embodiments, individual filer insulation layers prevent coil turns from coming into contact with each other when unwound leads are placed in a spiral configuration as shown in FIGS. can do. In addition, some embodiments include a sufficient insulator layer between the low voltage coil and the high voltage coil to prevent electrical coupling.
As described above, according to various embodiments of the present invention, at least one of the high voltage conductor coil 320 or the low voltage inner conductor coil 340 is normal (eg, for providing anti-tachycardia therapy). It is selectively configured to have a high impedance to minimize the effects of applied MRI irradiation without unduly affecting electrical performance under operating conditions. As will be described in more detail below, in various embodiments, at least one of the filer thickness, pitch, or average coil diameter for at least one of the high voltage conductor coil 320 or the low voltage inner conductor coil 340. Either is selectively chosen to provide the desired balance of electrical performance and MRI compatibility.
5A-5C illustrate various configurations of inner conductor coil 340, high voltage conductor coil 320, and shock coil 330, respectively, according to some embodiments of the present invention. According to various embodiments, the pitch of the helix is the width of one complete helix rotation measured along the helix axis. The distances 510a-510c in FIGS. 5A-5C indicate the pitch of the coils in the figure, reference numerals 520a-520c represent the filer thickness of each coil, and reference numerals 530a-530c represent the average coil diameter. According to one or more embodiments, the pitch may be a constant pitch along the length of the lead (see, eg, FIG. 5C), or may follow a pattern that repeats along the length of the lead ( For example, see FIGS. 5A and 5B). In some embodiments, ribbon-type conductors may be used for the high voltage conductor coil 320 and the shock coil 330. In some embodiments, the pitch directions of the coils 320, 330, 340 are the same.
FIG. 5A illustrates a portion of a high voltage conductor coil 320 according to some embodiments of the present invention. In the illustrated embodiment, the high voltage conductor coil 320 is a quad filer coil. However, in one or more embodiments, the high voltage multi-filer outer coil 320 can have other types of multi-filer structures. The multi-filer structure of the high voltage conductor coil 320 can be formed from two or more substantially cylindrically wound filers that produce a relatively low DC resistance, for example, less than approximately 10 ohms. With such a structure, the high voltage conductor coil 320 may be suitable for use in high voltage defibrillation lead applications.
In various embodiments, the high voltage multifilar outer coil has a desired coil inductance when the high voltage multifilar outer coil 320 is subjected to a high frequency (eg, 40 MHz to 300 MHz) electromagnetic field in a range typical for MRI scans. The pitch 510a and filer thickness 520a can be of various dimensions to produce a value (eg, 0.0079 μΗ / mm (0.2 μΗ / inch) or greater). In some embodiments, the desired coil inductance value is approximately 0.020 μΗ / mm (approximately 0.5 μΗ / inch). As discussed above (see, eg, the discussion of FIG. 2B), the impedance and inductance of lead 150 can be advantageously adjusted by selecting various structural features of the lead. Examples of structural features include, but are not limited to, pitch 510a, filer thickness 520a, coil diameter 530a, and others.
For a typical cylindrically wound coil, the inductance of the coil per unit length is:
L≈μ 0 πa 2 / 4b 2 N 2
Where μ 0 is the permeability of free space, a is the average coil diameter 530a, and b is the coil pitch 510a (ie, between adjacent filers). Distance) and N is the total number of filers. Based on the above equation, the coil inductance per unit length is proportional to the square of the radius and inversely proportional to the square of the pitch and the total number of filers.
FIG. 5B illustrates a portion of a high voltage shock coil 330 according to some embodiments of the present invention. In the illustrated embodiment, the high voltage shock coil 330 is a trifilar coil. However, in one or more embodiments, the high voltage shock coil 330 may have other types of multiple filer structures. The multiple filer structure of the high voltage shock coil 330 provides a relatively low DC resistance and can be formed from two or more substantially cylindrically wound filers. With such a structure, the high voltage shock coil 330 may be suitable for use in high voltage defibrillation lead applications.
In some embodiments, the third or shock coil 330 can have a first end connected to the distal section of the high voltage multifilar outer coil 320 via a coupler 350. The third coil 330 may be formed from two or more generally cylindrically wound filers in some embodiments. According to various embodiments, the filer thickness, pitch 510b, and average coil diameter 520b are determined when the shock coil 350 is subjected to a high frequency (eg, 40 MHz to 300 MHz) electromagnetic field characteristic of an MRI scan. The shock coil 330 can be configured to have a high impedance value. As discussed above (see, eg, the discussion of FIG. 2B), the impedance and inductance of lead 150 can be advantageously adjusted by selecting various structural features of the lead. Examples of structural features include, but are not limited to, pitch, filer thickness, coil diameter, and the like.
FIG. 5C illustrates a portion of a low voltage inner coil 340 according to some embodiments of the present invention. In the illustrated embodiment, the low voltage inner coil 340 is a single filer coil. However, in one or more embodiments, the low voltage inner coil 340 can have other types of multiple filer structures (eg, 2 filers, 3 filers, etc.). The single filer structure of the low voltage inner coil 340 has a higher DC resistance, for example, a DC resistance of approximately 200 ohms. With such a structure, the low voltage inner coil 340 may be suitable for use in pacing applications.
In some embodiments, the inner conductor coil 340 can be split into two paths; one for the pacing pulse, one for the cathode and one for the anode. In one embodiment, the inner conductor coil 340 has a pitch 510c, a filer thickness 520c and an average having a desired impedance value for the coil when the inner conductor coil 340 is subjected to a range of high frequencies (eg, 40 MHz to 300 MHz). The coil diameter is 530c. As discussed above (see, eg, the discussion of FIG. 2B), the impedance and inductance of at least one of lead 150 or lead coil can be determined by selecting various structural features of the lead. It is advantageously adjustable. Examples of structural features include, but are not limited to, pitch, filer thickness, coil diameter, and the like.
In one embodiment, the high voltage conductor coil 320 has a pitch 510a of about 0.25 mm (about 0.010 inch), a total number of four filers, and an average coil diameter 530a of about 1.3 mm (about 0.050 inch). A coil inductance value of about 0.0051 μΗ / mm (about 0.13 μΗ / inch). Thus, the lower limit for the high voltage coil is set to be 0.1 μΗ in one embodiment. Inner conductor coil 340, in one embodiment, has a pitch 510c of about 0.005 inches, a total number of filers of 1, and an average coil diameter of about 0.023 inches. This produces a coil inductance per unit length of about 0.020 μｍｍ / mm (about 0.5 μΗ / inch). The lower limit for the low voltage coil may be set to approximately 0.2 μΗ in some embodiments. In some embodiments, the inductance limit of the low voltage coil and the high voltage coil may be different, and in other embodiments, the inductance limit may be the same.
As discussed above, the design of various embodiments of the present invention can result in significant thermal reduction over conventional lead designs when exposed to frequencies associated with MRI. In one exemplary embodiment, the test sample may have a single filer low voltage coil made from an outer diameter wire of approximately 0.10 mm (approximately 0.004 inches). The outer diameter of the coil is approximately 0.69 mm (approximately 0.027 inch) and the coil pitch is approximately 0.10 mm (0.004 inch). The test sample further has a 4-filer high voltage coil made from approximately 0.25 mm (approximately 0.010 inch) of wire. The high voltage coil has an outer diameter of approximately 2.3 mm (approximately 0.090 inch) and the coil pitch is approximately 0.30 mm (approximately 0.012 inch).
FIG. 6 shows the temperature rise that occurs when a standard lead design and an example lead design are subjected to frequencies associated with MRI. The total length of the prototype (test mule) is 60 cm. The heating test for the standard lead design and the example lead design was performed under the same 64 MHz test conditions. As seen in FIG. 6, the example lead design results in a temperature increase at the tip that is approximately 10 degrees less than the standard lead temperature increase. In addition, the example lead design provides a temperature increase of approximately 4 degrees less than the standard lead temperature increase at the ring electrode.
While the above embodiments describe and exemplify a multi-conductor lead with coil conductors configured as coaxial, the high-inductance conductor coils 320, 340 are advantageously used for other lead configurations within the scope of the present invention. It is also possible to do. For example, FIG. 7 shows a cross-section of another embodiment of a lead 150 that utilizes a multi-lumen lead body as commonly used in conventional defibrillation leads. As shown in FIG. 7, the lead body includes an inner tubular member 710 and an outer tubular member 720 disposed on the surface of the inner tubular member 710 and joined to the tubular member. Tubular members 710, 720 can be made from any number of flexible, biocompatible insulating materials, such as, but not limited to, polymers such as silicone and polyurethane, and copolymers thereof. As further shown, the inner tubular member 710 includes a plurality of lumens 730, 740, 750, with conductors 760, 770, and 780 disposed within the lumens 730, 740, and 750, respectively. Each conductor 760, 770 and 780 extends longitudinally within the respective lumen 730, 740 and 750 and is electrically coupled to an electrode (eg, electrode 360 of FIG. 3) and further to an electrical contact of connector assembly 310. Is done.
Further, the inner tubular member 710 may include more or fewer lumens depending on the particular configuration of the lead 150. For example, the inner tubular member 710 houses at least one of an additional conductor wire or electrode coil within the lead 150 to supply current to at least one of the other shock coils or pace / sense electrodes. In order to do so, a larger number of lumens may be provided.
In the embodiment of FIG. 7, conductor 760 is configured in much the same manner as coil conductor 320 described above and can operate as a low voltage pace / sense circuit as described above. Accordingly, conductor 760 advantageously has the same high inductance characteristics as described above for conductor 320. In the illustrated embodiment, the conductors 770, 780 are used in high voltage applications to provide defibrillation stimulation to a high voltage shock coil, such as the shock coil 330 of FIG. Is a well-known stranded cable conductor.
The various embodiments of lead 150 described above advantageously minimize the induced current in the lead conductor due to exposure to an external MRI electromagnetic field. This is in contrast to conventional ICD lead systems that utilize stranded cable conductors to transmit shock current from the PG to the shock electrode. While such cable conductors provide superior electrical performance for delivering anti-tachycardia therapy, stranded cable conductors also have low impedance and are therefore exposed to alternating electromagnetic fields such as those present during MRI scans. It is easy to generate an induced current when The high impedance conductor configuration of the lead 150 described above provides adequate electrical performance for use in anti-tachycardia therapy applications while minimizing the effects of MRI irradiation.
Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, although the embodiments described above represent particular features, the scope of the invention includes embodiments having various combinations of features and embodiments that do not necessarily include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications and variations that fall within the scope of the claims, along with all their equivalents.
An electrical lead,
A flexible body having a proximal region with a proximal end and a distal region; and
A connector coupled to the proximal end of the flexible body of the lead to electrically and mechanically connect the lead to the implantable pulse generator;
One or more generally cylindrical shapes having a filer thickness, pitch, and average coil diameter configured to have a first inductance value greater than or equal to 0.0079 μ で あ / mm, the low voltage inner conductor coil A low voltage inner conductor coil formed from a filer wound on
A high voltage multiple filer outer coil having a proximal section, a distal section, and a length, the high voltage multiple filer outer coil having a DC resistance of less than about 10 ohms and each having a filer thickness The high-voltage multi-filer outer coil is formed of two or more substantially cylindrically wound filers, and the high-voltage multi-filer outer coil is configured to have a second inductance value of 0.0039 μΗ / mm or more. A high voltage multifilar outer coil having a defined pitch and average coil diameter , wherein the low voltage inner conductor coil and the high voltage multifilar outer coil are coaxially arranged to be spaced apart from each other .
The electrical lead of claim 1, wherein a layer of insulator is disposed around at least a portion of the inner conductor coil.
The electrical lead of claim 1, wherein the inner conductor coil has a single filer structure.
The electrical lead of claim 1, wherein the inner conductor coil has an average pitch of 0.13 mm.
The electrical lead of claim 4, wherein the inner conductor coil has a single filer structure and an average coil diameter of 0.58 mm.
The electrical lead according to claim 1, wherein the inner conductor coil has an inductance greater than 0.020 μΗ / mm.
The first inductance value (L) depends on the number of filers wound in a cylindrical shape (N), the pitch (b) of the inner conductor coil, and the average coil diameter (a), and the expression L≈μ0πa2 / 4b2N2 (expression The electrical lead according to claim 1, wherein μ 0 is a permeability of free space.
The electrical lead of claim 1, wherein the inner conductor coil has a direct current resistance of less than 200 ohms.
The electrical lead of claim 1, wherein the inner conductor coil is bipolar or unipolar.
The electrical lead of claim 1, wherein the high voltage multifilar outer coil is a ribbon-type conductor coil.
A medical lead,
A connector coupled to the proximal end of the body configured to electrically and mechanically connect the lead to the implantable pulse generator;
A low-voltage inner conductor coil configured to transmit an electrical signal between a distal end region and a proximal end region of the lead wire, wherein the first inner electrode coil has a low voltage inner conductor coil of 0.0079 μΗ / mm or more. A low voltage inner conductor coil formed from one or more generally cylindrically wound filers having a pitch and an average coil diameter configured to have inductance;
A multifilar high voltage outer conductor coil, a quad filer spiral-like shape that radially surrounds at least a portion of the low voltage inner conductor coil, a DC resistance of less than 10 ohms, and a first resistance of 0.0039 μΗ / mm or more. A multi-filer high voltage outer conductor coil with an outer diameter and an average pitch configured to provide a multi-filer high voltage outer conductor coil having an inductance of two;
A trifilar shock coil having a proximal end, the proximal end of the trifilar shock coil being connected to the distal end of the multiple filer high voltage outer coil via a coupler , and a shock coil bird filer, low voltage inner conductor coil and said multiplexing filers high voltage outer conductors coils, medical lead that will be coaxially disposed so as to be separated from each other.
12. The medical lead of claim 11, further comprising one or more insulating layers surrounding one or more of the low voltage inner conductor coil, the multi-filer high voltage outer conductor coil, and the trifilar shock coil.
The medical lead according to claim 11, wherein the multiple filer high voltage outer coil has an outer diameter greater than the outer diameter of the trifilar shock coil.
12. The medical lead of claim 11, wherein the low voltage inner conductor coil, the multi-filer high voltage outer conductor coil, and the trifilar shock coil have different pitches.
The medical lead according to claim 11, wherein the low voltage inner conductor coil, the multi-filer high voltage outer conductor coil, and the trifilar shock coil each have a pitch of 0.127 mm or less.
A lead having a flexible body with a proximal region having a proximal end mechanically and electrically coupled to a pulse generator and a distal region implanted within a patient's heart, Including a lead configured to carry electrical signals between the heart and a pulse generator;
The lead wire is
A low voltage inner conductor coil configured to conduct electrical signals between a distal end region and a proximal end region of a lead wire, wherein the lower voltage inner conductor coil is formed from one or more wound filers. The low voltage inner conductor coil has separate turns with a pitch, average coil diameter, and the number of one or more wound filers is 0.0079 μΗ / mm for the low voltage inner conductor coil. A low voltage inner conductor coil configured to have the above first inductance value;
A high voltage outer coil with a quad filer spiral-like shape having a DC resistance of less than 10 ohms, the high voltage outer coil radially surrounding at least a portion of the low voltage inner conductor coil, and 0 A high voltage outer coil having an outer diameter, a filer diameter, and an average pitch configured to obtain a high voltage outer coil having a second inductance value greater than or equal to .0039 μΗ / mm;
A trifilar shock coil having a proximal end, the proximal end connected to the distal end of the high voltage outer coil via a coupler; the equipped, low voltage inner conductor coil and the high voltage outer coil is implantable medical devices that will be coaxially disposed so as to be separated from each other.
The implantable medical device of claim 16, wherein the lead has a direct current resistance of less than 200 ohms.
17. The implantable medical device according to claim 16, wherein the low voltage inner conductor coil comprises a filer made from dft (R) MP35N (TM).
The implantable medical device of claim 16, wherein the low voltage inner conductor coil is bipolar or unipolar.
The pitch of the high voltage conductor coil is 0.25 mm, the average coil diameter of the high voltage conductor coil is 2.3 mm, resulting in a coil inductance value of 0.0051 μΗ / mm, and the pitch of the inner conductor coil is 0. The inner conductor coil is formed of one cylindrically wound filer, and the inner coil has an average coil diameter of 0.58 mm and a coil inductance per unit length of 0.020 μΗ / mm. The implantable medical device according to claim 16, comprising:
The implantable medical device according to claim 16, wherein the pulse generator is a pacemaker or a defibrillator.
JP2012554059A 2010-02-19 2011-02-18 Lead and implantable medical device comprising a conductor configured for reduction of MRI induced current Active JP5671069B2 (en)
US30637710P true 2010-02-19 2010-02-19
US61/306,377 2010-02-19
PCT/US2011/025457 WO2011103444A1 (en) 2010-02-19 2011-02-18 Lead including conductors configured for reduced mri-induced currents
JP2013520238A JP2013520238A (en) 2013-06-06
JP5671069B2 true JP5671069B2 (en) 2015-02-18
ID=43837942
JP2012554059A Active JP5671069B2 (en) 2010-02-19 2011-02-18 Lead and implantable medical device comprising a conductor configured for reduction of MRI induced current
US (3) US8326436B2 (en)
EP (1) EP2536464A1 (en)
JP (1) JP5671069B2 (en)
WO (1) WO2011103444A1 (en)
WO2015164340A1 (en) 2014-04-21 2015-10-29 University Of South Florida Magnetic resonant imaging safe stylus
2011-02-18 JP JP2012554059A patent/JP5671069B2/en active Active
2011-02-18 EP EP11706425A patent/EP2536464A1/en not_active Withdrawn
2011-02-18 US US13/030,467 patent/US8326436B2/en active Active
2011-02-18 WO PCT/US2011/025457 patent/WO2011103444A1/en active Application Filing
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US8738150B2 (en) 2014-05-27
US20130310910A1 (en) 2013-11-21
US20130060314A1 (en) 2013-03-07
EP2536464A1 (en) 2012-12-26
US8498719B2 (en) 2013-07-30
US8326436B2 (en) 2012-12-04
WO2011103444A1 (en) 2011-08-25
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US20110208280A1 (en) 2011-08-25
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