Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/02—Details
  • A61N1/04—Electrodes
  • A61N1/05—Electrodes for implantation or insertion into the body, e.g. heart electrode
  • A61N1/056—Transvascular endocardial electrode systems
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/02—Details
  • A61N1/04—Electrodes
  • A61N1/05—Electrodes for implantation or insertion into the body, e.g. heart electrode
  • A61N1/056—Transvascular endocardial electrode systems
  • A61N1/0565—Electrode heads
  • A61N1/0568—Electrode heads with drug delivery
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/02—Details
  • A61N1/04—Electrodes
  • A61N1/05—Electrodes for implantation or insertion into the body, e.g. heart electrode
  • A61N1/056—Transvascular endocardial electrode systems
  • A61N2001/0585—Coronary sinus electrodes

Definitions

• the present invention pertains to medical electrical leads and more particularly to pre-shaped distal lead portions.
• Cardiac stimulation systems commonly include a pulse-generating device, such as a pacemaker or implantable cardioverter/defibrillator that is electrically connected to the heart by at least one medical electrical lead.
• a medical electrical lead delivers electrical pulses emitted by the pulse generator to the heart, stimulating the myocardial tissue via electrodes included on the lead.
• Cardiac signals may also be sensed by lead electrodes and conducted, via the lead, back to the device to monitor the electrical activity of the heart.
• These leads are coupled to the devices via connector terminals carrying one or more contact surfaces, which are in turn coupled to corresponding lead electrodes by elongate conductors extending within the lead.
• transvenous lead electrodes in the coronary venous system of the heart to stimulate an epicardial surface of the left ventricle.
• Precise placement of lead electrodes through the coronary veins is often difficult, forcing clinicians to work around sub-optimal pacing thresholds and/or unwanted extra-cardiac stimulation, for example phrenic nerve stimulation.
• Transvenous leads including a plurality of electrodes can provide an increased opportunity to provide more optimal pacing in that, once the lead is best positioned within a coronary vein, a choice of pacing sites is provided by the plurality of electrodes.
• pre-shaped distal portions of leads can enable stable placement of electrodes and enhance contact between the electrodes and electrically active cardiac muscle.
• Figure IA is a plan view of a medical electrical lead according to one embodiment of the present invention.
• Figure IB is a schematic of the lead of Figure IA implanted in a coronary venous system from an anterior perspective;
• Figure 1C is an enlarged view of a distal portion of the lead shown in Figure IA implanted within a coronary vein;
• Figure 2 is an enlarged detailed plan view of a lead electrode assembly according to one embodiment of the present invention.
• Figure 3 is an enlarged detailed section view of another lead electrode assembly according to another embodiment of the present invention.
• Figure IA is a plan view of a medical electrical lead 100 according to one embodiment of the present invention.
• Figure IA illustrates lead 100 including an approximately straight proximal lead body portion 15, which is terminated at a proximal end by a lead connector 13, and a pre-formed distal lead body portion 17 extending distally from proximal portion 15.
• Figure IA further illustrates distal lead body portion 17 including a first arcuate segment 12 bending in a first direction, an approximately straight segment 14 extending from first arcuate segment 12, a second arcuate segment 16 extending from straight segment 14 and bending in a second, generally distal, direction, a third arcuate segment 18 bending in a third, generally proximal, direction, and a distal tip segment 19 extending from the third arcuate segment 18.
• lead 100 further includes a first electrode El coupled to approximately straight segment 14 and second electrode coupled to distal tip segment 19; the position of pre-formed curves of arcuate segments of distal portion 17 with respect to electrodes El and E2 provide for epicardial contact of electrodes El and E2 when implanted in a coronary vessel, as will be further described below.
• Figure IA further illustrates angles 125, 165 and 185 of arcs included in arcuate segments 12, 16 and 18, respectively; according to some embodiments of the present invention, dimensions of the arcs are as indicated in Table 1.
• Table 1 Arc Dimensions
• a length of straight segment 14, is from approximately 0.2 to approximately 0.7 inch and a length of distal tip segment 19 is from approximately 0.05 inch to approximately 0.2 inch.
• electrode E2 terminates distal tip segment 19, which may or may not extend proximally from electrode; according to another embodiment a portion of distal tip segment 19 extends distally from electrode E2 as illustrated by dashed lines in Figure 1 and this extension may or may not be curved.
• Distal lead body portion 17 is alternately described as being canted, bending at angle 125 with respect to a longitudinal axis Al 5 of proximal portion 15 and including a hump-like segment, corresponding to segment 18, extending from approximately straight segment 14 and having a distal apex 180.
• the arc of segment 18 has a chord length of approximately 0.4 inch to approximately 0.7 inch and distal apex 180 of segment 18 has a height H of approximately 0.1 inch to approximately 0.3 inch.
• Conductors coupling electrodes El and E2 to connector contacts of connector 13 may be side-by-side cables or coaxial coils, either of which may be formed of wires made from MP35N alloy; and insulation formed about conductors for electrical isolation may formed of polyurethane, fluoropolymers, silicone, polyimide or any combination thereof.
• Methods for pre-forming distal portion 17 include pre-forming of conductors extending therein and/or sheaths extending about the conductors; according to one method one or more sheaths extending between proximal lead body portion 15 and distal tip segment 17 are formed of polyurethane, which is heat set into the preformed curve; such a method is further described in U.S. 5,999,858, which is incorporated herein by reference. -A-
• Figure IB is a schematic of lead 100 implanted in a coronary venous system 193, and Figure 1C is an enlarged view of distal lead body portion 17 therein.
• Figure IB illustrates lead 100 having been passed through a coronary sinus 191 into coronary vasculature 193 such that electrodes El and E2 are positioned for left ventricular pacing.
• both electrodes El and E2 are designed for pacing stimulation so that one of the two electrodes may be selected for ventricular pacing based on a preferred implant position; as illustrated in Figure 1C, the pre-formed curvature of distal lead body portion 17 assures that both electrodes El and E2 contact a left ventricular epicardial surface 175.
• Electrodes El and E2 may each have a surface area ranging between approximately 2 square millimeters and approximately 10 square millimeters and may be formed from any suitable material known to those skilled in the art, for example platinum-iridium and titanium.
• Dashed lines in Figure 1C show an alternate distal lead body portion wherein a pre-formed hump (i.e. segment 18, Figure IA) is not included in order to illustrate a need for the hump when two electrodes are included in the distal lead body portion.
• Figure 1C also shows how canted distal portion 17 serves to force electrode E2 into contact with epicardial surface 175.
• Figure 1C further illustrates that pre-formed segments 12, 16 and 18 (Figure IA) of distal portion 17 are flexible to bend in compliance with external forces such as that applied by the vessel walls of coronary vasculature 193. These segments may also be bent in compliance with an internal force applied by a stylet inserted within a lumen of lead 100.
• Figure 2 is an enlarged detailed plan view of a lead electrode assembly, corresponding to first electrode El illustrated in Figures IA-C, according to one embodiment of the present invention.
• Figure 2 illustrates approximately straight segment 14 of distal lead body portion 17 extending away from electrode El toward segment 12( Figure IA); El may be positioned along segment 14 such that segment 14 further extends in an opposite direction from electrode El, or such that electrode El is in close proximity or adjacent to second arcuate segment 16 (thus segment 14/16 indicated in Figure 2).
• Figure 2 further illustrates electrode El including a central portion having a maximum diameter D2 that is greater than diameters Dl and Dl ' of segments 14 and 14/16, respectively, while either end of electrode El is approximately flush with diameters Dl and Dl '.
• a ratio of diameter D2 to diameters Dl and Dl ' is from approximately 1.1 to approximately 1.6. It is likely that an active outer surface of electrode El in proximity to D2 will make best contact with epicardial tissue, for example epicardial surface 175 illustrated in Figure 1C.
• the active outer surface of electrode El has a generally arcuate profile and includes a recess 21, approximately aligned with a longitudinal center of electrode El and in which a therapeutic or bioactive agent 22 is held, agent 22 being adapted to disperse out from recess 21 upon implantation of electrode El.
• a recess holding an agent is offset from the longitudinal center of El, as illustrated in Figure 2 with dashed lines in proximity to segment 14.
• Figure 1 illustrates recess extending about a circumference of electrode El
• alternate embodiments of the present invention include recesses, of a generally macroscopic scale, which are discrete in nature and of various orientations.
• agent 22 is embedded in a polymer matrix, and, according to a particular embodiment, agent 22 is an anti-inflammatory agent such as a steroid, for example dexamethasone sodium phosphate, dexamethasone acetate, or beclomethasone diproprionate, embedded in a polyurethane or silicone matrix such that the steroid may elute from the matrix to prevent inflammation at the electrode contact site.
• a surface of recess 21 includes a microstructure in which agent 22 is embedded, for example a platinized surface in which beclomethasone is embedded.
• Figure 3 is an enlarged detailed section view of another lead electrode assembly, corresponding to second electrode E2 illustrated in Figures IA-C, according to another embodiment of the present invention.
• Figure 3 illustrates lead 100 including a lumen 30 formed by a conductor coil 31 and a core 33 to which conductor coil 31 and electrode E2 are coupled; lumen 30 is terminated at a distal end of distal tip segment 19 with a resilient element 34 mounted upon core 33 and adjacent to electrode E2.
• element 34 is generally cup shaped and includes an outer surface 302, which forms a portion of an external surface 32 of distal tip segment 19 of distal lead body portion 17 (Figure IA), and an inner surface 300 adapted both to seal off lumen 30 and to spread apart to allow passage of an elongate member, for example a guide wire, by nature of the resiliency of element 34.
• an elongate member for example a guide wire
• element 34 further includes a therapeutic or bioactive agent embedded therein which is adapted to disperse out from outer surface 302 upon implantation of lead 100.
• the agent is an anti- inflammatory agent such as a steroid, for example dexamethasone sodium phosphate, dexamethasone acetate, or beclomethasone diproprionate, and element 34 is formed by transfer molding a blend of the steroid (10%-50% by weight) and a silicone rubber, according to methods known to those skilled in the art of silicone molding.
• a steroid for example dexamethasone sodium phosphate, dexamethasone acetate, or beclomethasone diproprionate
• element 34 is formed by transfer molding a blend of the steroid (10%-50% by weight) and a silicone rubber, according to methods known to those skilled in the art of silicone molding.
• inventive electrode assemblies described herein are not limited to the lead body embodiments described herein and may be incorporated in many types of medical electrical systems.
• embodiments of the present invention have been described herein in the context of cardiac pacing from the coronary venous vasculature, the scope of the present invention is not limited to this particular application and embodiments of the present invention may be applied to other vessel-like environments.

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• Health & Medical Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Cardiology (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Radiology & Medical Imaging (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Electrotherapy Devices (AREA)

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• 2005
  • 2005-08-22 WO PCT/US2005/029989 patent/WO2006023930A2/en active Application Filing
  • 2005-08-22 CA CA002578169A patent/CA2578169A1/en not_active Abandoned
  • 2005-08-22 JP JP2007530056A patent/JP2008510576A/ja active Pending
  • 2005-08-22 EP EP05793869A patent/EP1799298A2/en not_active Withdrawn

Non-Patent Citations (1)

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