USRE35779E - Post-heart surgery cardioverting system and method - Google Patents

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Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
  • A61N1/39—Heart defibrillators
  • A61N1/3918—Heart defibrillators characterised by shock pathway, e.g. by electrode configuration
• • 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
• • 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
  • A61N1/0587—Epicardial electrode systems; Endocardial electrodes piercing the pericardium
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
  • A61N1/39—Heart defibrillators
  • A61N1/395—Heart defibrillators for treating atrial fibrillation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
  • A61N1/39—Heart defibrillators
  • A61N1/3904—External heart defibrillators [EHD]

Definitions

• the present invention is generally directed to a cardioverting system and method for providing temporary cardioversion of the heart of a heart surgery patient following a heart surgery procedure.
• the present invention is more particularly directed to such a system and method for providing post-surgery cardioversion of the atria of the heart.
• the hearts of post-surgical heart patients are temporarily paced for a few days following surgery, when required, to maintain the heart rates at a normal rate. This is accomplished by releasably attaching heart wires to the heart before the pericardium is sutured and the chest cavity is closed. First and second heart wires are attached to the myocardium of one of the ventricles such as the left ventricle. The heart wires are then brought outside of the chest. Thereafter, the pericardium is sutured and the chest cavity is closed. The proximal ends of the heart wires are then coupled to a temporary pacemaker to permit the heart to be paced. After the patient has recovered sufficiently wherein pacing is no longer required, the heart wires are pulled out of the patient.
• the physician terminates the fibrillation by cardioverting the heart.
• the physician contacts each atria with a spoon-sized conductive paddle which is coupled to an external defibrillator.
• the external defibrillator includes a storage capacitor which is charged to a selected voltage. When the storage capacitor is fully charged, the stored energy is discharged into the atria of the heart through the paddles.
• Drug therapy is also an available option. Its use however is often attended with significant side effects. In addition, there is a substantial potential interaction of such drugs with the many different types and amounts of other drugs the patient is already being given during this initial recovery period.
• the present invention therefore provides a post-surgical cardioverting system for applying cardioverting electrical energy to the heart of a post-surgical heart patient.
• the system includes a first lead including a first elongated electrode having a proximal end and a distal end, a second lead including a second elongated electrode having a proximal end and a distal end, and first anchor means for releasably anchoring the distal ends of the first and second electrodes to body tissue external to but in close proximity to the heart beneath the skin of the patient to dispose the first and second electrodes in electrical contact with the heart.
• the system further includes a non-implantable cardiovertor coupled to the first and second leads for applying the cardioverting electrical energy to the first and second electrodes.
• the present invention further provides a method of cardioverting the heart of a heart surgery patient subsequent to a heart surgery procedure.
• the method includes the steps of providing a first lead having a first elongated electrode and a second lead having a second elongated electrode, the first and second electrodes each having a distal end and a proximal end.
• the method further includes the steps of, following the heart surgery procedure and before closing the chest of the patient, releasably anchoring the distal ends of the first and second electrodes to body tissue external to but in close proximity to the heart beneath the skin of the patient to dispose the first and second electrodes in electrical contact with the heart.
• the method further includes the steps of providing a non-implanted cardiovertor for providing cardioverting electrical energy, coupling the non-implanted cardiovertor to the first and second electrodes, and causing the cardiovertor to apply the cardioverting electrical energy to the first and second electrodes when the heart of the patient is in need of cardioversion.
• the present invention still further provides a method of cardioverting the atria of the heart of a heart surgery patient subsequent to an opened chest heart surgery procedure.
• the method includes the steps of providing a first lead having a first elongated electrode, the first electrode having a distal end and a proximal end, providing a second lead having a second elongated electrode, the second electrode having a distal end and a proximal end, and following the heart surgery procedure and prior to closing the chest of the patient, releasably anchoring the distal ends of the first and second electrodes to the pericardium.
• the method further includes the steps of disposing the first electrode along the pericardium adjacent to the right atrium of the heart, disposing the second electrode along the pericardium adjacent to the left atrium of the heart, providing a non-implanted cardioverting means for providing cardioverting electrical energy, coupling the cardioverting means to the first and second electrodes through the first and second leads, and applying the cardioverting electrical energy with the cardioverting means to the first and second electrodes when the atria are in need of cardioversion.
• FIG. 1 is a schematic block diagram of a cardioverting system embodying the present invention including an atrial cardiovertor for applying post-surgery cardioverting electrical energy to the atria of a human heart;
• FIG. 2 is a partial plan view illustrating one manner in which the temporary cardioverting electrodes may be releasably anchored to the pericardium of the heart in practicing the present invention.
• FIG. 3 is another partial plan view illustrating another manner in which the temporary cardioverting electrodes may be releasably anchored to the pericardium in practicing the present invention.
• FIG. 1 it illustrates a cardioverting system 30 embodying the present invention shown in association with a human heart 10 which has undergone surgery and which may require cardioversion of, for example, the atria, during the post-surgery period.
• the portions of the heart 10 illustrated in FIG. 1 and which will be referred to hereinafter are the right ventricle 12, the left ventricle 14, the right atrium 16, the left atrium 18, and the ventricular myocardium 20.
• the heart 10, as illustrated, is within the pericardial sac 24 which separates the heart from the lungs (not shown).
• the cardioverting system 30 generally includes an external cardiovertor or defibrillator 32 for providing cardioverting electrical energy.
• This system 30 further includes a first lead 34, a second lead 36, a third lead 38, and a fourth lead 40.
• the third and fourth leads 38 and 40 preferably comprise heart wires of the type well known in the art which are releasably attached to the myocardium 20 of the left ventricle 14.
• the heart wires 38 and 40 have electrodes 38a and 40a in contact with the myocardium to permit bi-polar sensing of ventricular activations or R waves of the heart 10.
• the heart wires 38 and 40 and their respective electrodes 38a and 40a may also be used for temporarily pacing the heart 10.
• the first lead 34 includes a first elongated electrode 42 having a distal end 44 and a proximal end 46.
• the distal end 44 of electrode 42 is releasably anchored to the pericardium 24 by suture 53 which has been given a loose suture knot to permit the electrode 42 to extend along the pericardium 24 and disposed overlying the right atrium 16 while permitting the lead 34 and electrode 42 to be withdrawn from the patient, as by pulling, to disengage the loose suture after the patient has recovered sufficiently so as to no longer require cardioversion.
• the electrode 42 may be disposed along either the inner surface or the outer surface of the pericardium.
• the proximal end 46 of electrode 42 may also be releasably anchored to the pericardium by a suture 54 in a similar manner with a loose suture knot.
• the electrode 42 may be inserted through the pericardium 24 with the distal end 44 sutured to the pericardium as described above and the proximal end 46 releasably anchored by the point of entry into the pericardium 24.
• the second lead 36 similarly includes an elongated electrode 48 having a distal end 50 and a proximal end 52.
• the distal end 50 of electrode 48 is also releasably anchored to the pericardium 24 by a suture 55 in a manner previously described.
• the electrode 48 is disposed along the pericardium 24 for overlying the left atrium. Again, the electrode 48 may be disposed along either the inner surface or the outer surface of the pericardium 24.
• the proximal end 52 of electrode 48 may also be releasably anchored to the pericardium by suture 56 in a manner as previously described.
• one of the electrodes 42 or 48 is shown disposed along the inner surface of the pericardium 24.
• the distal end 44 of electrode 42 is releasably anchored by the loose suture 53 at the point of exit 61 from the pericardium.
• the proximal end 46 of electrode 42 is also releasably anchored by the loose suture 54 at the point of entry 63 into the pericardium.
• the proximal end 46 of electrode 42 may be releasably anchored by the point of entry 63, in which case, loose suture 54 may be dispensed with.
• FIG. 3 it illustrates one of the electrodes 42 or 48, again for example electrode 42, disposed along the outer surface of the pericardium 24.
• the electrode 42 is first inserted into the pericardium 24 at a first point of entry 65 and is exited from the pericardium 24 at a first point of exit 67 to form a first pericardial flap 69.
• the electrode is then extended along the outer surface of the pericardium 24 for substantially its entire length until it reaches a second point of entry 71 into the pericardium 24, and then is exited from the pericardium 24 at a second point of exit 73. This forms a second pericardial flap 75.
• the distal end 44 of electrode 42 is then releasably anchored to the pericardium with the loose suture 53 at a point beyond the second pericardial flap 75.
• the second pericardial flap 75 lends to further assist in the releasable anchoring of distal end 44.
• the first pericardial flap 69 may be used to releasably anchor the proximal end 46.
• the loose suture 54 may also be employed for this purpose.
• the heart wires 38 and 40 may take the form as described in U.S. Pat. No. 4,010,756.
• the heart wire described in that patent includes a needle-shaped proximal end and a distal end having an electrode with attachment means.
• the needle shape permits the proximal end to pierce body tissue for bringing the wire proximal end outside of the chest.
• the needle shape includes a weakened shank portion for breaking off the needle.
• the shank portion which is left forms a connector for connecting the wire to an external heart stimulating device.
• the attachment means may include a suture for releasably suturing the distal end electrode.
• the leads 34 and 36 may be similarly constructed. However, as contemplated by the present invention, certain modifications are preferred.
• the electrodes of the referenced heart wire are approximately one centimeter in length, it is preferred that the electrodes of leads 34 and 36 be approximately six centimeters in length. Further, it is preferred that the electrodes 42 and 48 be flexible to permit the electrodes to conform to the shape or contour of the pericardium and the heart to assure continuous electrical contact between the electrode and the body tissue. In addition, it is preferred that the impedance of the leads 42 and 48 be made substantially lower than the impedance of prior art heart wires. Such wires may have an impedance of fifteen ohms or more whereas an impedance on the order of one ohm is preferred for leads 34 and 36. Such a low impedance may be achieved by forming the conductor of leads 34 and 36 with stranded wire of stainless steel and providing the conductor with a continuous central core of silver. The conductor may then be provided with insulation up to the electrodes.
• the cardiovertor 32 includes a sense amplifier 60 and an R wave detector 62.
• the output of the sense amplifier 60 is coupled to the R wave detector 62.
• the sense amplifier 60 and the R wave detector 62 form a detecting means which, together with the heart wires 38 and 40 to which sense amplifier 60 is coupled, senses ventricular activations or R waves of the heart.
• the R wave detector 62 is of the type well known in the art which provides an output pulse upon the occurrence of an R wave being sensed during a cardiac cycle of the heart.
• the cardiovertor 32 further includes a microprocessor 64.
• the implementation of the microprocessor 64 in accordance with this embodiment of the present invention results in a plurality of functional stages.
• the stages include a timer 66, an interval set stage 68, a comparator stage 70, and a charge delivery and energy control stage 72.
• the microprocessor 64 is arranged to operate in conjunction with a memory (not shown) which may be coupled to the microprocessor by a multiple-bit address bus (not shown) and a bi-directional multiple-bit databus (not shown). This permits the microprocessor 62 to address desired memory locations within the memory for executing write or read operations.
• the microprocessor stores data, such as time intervals or operating parameters in the memory at the addresses defined by multiple-bit addresses conveyed over the address bus and conveys the data to the memory over the multiple-bit data bus.
• the microprocessor 64 obtains data from the memory at the storage locations identified by the multiple-bit addresses provided over the address bus and receives the data from the memory over the bi-directional data bus.
• the cardiovertor 32 further includes a charger and storage capacitor circuit 74 of the type well known in the art which charges a storage capacitor to a peak voltage level determined by a voltage setting control 78 and a discharge circuit 76 for discharging the storage capacitor within circuit 74 for a predetermined time period to provide a controlled discharge output of electrical energy when enabled by an enable switch 84.
• the discharge circuit 76 is coupled to the first electrode 42 of the first lead 34 and the second electrode 48.of the second lead 36 for applying the cardioverting electrical energy to the atria.
• a manually operated charge switch 80 and a charge indicator 82 Associated with the charger and delivery control 72 is a manually operated charge switch 80 and a charge indicator 82.
• the switch 80 When it is desired to charge the capacitor of circuit 74, the switch 80 is actuated.
• the indicator When the capacitor is charged to a desired peak voltage selected with setting control 78, the indicator, such as an LED, will provide a suitable indication.
• the defibrillator 32 further includes a pacemaker circuit 86 of the type well known in the art for providing pacing electrical energy pulses.
• the pacemaker circuit is preferably operable in a demand mode (VVI) and is coupled to the heart wires 38 and 40 for providing demand pacing of the heart.
• VVI demand mode
• the pacer 86 may be operative in a dual chamber pacing mode, such as the DDD mode. This however would require another pair of heart wires to be attached to one of the atria.
• the cardiovertor 32 includes a power source 88 for providing power to the electrical components of the atrial cardiovertor 32.
• the power source 88 may be an AC power supply since the cardiovertor 32 is intended for external use, or it may be a battery if portability of the cardiovertor 32 is preferred.
• the heart wires 38 and 40 and leads 34 and 36 are attached to the heart as previously described, and the patient's chest is closed, the cardiovertor 32 is coupled to the heart wires 38 and 40 and leads 34 and 36 as illustrated.
• the pacer 86 is then activated to provide demand pacing and the sense amplifier 60 and the R wave detector 62 begin detecting the occurrence of ventricular activations of the heart to support the demand pacing modality.
• the patient will be coupled to an external ECG monitor by which such arrhythmias may be detected.
• a desired peak voltage from which cardioversion is to begin is manually selected with setting control 78.
• the charger and delivery control switch 80 is then manually actuated. This causes the storage capacitor of circuit 74 to begin being charged. When the voltage on the capacitor reaches the desired peak voltage, the indicator 82 will indicate that the capacitor is fully charged.
• the enable switch 84 is manually actuated to condition the discharge circuit 76 to initiate the discharge of the storage capacitor within circuit 74 into leads 34 and 36 and electrodes 42 and 48 at the appropriate time to cardiovert the atria
• the discharge circuit 76 initiates the discharge of the cardioverting electrical energy under the control of the charger and delivery control 72.
• the discharge is preferably synchronized with an R wave, detected by sense amplifier 60 and the R wave detector 62, which establishes the first R to R interval falling between a minimum interval and a maximum interval previously set in the interval set stage 68.
• the timer 66 determines the time between immediately successive detected R waves. After the enable switch is actuated and with each detected R wave, microprocessor 64 interrogates the timer 66 for the time between the last immediately successive ventricular activations of the heart 10.
• the compare stage 70 of the microprocessor determines if the time between the last two immediately successive ventricular activations is greater than the minimum time interval and less than the maximum time interval. As soon as the microprocessor 64 finds an R to R interval greater than the preselected minimum time interval (I min ) and less than the preselected maximum time interval (I max ), the charge delivery control stage 72 of microprocessor 64 causes the discharge circuit 76 to immediately initiate the discharge of the electrical energy stored in the storage capacitor of circuit 74 for applying the cardioverting electrical energy to electrodes 42 and 48 and thus to the atria 16 and 18 of the heart 10.
• the discharge circuit 76 will apply the cardioverting electrical energy to the atria of the heart substantially coincident or in synchronism with the detected ventricular activation establishing the R to R interval satisfying the discharge criteria.
• the minimum and maximum R to R intervals may also be selected automatically as fully disclosed in U.S. Pat. No. 5,207,219 which is assigned to the assignee of the present invention and incorporated herein by reference. As fully disclosed therein, the R to R interval timing prior to cardioversion assures safe cardioversion by avoiding the application of the cardioverting energy when the heart may be vulnerable to induced ventricular fibrillation.
• the cardioverting electrical energy is preferably applied for a fixed time period using a time symmetrical biphasic waveform. Because the electrodes 42 and 48 are either on the inner surface or outer surface of the pericardium, energies between only one and five joules, depending upon the patient, are required for successful cardioversion. These energy levels are much less than the energy levels of fifty to three hundred and sixty joules generally required for external cardioversion.
• the post-surgery cardioverting system and method of the present invention satisfies a long felt need in the art for safe and effective treatment of post-heart surgery fibrillation.
• the system and method of the present invention avoids the need for drug therapy. Further, the option of external cardioversion with high energy requirements no longer need be considered.
• the post-heart surgery patient suffering from atrial fibrillation is no longer required to endure the effects of such a condition.
• the fibrillation by virtue of the present invention, may be effectively terminated without prolonging the patient's recovery.
• the heart wires and cardioverting leads may be pulled out of the patient's chest.
• the system and method of the present invention may also be utilized to advantage to terminate ventricular tachycardia or even ventricular fibrillation during the post-surgery period.
• the elongated electrodes would be disposed along the pericardium to overlie the ventricles.
• the electrodes may be releasably anchored to the pericardium as disclosed herein to enable the electrodes to be removed from the patient by pulling on the leads to which the electrodes are attached.

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• Health & Medical Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Radiology & Medical Imaging (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Cardiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Electrotherapy Devices (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)

Abstract

Description

Claims (37)

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Applications Claiming Priority (2)

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ID=22280039

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Cited By (6)

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• 1993
  • 1993-07-30 US US08/100,492 patent/US5403353A/en not_active Ceased
• 1994
  • 1994-07-11 CA CA002127782A patent/CA2127782C/en not_active Expired - Fee Related
  • 1994-07-13 DE DE69428240T patent/DE69428240T2/en not_active Expired - Fee Related
  • 1994-07-13 DE DE0636385T patent/DE636385T1/en active Pending
  • 1994-07-13 EP EP94250180A patent/EP0636385B1/en not_active Expired - Lifetime
• 1996
  • 1996-02-28 US US08/608,410 patent/USRE35779E/en not_active Expired - Lifetime

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