Defibrillator interface device for atrial cardioversion therapy

Abstract

Certain embodiments of the present disclosure relate to a defibrillator interface device for use in an atrial cardioversion system. In one embodiment, the defibrillator interface device includes an input terminal configured to receive an input signal from the defibrillator when coupled to the defibrillator, an output terminal configured to deliver an output signal to the multiple cardiac leads when coupled to the multiple cardiac leads, the output signal including at least one discrete pulse, and an attenuation circuit configured to generate the output signal by reducing input signal energy.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 089,287, filed on October 8, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This application relates to atrial cardioversion therapy and devices for use in atrial cardioversion therapy.

Background Art

[0003] Cardiac arrhythmias such as atrial fibrillation are frequent occurrences. In particular, postoperative atrial fibrillation is the most frequent cardiac arrhythmia after cardiac surgery, and its occurrence varies depending on the underlying heart disease and treatment. Detection of postoperative atrial fibrillation is significant because of its frequency and because it is often associated with an increased risk of death, non - fatal myocardial infarction, and non - fatal stroke.

[0004] In current practice, treatment of patients typically involves pharmacological treatment and / or electrical shock conversion. Electrical shock conversion requires a large amount of energy, and it is difficult to maintain sinus rhythm using this approach. Furthermore, conventional techniques pose additional problems in the treatment of patients suffering from abnormal heart rhythms. Conventional external defibrillation procedures typically require a large amount of electrical energy (i.e., about 50 - 150 joules) and, as a result of the strong shock and associated patient discomfort, are usually performed after general anesthesia or deep sedation, both of which are time - consuming procedures. Additionally, the large amount of energy required to return the patient to sinus rhythm requires expensive sedative medications and may cause external skin damage and pain.

[0005] Furthermore, external shock defibrillation is a time-consuming process requiring additional medical personnel, including anesthesiologists, cardiologists, and nurses. The procedure itself is not without significant risks to the patient's life. The numerous complications, drawbacks, and failures associated with the conventional systemic use of external electric shock procedures have prompted many attempts to significantly improve treatment and patient care.

[0006] While transthoracic electrocardioversion is effective in restoring sinus rhythm, it is also associated with serious complications such as new arrhythmias, anesthesia-related problems, and electrocutaneous burns in different tissue layers. To address these issues, attempts have been made to provide low-energy delivery through temporary epicardial leads as an alternative to transthoracic electrocardioversion. However, the technical difficulties during suturing in the atria, the increased procedure time, and the risk of bleeding during lead extraction make these methods challenging. [Overview of the Initiative]

[0007] The following summary provides a simplified overview of various aspects of the Disclosure to give a basic understanding of those aspects. This summary is not a comprehensive overview of the Disclosure. This summary is not intended to identify any key or material elements of the Disclosure, nor to describe any scope of any particular embodiment of the Disclosure or any scope of any claim. The sole purpose of this summary is to provide a simplified introduction to some of the concepts of the Disclosure as a preface to the more detailed descriptions that will be presented later.

[0008] In one embodiment, the defibrillator interface device includes an input terminal configured to receive an input signal from a defibrillator when coupled to a defibrillator, an output terminal configured to deliver an output signal containing at least one discrete pulse to a plurality of cardiac leads when coupled to a plurality of cardiac leads, and an attenuation circuit configured to convert the input signal into an output signal such that the pulse energy of each discrete pulse in the output signal is less than 6 joules.

[0009] In at least one embodiment, the pulse energy is less than 5.5 joules, less than 5.0 joules, less than 4.5 joules, less than 4.0 joules, less than 3.5 joules, less than 3.0 joules, less than 2.5 joules, less than 2.0 joules, less than 1.5 joules, less than 1.0 joule, less than 0.5 joules, less than 0.4 joules, less than 0.3 joules, less than 0.25 joules, or less than 0.2 joules.

[0010] In at least one embodiment, at least one of the discrete pulses of the output signal includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof.

[0011] In at least one embodiment, the defibrillator interface device includes a cardioverter-version cable coupled between an output terminal and a plurality of cardiac leads.

[0012] In at least one embodiment, the input terminal is configured to connect to the defibrillator via a cable connector without physical contact with the defibrillator paddle.

[0013] In another embodiment, the defibrillator interface device includes an input terminal configured to couple to a defibrillator, an output terminal configured to couple to a plurality of cardiac leads, and an attenuation circuit configured to couple the input terminal to the output terminal. In at least one embodiment, the attenuation circuit includes a plurality of resistors arranged in a voltage divider configuration, each of which has a resistance of less than 1 kΩ.

[0014] In at least one embodiment, the input terminal is directly coupled to the attenuation circuit without an intervening voltage discharge tube.

[0015] In at least one embodiment, the resistor is selected such that the pulse energy of the output pulse generated by the attenuation circuit is less than 6 joules.

[0016] In at least one embodiment, the defibrillator interface device further includes at least one voltage discharge tube coupled in parallel between the attenuation circuit and the output terminal.

[0017] In at least one embodiment, the input terminal is configured to connect to the defibrillator via a cable connector without physical contact with the defibrillator paddle.

[0018] In another embodiment, the atrial cardioversion system includes a defibrillator, a defibrillator interface device electrically coupled to the defibrillator via a cable connection without physical contact with the defibrillator paddles, and a plurality of cardiac leads electrically coupled to the defibrillator interface device to deliver signals from the defibrillator interface device to the patient's heart when coupled to the patient's heart.

[0019] In at least one embodiment, the defibrillator interface device is configured to convert an input pulse signal from a defibrillator into an output pulse signal that is sent to the patient's heart. In at least one embodiment, the pulse energy of the output pulse signal is less than 6 joules.

[0020] In at least one embodiment, the pulse energy is less than 5.5 joules, less than 5.0 joules, less than 4.5 joules, less than 4.0 joules, less than 3.5 joules, less than 3.0 joules, less than 2.5 joules, less than 2.0 joules, less than 1.5 joules, less than 1.0 joule, less than 0.5 joules, less than 0.4 joules, less than 0.3 joules, less than 0.25 joules, or less than 0.2 joules.

[0021] In at least one embodiment, the output pulse signal includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof.

[0022] In at least one embodiment, the system further includes a cardioversion cable coupled between a defibrillator interface device and a plurality of cardiac leads.

[0023] In another aspect, a method of performing atrial cardioversion includes receiving an input pulse from a defibrillator through a cable connector coupling the defibrillator to an input terminal of a defibrillator interface device by the input terminal of the defibrillator interface device, converting the input pulse to an output pulse having a pulse energy of less than 6 joules by an attenuation circuit, and transmitting the output pulse to a patient's heart through a plurality of cardiac leads in contact with the patient's heart.

[0024] In at least one embodiment, the pulse energy is less than 5.5 joules, less than 5.0 joules, less than 4.5 joules, less than 4.0 joules, less than 3.5 joules, less than 3.0 joules, less than 2.5 joules, less than 2.0 joules, less than 1.5 joules, less than 1.0 joules, less than 0.5 joules, less than 0.4 joules, less than 0.3 joules, less than 0.25 joules, or less than 0.2 joules.

[0025] In at least one embodiment, the output pulse includes a square waveform, a plateau waveform, a clipped exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof.

[0026] In at least one embodiment, the method further includes coupling an input terminal of the defibrillator interface device through a cable connector without physically contacting the input terminal with a defibrillator paddle.

[0027] In at least one embodiment, the attenuation circuit is electrically coupled to the input terminal without an intervening gas discharge tube.

[0028] In at least one embodiment, successful atrial cardioversion is achieved with a defibrillation threshold greater than 0.1 J and less than 1 J, less than 0.9 J, less than 0.8 J, less than 0.7 J, less than 0.6 J, less than 0.5 J, less than 0.4 J, less than 0.3 J, or less than 0.2 J. In at least one embodiment, success of atrial cardioversion is achieved using single-stage energy delivery.

[0029] For the sake of facilitating a more complete understanding of the present disclosure, reference is now made to the accompanying drawings in which like elements are referred to by like numerals. These drawings should not be construed as limiting the present disclosure and are for illustrative purposes only.

Brief Description of the Drawings

[0030] [Figure 1] FIG. 1 is a block diagram showing an exemplary atrial cardioversion system according to a particular embodiment. [Figure 2] FIG. 2 is a block diagram showing an exemplary defibrillator interface device according to a particular embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an attenuation circuit and a gas discharge tube according to a particular embodiment. [Figure 4] FIG. 4 shows an electrocardiogram trace of induced atrial fibrillation. [Figure 5] FIG. 5 shows a complete return from induced atrial fibrillation to normal sinus rhythm using a defibrillator interface device according to a particular embodiment. [Figure 6] FIG. 6 is a flowchart showing an exemplary method for performing cardioversion according to a particular embodiment.

Modes for Carrying Out the Invention

[0031] Embodiments of the present disclosure relate to a defibrillator interface device for use in an atrial cardioversion system to reduce the amount of energy delivered to a patient's heart by a defibrillator, for example, during atrial cardioversion therapy. The defibrillator interface device includes an attenuation circuit for converting an input signal (received from a defibrillator) into an output signal with reduced energy (e.g., less than 6 joules).

[0032] Postoperative atrial fibrillation is generally a benign clinical condition with a favorable prognosis, but complications associated with postoperative atrial fibrillation can increase patient mortality. The treatment goals for postoperative atrial fibrillation include maintaining hemodynamic stability, suppressing symptoms, and preventing thromboembolism. Treatment guidelines are based on rate control or cardiovertermination achieved through drug therapy or the use of electrocardiography, but there is no consensus on optimal medical treatment.

[0033] Electrocardioversion accounts for approximately 10% of treatment efforts for postoperative atrial fibrillation. This treatment is known to cause side effects such as burns, arrhythmias, and pain, and can jeopardize anesthetic management. Furthermore, electrocardioversion usually requires sedatives (e.g., midazolam, propofol, ketamine) which are associated with adverse events.

[0034] Conventional methods in electrocardioversion to treat atrial fibrillation use an initial energy of approximately 100 joules (J), increasing up to a maximum of 400 J in increments of 100 J if the initial shock fails. The number of shocks that can be administered before classifying atrial fibrillation as refractory is debated, and there is no strong data that may help determine the number of shocks that can be safely delivered during external cardioversion. Other limitations of conventional methods include an increased risk of wire dislodgement and bleeding. Given these limitations and others, it is desirable to develop alternative methods of energy delivery for atrial defibrillation cardioversion in both chronic and postoperative settings.

[0035] Embodiments of this disclosure address these and other limitations by providing a low-energy method for converting atrial fibrillation to a normal sinus rhythm. The embodiments provide a safer, faster, and potentially painless alternative to conventional electrical conversion techniques. Certain embodiments utilize a defibrillator interface device that can be used with commercially available defibrillators, pacemakers, and epicardial wires to more favorably and effectively achieve cardiovertebralization using a single-stage defibrillation energy threshold of less than approximately 0.2 J. As used herein, “single-stage” in the context of energy delivery refers to energy delivery resulting from a single biphasic impact. The advantages of the embodiments described herein include, but are not limited to, the success of low-energy cardiovertebralization, reduced or minimized damage from lead suturing or removal at the atrial surface, and reduced exposure to antiarrhythmic drugs and their corresponding side effects.

[0036] In certain embodiments, connection to the defibrillator is achieved directly via a cable, which advantageously eliminates the need for defibrillator pads / paddles to make electrical connections to the interface device. This also advantageously eliminates the need for safety switches, which are typically part of the defibrillator paddles or pads, and the need to ensure proper positioning of the paddles or pads. Furthermore, by eliminating paddle / pad connections, the risks associated with unprotected connections at high voltages are also eliminated.

[0037] Current defibrillator interface device designs utilize a gas discharge tube at each input terminal. The gas discharge tube acts as an open circuit until a threshold voltage (i.e., discharge initiation voltage) is reached, at which point the gas discharge tube becomes energized. While gas discharge tubes are typically used in current systems for input / output isolation and energy transfer indication, they are the source of several complexities. For example, the gas discharge tube limits the minimum possible energy transfer (generally to 2J or more) by preventing any input below the discharge initiation voltage. The gas discharge tube also has an associated voltage drop (typically 15V), leading to a loss of energy efficiency. The gas discharge tube also distorts the two-phase waveform of the output signal, potentially preventing either of the two pulses of the two-phase pulse from exceeding the discharge initiation voltage. Furthermore, the gas discharge tube at the input can also prevent the defibrillator from delivering an impact to the expected patient load due to load mismatch, potentially resulting in the inability to deliver the desired energy.

[0038] By avoiding the use of paddles / pads, this eliminates the need for input / output isolation and allows for the elimination of gas discharge tubes at the input terminals. This advantageously avoids adverse effects on the shape of the output waveform, enabling the delivery of well-defined pulses to the patient's heart, such as square waveforms, plateau waveforms, truncated exponential waveforms, curvilinear waveforms, or their single-phase or two-phase forms.

[0039] Figure 1 shows an atrial cardioversion system 100 according to a specific embodiment. The atrial cardioversion system 100 includes a defibrillator 110, a pacemaker 120, a defibrillator interface device 200, and several cardiac wires 108 adapted to interface with the patient's heart. The defibrillator interface device 200, described in more detail with respect to Figure 2, facilitates atrial cardioversion in cardiac surgery patients prone to postoperative atrial fibrillation. The cardiac wires 108, including temporary pacing wires and cardioversion cardiac wires implanted during cardiac surgery, can usually be removed within 7 days when the patient is less prone to postoperative atrial fibrillation.

[0040] In certain embodiments, the defibrillator 110 is an external, adjustable low-energy two-phase defibrillator (such as a LIFEPAK® defibrillator) capable of performing a synchronized cardioid version. The defibrillator 110 may be coupled to a defibrillator interface device 200 via an interface cable 102. The defibrillator interface device 200 is described in more detail below with respect to Figure 2.

[0041] The interface cable 102 may include a cable compatible with the defibrillator 110 (e.g., a LIFEPAK® QUIK-COMBO therapeutic cable). The interface cable 102 may directly connect the defibrillator 110 to the input terminals of the defibrillator interface device 200. In certain embodiments, the interface cable 102 connects to the defibrillator interface device 200 without the input terminals physically contacting the defibrillator pads or paddles. For example, the interface cable 102 establishes a direct wired connection with the defibrillator interface device 200. In certain embodiments, the interface cable 102 may be manufactured by modifying a commercially available cable compatible with the defibrillator 110, removing the pads / paddles, and connecting the exposed leads to the input terminals of the defibrillator interface device 200. In certain embodiments, to reduce stress on the interface cable 102 in the defibrillator interface device 200, the input terminals of the defibrillator interface device 200 may include a tension relief connector that seals the incoming leads of the interface cable 102 and provides tension relief to the incoming leads of the interface cable 102. For example, the tension relief connector may include a tapered screw nut and / or a rubber O-ring.

[0042] The pacemaker 120 may be any suitable temporary external pacemaker compatible with the atrial cardioversion, such as Medtronic models 5392 and 53401. In certain embodiments, the pacemaker 120 may accept two temporary bipolar pacing wires for ventricular and atrial pacing. The pacemaker 120 may be connected to a subset of cardiac wires 108 via a ventricular pacing cable 122 and an atrial pacing cable 124.

[0043] In certain embodiments, the ventricular pacing cable 122 is an extension cable that connects the pacemaker 120 to the ventricular pacing wire 108A. The ventricular pacing cable 122 may be, for example, a Medtronic 5433V Reusable EPG ventricular safety cable or a Medtronic 5487 6-foot sterile disposable patient safety cable.

[0044] In certain embodiments, the atrial pacing cable 124 is an extension cable that connects the pacemaker 120 to the atrial pacing cardiac wire 108C. The atrial pacing cable 124 may be, for example, a Medtronic 5433A Reusable EPG Ventricular Safety Cable or a Medtronic 5487 6-foot sterile disposable patient safety cable.

[0045] In certain embodiments, the cardioversion extension cable 104 connects the defibrillator interface device 200 to at least one subset of the cardiac wire 108 to bridge the distance between the defibrillator interface device 200 and the patient's heart, due to the short distance the cardiac wire 108 extends from outside the patient's body when implanted in the patient's body. The cardiac wire 108 provides a direct connection to the patient's heart to enable cardiac pacing and atrial cardioversion. The cardiac wire 108 may be designed for implantation for up to 7 days and can be withdrawn by gentle pulling.

[0046] In certain embodiments, the cardiac wire 108 includes three different wires. The first wire is a ventricular wire 108B which includes a bipolar lead that provides bipolar myocardial ventricular pacing. The lead may include an anchoring mechanism distal to the electrode. The proximal end of the lead may be bifurcated with a connector for each electrode.

[0047] The second wire is the right atrial wire 108D. The right atrial wire is a tripolar lead with a bifurcated distal end, one end providing a unipolar epicardial conversion electrode and the other end providing a bipolar myocardial atrial pacing / sensing electrode. The pacing bifurcated end may include a fixation mechanism distal to the electrode. The proximal end of the lead may have connector pins for each electrode and may be branched into three.

[0048] The third wire is the left atrial wire 108E, which is a unipolar epicardial conversion lead.

[0049] Common features of the cardiac wire 108 include a connector, a chest needle, and a cardiac needle. In certain embodiments, the connector is located at the proximal end of the cardiac wire 108 and is a single-pole pin-type connector. Each connector of a given cardiac wire is attached to a chest needle to allow the lead to be placed externally through the skin. The exposed pins during pacing are covered when not connected to the pacing cable.

[0050] The most proximal end of the cardiac wire 108 includes a straight chest needle attached to a connector pin. The straight chest needle may be used to pass the cardiac wire from its attachment point to the heart for externalization through the skin. After externalization, the chest needle may be removed from the connector pin, and the pin may be separated for connection to its respective device.

[0051] It should be understood that the configuration of the cardiac wire 108 and other components for connecting the device of the atrial cardioversion system 100 to the heart is merely illustrative, and that other configurations may be available, as will be understood by those skilled in the art. For example, in certain embodiments, a pacemaker 120 and associated components are omitted from the atrial cardioversion system 100. In such embodiments, the atrial cardioversion system 100 may utilize only a defibrillator 110, a defibrillator interface device 200, and associated connectivity, such that a pair of unipolar epicardial wires are used to connect the cardioversion extension cable 104 to the heart.

[0052] The most distal end of each cardiac wire branch may include a curved cardiac needle. The curved cardiac needle may be used to attach electrodes to the heart. In pacing branches, the cardiac needle may also be used to implant a fixation mechanism into the myocardium for securing the electrode placement, and may be removed after use.

[0053] The atrial cardioversion system 100 further utilizes the cardiac wire cable guide 106 to reduce the stress on the right atrial wire 108D, which branches into two to connect the atrial pacing cardiac wire 108C to the cardioversion extension cable 104.

[0054] Figure 2 shows a defibrillator interface device 200 according to a particular embodiment. The defibrillator interface device 200 includes an input terminal 202 (for connection to interface cable 102), an output terminal 204 (for connection to cardiovertension extension cable 104), an attenuation circuit 210, and one or more gas discharge tubes 220. The defibrillator interface device 200 further includes an energy release and overvoltage detection circuit 230 (for indicating that the defibrillator has released a set amount of energy, visually indicated by an energy transfer indicator 240), a surge protection indicator 250, a battery status circuit 260 having a battery charge indicator 270 and a battery discharge indicator 280 for visually representing the battery status, and a button 290 for checking the battery status. It should be understood that some of the components may be omitted or modified, and that additional components may exist, as will be understood by those skilled in the art.

[0055] In certain embodiments, the attenuation circuit 210 is designed to attenuate the input signal from the defibrillator 110 to a level compatible with the atrial cardioversion, ensuring that the defibrillator 110 sees a low impedance, for example, in the range of 52.3 to 57 ohms (Ω). In certain embodiments, the resistors of the attenuation circuit 210 are non-inductive to prevent or reduce the phase shift of the waveform delivered to the patient's heart. In certain embodiments, the attenuation circuit 210 may be designed to reduce the amount of energy per pulse to 6 joules (J) or less, 5 joules (J) or less, 4 joules (J) or less, 3 joules (J) or less, 2 joules (J) or less, 1 joule (J) or less, 0.5 joules (J) or less, 0.2 joules (J) or less (e.g., about 0.17 J), 0.1 joules (J) or less, or any range defined by any of these values ​​(e.g., 0.1 J to 2 J). Furthermore, in certain embodiments, the attenuation circuit 210 is directly coupled to the input terminal 202 without an intervening voltage discharge tube.

[0056] Figure 3 is a schematic diagram showing an attenuation circuit 210 according to a particular embodiment. In this particular embodiment, the attenuation circuit 210 includes a plurality of resistors arranged in a voltage divider configuration, each of which has a resistance of less than 1 kΩ. In this particular embodiment, the resistors are selected such that R1=20Ω, R2=17Ω, R3=20Ω, R4=20Ω, R5=20Ω, and R6=175Ω. The value of R6 may be selected to be less than 1.5 kΩ or less than 1 kΩ to ensure compatibility with certain defibrillators, such as the LIFEPAK® 20 defibrillator. The value of R6 may, in certain embodiments, be adjusted based on the output specifications of the defibrillator 110 to identify the impedance of the attenuation circuit 210, which is within a suitable range for use (for example, between approximately 180 Ω and less than approximately 250 Ω). By selecting R6 to be less than 1 kΩ (or specifically 175 Ω), resulting in a low defibrillator load resistance of approximately 40–43 Ω, the voltage divider performance is not adversely affected. This is because most defibrillators tend to exhibit adaptive energy delivery by terminating shock delivery when the selected energy is delivered (for example, by widening the pulse width to accommodate changes in output from the attenuation circuit 210).

[0057] In certain embodiments, R2 is selected to be lower than R1, R3, R4, and R5. For example, R2 may be selected to be 17Ω, while R1, R3, R4, and R5 are selected to be 20Ω. This lower resistance may be selected to achieve a target attenuation that is below the nominal patient load of 50Ω (e.g., about 80% of that).

[0058] In certain embodiments, the defibrillator interface device 200 includes one or more gas discharge tubes 220 connected between an attenuation circuit 210, which may be arranged in parallel as shown in Figure 3, and an output terminal 204. One or more gas discharge tubes may be used to prevent excessive shock voltage from being discharged to the patient. The gas discharge tube maintains a high-impedance off state until the voltage exceeds the discharge initiation voltage, at which point the gas in the gas discharge tube is ionized, producing a pulse of current lasting less than 1 microsecond. During the arc, the gas discharge tube exhibits low impedance, producing a very low on-state voltage (arc-circuit voltage). This effectively limits the overvoltage to a low level and creates a shunt away from downstream components and circuits for the associated follow current. Once the surge event subsides and the system voltage returns to normal levels, the gas discharge tube resets to its high-impedance (off) state.

[0059] In certain embodiments, a discharge initiation voltage rating of 400V (or close to 400V) is selected to prevent the gas discharge tube from delivering a discharge of 15J or more to the patient's heart. In certain embodiments, if one of the gas discharge tubes cannot conduct at high voltage, multiple gas discharge tubes are used.

[0060] In certain embodiments, the energy release and overvoltage detection circuit 230 is separate from the attenuation circuit 210 and is designed to avoid interference with the attenuation circuit 210 and the output signal. This can be achieved, for example, by using a high-impedance path tapped across resistor R3. In other embodiments, the gas discharge tube may not be present at all in the defibrillator interface device 200.

[0061] In certain embodiments, the atrial cardioverter-version system 100 may be adapted to deliver a pacing signal comprising one or more discrete pulses or a sequence of low-energy pulses (with a maximum current amplitude of less than 0.1 milliamperes) for treating atrial fibrillation. In certain embodiments, the discrete pulses are applied, followed by the application of the pacing signal. The energy E delivered to the heart is given by E(t) = V(t)I(t)t, where V is the output voltage of the defibrillator interface device 200, I(t) is the output current, and t is time. The amplitude of the output current I is related to the output voltage V by V = IR, where R is the resistance of the current path through the heart. The amount of energy of a given pulse can be calculated by integrating the output voltage V over the duration of the pulse. For a continuous sequence of pulses, the total energy delivered can be calculated by integrating the total length of time the signal is applied to the heart. In certain embodiments, the voltage amplitude, duration, and shape of the discrete pulses may be selected to deliver a total amount of energy that is less than 6 joules. For example, the duration of a discrete pulse may be 0.1 seconds or less. Similarly, in certain embodiments, the pacing signal may be generated such that the current amplitude does not exceed 100 microamperes (e.g., the maximum current amplitude remains 100 microamperes or less, 50 microamperes or less, 10 microamperes or less, or 1 microampere or less), and the overall duration of the pacing signal is maintained such that the total energy delivery is less than 6 joules.

[0062] Examples The following embodiments are provided to aid in understanding this disclosure and should not be construed as specifically limiting the embodiments described herein and claimed. Any such variations of embodiments, including substitutions of all currently known or subsequently developed equivalents, and minor changes in formulation or experimental design, which would be within the skill of a person skilled in the art, should be construed as being within the scope of the embodiments incorporated herein. All data are reported as mean values ​​with standard deviation.

[0063] Anesthesia and surgical procedures Three male domestic pigs with an average weight of 60.6 ± 9 kg were used. The animals were premedicated with an intramuscular injection of terazole (3 mg / kg). The animals were intubated under direct visualization using appropriately sized cuffed endotracheal tubes, and anesthesia was administered with 1.5% isoflurane. Electrocardiograms were continuously monitored throughout the procedure using an electrophysiology recording system (BARD Electrophysiology Lab System). The animals were placed in a supine position, prepared, and covered with cloth.

[0064] In each animal, the chest was opened via a median sternotomy, and the heart was exposed. A pair of custom-made stainless steel wire electrodes (Medtronic Streamline electrodes), each with a 6 cm uninsulated area at the distal end, were woven into the myocardium, one at each atrial appendage at the base. The distal uninsulated portion was used as a cardioverter. Two to four bite wounds were used while positioning the leads and creating the straight line. Subepidial placement was preferred to reduce the risk of bleeding observed in full-thickness bite wounds and to enhance tissue conductivity. All wires were extruded subcutaneously at the level of the subxiphoid process and secured with non-absorbable sutures.

[0065] Impedance measurement The electrical impedance of the atrial tissue was measured using a known resistor of 100 Ω. A constant 2 V pulse signal with a pulse width of 0.5 milliseconds was supplied to the atrium through the atrial leads at a frequency of 1 Hz through the known resistor of 100 Ω. The resulting voltage across the known resistor was measured using an oscilloscope. The atrial impedance was then calculated from these measured voltages.

[0066] Induction of atrial fibrillation Atrial fibrillation was induced using a hybrid method (pharmacological and electrical). A 2.5 mg neostigmine IV bolus was administered, followed by a direct injection of 0.5 mg of acetylcholine near the SA node at the junction of the right atrium and superior vena cava (pharmacological method). Subsequently, 10 Hz pacing bursts were delivered using wire electrodes or alligator clips on the surface of both atria until atrial fibrillation was established (electrical method). Figure 4 shows the electrocardiogram trace of the atrial fibrillation lead, illustrating the hybrid induction of atrial fibrillation by acetylcholine injection into the SVC / RA junction and burst pacing at 10 Hz. Throughout the procedure, electrocardiogram leads I, II, III, aVR, aVF, aVL, and V1-V6 were recorded. Persistent atrial fibrillation was defined by uninterrupted changes in the electrocardiogram over a one-minute period, including the absence of discrete "P" waves, the presence of "f" waves, and a non-repetitive pattern of ventricular responses.

[0067] Atrial fibrillation cardioversion The atrial cardioversion lead was connected to a defibrillator interface device (e.g., defibrillator interface device 200) as described herein, which acts as a bridge to a defibrillator (LifePak20, Medtronic). Energy level selection was performed using the defibrillator, but the defibrillator interface device attenuated and delivered the final output.

[0068] Ultra-low energy was delivered through transient atrial cardioverter-proximal leads sutured to the left and right atrial appendages, as described above. To avoid inducing ventricular fibrillation, the impact was synchronized with the ventricular R wave. The initial impact energy was 0.15 J. If unsuccessful, the impact energy was increased in 0.03 J increments up to 0.3 J, and then delivered at the following energy levels: 0.45 J, 0.6 J, 0.9 J, 1.5 J, 2.1 J, and 3 J. Each energy level was tried at least twice before incrementing the energy to the next higher level.

[0069] A successful electrical cardioversion was defined as a transition from atrial fibrillation to a normal sinus rhythm without premature recurrence of atrial fibrillation within a 60-second cardioversion. The defibrillation threshold (DFT) was defined as the lowest shock energy required to successfully convert atrial fibrillation back to a normal sinus rhythm in two separate events. Figure 5 shows a complete return from AFIB to sinus rhythm with a DFT of 0.21 J.

[0070] Figure 6 is a flowchart illustrating an exemplary method 600 for performing cardioversion according to a particular embodiment, and summarizes the method described in this section. In block 610, an initial energy level is selected (e.g., 0.1 J, 0.15 J, 0.2 J, etc.). In block 620, cardioversion is attempted as described above. In block 630, if cardioversion is successful, method 600 then proceeds to block 640, where a return to a normal sinus rhythm is observed. Otherwise, method 600 proceeds to block 650. In a particular embodiment, in block 650, cardioversion is attempted again at the same energy level. In block 660, if cardioversion is successful, method 600 proceeds to block 640. Otherwise, method 600 proceeds to block 670, where time elapses to reach hemodynamic stability. The energy level is then incremented (e.g., 0.03 J increment, 0.3 J increment, etc.), and method 600 proceeds to block 620. Attempts in the cardio version may be repeated until a normal sinus rhythm is reached or until the maximum energy level is reached (e.g., 3 J).

[0071] Lead extraction As described above, the leads were attached in a linear fashion to the epicardial surface of both the left and right atrial appendages and extruded subcutaneously at the level of the subxiphoid process. This technical detail was done to mimic the temporary lead placement after cardiac surgery in a clinical setting. To ensure the safety of lead removal, both wires were pulled back sequentially by hand. Upon completion of the study, the animals were euthanized under deep anesthesia, and the hearts underwent macroscopic autopsy by a surgeon.

[0072] result Temporary lead placement in the atrial cavity was uninterrupted in all studies. A mean of 4.6 ± 1.24 inductions of atrial fibrillation were performed, with a 100% success rate. Table 1 summarizes the mean energy, defibrillation threshold (DFT), and impedance per study. No early recurrences of atrial fibrillation were observed during the duration of the studies. When the studies were completed, the temporary wires were removed by standard percutaneous manual traction, the leads were easily removed, and no bleeding was observed. Gross autopsy showed no major injuries other than suture bites. No impact-related injuries were observed.

[0073] The mean defibrillation threshold in this study was 0.87 ± 0.52 J, and the minimum DFT value was 0.21 J, which is unexpectedly low for a single-step energy value for epicardial wire defibrillation. [Table 1]

[0074] The above description contains numerous details. However, it will be apparent to those skilled in the art who are interested in this disclosure that it can be implemented without these specific details. In some cases, well-known structures and devices are shown in block diagram form rather than in detail, in order to avoid obscuring this disclosure.

[0075] The words “example” or “exemplary” are used herein to mean that they serve as an example, instance, or illustration. No aspect or design described herein as “example” or “exemplary” should necessarily be construed as preferable or advantageous to any other aspect or design. Rather, the use of the words “example” or “exemplary” is intended to present a specific concept. Where used in this application, “or” is intended to mean inclusive “or” rather than exclusive “or.” That is, unless otherwise specified or it is clear from the context, “X includes A or B” is intended to mean any natural inclusive substitution. That is, if X includes A, if X includes B, or if X includes both A and B, then “X includes A or B” is satisfied under any of the above examples. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed as meaning “one or more” unless otherwise specified or it is clear from the context that they refer to a singular form. Throughout this specification, any reference to "an embodiment" or "one embodiment" means that a particular function, structure, or characteristic described in relation to that embodiment is included in at least one embodiment. Therefore, the phrase "an embodiment" or "one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment.

[0076] This disclosure is not limited in scope by the specific embodiments described herein. Indeed, various other embodiments and modifications of this disclosure, as well as those described herein, will be apparent to those skilled in the art from the description and accompanying drawings. Accordingly, such other embodiments and modifications are intended to fall within the scope of this disclosure. Furthermore, although this disclosure has been described in the context of specific embodiments in specific environments for specific purposes, those skilled in the art will recognize that its usefulness is not limited thereto, and that this disclosure can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed together with the full breadth and spirit of this disclosure as described herein, and the entire scope of equivalents to which such claims are entitled. The present invention also includes the following embodiments. <1> A defibrillator interface device, An input terminal configured to receive an input signal from a defibrillator when connected to the defibrillator, An output terminal configured to deliver an output signal containing at least one discrete pulse to multiple cardiac lead wires when connected to the multiple cardiac lead wires, An attenuation circuit configured to convert the input signal to the output signal such that the pulse energy of each discrete pulse in the output signal is less than 6 joules, The defibrillator interface device comprising the above-mentioned features. <2> The defibrillator interface device according to item 1 above, wherein the pulse energy is less than 0.2 joules. <3> The defibrillator interface device according to claim 1 or 2, wherein at least one of the discrete pulses of the output signal includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof. <4> The defibrillator interface device according to any one of the above 1 to 3, further comprising a cardioverter-version cable connected between the output terminal and the plurality of cardiac lead wires. <5> A defibrillator interface device according to any one of the above 1 to 4, wherein the input terminal is configured to connect to the defibrillator via a cable connector without physically contacting the defibrillator paddle. <6> A defibrillator interface device, An input terminal configured to be connected to a defibrillator, Output terminals configured to connect to multiple heart leads, An attenuation circuit configured to couple the input terminal to the output terminal, wherein the attenuation circuit comprises a plurality of resistors arranged in a voltage divider configuration, and each of the plurality of resistors exhibits a resistance of less than 1 kΩ, and The defibrillator interface device comprising the above-mentioned features. <7> The defibrillator interface device according to 6 above, wherein the input terminal is directly coupled to the attenuation circuit without an intervening voltage discharge tube. <8> The defibrillator interface device according to 6 or 7, wherein the resistor is selected such that the pulse energy of the output pulse generated by the attenuation circuit is less than 6 joules. <9> The defibrillator interface device according to any one of 6 to 8 above, further comprising at least one voltage discharge tube coupled in parallel between the attenuation circuit and the output terminal. <10> A defibrillator interface device according to any one of 6 to 9 above, wherein the input terminal is configured to connect to the defibrillator via a cable connector without physically contacting the defibrillator paddle. <11> It is an atrial cardioversion system, Defibrillator and, A defibrillator interface device electrically coupled to the defibrillator via a cable connection without physical contact with the defibrillator paddles, When coupled to the patient's heart, a plurality of cardiac leads electrically coupled to the defibrillator interface device deliver signals from the defibrillator interface device to the patient's heart. The atrial cardioversion system comprising the above. <12> The system according to 11, wherein the defibrillator interface device is configured to convert an input pulse signal from the defibrillator into an output pulse signal transmitted to the patient's heart, and the pulse energy of the output pulse signal is less than 6 joules. <13> The system according to 12 above, wherein the pulse energy is less than 0.2 joules. <14> The system according to 12, wherein the output pulse signal includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof. <15> The system according to any one of 11 to 14, further comprising a cardioverter-version cable coupled between the defibrillator interface device and the plurality of cardiac leads. <16> How to perform the atrial cardioversion, The input terminal of the defibrillator interface device receives input pulses from the defibrillator via a cable connector that connects the defibrillator to the input terminal, The attenuation circuit converts the input pulse into an output pulse having a pulse energy of less than 6 joules, The output pulse is transmitted to the patient's heart via multiple cardiac lead wires that are in contact with the patient's heart. The method, including the method described above. <17> The method according to 16 above, wherein the pulse energy is less than 0.2 joules. <18> The method according to 16 or 17, wherein the output pulse includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof. <19> The input terminals of the defibrillator interface device are connected via the cable connector without physically contacting the input terminals with the defibrillator paddles. The method described in any of items 16 to 18 above, further including the method described in any of the above items. <20> The method according to any one of 16 to 19, wherein the attenuation circuit is electrically coupled to the input terminal without an intervening voltage discharge tube. <21> The method according to any of the above 16-20, wherein a successful atrial cardioversion is achieved at a defibrillation threshold greater than 0.1 J but less than 1 J, less than 0.9 J, less than 0.8 J, less than 0.7 J, less than 0.6 J, less than 0.5 J, less than 0.4 J, less than 0.3 J, or less than 0.2 J. <22> The method according to 21 above, wherein the successful atrial cardioversion is achieved using single-step energy delivery.

Claims

1. A defibrillator interface device, An input terminal configured to receive an input signal from a defibrillator when connected to the defibrillator, An output terminal configured to deliver an output signal containing at least one discrete pulse to multiple cardiac lead wires when connected to multiple cardiac lead wires, An attenuation circuit configured to convert the input signal to the output signal such that the pulse energy of each discrete pulse in the output signal is less than 6 joules, Equipped with, The defibrillator interface device is electrically coupled to the plurality of cardiac leads adapted to interface with the patient's heart. The defibrillator interface device is electrically coupled to the defibrillator via a cable connector without physically contacting the defibrillator paddles.

2. The defibrillator interface device according to claim 1, wherein the pulse energy is less than 0.2 joules.

3. The defibrillator interface device according to claim 1 or 2, wherein at least one of the discrete pulses of the output signal includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof.

4. The defibrillator interface device according to any one of claims 1 to 3, further comprising a cardioverter-version cable connected between the output terminal and the plurality of cardiac lead wires.

5. The defibrillator interface device according to any one of claims 1 to 4, wherein the input terminal is configured to connect to the defibrillator via a cable connector without physically contacting the defibrillator paddle.

6. A defibrillator interface device, An input terminal configured to be connected to a defibrillator, Output terminals configured to connect to multiple heart leads, An attenuation circuit configured to couple the input terminal to the output terminal, wherein the attenuation circuit comprises a plurality of resistors arranged in a voltage divider configuration, and each of the plurality of resistors exhibits a resistance of less than 1 kΩ, and Equipped with, The defibrillator interface device is electrically coupled to the plurality of cardiac leads adapted to interface with the patient's heart. The defibrillator interface device is electrically coupled to the defibrillator via a cable connector without physically contacting the defibrillator paddles.

7. The defibrillator interface device according to claim 6, wherein the input terminal is directly coupled to the attenuation circuit without an intervening voltage discharge tube.

8. The defibrillator interface device according to claim 6 or 7, wherein the resistor is selected such that the pulse energy of the output pulse generated by the attenuation circuit is less than 6 joules.

9. The defibrillator interface device according to any one of claims 6 to 8, further comprising at least one voltage discharge tube coupled in parallel between the attenuation circuit and the output terminal.

10. The defibrillator interface device according to any one of claims 6 to 9, wherein the input terminal is configured to connect to the defibrillator via a cable connector without physically contacting the defibrillator paddle.

11. It is an atrial cardioversion system, Defibrillator and, A defibrillator interface device according to any one of claims 1 to 10, which is electrically coupled to the defibrillator via a cable connection without physical contact with the defibrillator paddles, When coupled to the patient's heart, a plurality of cardiac leads electrically coupled to the defibrillator interface device deliver signals from the defibrillator interface device to the patient's heart. The atrial cardioversion system comprising the above.

12. The system according to claim 11, wherein the defibrillator interface device is configured to convert an input pulse signal from the defibrillator into an output pulse signal transmitted to the patient's heart, the pulse energy of the output pulse signal being less than 6 joules.

13. The system according to claim 12, wherein the pulse energy is less than 0.2 joules.

14. The system according to claim 12, wherein the output pulse signal includes a square waveform, a plateau waveform, a truncated exponential waveform, a curvilinear waveform, or a single-phase or two-phase form thereof.

15. The system according to any one of claims 11 to 14, further comprising a cardioverter-version cable coupled between the defibrillator interface device and the plurality of cardiac leads.

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