US RE38705 E1
An electro-stimulation device includes a pair of electrodes for connection to at least one location in the body that affects or regulates the heartbeat. The electro-stimulation device both electrically arrests the heartbeat and stimulates the heartbeat. A pair of electrodes are provided for connection to at least one location in the body that affects or regulates the heartbeat. The pair of electrodes may be connected to an intravenous catheter for transvenous stimulation of the appropriate nerve. A first switch is connected between a power supply and the electrodes for selectively supplying current from the power supply to the electrodes to augment any natural stimuli to the heart and thereby stop the heart from beating. A second switch is connected between the power supply and the electrodes for selectively supplying current from the power supply to the electrodes to provide an artificial stimulus to initiate heartbeating. In another aspect, the invention is directed to a method for arresting the beat of a heart in a living body comprising the steps of connecting the pair of electrodes to at least one location in the body that affects or regulates the heartbeat and supplying an electrical current to the electrodes of sufficient amplitude and duration to arrest the heartbeat. The device may also serve to still the lungs by input to a respirator or by stimulation of the phrenic nerve during surgical procedures.
1. A method for stimulating desired nerve fibers within a living body, comprising the steps of:
advancing a lead carrying an array of electrodes through the vascular system to a point within a vein adjacent the nerve fibers to be stimulated;
selectively employing electrodes within the array to direct electrical pulses applied to the electrodes to the desired nerve fibers; and
delivering electrical pulses to the selectively employed electrodes.
2. A method for stimulating desired nerve fibers within a living body, comprising the steps of:
advancing a lead carrying electrodes through the vascular system to a point within an internal jugular vein adjacent the nerve fibers to be stimulated;
employing electrodes to direct electrical pulses applied to the electrodes to the desired nerve fibers; and
delivering electrical pulses to the employed electrodes.
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10. An apparatus for stimulating desired nerve fibers within a living body, comprising:
a transverse lead carrying an array of electrodes locatable in the vascular system at a point within a vein adjacent the nerve fibers to be stimulated;
switch means for selectively employing electrodes within the array to direct electrical pulses applied to the electrodes to the desired nerve fibers; and
pulse generator means for delivering electrical pulses to the selectively employed electrodes.
11. An apparatus according to
12. An apparatus according to
Continuation in part of application Ser. No. 08/640,013 filed on Apr. 30, 1996 now abandoned.
1. Field of the Invention
This invention relates to methods and devices for controlling the operation of the human heart or other organs by means of electrical stimulation, and more particularly, to devices for electronically slowing or stopping the heart.
2. Description of the Related Art
In some surgical procedures, such as coronary bypass surgery, it is necessary to stop the heart from beating so that the surgeon can perform necessary techniques. The use of a cardioplegia solution to stop the heart from beating without rerouting the blood would permit the surgeon to accomplish the required task without interference from heart movement. However, this is not a viable approach, since the body needs a constant supply of oxygen. Thus, there exists a need to temporarily slow down or stop heart movement during minimally invasive CABG or other surgical procedures to permit the surgeon to accomplish the required task. In the context of treatment of the heart by means of implanted medical devices, such as pacemakers, defibrillators and drug dispensers, it is also sometimes beneficial to slow or temporarily stop the heart, either for diagnostic or therapeutic purposes.
It has been known in the past to stimulate the vagal nerves by invasively dissecting the major nerve bundle and placing a spiral or enveloping nerve-type cuff around the nerve bundle. The nerve fibers are then directly stimulated by electrical field to achieve reduction in epilepsy, heart rate slowing, and potential blood pressure changes. In a study entiteld “Selective Stimulation of Parasympathetic Nerve Fibers to the Human Sinoatrial Node”, Circulation, Vol. 85, No. 4, April 1992, it was reported that cardiac parasympathetic nerve fibers located in an epicardial fat pad at the margin of the right atrium, the superior vena cava, and the right pulmonary vein in humans could be electrically stimulated to affect the heart rate. Additional reference is found in PACE October 1992 Vol. 15, No. 10, pt. 11, pages 1543-1630 on the use of nerve cuff stimulation of the vagal nerves (left side) in humans for reducing of epilepsy and it's side-effects. Additional uses for electical nerve stimulation have been disclosed for the prevention of arrhythmias, alteration of hemodynamics, stimulation of the hypoglossal nerve for sleep apnea, stimulation of the stomach, and control of the sphincter for blader or colon evacuation.
Currently, only nerve cuff-type electrodes or impalement-type electrodes are used for nerve stimulation, other than in the spinal cord. These types of electrodes can potentially cause irreversible nerve damage due to swelling or direct mechanical damage of the nerve. The placement of these electrodes either around the nerve bundle or into the neural perineum also poses a significant risk. The electrode placement is usually perfomred through very invasive surgery which in and of itself produces a high risk to nerve damage, and would be self-defeating when performing minimally invasive surgery. However, it has been demonstrated that the paraympathetic nerve fibers associated with the heart can also be stimulated by means of electrodes located on transvenous leads, as in U.S. Pat. No. 5,243,980, issued to Mehra et al, U.S. Pat. No. 5,507,784, issued to Hill et al and U.S. Pat. No. 5,356,4215, issued to Bardy et al. The use of transvenous electrode leads to stimulate parasympathetic nerves associated with the heart is also discussed in the article “Neural effects on Sinus Rate and Atrial Ventricular Conduction Produced by Electrical Stimulation From a Transvenous Electrode Catheter in the Canine Right Pulmonary Artery, by Cooper et al., published in Circulation research, Vol. 46, No. 1, January 1980, pp. 48-57.
In conjunction with spinal cord stimulation, electrodes or electrode arrays located on pliant electrode pads are often employed. Recently, the ability to select from among various pairs of electrodes located on such electrode pads has been proposed to allow steering of the electrical field produced by the electrodes, as in U.S. Pat. No. 5,501,703, issued to Holscheimer, incorporated herein by reference in its entirety. Such electrode arrays offer additional possibilities to stimulate nerve fibers without direct and possibly damaging contact.
It is with these problems in mind that a new apparatus and mehtod have been developed for electrically stimulating or destimulating certain nerves associated with the functioning of the heart or other organs which can be combined with certain surgical procedures or incorporated into implantable medical devices. According to one aspect of the invention, the invention is embodied in an electro-stimulation device includes at least two electrodes for connection to at least one location in the body that affects or regulates the heartbeat. At least one switch is connected between a power supply and the electrodes for selectively supplying current from the power supply to the electrodes to augment the natural stimuli to the heart in order to control the beating of the heart, and preferably to stop the heart from beating. Preferably, the switch is a foot switch operable by a surgeon to free a surgeon's hands during surgery.
According to another aspect of the invention, the at least two electrodes are connected to an intravenous catheter for transvenous stimulation/destimulation of the heartbeat.
According to another feature of the invention, an electro-stimulation device for both electrically destimulating and stimulating the heart includes a pair of electrodes for connection to at least one location in the body that affects or regulates the heartbeat. A first switch is connected between a power supply and the electrodes for selectively supplying current from the power supply to the electrodes to augment the natural stimuli to the heart and thereby stop the heart from beating. A second switch is connected between the power supply and the electrodes for selectively supplying current from the power supply to the electrodes to provide an artificial stimulus to initiate the heartbeat.
In a further aspect of the invention, a method for arresting the beat of a heart in a living body includes the process of connecting a pair of electrodes to at least one location in the body that affects or regulates the heartbeat and supplying an electrical current to the electrodes of sufficient amplitude and duration to arrest the heartbeat. According to one aspect of the inveiton, the step of supplying an electrical current to the electrodes includes supplying an alternating current.
In yet further aspects of the invention, the invention is embodied in an external or implantable device which employs electrodes located on transvenous leads located in veins adjacent nerve fibers to be stimulated, in these aspects of the invention, the leads preferably carry an array of electrodes from which pairs of electrodes can be chosen in order to direct the electrical field appropriately with respect to the desired nerve fibers.
It is to be noted that with regard to the effect of the delivered nerve or other stimulus pulses relative to the action of the heart the phrase “stimulate the heart” and its derivatives as used herein refer to the initiation of the heartbeat through the application of electricity, while the phrase “destimulate the heart” and its derivatives refer to stopping or arresting the heartbeat through the application of electricity.
The iunvention will now be described with reference to the drawings in which:
Referring now to
A foot petal assembly 30 has a normally open heart stimulation foot switch 32 and a heart destimulation foot switch 34 that can be used as an alternative to switches 24, 26. The provision of a foot petal assembly permits the surgeon to control when the heart stimulation and destimulation occurs while leaving the hands free to perform other procedures. This also permits the surgeon's hands to remain sterile since contact with the housing 12 or switches 26, 28 is avoided. The foot pedal assembly 30 is connected via cable 36 to an electronic control device 50 (
A pair of electrodes 37, 38 are connected via a pair of leads 39A, 39B, respectively, to the electronic control device 50 for supplying electrical current to the heart during stimulation and destimulation. A second pair of electrodes 43A, 45A can also be connected via a pair of leads 43, 45, respectively, to the electronic control devices 50 for supplying electrical current to the phrenic nerve to control breathing during heart stimulation and destimulation. A lead 48 having a connector 49 may be provided in addition to or alternatively of the phrenic nerve electrodes 43A, 43B. The connector 49 interfaces with a respirator (not shown) and, upon stimulation or destimulation of the heart, sends a logic signal to activate or deactivate the respirator.
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With reference now to
When the electrodes are connected to other locations besides the heart, a series of current pulses is passed long enough through the tissue to augment any recurring natural heartbeat stimuli to stop the heart from beating. In has been found that a continuous pulse train for 10-30 seconds using a constant current of 10-100 mA in conjunction with a constant pulse width of 0.01-0.5 msec. and a frequency between 6 Hz and 50 Hz applied to the epicardial parasympathetic nerves is sufficient to augment the recurring natural heartbeat stimuli to stop the heart. When the electrodes are connected directly to the heart, it is preferred that a burst pulse width of current be applied instead of a continuous pulse train. Once activity from the heart is sensed, a burst pulse width having the same current amplitude and frequency as in the constant pulse width is applied during the repolarization phase. Typically, the burst pulse time will be less than the continuous pulse train to stop the heart. Preferably, the burst pulse is programmable for different burst times, current amplitudes, and frequency. Upon cessation of heart destimulation, the natural heart beat stimuli will typically occur again automatically a short time thereafter. The separate heart stimulation leads, therefore, provide an added safety feature in the event that the heart does not automatically restart. In order to stimulate the heart, if required, a series of current pulses are passed through the tissue to initiate the natural heartbeat stimuli. These current pulses are similar to those used in pacemakers.
In use, the electrodes 37, 38 are secured at an appropriate position on the patient 80 (FIG. 6). During open surgery or minimally invasive surgery, as the surgeon 82 performs various steps such as cutting, stitching, etc., one of the foot switches 32, 34 is pressed to initiate or stop the heartbeat as required. For example, the surgeon may wish to stop the heartbeat while making one or a plurality of stitches where movement of the heart would normally be a hindrance. The heart may then be stimulated either naturally or artificially through the present device to beat for a predetermined time to permit blood flow throughout the body and then be destimulated or stopped again to continue stitching. If desired, the electrodes 43A, 45A may be connected to the phrenic nerve and/or the connector 49 may be attached to a respirator to still the lungs during the surgical procedure. When the electrodes are attached to the phrenic nerve, a continuous pulse train having the range of values as discussed previously is sufficient for controlling lung movement.
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Although the catheters 100, 120 have been described with three or four electrodes, any number of electrodes may be provided, depending on the particular nerve stimulation application. For example, as shown in
In yet another embodiment, as shown in
The catheters 100-160 as shown in
Referring now to
An axial current distribution may be required in addition to or in place of the circumferential distribution, as shown in
The preferred use of the electro-stimulation device would be a transvenous implementation through standard transvenous implantation techniques such as those used to implant pace/sense leads into the heart. For the method of transvenous vagal stimulation in laproscopic/endoscopic/minithorascopic surgical coronary artery bypass graft (CABG) procedures, the use of vagal nerve stimulation provides a reversible, quick acting (like an on/off switch) method for slowing the heart rate.
Although the foregoing description relates to the stimulation/destimulation of the heart during surgical procedures, it is not intended that the invention be limited thereto. The electro-stimulation device could be provided with two or more electrode-welding catheters for use in multiple transvenous regions for the stimulation of different nerves. For example, a pair of catheters could be inserted into the internal jugular vein for stimulation of the right and left vagal nerve bundles. The right bundle could be used to elicit more specific heart effects and reduce heart rate and increase AV delay for antiarrhythmic and hemodynamic benefits; whereas the left bundle could be used to effect afferent vagal information and potentially reduce epileptic activity. An electrode-wielding catheter could be inserted into the very high internal jugular vein to stimulate the hypoglossal nerve and/or into the very low internal jugular vein or superior vena cava to stimulate the phrenic nerve for respiratory control. The stimulation of the phrenic nerve in conjunction with heart stimulation would insure that the blood is properly oxygenated during surgical procedures on the heart with intermittent heart destimulation. Likwise, catheters of the present invention could be inserted into the azygos or accessory hemizygous veins to stimulate the sympathetic nerves for increasing heart rate to altering DFT efficacy for antiarrhythmic and hemodynamic benefits. Other transvenous routes to nerve stimulation for functional purposes may also be applicable.
The electro-stimulation device may also have sepcificity for direction of neural stimulation in regards to the location of the vessel and the nerve bundle that is to be stimulated. For example, the phrenic nerve could be elicited on and off by a mere rotation of the transvenous catheter, depending on the location of the electrodes on the catheter and the resulting electric current density generated. In order to observe and control the amount of catheter rotation, a series of degree markings may be located on an outer circumference of the catheter at a position readily observable by the surgeon. Alternatively, the catheter may be associated with a rotary encoder to obtain a digit read-out of the amount of catheter rotation.
The electrodes of the intravenous catheters according to the present invention could also be used to manipulate the heart rate or hemodynamics in response to device sensors. In addition, in response to precursors of an arrhythmic event, the devices may stimulate either the sympathetic or the parasympathetic individually or in combination to attempt to delay or prevent the event. Alternatively, current may be applied to different pairs of electrodes as discussed above.
Although the use of catheters having electrodes permanently mounted thereto for temporarily manipulating or stimulating nerves accessibly through blood carrying vessels, it is to be understood that a more permanent nerve stimulation arrangement is possibly by fixing electrodes onto the inside of the vessel adjacent to the nerve to be stimulated. Thus, this new device in its preferred embodiment, eliminates the potential for direct nerve damage and reduces the invasiveness of the placement of the electrodes for direct neural stimulation in conjunction with implantable medical devices. Examples of how the present invention may be employed in the context of implantable medical devices are illustrated in
Electrode lead 304 has an array of electrodes as illustrated in
Pulse generator 600 is provided with an electrical lead 604 which carries adjacent its distal end 606 an array of electrodes as described in conjunction with
The embodiments of the invention illustrated in
Reasonable variation and modification are possible within the spirit of the foregoing specification and drawings without departing from the scope of the invention.