Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-10-14
2001-08-28
Getzow, Scott M. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C607S005000
Reexamination Certificate
active
06282445
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cardiac assist system for helping a heart to properly function. More particularly, the invention relates to a cardiac assist system that applies compressive force to assist the heart in properly contracting, and also applies electrical energy to the heart when needed, such as when the heart is fibrillating.
2. Discussion of the Related Art
The human heart is a very complicated organ that relies on both mechanical and electrical operation to properly function. Over time, the electrical pathways in the heart (which sequentially cause the atria and ventricles to contract) may fail, thereby causing the heart to lose its rhythm, which is known as arrhythmia. In that event, the ventricles will contract at improper times, and as a result the quantity of blood output by the heart decreases. In addition, in some failing hearts the heart muscles do not sufficiently contract the ventricles, also resulting in a dangerous reduction in the amount of blood flow. Furthermore, some hearts occasionally fibrillate (i.e., the muscles of the heart rapidly and irregularly contract), resulting in a lack of synchronism between the heart beat and pulse beat. If not remedied, all of these ailments can cause serious problems, including death.
Numerous attempts have been made to assist diseased or failing hearts by applying external pressure directly to the heart. One such example is direct manual compression of the heart by a person's hand during open chest cardiopulmonary resuscitation. Often, however, the patient requires cardiac or circulatory support for extended periods of time, such as hours, days, or even weeks, and it is quite difficult, if not impossible, for medical personnel to apply a rhythmic pulsating pressure for such an extended period of time. Further, it is difficult, if not impossible, to apply by hand a uniform compressing force to a significant portion of the exterior ventricle surface of the heart. Moreover, the chest should not be opened for extended periods of time because of, among other things, the increased risk of infection. As such, manual manipulation of the heart is not a solution to the problem in most cases.
To overcome this problem, different types of mechanical devices have been developed which intermittently apply external pressure directly to the heart. Some of these devices utilize an inflatable liner that surrounds the heart. For example, U.S. Pat. No. 5,119,804 to Anstadt discloses a cup that is provided with an elastomeric liner. The heart is held in place within the liner, which is cyclically inflated and deflated to apply external pressure to the heart.
In addition, it has been found that these inflatable liner devices can act as electrical insulators to insulate the heart from externally applied energy, such as the energy from defibrillation paddles. Therefore, when such a device is in place over the heart (which can be on the order of days or even weeks), the heart in many instances cannot be defibrillated, if the need arises. It is believed that the polymer material of the liner device, and the air in the liner when it is inflated, act as insulators around the heart, preventing the defibrillation current from reaching the heart.
Accordingly, it will be apparent that there continues to be a need for a cardiac assist system that assists the ventricles to contract in a natural and safe manner, and which also can apply electrical energy to the heart, for example in cases where the heart is fibrillating. The present invention addresses these and other needs.
SUMMARY OF THE INVENTION
Briefly, and in general terms, the present invention in one illustrative embodiment is directed to a cardiac assist system that includes a ventricular assist device adapted to be extended over a portion of a patient's heart to assist the ventricles of the heart to contract. One or more passive, stimulating electrodes are mounted on the ventricular assist device in selected locations, such that when the ventricular assist device is extended over the heart, the stimulating electrodes are in close proximity, or contact, with the surface of the heart. The system further includes one or more external pick-up electrodes that collect externally applied energy and conduct that energy to the one or more stimulating electrodes via conductive leads. The external electrodes may be mounted on the outer surface of the ventricular assist device, or can be located elsewhere inside the patient's body, or even at a location outside of the patient's body. The externally-applied energy will typically be supplied by standard defibrillation paddles located outside the patient's body. Thus, with the present invention, externally applied defibrillation energy can be applied to the heart, even when an insulating ventricular assist device is extended over the heart.
Thus, in one illustrative embodiment the present invention comprises a defibrillation system for defibrillating a heart, including at least one pick-up electrode located inside a patient's body, the pick-up electrode being responsive to the application of external energy to the patient to collect at least a portion of the energy, and at least one stimulating electrode in electrical communication with the at least one pick-up electrode, the stimulating electrode being disposed at a predetermined location adjacent to the heart and responsive to receipt of collected energy from the pick-up electrode to apply the energy to the heart.
In another illustrative embodiment the present invention is directed to a cardiac assist system comprising: a ventricular assist device adapted to be placed over at least a portion of the heart and operative to intermittently apply a compressive force on the ventricles of the heart to force the ventricles to contract; at least one stimulating electrode connected to the ventricular assist device at a predetermined location thereon to be located adjacent the heart when the ventricular assist device is placed over the heart; and at least one pick-up electrode electrically connected to the at least one stimulating electrode, the pick-up electrode being operative to collect externally applied energy and to conduct the externally applied energy to the stimulating electrode to defibrillate the heart.
The present invention, in yet another illustrative embodiment, is directed to a method of defibrillating a human heart, comprising: applying defibrillation energy to a patient from a location external to the patient; receiving the externally applied energy at one or more electrodes inside the patient's body and spaced from the heart; and conducting the received energy to one or more electrodes in contact with the patient's heart to apply the energy to the heart.
REFERENCES:
patent: 4651716 (1987-03-01), Forester et al.
patent: 4925443 (1990-05-01), Heilman et al.
patent: 5498228 (1996-03-01), Royalty et al.
Easterbrook, III William A.
Guttman Michael
Levin Howard R.
Reinhardt Robert W.
Cardio Technologies, Inc.
Darby & Darby
Getzow Scott M.
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