Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1999-07-09
2001-12-11
Schaetzle, Kennedy (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C607S129000, C607S130000, C607S116000, C607S149000, C600S374000, C600S375000, C600S372000, C600S386000
Reexamination Certificate
active
06330480
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION AND PRIOR ART
The present invention relates to an electrode device according to the preamble of claim
1
.
Such electrode devices may be used in many different applications for medical short and/or long term treatment and diagnosis. Even if the following description first of all is directed to the problem occurring in relation with heart pacing and in particular atrium pacing, it is to be noted that the present invention not in any way is restricted to these applications but may be used in all situations where an electrode is to be attached to a body part of a patient. The invention is applicable to human beings as well as animals. The word pacing means stimulation of a body part by means of electric impulses at a desired frequency.
After a heart surgery, a too low and thus a suboptimal heart frequency is often observed among many patients. Usually, the heart frequency is then increased by breaking a so called beta blockade with a competitive anti-beta blocker or by drugs with a frequency increasing effect. The problem with these drugs is that they at the same time increase the myocardial oxygen consumption (in comparison with pacing only), which leads to an increased myocardial injury when the perfusion of the heart tissue is restricted or compromised, which for example is the case after an infarct. A better alternative is to stimulate directly the function of the heart (pacing) via external pacemaker electrodes attached to the surface of the heart, which causes less influence on the myocardial oxygen consumption than with inotropes/beta-agonists. The pacemaker electrodes are attached to the surface of the atrium and/or the ventricle and are removed by being pulled out through the skin. In the cases, when the conduction between the atrium and the ventricle is intact, which is the case at approximately 80-90% of all patients, electrodes on the surface of the atrium (pacing of atrium) are used in the first place. In this case, the heart's own conduction is used and thereby a synchronising according to the body proper between the atrium and the chamber is obtained.
However, in the case that the conduction between the atrium and the ventricles does not work, so called AV-block III, ventricle pacing has to be used. This occurs above all in connection with the operation of the mitral or aortic valve, since a swelling, bleeding or more permanent injury with respect to the conduction between the ventricles and the atria then may occur. Frequently, these problems with the conduction are temporary and they decrease after a few days when the swelling of the tissue has gone down. In these cases, ventricle pacing is used but furthermore atrium pacing ought to be used and the ventricle pacing ought to be synchronised to the latter in order to obtain an optimal effect. In particular, these measures concern patients with thickened ventricle walls, so called ventricular hypertrophy (due to hypertension or for example aortic stenosis) or patients with a seriously reduced function of the ventricle. These two categories of patients are highly dependent on the contraction of the atrium. A poorly functioning left ventricle is stiff and is not so easily filled as a healthy ventricle. The contraction of the atria leads to an improved filling of a stiff ventricle and this may be decisive in case of a marginal heart function directly after a heart surgical operation. The cardiac output of the heart may be increased with approximately 25% by stimulating the atria synchronisely with the ventricles in comparison with a mere stimulation of the ventricle.
Thus, it may be established that much can be gained by regular atrium pacing of patients after heart surgical operations, irrespective of the existence of a conduction block. However, due to the structure of the tissue of the atria and due to the construction of the electrodes and the method by which they are attached in the atrium, external atrium electrodes are often not used during heart surgery.
The most common a trial pacemaker electrodes consist of simple wires which, via thin sutures, are attached to the surface of the atrium by sewing. It is often difficult from a surgical point of view to sew such electrode wires without the appearance of a bleeding and at the same time to obtain a low electrical threshold value, i.e. a voltage required to provide stimulation of the heart. The technical survival of these electrodes is usually short, often not even twentyfour hours due to a quickly increasing threshold value, i.e. the voltage has to be increased to maintain the stimulating effect. Furthermore, there is a considerable risk for bleedings during this time period and a certain risk for new bleedings when the electrodes are removed.
It is also known to use an electrode with a silver contact from which a helically shaped plastic wire extends. The plastic wire is provided with a needle at its end and is sewed onto the tissue by being extended backwards and forwards through the atrium wall. In such a way the silver contact is kept in place and abuts to the wall closely. After sewing of the plastic wire, the needle is removed. This electrode has a longer time of survival and leads to a lower threshold value in most cases compared to prior technique. A disadvantage with this technique is the risk for dislocation and the fact that the electrode is not easy to attach in such a way that a low threshold value is obtained without any damage of the tissue with a following bleeding.
U.S. Pat. No. 4,144,889 discloses an electrode device intended to be attached to the heart and comprising a releasable cable member and an electrode member for gripping the heart tissue. This document discloses two different embodiments for the attachment of the electrode member. According to the first one, the electrode member is sewed by means of a suture, which extends into the heart tissue and according to the other embodiment, the electrode member is clamped by means of two clamping parts, These clamping parts are mounted to a metal strip forming the electrode proper for transferring a voltage to the heart. The metal strip is embedded between two silicon rubber plates. The first clamping part is attached to the side of the strip facing the heart tissue and bent to a C-shape and is intended to penetrate the heart tissue when the electrode device is applied thereto. The other clamping part is located on the opposite side of the metal strip and has been given a folded shape by means of “spring tempering”. The other clamping part projects from the metal strip through holes in the outer silicon rubber plate. By application of the electrode device, the other clamping part is compressed in such a manner that the metal strip is compressed and the first clamping part penetrates the hearts tissue.
To sum up, the lack of suitable attachment devices and attachment methods leads to the matter of fact that the atrium pacing is not used in an optimal way in connection with heart surgery in spite of the medical advantages this treatment could give.
SUMMARY OF THE INVENTION
The object of the present invention is to remedy the above discussed problems and to provide a device affording a simpler way of attachment of an electrode to a body part. Furthermore, it is aimed at a reliable attachment and a reduced risk for injuries and bleedings on the body part in relation to prior known methods.
This object is achieved by the electrode device initially mentioned and which discloses the features specified in the claim
1
.
Consequently, the solution of the invention offers a very simple way of attaching an electrode to a body part. By such a clamping member, the electrode may be attached very quickly to the body part by compressing the clamping member by hand or by means of a tool, onto a part of the tissue of the body part. Since it is not necessary for such a clamping member to extend through the tissue of the body member, which for example is the case when the electrode is attached by means of sewing technique, the risk for bleedings in the body part is reduced. T
Bengtsson Lars
Engblom Carl
Van der Linden Jan
Welander Bengt
Cardia Innovation AB
Greer, Burns & Cain, Ltd.
Schaetzle Kennedy
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