Surgery – Internal organ support or sling
Reexamination Certificate
1999-05-28
2001-03-20
Gilbert, Samuel G. (Department: 3736)
Surgery
Internal organ support or sling
Reexamination Certificate
active
06203490
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a myocardial stabilizer for immobilizing a particular part of a working heart, so as to enable an indicated operation on heart wall structures, particularly the coronary arteries.
For illustration of the invention there may be considered the most frequent cardiosurgical operation, which is indisputably a direct revascularization of the myocardium through operation on coronary arteries. Most of these operations are still performed using extra-corporeal circulation on an arrested heart. In recent years, however, a method has been used more and more often in indicated cases where reconstruction, i.e., peripheral anastomosis of vascular substitute, is feasible on a working heart without its arrest and without using extra-corporeal circulation. This means, of course, the risk in these operations is taken to another, substantially lower level in order.
Anastomosis of the vascular substitute, most often of the patient's veins themselves, is a delicate operation. When applied to as delicate an artery as the coronary artery, a necessary and sufficient condition is a perfect technical execution for the operation to be viewed as successful. The coronary artery is located under the epicardium, and its movement is therefore connected with the heart muscle movement itself. Since the frequency of cardiac beats cannot be decreased below a certain level, this method has its physiological limits. Thus, there is a certain contradiction in the necessity of a perfect placing of stitches into edges of a longitudinally opened coronary artery, on the one hand, and a continuous movement of the operation field, i.e., the heart and artery, on the other hand.
At the present time, there are two devices which are applied to immobilize the portion of the coronary artery to be operated on during the operation. In principle, these involve something like a fork with arms either joined together or individually controlled. One method brings calm to the operation field by applying pressure on a specific point of the cardiac muscle. Another method consists in contacting a respective area of the cardiac muscle with a surface of the device which is provided with suction holes, so that the muscle area is sucked into the device at the contact point of the device and the cardiac muscle.
These devices are much in use at the present time. However, they have their disadvantages. Thus, the handling of a device using pressure cannot exclude the possibility of pressure damage to the cardiac wall structures, particularly with longer operations and the application of higher pressures. Other disadvantages of these methods include limits on pressure adjustment, the tendency of a moving cardiac muscle to slip out from under the device, and the impossibility of using these devices, in practice, for all coronary arteries now being reconstructed, regardless of their anatomical position.
The device using a vacuum or suction principle is an improvement over the previous one. The stabilizer OCTOPUS™ is considered the most acceptable. It is characterized by two independent flexible arms with terminals of various forms provided with various numbers of suction holes. The bases of the arms and the whole suction mechanism are placed outside the operating table, and the surgeon handles only the terminals, which he can place as desired and then clamp the terminal walls on a given area by connecting the suction. This enables access even to coronary arteries on the adverse side of the heart.
A disadvantage of this procedure is again the possible damage of the cardiac muscle structures by negative pressure and generation of slight subepicardial and myocardial bleeding, the long-term consequences of which are not yet quite clear. In principle, there arises a range of small phenomena which are colloquially referred to in some places as “suckflecks.”
Both of these devices are, in their various modifications, also relatively quite expensive. Therefore, there is a need in the art for a myocardial stabilizer to immobilize a particular part of a working heart to enable an operation on the coronary arteries, without the disadvantages of the above-described prior art devices and procedures.
BRIEF SUMMARY OF THE INVENTION
The above-described deficiencies of the prior art are overcome or alleviated by the device of the present invention for local stabilization of the cardiac muscle, which includes two physically independent but functionally dependent parts. One part comprises a permanent magnet or adjustable electromagnetic core, roughly resembling a fork, having a bent arm or terminal end which forms a contact surface for application to an external surface of the heart, with the contact surface having sufficient size or length to immobilize the desired area of the heart. The second part comprises a fiber made of ferromagnetic, magnetically hard material which is drawn through the myocardium at a desired point and in the desired length of the area to be immobilized.
After drawing or inserting the ferromagnetic fiber into the desired area of the cardiac muscle, the contact surface of the magnet is placed over the area of the myocardium containing the ferromagnetic fiber, so that the magnetic force attracts or draws the fiber toward the contact surface of the permanent magnet or electromagnet. As a result, the contact surface of the magnet and the ferromagnetic fiber hold the portion of the myocardium between them and thereby immobilize this area of the cardiac muscle. By providing two ferromagnetic fibers at opposite edges of the myocardium to be immobilized, with the two fibers being spaced at approximately the same distance as two magnet contact surfaces, so that each ferromagnetic fiber has its independent magnet to which the fiber is attracted, a good immobilization of the area of the heart muscle bounded by these fibers can be achieved.
The device according to the invention uses a magnetic induction effect in a stationary magnetic field. Both the principle of the invention and its practical use are relatively simple. A model stationary magnetic field is realized approximately by the field between discordant extensive (oppositely charged) poles of a magnet. The magnetic field is characterized by a vectorial variable called magnetic induction. The unit of magnetic induction is TESLA (T); and the magnitude of the magnetic induction of the field, e.g., with current permanent magnets, is 10
−1
to 10
−2
T. Of course, in principle, there are magnets, particularly electromagnets, which can be made whose field size values reach a magnitude on the order of units of TESLA. For reference purposes, it is noted that the earth within our geographic latitudes has a magnetic induction on the order of 10
−5
T.
It is not critical for the device according to the present invention how the magnetic field is generated, whether by permanent magnet or by electromagnetic induction, either with a classic electromagnet or solenoid. The theory and practice of using a magnetic field are widely known per se in many fields, and the principle of its effect is always the same.
The size of the magnetic induction depends to a considerable extent on the s.c. environmental permeability within the magnetic field. This can be demonstrated by the example of an electromagnetic coil. Thus, steel has a very high relative permeability, and therefore the magnetic field induction of a coil wound on a closed steel core is much higher than for the same coil without a core. Three types of materials may be considered according to the values of their relative permeability, depending on the arrangement of the magnetic fields of the individual atoms. The highest values are those of s.c. ferromagnetic materials, whose atomic arrangement considerably magnifies the magnetic field. For example, the relative permeability of steel is &mgr;r=8,000.
Even a weak external magnetic field on a ferromagnetic material is sufficient to generate such an arrangement of atoms that the magnetic field becomes magnified. The materia
Akin Gump Strauss Hauer & Feld L.L.P.
Gilbert Samuel G.
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