Surgery – Means for introducing or removing material from body for...
Reexamination Certificate
2000-01-14
2003-02-18
Walberg, Teresa (Department: 3742)
Surgery
Means for introducing or removing material from body for...
C604S508000, C604S511000, C128S898000
Reexamination Certificate
active
06520927
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to the conduction system of the heart and the creation of artificial lines of conduction in the wall of the heart to reduce or eliminate cardiac dysrhythmias, for example atrial fibrillation and also to conduct normal impulses from the senatorial node to avoid the necessity of implanting an artificial pacemaker.
INTRODUCTION AND SUMMARY OF THE INVENTION
The conduction system of the normal heart involves impulse formation at the sinus node and impulse propagation through the rest of the heart. Automaticity, or the property of generating spontaneous depolarization to threshold, enables the SA and AV nodes to generate cardiac action potentials without any stimulus. Automaticity is also present in the left atrium and is thought to contribute to the cause of atrial fibrillation.
The SA node sets the pace because normally it has the fastest rate, which is why it is called the natural pacemaker of the heart. The impulse propagates from the SA note to the AV node and from there to the bundle of His (atrioventricular bundle, common bundle) and finally through the bundle branches of the interventricular septum to Purkinje fibers in the heart wall.
Failure of conduction along the pathways can cause various pathologies. A failure of conduction between the sinus node and the atrium will result in the arrhythmia known as SA block. Failure of conduction can also occur at the level of the connection between the atrium and ventricle. This would produce arrhythmias known as AV block. Establishment of a conduction pathway between these sites should prevent these forms of arrhythmias. This invention provides a means and method for creating conduction pathways between these sites to prevent AV and SA block.
Atrial fibrillation may be caused in part by the failure (partly or totally) of conduction from the AV node to the left atrium. This would reduce the regulating effect of the AV node impulse on the left atrium and leave the areas of automaticity in the left atrium to initiate impulses independently of AV regulation, or in competition with residual AV impulses. The establishment of a conduction pathway from the AV node to the left atrium may prevent atrial fibrillation without recourse to ablative surgery and the implantation of artificial pacemakers. This invention provides a method and a means to provide artificial conduction pathways between these sites. This method would address the cause of fibrillation more directly than present methods.
Another approach to treating atrial fibrillation would be to create a network of pathways, for example in a grid pattern, that would in effect short circuit the impulses or isolate them into small areas, before they are able to propagate sufficiently to cause fibrillation. This grid pattern would be imparted into the walls of the fibrillating atria. Another pattern might be an array of spiral patterns that would act as a capacitor and dissipate the unwanted impulses. These spiral patterns could be connected to each other or disconnected or some of both. Interleaved X's or spider patters might also be effective.
Conduction through the tissue can also be affected by the orientation of cells forming the tissue. The cells favour transmission in a direction that follows the line joining the gap junctions between the cells and this can cause the impulse to travel through the heart muscle at different rates and in diverging directions. If these impulse fronts later merge or “reenter”, from different directions they cause the tissue fibrillate. The establishment of conduction pathways that would even-out the speed of the impulse front through the heart tissues should reduce fibrillation due to reentry. Angina might also be treated by establishing conduction pathways in the walls of the hears where angina pain is experienced.
What is needed then is a method to create conduction pathways between various parts of the heart. Conduction pathways generally being lines or fields along which or through which conduction is favoured or modified.
The use of carbon as a means of reducing resistance of the skin tissue to electrical impulses by tattooing carbon into the skin tissue for the purpose of attaching diagnostic sensors was described by S. A. Hoenig, P. L. Gildenberg and K. S. Krishna Murthy,
Generation of Permanent, Dry, Electrical Contacts by Tatooing Carbon into Skin Tissue
, IEEE Transactions on Biomedical Engineering, Vol. BME-25, No. 4, July 1978, Pages 380-382. The carbon with fluid carrier was injected into the skin with a syringe having a standard hollow needle. It was found that this method produced better results that standard reciprocating tattoo electrical appliances.
What has not been appreciated until now is that the hearts conductive system can be selectively modified by impregnating materials that impart particular electrical properties to the tissue. This approach will essentially rewire the heart.
Pathways or fields of conduction can best be created by impregnating the tissue with materials that enhance the particular electrical properties being sought. In most cases what will be sought is greater conduction; but in other cases greater impedance or insulation may be sought.
The location of the pathways that are most beneficial will depend upon the electrophysiology of the particular heart being treated. As three dimensional imaging becomes more refined, the conductance pathways of a heart may be studied in greater detail and more sophisticated strategies developed to alter and improve these preexisting pathways with artificial pathways that are described in this invention.
The artificial conduction pathways that are the subject of this patent can be applied by different methods depending on the location and pattern of the pathways that the surgeon wishes to create. Open heart surgery will give the surgeon the most flexibility in applying the pathways and if open heart surgery is necessary due to the location of the pathways required, a simple syringe will be suitable for most cases. In other cases the paths can be applied with a automated syringe that is described in this patent and forms a part of this invention. This hand-held automated syringe can apply any pattern to the inner or outer surface of the walls of the heart, although in most cases the inner pathways will be created on the inside of the heart. While tattooing instruments exist such as those described in U.S. Pat. No. 5,401,242 of Dr. Harold Yacowitz, the existing systems do not permit real-time adjustments in needle depth, amount of material delivered, or changes in the part of the stroke that material is delivered. The automated syringe that is a preferred embodiment of this invention can produce conductive tracts of varying depth, varying densities of material deposited, all without stopping to adjust the instrument. No other system can do all these things.
If a syringe is used, the pathway of conductive materials can be applied by a number of insertions with concomitant injections of a desired amount of conductive material. This series of injections can form a pathway or field, depending upon what is required at various depths in the tissue. This method would be similar to tattoo methods, except that it is not automated, but allows for more control of the pattern of the pathway and field, its extent and depth at various points. This methods would be used of creating conduction pathways close to the surface of the interior heart walls.
The second method of applying a pathway to the heart tissue would be more direct and involve creating an approximately continuous ribbon of conduction material. This would involve inserting the syringe, usually a relatively long distance, and injecting the conducting material while inserting the needle or withdrawing it, or both. The conductive material can be continuous or discontinuous, depending upon what is required. This would be controlled by the surgeon's application of the syringe plunger, or activation of a pump. This method typically would be used for establishing a conductio
Dahbour Fadi H.
Walberg Teresa
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