Surgery – Diagnostic testing – Structure of body-contacting electrode or electrode inserted...
Reexamination Certificate
1999-06-14
2001-10-23
Dvorak, Linda C. M. (Department: 3739)
Surgery
Diagnostic testing
Structure of body-contacting electrode or electrode inserted...
C600S585000, C606S041000, C607S122000
Reexamination Certificate
active
06308090
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a medical device and its use for cardiac mapping and ablation. More particularly, this invention relates to devices and methods for coronary sinus mapping as a diagnostic device, and for coronary sinus ablation in the treatment of atrial arrhythmia indications.
BACKGROUND OF THE INVENTION
Symptoms of abnormal heart rhythms are generally referred to as cardiac arrhythmias, while an abnormally rapid rhythm is referred to as a tachycardia. The present invention is concerned with the diagnosis and treatment of tachycardias, which are frequently caused by the presence of an “arrhythmogenic region” or an “accessory atrioventricular pathway” close to the inner surface of the atrium of a heart. The heart includes a number of normal pathways, which are responsible for the propagation of electrical signals from the upper chamber to the lower chamber, and which are necessary for performing normal systole and diastole function. The presence of an arrhythmogenic region or an accessory pathway in the atria can bypass or short circuit the normal pathway, potentially resulting in very rapid heart contractions, referred to here as atrial flutter. Atrial flutter is generally characterized by a saw tooth pattern with negative deflections in inferior leads of the ECG, while the atrial rate is in the range of 240-340 beats per minute.
Treatment of atrial flutter may be accomplished by a variety of approaches, including drugs, surgery, implantable pacemakers/defibrillators, and catheter ablation. While drugs may be the choice of treatment for many patients, they only mask the symptoms and do not cure the underlying causes, and they may also cause side effects. Implantable devices only correct the arrhythmia after it occurs. Surgical and catheter-based treatments, on the other hand, will actually cure the problem, usually by ablating the abnormal arrhythmogenic tissues or the accessory pathways responsible for the tachycardia.
There are, however, several drawbacks of the current mapping catheter as a device to assist in locating areas of aberrant electrical conduction for the catheter-based ablation of coronary sinus or pulmonary ostia. One of the major problems lies in the unstable positioning of the catheter inside the right atrium or about the pulmonary veins of the heart. When a catheter is not stabilized, the heart's electrical conduction pattern is difficult to map and establish. Furthermore, the catheter shall have a longitudinally stretchable/compressible soft tip portion so that the shock from contacting the catheter tip on the tissue is absorbed.
Therefore there is a need for an improved catheter having a capability of longitudinally stretchable/compressible to be used in coronary sinus mapping as a diagnostic device, and also used in coronary sinus ablation in the treatment of atrial flutter and atrial fibrillation indications.
SUMMARY OF THE INVENTION
In general, it is an object of the present invention to provide a catheter and a catheter-based method that is used for mapping, pacing, and ablation of the coronary sinus. It is another object of this invention to provide a method for mapping, pacing, and ablation of the coronary sinus, using a catheter comprising a plurality of electrodes, a pre-shaped tip section having an appropriate transition angle, and an appropriate length of the pre-shaped tip section. It is a further object of the present invention to provide a catheter having longitudinally stretchable and compressible soft tip section so that the catheter tip moves and rebounds longitudinally.
The “transition angle” is defined as the angle of the catheter shaft where the distal section protrudes from a catheter plane, wherein the catheter plane is the one formed by the deflected catheter. In one embodiment, the appropriate length of the pre-shaped tip section is preferably 20 to 40 cm. The “length of the pre-shaped tip section” is the length of the catheter shaft from the point of the beginning of the transition angle to the distal end of the catheter shaft. In another embodiment, the number of electrodes is preferably more then twenty. And yet, in still another embodiment, a reference electrode, which is one of the above-mentioned electrodes, is located about 20-40 cm from the distal tip of the catheter, wherein the reference electrode is to be positioned at the wall of the inferior vena cava during procedures.
A catheter of this invention for mapping the electrical conduction pattern of the coronary sinus in the right atrium of the heart may comprise an elongate tubular element having a tip section, a distal end, a proximal end, and at least one lumen extending therebetween, wherein a plurality of electrodes is disposed on the tip section; a pre-shaped tip section having an appropriate transition angle; an appropriate length of the pre-shaped tip section; a handle means attached to the proximal end of the elongate tubular element; a steering mechanism located at the handle means, wherein the steering mechanism is to cause at least one deflection for the tip section; and said tip section comprising a longitudinally stretchable/compressible soft portion at about the distal end of the elongate tubular element, wherein the stretchable/compressible soft portion has capability of moving and rebounding longitudinally.
The pre-shaped tip section has preferably a transition angle of 30 to 60 degrees. More preferably, the transition angle is between 40 and 50 degrees. In one embodiment, the stretchable and compressible portion comprises a supporting coil, spring, a superelastic supporting coil, and the like wherein a distal end of the supporting coil is attached to about a distal end of the stretchable/compressible soft portion and a proximal end of the supporting coil is attached to about a proximal end of the stretchable/compressible soft portion, and wherein said soft portion is at a stretchable state so that the stretchable/compressible soft portion has capability of moving and rebounding longitudinally. In another embodiment, the stretchable/compressible soft portion has a braided coil or a braided superelastic coil, and wherein the braided coil is at a stretched state so that the stretchable/compressible soft portion has capability of moving and rebounding longitudinally.
The stretchable/compressible portion of the elongate tubular element may be made of a material selected from the group consisting of silicones, polyurethanes, fluoroelastomers, nylons, porous plastic materials, and the like. Any other man-made material that is stretchable and compressible may be used for the stretchable/compressible portion of the elongate tubular element of the present invention.
These objects, as well as others, are further provided in a method for the mapping and the pacing of the coronary sinus in the right atrium of the heart comprising the steps of: a) inserting a catheter into the right atrium of the heart, the catheter having a plurality of electrodes, a pre-shaped tip section having an appropriate transition angle and an appropriate length of the pre-shaped tip section; b) deflecting the tip section inside the right atrium, wherein the inferior vena cava wall and the upper right atrium wall are used as anchoring points of stabilizing said tip section to position the distal end in the coronary sinus; c) exposing the electrodes to the endocardial tissues around the coronary sinus; and d) mapping the surface of the endocardial tissue, including the coronary sinus site, wherein the mapped electrical conduction pattern is used to assist in locating the areas of aberrant electrical conduction, and to assist the catheter-based ablation of atrial flutter indications.
In another embodiment, RF energy is applied to the endocardial tissue surrounding the plurality of electrodes by delivering the RF energy through electrical conducting means to said electrodes to effect ablation of the coronary sinus.
REFERENCES:
patent: 5462545 (1995-10-01), Wang et al.
de la Rama Alan
Tu Hosheng
Dvorak Linda C. M.
Irvine Biomedical , Inc.
Ruddy David M.
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