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WO1996039929A1 - Apparaus and method for treating cardiac arrhythmias with no discrete target - Google Patents
Apparaus and method for treating cardiac arrhythmias with no discrete target Download PDF
WO1996039929A1
WO1996039929A1 PCT/US1996/008164 US9608164W WO9639929A1 WO 1996039929 A1 WO1996039929 A1 WO 1996039929A1 US 9608164 W US9608164 W US 9608164W WO 9639929 A1 WO9639929 A1 WO 9639929A1
PCT/US1996/008164
1996-05-31 Application filed by Biosense, Inc. filed Critical Biosense, Inc.
1996-12-19 Publication of WO1996039929A1 publication Critical patent/WO1996039929A1/en
In the healthy heart, cardiac muscle cells are elec- trically stimulated to contract in a sequential, synchronized manner, the propagation starting in the sinus node in the right atrium and spreading through the heart as each cell stimulates neighboring cells. The activation of each muscle cell is followed by a period in which the cell is incapable of being stimulated again. This period is called the refractory period, and it functions to ensure a smooth contraction of the muscle and the efficient flow of blood through the chambers of the heart. In a patient with a cardiac arrhythmia, the propagation of the electrical stimulation of the muscle does not proceed as it should. The heart rate may be too fast or too slow, or the electrical stimulation of the heart may progress through an abnormal pathway. The abnormal pathways may be fixed or they may be functional, i.e., with no fixed circuit or focus.
There are several types of cardiac arrhythmias in which the presence of some fixed anatomical defect (such as non-conducting scar tissue left as a result of myocardial infarction) gives rise to the creation of an abnormal electrical pathway that may lead to the development of a sustained arrhythmia that would develop under the proper conditions. Current medical therapy of arrhythmias with fixed pathways includes ablation of the superfluous pathway. Such fixed anatomical pathways are localized using electro-physiological mapping of the cardiac chambers. In the minimally invasive procedures common today, cardiac electrical activation mapping is performed with the aid of x-ray transillumination (fluoroscopy) . For identifying the electrical activation sequence of the heart, the local electrical activity is acquired at a site within the patient's heart chamber using a steerable catheter, the position of which is assessed by transillumination images in which the heart chamber is not visible. Local electrical activation time, measured as time elapsed from a common reference event in the cardiac cycle to a fiducial point during the electrical systole, represents the local electrical information needed to construct the activation map data point at a single location. The location of the catheter tip is obtained by an x-ray transillumination that results in a 2-D projection of the catheter within the heart of a patient. Since the heart muscle is translucent to the radiation, the physician can locate a catheter tip position by comparing its shape to a set of known catheter shapes at different positions in the heart (usually after having seen two orthogonal projections) .
In another subset of cardiac arrhythmias, the patho- logic mechanism entails emergence of several functional, not anatomically fixed, superfluous electrical pathways. Therefore, ablation of one or more functional pathways in these arrhythmias cannot be curative, as different func¬ tional and superfluous pathways would emerge. Currently the treatment of patients suffering from arrhythmias of this category is limited to either anti-arrhythmic medication or implantation of an automatic cardiac defibrillator. In selected cases successful treatment has been achieved by extensive surgical procedures in which the cardiac tissue is remodeled such that the remaining electrically conducting tissue is least likely to support the development or sustainment of cardiac arrhythmias. This approach is associated with high risk for intra-operative mortality. Atrial fibrillation (AF) is the most common arrhythmia with no anatomically fixed aberrant pathway, and it is a major health care problem. An estimated one million US citizens suffer from atrial fibrillation and are at risk from the effects of the arrhythmia. The most complete epidemiological data compiled on the incidence of atrial fibrillation is the Framingham Heart Study (Wolf, P.A., Dawber, T.R., Thomas, H.E. Jr., Kannel, W.B., Epidemiologic assessment of chronic atrial fibrillation and the risk of stroke: The Framingham study, Neurology, 1978 (Vol. 28), pp 373-375) which demonstrated that more than 5% of healthy people will develop AF after 30 years of follow-up. The incidence of AF in subjects who are in the 25-34 year old age group was 0.2%, and the incidence climbed steadily through the 55-64 year old age group, where it reached 3.8%. Overall, the chance of developing AF in the total population studied was 2.0% over twenty years. In normal hearts the refractory period of the heart muscle cell is variable with heart rate, and also with its location in the heart chamber, in a manner that facilitates the synchronized contraction of the chamber. In patients with AF, the refractory period of the heart muscle cells may not respond properly to changes in heart rate, and the spatial distribution of refractory periods in the heart chamber may be non-uniform. The substrate of the heart of AF patients also generally exhibits evidence of prolonged conductivity. Under these conditions it becomes possible for functional reentrant electrical pathways to develop. Previous studies have indicated that the product of conduction velocity times atrial refractory period is indicative of the propensity for development of atrial fibrillation.
If drug or electrical therapy are not effective in managing the symptomatic atrial fibrillation, a more aggressive treatment, called catheter ablation of the AV junction, may be undertaken. The purpose of such treatment is to permanently block conduction between the atrium and the ventricles. Ventricular rhythm is restored by implanting a permanent ventricular pacemaker. This technique has been successful in controlling supraventri- cular arrhythmias without the use of adjunct pharmacological agents in more than 75% of patients. However, this therapy causes complete heart block and requires a permanent pace-maker to support ventricular rhythm. The therapy may have detrimental hemodynamic effects in the case of co-existing cardiomyopathy, since the mechanical contribution of the timed atrial contraction is lost. The risk of stroke is still present, and, moreover, complications related to implantation of ventricular pacemakers are now becoming a source of concern.
The first surgical treatment reported for patients with atrial fibrillation was in 1990, by Cox, J.L., Schuessler R.B., Boineau J.B., in Surgery for Atrial Fibrillation, Cardiac Surgery; State of the Art Reviews, 1990 (Vol. 4) , pp 207-217. It is also reported in Williams, J.M. , Ungerleider, R.M. , Lofmand, J.K., Cox, J.L., Left Atrial Isolation: A New Technique for the Treatment for Supraven- tricular Arrhythmias, Journal of Thoracic Cardiovascular Surgery, 1980 (Vol. 80), pp 373-380. In this report the surgical technique was capable of electrically isolating the majority of the left atrium from the rest of the heart. This procedure was successful in treatment of left atrial focus of atrial fibrillation. However, although sinus rhythm was restored, the mechanical function of the left atrium was not, and the risk of thromboembolism still exists. The corridor procedure for the treatment of atrial fibrillation was reported by Guiraudon G.N., Campbell C.S., Jones D.L., McLellan D.G., and MacDonald J.L., Combined Sino-atrial Node Ventricular Node Isolation: A Surgical Alternative to AV Node Ablation in Patients with Atrial Fibrillation (abstract) , Circulation, 1985(72), p III-220. This procedure allows the sinus impulse, originating from the sinus node, to propagate exclusively down a surgically created corridor toward the AV node and then to the ventricles. The segmentation of the atrium does not allow for organized contraction of the atrium and the rest of the atrium may still be in fibrillation, although the heart rate will be restored to its normal sinus rhythm. In the maze procedure, Cox, J.L., Boineau, J.P., Schuessler, R.B., Kater, K.M., and Lappas, D.G., Surgical Interruption of Atrial Reentry as a Cure for Atrial Fibrillation, Olsson, S.B., Allessie, M.A., Campbell, R.W.F. (editors) , Atrial Fibrillation: Mechanisms and Therapeutic Strategies, Futura Publishing Co., Inc., Armonk, NY, 1994, after cardiopulmonary bypass is initiated, the heart is arrested with cardioplegic solutions and left and right atrial incisions are performed. Surgical incisions are placed on either side of the sino-atrial node. Surrounding the sino-atrial node with incisions ensures that the sinus impulse can travel in only one direction. Subsequent surgical incisions are then placed so that the impulse can activate both atria and the AV node. As a result of the surgery, the electrical impulse originating from the sinus node is incapable of establishing a reentrant circuit because all the tissue remains refractory after its recent depolarization. By creating a surgical maze of electrical pathways, the atrial tissue can be stimulated, but the substrate necessary to support macro reentry is eliminated.
Both the corridor and the maze procedures as described in the references cited above require major open heart surgery. During the lengthy surgery the patient's circulation must be artificially supported by a heart-lung bypass machine while the electrical activity of both atria are mapped and the atrial incisions are made. Also, these procedures include several right atrial incisions that may interrupt the integrity of the sino-atrial node or its arterial supply, and may require permanent artificial pacing to overcome iatrogenic SA node destruction or blockade. Another complication is the tendency of patients who have undergone the maze procedure to retain fluids. This is associated with damage caused by the surgical incisions to the ability of the right atrium to secrete natriuretic peptides. Recent work has been reported in which a modification of the maze procedure using RF catheter ablation rather than surgical incisions to create lines of conduction block has been attempted. Swartz, J.F, Pellersels, G. , Silvers, J. , Patten, L., and Cervantez, D., A Catheter
Based Curative Approach to Atrial Fibrillation in Humans (abstract), Circulation, 1994(90,4), Part 2, p 1-335, reported on one patient who was successfully treated by eight lines of ablation delivered to the right and left atria. The abla-tion lines were delivered by a 7 Fr. catheter with a 4 mm ablation tip using a series of seven anatomically conforming 8 Fr. intravascular introducers. Haines, D.E., McRury, I.A., Whayne, J.G., and Fleischman, S.D., Atrial Radiofrequency Ablation: The Use of a Novel Deploying Loop Catheter Design to Create Long Linear
Lesions (abstract), Circulation, 1994, (90,4), Part 2, p 1-335, reported on the use of an ablation catheter with an 8 Fr. shaft and two splines at its terminus which form a loop. The report concludes that it is possible to create long linear transmural atrial lesions with this catheter design. Seifert, M.J., Friedman, M.F., Selke, F.W., and Josephson, M.E., Radiofrequency Maze Ablation for Atrial Fibrillation (abstract), Circulation, 1994(90,4), Part 2, p. 1-595, report on the epicardial application of RF energy from a custom designed plaque that generates linear lesions. Five swine were studied and the technique showed success in four.
OBJECTS OF THE INVENTION It is an object of the invention to provide a treatment for cardiac arrhythmias. It is also an object of the invention to provide an apparatus and a method for the treatment of cardiac arrhythmias that have no fixed aberrant pathways, such as atrial fibrillation. It is a further object of the invention to provide an apparatus and a method for designing an intervention that will decrease the likelihood of sustainment of cardiac arrhythmias that have no fixed aberrant pathways, such as atrial fibrillation. These and other objects of the invention will become more apparent in the discussion below.
The present invention includes means of a locatable, mapping, pacing and ablation catheter tip, and methods for using same for therapy of cardiac arrhythmias with no discrete target. For example, a patient suffering from atrial fibrillation or paroxysmal atrial fibrillation is a candidate for the new mapping and ablation procedure. According to the invention, a description of the heart chamber anatomy, i.e., the physical dimensions of the chamber, is obtained and an activation map of a patient's heart is created using locatable catheters. A conduction velocity map is derived from the activation map. Then, a refractory period map is acquired.
Appropriate values from the conduction velocity map and the refractory period map are used to create a dimension map, which is then analyzed to determine ablation lines or points. BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 6 is a flowchart describing the procedure used to calculate the dimension map; Fig. 7 is a flowchart depicting the procedure for designing the ablation lines;
Fig. 9a represents possible circular reentrant circuits around an approximately circular conduction block; Fig. 9b depicts possible circular reentrant circuits along the edge of an approximately circular conduction block; Fig. 10 shows possible ablation lines λ and Ψ that would prevent circular reentrant circuits of length D or longer from forming around or alongside an approximately circular conduction block; Fig. 11 shows how oval-shaped reentrant pathways of length D might form between the circular conduction block and the ablation lines λ and Ψ;
Fig. 12b shows how placing additional radial ablation lines of type λ between the block and the ablation line Ψ prevents reentrant circuits from forming alongside the conduction block because there is no area within big enough to form a reentrant circuit of length D (with curvature no greater than a) ;
Fig. 13 shows that considering ablation line Ψ as a circular conduction block and calculating ablation lines of type λ and type Ψ will prevent the formation of reentrant circuits around and alongside it. Other ablation lines may be used to optimize the suggested lines to a minimum total length; Fig. 14, describes a possible embodiment of an electro-magnetic mapping/ablation catheter tip location system;
An additional catheter, a mapping and ablation catheter 13, is introduced 2 into the right atrium 14. The steps followed in performing activation mapping 3 are outlined in the flowchart of Fig. 3. During the mapping procedure 3, the patient should be in a regular sinus rhythm 15. This can be achieved by cardioverting the patient using an external defibrillator. The location of the mapping catheter 13 relative to the reference catheter 10 is registered continuously using the locating means, as is discussed more fully below. By use of an electrode in or at the tip of the mapping catheter 13, the catheter 13 is placed at a site 12 in the atrium 16. Local activation is recorded only after assuring endocardial contact by, for example, evidence of stable location, stable activa- tion times, and stable and suitable recordings of the local impedance to induced low amplitude, non-stimulating, electrical current (e.g., low current RF source) 17. Local electrical activity is then acquired and the local activation time relative to a fiducial point in the body surface QRS complex is recorded 18.
The activation map is updated after the acquisition of each data point 19, and the information acquired (location and local activation time) is portrayed as the activation map of the atrium under study 20. At the same time, the locations of anatomical obstacles to propagation of electrical activation (conduction blocks such as the entry of veins, ligaments, etc.) are recorded as locations that are not associated with local electrical activity, as evidenced by lack of endocardial contact. More data points are acquired until an activation map superimposed on a reconstruction of the chamber anatomy is sufficiently detailed 21. A conduction velocity map is derived from the activation map created. In a preferred embodiment, spatial derivation 23 and appropriate interpolation 24 are performed on the activation map 22 to form the conduction velocity map 25. The conduction velocity map 25 can be displayed separately or superimposed on a representation of the chamber anatomy.
Fig. 5 is a flowchart illustrating the steps followed in performing refractory period mapping 5. Again, the patient must be in a regular sinus rhythm 26, which can be achieved by cardioversion. The mapping catheter is moved to touch the endocardium of a site of the atria 27, and when stable contact is assured 28, an external stimulator delivers electrical stimuli to the endocardium in a programmed order 29 (a train of constant rate pacing followed by premature extra stimuli) . This train of external pacing of the atria is repeated each time with a premature extra stimuli coupled at a shorter interval 30. The longest interval used for coupling the premature stimuli that does not cause local activation is termed the local refractory period 31. The information is recorded and incorporated into the map calculations 32, namely, a plurality of local refractory periods, is portrayed as the local refractory map of the atrium 33, and the process is continued until a map of sufficient detail is constructed 34. Alternatively, the local refractory period can be approximated by measuring the duration of the monophasic action potential (MAP) duration at each site 35. The data for the refractory period map may be collected at the same sites as for the activation map, by measuring the local activation time and the local refractory period in turn. Alternatively, the data for each map may also be collected at different sites.
The product of conduction velocity (mm/ms) times the refractory period (ms) results in the distance (mm) that a stimulating wave front must travel in a reentry circuit in order to travel the entire circuit always meeting the next cell just after the end of its refractory period i.e., when it is ready to be stimulated. To calculate the product of the previously acquired conduction velocity map times the refractory period map to obtain the dimension map 6 the procedure outlined in the flowchart of Fig. 6 is used. The local conduction velocity v can be multiplied by the refractory period value RP for each point on the conduction velocity map 39 to yield the local dimension value D, i.e., D=v x RP, for each point. If two separate sets of sites were used to create the activation map and the refractory period map, then for each data point in the conduction velocity map 36, a corresponding refractory period value RP is calculated by interpolating between points 37 on the refractory period map 38. All the points D can then be displayed in a dimension map 40, which can be shown superimposed on the heart anatomy 41.
Once the activation map and the dimension map have been created, the information contained therein must be processed to calculate possible lines and/or points of ablation. Such calculations are related to an assumption that any electrical activation wavefront will spread on a path that is not tightly curved. Based upon experimental data, the minimum radius of curvature of an activation wavefront can be approximated by a, which is believed to be about 3 mm. A circle of a radius a can be defined such that the circum-ference X, where X=2ιra, is the shortest circular path physically possible in the human heart. In the normal human heart, if the activation wavefront were to travel in such a circular path it would not create a reentrant circuit, since upon arriving at the beginning of the circle the next cell would still be in a state where it is unable to be stimulated (i.e., refractory), and the circular path of activation would be terminated. Even in circular paths with a radius much larger than a, the normal human heart cannot create reentrant circuits. In the heart of an AF patient, however, the conduction of the activation wavefront is usually much slower, and the wavefront may arrive at the tail of a circular path later than the refractory period of that site. Hence there exist many possible propagation circuits that could cause reentry, so long as the path that the wavefront has traveled is at least of length D, the local dimension value.
2. Any path closing a loop at a particular location in the heart must be of length D, the local dimension number, in order to cause the development of a reentrant conduction path. 3. The electrical continuity between the SA node and the AV node must be preserved.
These criteria may be implemented in a number of different algorithms that are designed to compute ablation lines that prevent the formation of reentry circuits in the tissue, and at the same time preserve the electrical continuity between the SA and AV node. An example of such an algorithm is outlined in the flowchart in Fig. 7. Given an input of the dimension map and the activation map superimposed on the atrial anatomy 50, critical areas such as fixed conduction blocks (caused by the entry of veins into the heart, scar tissue or other factors) 51, the SA node 52 and the AV node 53 can be identified. In this example algorithm the computing means starts at any one of the conduction blocks identified 54. Possible ablation lines λ and Ψ are calculated 55 for each conduction block 56. Then, each ablation line is assumed to be a conduction block 57, and the process of calculating additional ablation lines is repeated 58. Once the possible sets of ablation lines have all been calculated 59, the length and number of ablation lines is optimized, for example, by determining the least number of ablation lines, the shortest ablation lines, the most easily generated ablation lines, or similar criteria. The ablation lines determined can be superimposed on a 3-D display of the anatomy 60.
Exemplary applications of the algorithm represented in Fig. 7 are described in Fig.s 8a-12b. For a theoretical linear conduction block 65, circular reentrant circuits 66 of length D could form along the edge of the block 65, as in Fig. 8a. The size of the circle at each point along the block 65 depends on the local value of D at each site. In this case a possible ablation line Ψ could be a line just inside the outermost edge of the circles. Since ablated tissue becomes a conduction block, this would prevent all circular circuits of length or circumference D or greater from forming. The circuits 67 could, however, be more oval in shape, as shown in Fig. 8b. Then, even after applying the ablation line shown in Fig. 8a, a reentrant pathway of length D could develop alongside the conduction block. In order to prevent the formation of both types of circuits, an ablation line could be placed along the outer edge of the most narrow oval-shaped pathways. Since the minimum turning radius of the pathway must be at least a, the narrowest oval shapes that might form are of width 2a. Then a possible ablation line 68 would be a small distance e less than 2a from the boundary edge (Fig. 8c) .
In the case of an approximately circular conduction block, circular reentrant circuits 69 could form around the block 70 (Fig. 9a) or alongside it (Fig. 9b) .
Possible ablation lines that would prevent the formation of circular reentrant circuits 69 from forming around or alongside a circular conduction block 70 might be a line Ψ just inside the outer edge of the possible circuits alongside the block 70, and a line λ connecting this ablation line with the block 70 (Fig. 10) . While line λ would prevent circuits of any shape forming around the conduction block within line Ψ, more oval reentrant circuits 71 might still develop between the ablation lines and the circular conduction block 70 (Fig. 11) . Different algorithms might use different ablation lines to prevent these types of reentry circuits 71 from forming. Since the minimum radius of curvature of a stimulation wavefront is a, and the minimum width of an oval pathway is 2a as in the case with a linear conduction block, one possible solution would be to place an ablation line 75 a distance just less than 2a around the circular conduction block 70 (Fig. 12a) . Another solution might be to add extra radial lines of type λ that would prevent reentry circuits from forming since there would remain no possible paths of length D (with curvature always equal to or less than a) within the tissue inside ablation line Ψ (Fig. 12b) .
In turn, the suggested ablation lines around and alongside each conduction block identified are calculated. The ablation lines of type Ψ are then taken into consideration in the calculations, since they can be considered conduction blocks (Fig. 13) , and may be used to minimize the total length of the suggested ablation lines. The process is repeated until the entire area of the atria has been covered, and there is no area remaining in which an reentrant circuit could form.
The entire calculation is then repeated starting from a different conduction block, since the total length of the ablation lines suggested will differ depending on the starting point. After completing the entire calculation starting at each conduction block, the optimal set of suggested ablation lines (shortest/easiest to perform, or some other criteria) that conforms to the three design criteria listed above is chosen and displayed superimposed on the heart anatomy. The computer generated boundary lines can be superimposed on the heart anatomy along with the location of the SA node, the AV node and the entrance of the blood vessels into the chamber. Since the catheter tip is continuously locatable, it can be superimposed on the display to guide the performance of the ablation procedure. The results of the mapping and ablation procedure are checked by performing another activation map procedure. Real time locating of the mapping and ablating catheter tip can be achieved by several technologies. The advantage of using x-ray fluoroscopy for locating the tip of a cardiac catheter is based on the ease of performance using regular, available catheters. However, the resolution of this method is at best about 1 cm. Another disadvantage is that utilizing x-ray radiation for mapping procedures requires repeated transilluminations, thus increasing the exposure of the physician and the patient to the x-ray radiation. In the last decade alternative methods have been developed for permanent portrayal of catheters during mapping procedures by making use of non-ionizing waves or fields, and these methods have the advantage of limiting the radiation exposure for the patients and the physician. These methods offer better quantitative, high resolution locating information than the location information offered by the x-ray radiation technique. Several technical realizations have been disclosed in U.S. Patent No. 4,173,228 to Van Steenwyk, U.S. Patent No. 4,697,595 to Breyer, U.S. Patent No. 4,945,305, to Blood, and U.S. Patent No. 5,042,486 to Pfeiler. Other possible embodiments of the means to find the real-time location of the catheter tip will be discussed below. The physical principle common to these non x-ray locating technologies is that they make use of a transmitter for electromagnetic or acoustic waves located at the tip of a catheter, these waves being acquired by a receiving antenna attached to, or disposed in or near the patient and being converted into electrical signals. The location of the catheter can then be superimposed on a heart chamber image disclosing wall architecture acquired by same or other means of imaging, or by reconstructing the surface formed by the plurality of endocardial points acquired during the mapping procedure. In an alternative embodiment, the catheter tip may be a receiving antenna, and the external antennas may be transmitting antennas. For locating catheter tips by use of electromagnetic fields, marking of the catheter tip is achieved by an antenna disposed at the catheter tip, with an antenna feed guided in or along the catheter. An electrical antenna (dipole) or a magnetic antenna such as a magneto-resistor sensor, concentric coil, fluxgate magnetometer, Hall effect sensor, coils, etc., can be used. The antenna can be operated as a transmission antenna or as a reception antenna, with the extracorporeal antennas located outside of the patient's body correspondingly functioning as reception antennas or transmission antennas.
In another embodiment of the invention a thermistor is incorporated within the catheter tip for measuring the tip temperature as a way for controlling the amount of energy delivered to the tissue. The location, positioning, and sensing technology and the construction and use of sensing, reference, and ablation catheters, especially ablation catheters using RF or laser energy, to which reference is made above, is set forth in more detail in U.S. Patent No. 5,391,199, co¬ pending U.S. patent application Serial No. 08/293,859, filed August 19, 1994, and PCT patent application Serial No. PCT/US95/01103, filed January 24, 1995, each of which is commonly assigned and each of which is incorporated herein by reference.
Information regarding the heart chamber architecture is supplied to the signal processor via a separate input 87. The images are superimposed and are portrayed on the display 88. To overcome the problems introduced by the repetitive heart movement of each cardiac cycle, the location information that is recorded is gated to a fixed point in the cardiac cycle. Therefore, anatomical maps of the studied chamber will be presented "frozen" and will correspond to the chamber geometry at a fiducial point in time of the cardiac cycle.
In an alternative embodiment the antennas 79 in the tip of the catheter 77 are transmitting antennas and the receiving antennas are located outside the body of the patient .
Fig. 15 describes the system for detection and location of the mapping/ablating catheter using a piezo-electric embodiment. In this particular example, three reference catheters are used. A multiplexer 89, driven by a Central Processing Unit (CPU) 90, controls the connection of each of the piezo-electric crystals 91, 92, 93 and 94 deposited in each of the four catheters, one of the catheters being the mapping/ablating catheter and the other three being the reference catheters. Included are four amplifiers 95, 96, 97 and 98, one of them 95 connected to the transmitting means 99 and the other three 96, 97 and 98 connected to the receiving means 100. The CPU 90 switches each of the catheters, sequentially, so that each in turn is connected to the transmitting means 99 and the rest are connected to the receiving means 100. The basic frequency of the CPU switching function can be programmed by the user and is usually set to be 1/lOth of the basic frequency of operation of the piezo-electric crystals (between 40 - 80 KHZ) . A transmitting means 99 is designed such that a linear frequency sweep device 101 drives the piezo-electric crystal via an amplifier 95. The oscillator 102 scans a pre-pro-grammed frequency band at a CPU 90 controlled rate.
Fig. 17 shows the details of the tip of a catheter designed to be used in a piezo-electric embodiment of the system. The piezo-electric crystal 109 is located inside the catheter tip 110 and two electrically conducting wires 111, 112 are receiving or transmitting electromagnetic signals to or from the piezo-electric crystal. In an alternative embodiment of the catheter tip 110 for use with a piezo-electric embodiment, a bio-compatible piezo- electric material can be disposed on the outer surface of the distal tip of the catheter, said coating being connected at separate points to two electrically conducting wires.
(a) collecting local information concerning a patient' s heart;
(b) analyzing said information to determine lines or points of ablation; and
2. The method of Claim 1, wherein the cardiac arrhythmias have no focus .
3. The method of Claim 1, wherein the lines or points of ablation are created percutaneously.
4. The method of Claim 1, wherein in step (b) the information is analyzed to optimize the lines or points of ablation, wherein the continuous or discontinuous ablation lines interrupt each possible geometric shape having a radius ≥ a and a circumference or outer perimeter greater than or equal to the dimension value at a given location.
5. The method of Claim 4, wherein the geometric shapes are each circular or oval.
6. A method of Claim 1, which comprises the steps of:
(d) analyzing the dimension map of step (c) to determine lines or points of ablation; and
(e) creating lines or points of ablation.
7. The method of Claim 6, wherein the dimension map of step (c) is created from the information gathered in steps (a) and (b) .
8. The method of Claim 1, which comprises the steps of:
(a) creating an activation map of all or a portion of a chamber of the heart;
(b) creating a refractory period map of said chamber or part thereof;
(c) creating a dimension map of said chamber or part thereof;
(d) analyzing the dimension map of step (d) to determine lines or points of ablation; and
9. The method of Claim 8, which also comprises the step of obtaining a three-dimensional image of one or more chambers of the heart .
10. The method of Claim 9, wherein the three- dimensional image of a chamber of the heart is reconstructed by the steps comprising:
11. The method of Claim 10, wherein the data points from step (d) are transmitted to a receiving means.
12. The method of Claim 8, wherein the dimension map of step (c) is created from the information gathered in steps (a) and (b) .
13. The method of Claim 6 or 8, wherein a conduction velocity map is derived from the activation map.
14. The method of Claim 6, wherein the activation map is created by the steps comprising:
15. The method of Claim 14, wherein the data points from step (e) are transmitted to a receiving means.
16. The method of Claim 14, wherein a conduction velocity map is derived from the activation map.
17. The method of Claim 6 or 8, wherein a refractory period map is created by the steps comprising:
(a) positioning the distal tip of each of one or more catheters at a site on the endocardium of a patient' s heart;
18. The method of Claim 17, wherein the data points from step (e) are transmitted to a receiving means.
19. The method of Claim 6 or 8, wherein a dimension map is created by the steps comprising:
20. The method of Claim 19, wherein the data points from step (d) are transmitted to a receiving means.
21. The method of Claim 10, 14, or 16, wherein the location information in step (b) is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
22. A method for determining lines or points of ablation to treat arrhythmias in the heart of a patient, which comprises the steps of :
23. The method of Claim 22, wherein the dimension map of step (c) is created from the information gathered in steps (a) and (b) .
24. A method for determining lines or points of ablation to treat arrhythmias in the heart of a patient, which comprises the steps of:
(a) creating an activation map of all or part of a chamber of the patient's heart;
(c) creating a dimension map of said chamber or part thereof; and
25. The method of Claim 22 or 24, wherein a conduction velocity map is derived from the activation map.
26. The method of Claim 22 or 24, wherein the activation map is created by the steps comprising:
27. The method of Claim 26, wherein a conduction velocity map- is derived from the activation map.
28. The method of Claim 26, wherein the location information in step (b) is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
29. The method of Claim 22 or 24, wherein a refractory period map is created by the steps comprising:
30. The method of Claim 22 or 24, wherein a dimension map is created by the steps comprising:
31. The method of Claim 29, wherein the location information in step (b) is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
32. A method of determining lines or points of ablation to treat arrhythmias in the heart of a patient, which comprises the steps of : (a) positioning the distal tip of each of one or more catheters at a site within a chamber of a patient's heart;
(d) repeating steps (a) , (b) , and (c) one or more times to create sufficient data points for an activation map;
(g) repeating steps (a) , (b) , and (f) one or more times to create sufficient data points for a refractory period map;
33. A method for determining areas of ablation to treat arrhythmias in the heart of a patient, which comprises the steps of:
(a) positioning the distal tip of each of one or more catheters at a site within a chamber of the patient' s heart;
(b) sensing location information at each site; (c) sensing local information at each site;
(d) . sensing or determining the refractory period at each site;
(e) processing sensed information from steps (b) , (c) , and (d) to create one or more data points;
(f) repeating steps (a) , (b) , (c) , (d) , and (e) one or more times to create sufficient data points for an activation map and a refractory period map;
34. The method of Claim 33, wherein a corresponding refractory period value on the refractory period map of step (f) is determined for a data point on the conduction velocity map of step (g) .
35. A method of creating a refractory period map of a patient's heart, which comprises the steps of:
(c) determining the refractory period at each site; (d) processing sensed information from steps (b) and (c) to create one or more data points;
36. The method of Claim 32, 33, or 35 wherein the location information in step (b) is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
37. A method of creating a dimension map of a patient's heart which comprises:
38. The method of Claim 37, wherein the data points from step (d) are transmitted to a receiving means.
39. The method of Claim 37, wherein a corresponding refractory period value is determined for a data point on the conduction velocity map of step (a) .
40. A method for determining lines or points of ablation to treat arrhythmias with no discrete target in the heart of a patient, which comprises the steps of:
(a) creating an activation and refractory period map of all or part of a chamber of a patient's heart; (b) creating a dimension map of said chamber or a part thereof; and
(c) calculating lines or points of ablation according to the criteria that any path with a radius of curvature larger than a, a being the minimum radius of curvature, closing a loop at a particular location in the heart must be of a length equal to or greater than the local dimension number, to cause the development of a reentrant conduction path, and that the electrical continuity must be preserved.
41. The method of Claim 40 for determining lines or points of ablation to treat atrial arrhythmias with no discrete target in the heart of a patient, which comprises the steps of:
(a) creating an activation map of all or part of a chamber of a patient's heart;
(f) calculating each continuous or discontinuous line necessary to interrupt each possible geometric shape having a radius of ≥ a and a circumference ≥ D, positioned around or alongside the outer perimeter of a conduction block;
(g) repeating step (f) for each additional conduction block while also treating a continuous or discontinuous line from step (f) as a conduction block and calculating each additional continuous or discontinuous line necessary to interrupt each geometric shape having a radius ≥ a or a circumference ≥ D, positioned contiguous to the continuous or discontinuous line from step (f) ;
(h) repeating steps (f) and (g) starting from each conduction block identified in step (e) ; and
(i) choosing an optimal set of ablation lines or points wherein the length of the lines and/or the number of points is minimal or the ablation lines or points are easiest to perform and there is electrical continuity between the SA node and the AV node and no reentrant circuit of length ≥ D and radius of curvature ≥ a may form.
42. The method of Claim 41, wherein the geometric shapes are each circular or oval.
43. An apparatus for the treatment of cardiac arrhythmias, which comprises:
(a) means for collecting local information concerning a patient's heart;
(b) means for analyzing said information to determine lines or points of ablation; and
44. The apparatus of Claim 43, wherein the cardiac arrhythmias have no focus.
45. The apparatus of Claim 43, wherein the lines or points of ablation are created percutaneously.
46. The apparatus of Claim 43, wherein with means (b) the information is analyzed to optimize the lines or points of ablation, wherein the continuous or discontinuous ablation lines interrupt each possible geometric shape having a radius ≥ a and a circumference or outer perimeter greater than or equal to the dimension value at a given location.
47. The apparatus of Claim 46, wherein the geometric shapes are each circular or oval.
48. An apparatus of Claim 43, which comprises:
(c) means for creating a dimension map of said heart;
(d) means for analyzing the dimension map to determine lines or points of ablation; and
(e) means for creating lines or points of ablation.
49. The apparatus of Claim 48, wherein the dimension map is created from the information gathered with means
50. The apparatus of Claim 43, which comprises:
(a) means for creating an activation map of all or a portion of a chamber of the heart;
(b) means for creating a refractory period map of said chamber or part thereof;
(c) means for creating a dimension map of said chamber or part thereof;
51. The apparatus of Claim 50, which also comprises means for obtaining a three-dimensional image of one or more chambers of the heart .
52. The apparatus of Claim 51, wherein the three- dimensional image of a chamber of the heart is reconstructed by means comprising: (a) means for positioning the distal tip of each of one or more catheters at a site on the endocardium of a patient's heart chamber;
54. The apparatus of Claim 50, wherein the dimension map is created from the information gathered with means
55. The apparatus of Claim 48 or 50, wherein a conduction velocity map is derived from the activation map.
56. The apparatus of Claim 48, wherein the activation map creation means comprises:
58. The apparatus of Claim 56, wherein a conduction velocity map is derived from the activation map.
59. The apparatus of Claim 48 or 50, wherein the refractory period map creation means comprises:
(a) means for positioning the distal tip of each of one or more catheters at a site on the endocardium of a patient' s heart;
60. The apparatus of Claim 59 also having means for transmitting the data points to a receiving means.
61. The apparatus of Claim 48 or 50, wherein the dimension map creation means comprises:
62. The apparatus of Claim 61 also having means for transmitting the data points to a receiving means.
63. The apparatus of Claim 52, 56, or 59, wherein the location information is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
64. An apparatus for determining lines or points of ablation to treat arrhythmias in the heart of a patient, which comprises :
65. The apparatus of Claim 64, wherein the dimension map is created from the information gathered with means
66. An apparatus for determining lines or points of ablation to treat arrhythmias in the heart of a patient, which comprises :
(a) means for creating an activation map of all or part of a chamber of the patient's heart;
67. The apparatus of Claim 64 or 66, wherein a conduction velocity map is derived from the activation map.
68. The apparatus of Claim 64 or 66, wherein the activation map creation means comprises:
69. The apparatus of Claim 68, wherein a conduction velocity map is derived from the activation map.
70. The apparatus of Claim 68, wherein the location information is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
71. The apparatus of Claim 64 or 66, wherein the refractory period map creation means comprises:
(b) means for sensing location information at each site; (c) means for determining the refractory period at each site;
72. The apparatus of Claim 64 or 66, wherein the dimension map creation means comprises:
73. The apparatus of Claim 71, wherein the location information is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
74. An apparatus for determining lines or points of ablation to treat arrhythmias in the heart of a patient, which comprises:
(b) means for sensing location and local information at the site; (c) means for processing sensed information from step (b) to create one or more activation mapping data points;
75. An apparatus for determining areas of ablation to treat arrhythmias in the heart of a patient, which comprises :
(c) means for sensing local information at each site; (d) means for sensing or determining the refractory period at each site;
76. The apparatus of Claim 75 also having means for determining a corresponding refractory period value on the refractory period map for a data point on the conduction velocity map.
77. An apparatus for creating a refractory period map of a patient's heart, which comprises:
(c) means for determining the refractory period at each site; (d) means for processing sensed information to create one or more data points;
78. The apparatus of Claim 74, 75, or 77, wherein the location information is measured relative to a reference catheter within the patient's body or to a reference outside the patient's body.
79. An apparatus for creating a dimension map of a patient's heart which comprises:
80. The apparatus of Claim 79 also having means for transmitting the data points to a receiving means.
81. The apparatus of Claim 79 also having means for determining a corresponding refractory period value for a data point on the conduction velocity map.
82. An apparatus for determining lines or points of ablation to treat arrhythmias with no discrete target in the heart of a patient, which comprises: (a) means for creating an activation and refractory period map of all or part of a chamber of a patient's heart;
(c) means for calculating lines or points of ablation according to the criteria that any path with a radius of curvature larger than a, a being the minimum radius of curvature, closing a loop at a particular location in the heart must be of a length equal to or greater than the local dimension number, to cause the development of a reentrant conduction path, and that the electrical continuity must be preserved.
83. The apparatus of Claim 82 for determining lines or points of ablation to treat atrial arrhythmias with no discrete target in the heart of a patient, which comprises :
(f) means for calculating each continuous or discontinuous line necessary to interrupt each possible geometric shape having a radius of ≥ a and a circumference ≥ D, positioned around or alongside the outer perimeter of a conduction block;
(g) means for repeating the calculation of such a continuous or discontinuous line for each additional conduction block while also treating a prior continuous or discontinuous line as a conduction block and calculating each additional continuous or discontinuous line necessary to interrupt each geometric shape having a radius ≥ a or a circumference ≥ D, positioned contiguous to the continuous or discontinuous line;
(i) means for choosing an optimal set of ablation lines or points wherein the length of the lines and/or the number of points is minimal or the ablation lines or points are easiest to perform and there is electrical continuity between the SA node and the AV node and no reentrant circuit of length ≥ D and radius of curvature ≥ a may form.
84. The apparatus of Claim 83, wherein the geometric shapes are each circular or oval.
PCT/US1996/008164 1995-06-07 1996-05-31 Apparaus and method for treating cardiac arrhythmias with no discrete target WO1996039929A1 (en)
DE69631801T DE69631801T2 (en) 1995-06-07 1996-05-31 An apparatus for treating cardiac arrhythmias with no discrete target
AU59592/96A AU5959296A (en) 1995-06-07 1996-05-31 Apparaus and method for treating cardiac arrhythmias with no discrete target
AT96916858T AT260599T (en) 1995-06-07 1996-05-31 Apparatus for the treatment of herzarrhthmien without discrete target
DE69631801A DE69631801D1 (en) 1995-06-07 1996-05-31 Apparatus for the treatment of herzarrhthmien without discrete target
EP96916858A EP0955880B1 (en) 1995-06-07 1996-05-31 Apparaus for treating cardiac arrhythmias with no discrete target
CA002224152A CA2224152C (en) 1995-06-07 1996-05-31 Apparatus and method for treating cardiac arrhythmias with no discrete target
JP50090097A JP3782456B2 (en) 1995-06-07 1996-05-31 Therapy device without cardiac arrhythmias of the individual target
WO1996039929A1 true WO1996039929A1 (en) 1996-12-19
EP1740222A1 (en) * 2004-02-26 2007-01-10 Merck &amp; Co., Inc. Biological assay
See also references of EP0955880A4 *
WOLF, P.A., DAWBER, T.R., THOMAS, H.E., KANNEL, W.B.: "Epidemiologic Assessment of Chronic Atrial Fibrillation and the Risk of Stroke", THE FRAMINGHAM STUDY, NEUROLOGY 1978, vol. 28, 1 January 1978 (1978-01-01), pages 373 - 375
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