Surgery – Instruments – Electrical application
Reexamination Certificate
1999-07-07
2002-04-02
Peffley, Michael (Department: 3739)
Surgery
Instruments
Electrical application
C607S150000, C607S122000
Reexamination Certificate
active
06364878
ABSTRACT:
TECHNICAL FIELD
The present description generally relates to medical tools and methods, and more particularly, a percutaneous transluminal ablation catheter holding tool and method of use.
BACKGROUND
Percutaneous transluminal ablation (PTA) catheters for tissue ablation are available for the treatment of many conditions of the heart, including atrial fibrillation, atrial and ventricular arrhythmias or dysfunction, as well as others. The PTA catheters are long, slender, and flexible such that they can be inserted through a small incision through the skin into a blood vessel, such as an artery or vein, and advanced to the treatment site near to or inside the heart. Once positioned, the PTA catheter is used to selectively ablate or “burn” selected tissue which results in a change in the physiology of the treatment site. Such treatments may be used to block electrical conduction to correct abnormal cardiac rhythm that interferes with proper organ function.
Since its initial description in 1982, catheter ablation has evolved from a highly experimental technique to its present role as first-line therapy for most supraventricular arrhythmias, including atrioventricular nodal reentrant tachycardia, Wolff-Parkinson-White syndrome, focal atrial tachycardia, and atrial flutter. Over the past five years, increasing attention has been focused on the development of catheter ablation techniques and ablation systems to cure atrial fibrillation. J. F. Swartz, et al., is credited with being the first to demonstrate that chronic atrial fibrillation can be cured using catheter ablation techniques (Swartz J F, Perrersels G, Silvers J, Patten L, Cervantez D., A Catheter Based Curative Approach to Atrial Fibrillation in Humans, Circulation. 1994; 90 (suppl 1): 1-335). These authors reported that creation of linear lesions in the right and left atrium results in a progressive increase in the organization of atrial activity until sinus rhythm is restored. M. Haissaguerre, et al., reported successful ablation of atrial fibrillation in a patient with paroxysmal atrial fibrillation by the creation of three linear lesions in the right atrium, two longitudinal and one transverse, that connected the two longitudinal lesions using a specially designed catheter (Haissagucrre M, Gencel L, Fischer B, Metayer P L, Poquet F, Marcus F l, Clementy J., Successful Catheter Ablation of Atrial Fibrillation, J Cardiovasc Electrophysiol 1994;5:1045-1052).
Currently available ablation systems are limited because they can only create singular spot lesions or short drag lesions, requiring a significant amount of time to perform biatrial lesions. Systems that can create linear lesions are currently undergoing investigation at this time and hold exciting promise for the future. One such system currently under clinical investigation is the Guidant's Heart Rhythm Technology's (HRT; Guidant Corporation, Cardiac Rhythm Management Group, St. Paul, Minn.) Linear Phased Radio Frequency Ablation System consisting of a 7 Fr., 5-mm tipped quadripolar deflectable electrode catheter and multiple pre-shaped steerable linear catheters which incorporate 12-3-mm platinum band electrodes with an inter-electrode spacing of 4 mm. Thermocouples are positioned on the outside curvature of the catheter to allow for temperature monitoring during radio frequency (RF) delivery. A variety of 3-dimensional catheter shapes, are designed to be used in conjunction with sheaths to achieve specific linear lesions within the right and left atria. The pre-shaped steerable linear catheters are created by means of a pre-shaped Nitinol stylet embedded within the shaft. These catheters are used in conjunction with the Guidant HRT Linear Phased RF Ablation Generator, which is a multi-channel RF generator capable of delivering phased RF energy at a frequency of 540 kHz to selected electrodes, in order to modify the lesion length, from localized, spot lesions to lesions which are 8 cm in length. When using the multi-electrode catheters, by delivering RF energy at adjacent electrodes out of phase with each other, a voltage gradient is created between electrodes and also to the back plate. This results in current paths both between electrodes and also to the return electrode (back plate), thereby creating a continuous linear lesion. The generator has the ability to continuously monitor the impedance and temperature of each active band electrode. Power output for pre-shaped linear catheters can be varined from 0 to 20 Watts per electrode. Power delivery is in the form of a duty cycle with a constant output amplifier with power variability controlled by varying the amount of time energy is delivered. This approach to power delivery allows for electrode cooling during the off cycle. Adjustments in the power output can be made to all electrodes at once or in three zones of four electrodes each. The generator incorporates additional safety features if excessive temperature or impedance is detected. The generator automatically shuts down power delivery to any band electrode if the impedance of that circuit exceeds a pre-set limit, or if the temperature exceeds a preset value. For the 5-mm tip ablation catheter, the RF generator will deliver RF energy with a maximal power output of 50 Watts to the tip only, while continuously monitoring the impedance and temperature of the tip electrode. Ablation duration can be adjusted from 5 seconds to 5 minutes.
Successful ablation therapy is defined as a return to normal sinus rhythm. To achieve this, lesions need to be continuous, transmural, and connected with other lesions or anatomical structures that cause blockage of atrial conduction. The seven recommended lesions are as follows: 1) right atrial isthmus ablation: linear lesion applied to the right atrium between the tricuspid annulus and the eustachian ridge, 2) right atrial inter-caval ablation: linear lesion applied along the posterior wall of the right atrium, between the superior vena cava and the inferior vena cava, 3) right pulmonary vein ablation (RPV): linear lesion applied to the left atrium, beginning below Bachmann's bundle, across the right superior pulmonary vein (RSPV) to the right inferior pulmonary vein (RIPV) and adjoining the mitral annulus, 4) left pulmonary vein ablation (LPV): linear lesion applied to the left atrium, beginning below Bachmann's bundle, across the left superior pulmonary vein (LSPV) to the left inferior pulmonary vein (LIPV) and reaching the mitral annulus, 5) superior pulmonary vein ablation (SPV): linear lesion applied to the left atrium, across the right superior pulmonary vein to the left superior pulmonary vein, 6) left atrial roof ablation (ROOF): linear lesion applied from the trigone, across the roof of the left atrium, to the left superior pulmonary vein, and 7) left atrial septal ablation (SEP): linear lesion applied to the foramen ovale to the right superior pulmonary vein. During creation of the right atrial inter-caval line, pacing is performed from each pair of electrodes at high output to assure the absence of diaphragmatic stimulation.
PTA catheters use any of a number of methods to deliver ablative energy to the tissue. Some of these methods include electric heating, microwave radiation, ultrasound radiation, and cryogenics. The energy delivery component of the PTA catheter, sometimes referred to as an electrode, is located either at the distal tip or along a portion of the distal end of the PTA catheter. When the PTA catheter is advanced through the blood vessel to the treatment site, either the tip or the side of the PTA catheter, depending on electrode type, is pressed against the tissue to be ablated.
There is a need to have the capability to apply ablation therapy non-transluminally, such as during open heart surgery, on either epicardium or endocardium. For example, some patients having surgery for the treatment of atrio-ventricular valve disease would benefit from ablation therapy in order to correct cardiac arrhythmias of the atria or ventricle. Up to 40% of patients requiring mitral valve replaceme
Cardiac Pacemakers Inc.
Gibson Roy
Peffley Michael
Schwegman Lundberg Woessner & Kluth P.A.
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