Surgery – Instruments – Electrical application
Reexamination Certificate
1999-05-04
2001-07-10
Peffley, Michael (Department: 3739)
Surgery
Instruments
Electrical application
C600S374000, C607S101000, C607S133000
Reexamination Certificate
active
06258087
ABSTRACT:
FIELD OF THE INVENTION
In a general sense, the invention is directed to systems and methods for treating interior tissue regions of the body. More specifically, the invention is directed to systems and methods for treating dysfunction in body sphincters and adjoining tissue, e.g., in and around the lower esophageal sphincter and cardia of the stomach.
BACKGROUND OF THE INVENTION
The gastrointestinal tract, also called the alimentary canal, is a long tube through which food is taken into the body and digested. The alimentary canal begins at the mouth, and includes the pharynx, esophagus, stomach, small and large intestines, and rectum. In human beings, this passage is about 30 feet (9 meters) long.
Small, ring-like muscles, called sphincters, surround portions of the alimentary canal. In a healthy person, these muscles contract or tighten in a coordinated fashion during eating and the ensuing digestive process, to temporarily close off one region of the alimentary canal from an other.
For example, a muscular ring called the lower esophageal sphincter surrounds the opening between the esophagus and the stomach. The lower esophageal sphincter (or LES) is a ring of increased thickness in the circular, smooth-muscle layer of the esophagus. Normally, the lower esophageal sphincter maintains a high-pressure zone between fifteen and thirty mm Hg above intragastric pressures inside the stomach.
When a person swallows food, muscles of the pharynx push the food into the esophagus. The muscles in the esophagus walls respond with a wavelike contraction called peristalsis. The lower esophageal sphincter relaxes before the esophagus contracts, and allows food to pass through to the stomach. After food passes into the stomach, the lower esophageal sphincter constricts to prevent the contents from regurgitating into the esophagus.
The stomach muscles churn the food and digestive juices into a mass called chyme. Then the muscles squeeze the chyme toward the pyloric (intestinal) end of the stomach by peristaltic waves, which start at the top of the stomach and move downward. The pyloric sphincter, another ringlike muscle, surrounds the duodenal opening. The pyloric sphincter keeps food in the stomach until it is a liquid. The pyloric sphincter then relaxes and lets some chyme pass into the duodenum.
Dysfunction of a sphincter in the body can lead to internal damage or disease, discomfort, or otherwise adversely affect the quality of life. For example, if the lower esophageal sphincter fails to function properly, stomach acid may rise back into the esophagus. Unlike the stomach, the esophagus has no natural protection against stomach acids. When the stomach contents make contact with the esophagus, heartburn or other disease symptoms, including damage to the esophagus, can occur.
Gastrointestinal reflux disease (GERD) is a common disorder, characterized by spontaneous relaxation of the lower esophageal sphincter. It has been estimated that approximately two percent of the adult population suffers from GERD. The incidence of GERD increases markedly after the age of 40, and it is not uncommon for patients experiencing symptoms to wait years before seeking medical treatment.
GERD is both a normal physiologic phenomenon that occurs in the general population and a pathophysiologic phenomenon that can result in mild to severe symptoms.
GERD is believed to be caused by a combination of conditions that increase the presence of acid reflux in the esophagus. These conditions include transient LES relaxation, decreased LES resting tone, impaired esophageal clearance, delayed gastric emptying, decreased salivation, and impaired tissue resistance. Since the resting tone of the lower esophageal sphincter is maintained by both myogenic (muscular) and neurogenic (nerve) mechanisms, some believe that aberrant electrical signals in the lower esophageal sphincter or surrounding region of the stomach (called the cardia) can cause the sphincter to spontaneously relax.
Lifestyle factors can also cause increased risk of reflux. Smoking, large meals, fatty foods, caffeine, pregnancy, obesity, body position, drugs, hormones, and paraplegia may all exacerbate GERD. Also, hiatal hernia frequently accompanies severe GERD. The hernia may increase transient LES relaxation and delay acid clearance due to impaired esophageal emptying. Thus, hiatal hernias may contribute to prolonged acid exposure time following reflux, resulting in GERD symptoms and esophageal damage.
The excessive reflux experienced by patients with GERD overwhelms their intrinsic mucosal defense mechanisms, resulting in many symptoms. The most common symptom of GERD is heartburn. Besides the discomfort of heartburn, reflux results in symptoms of esophageal inflammation, such as odynophagia (pain on swallowing) and dysphagia (difficult swallowing). The acid reflux may also cause pulmonary symptoms such as coughing, wheezing, asthma, aspiration pneumonia, and interstitial fibrosis; oral symptoms such as tooth enamel decay, gingivitis, halitosis, and waterbrash; throat symptoms such as a soreness, laryngitis, hoarseness, and a globus sensation; and earache.
Complications of GERD include esophageal erosion, esophageal ulcer, and esophageal stricture; replacement of normal esophageal epithelium with abnormal (Barrett's) epithelium; and pulmonary aspiration.
Treatment of GERD includes drug therapy to reduce or block stomach acid secretions. Still, daily drug therapy does not eliminate the root cause of the dysfunction.
Invasive abdominal surgical intervention has also been tried with success. One procedure, called Nissen fundoplication, entails invasive, open abdominal surgery. The surgeon wraps the gastric fundis about the lower esophagus, to, in effect, create a new “valve.” Less invasive laparoscopic tehniques have also been tried to emulate Nissen fundoplication, also with success. Still, all surgical intervention entails making an incision into the abdomen and carry with it the usual risks of abdominal surgery.
SUMMARY OF THE INVENTION
The invention provides expandable electrode assemblies for treating a tissue region at or near a sphincter.
According to one aspect of the invention, an assembly includes a support structure comprising an array of jointed spines having proximal and distal ends joined to form a basket. A mechanism is provided to flex the jointed spines to expand and collapse the basket. Electrodes are carried by the jointed spines for advancement in a path to penetrate the tissue region upon expansion of the basket.
In one embodiment, at least one of the jointed spines includes a molded hinge about which flexure occurs.
In one embodiment, at least one of the jointed spines includes a mechanical hinge about which flexure occurs.
In one embodiment, at least one of the electrodes comprises an integrally molded part of the respective spine.
In one embodiment, at least one of the electrodes is secured to the respective spine.
In one embodiment, when the basket is collapsed, the electrodes nest within the jointed spines. As the basket expands, the electrodes swing relative to the jointed spines in the path to penetrate tissue.
In one embodiment, a connector couples the electrodes to a source of radio frequency energy to ohmically heat tissue and create lesions in the tissue region.
According to another aspect of the invention, an assembly includes a support structure comprising an extruded tube having axial slits forming an array of spines forming a basket. A mechanism flexes the spines to expand and collapse the basket. Electrodes are carried by the spines for advancement in a path to penetrate the tissue region upon expansion of the basket.
In one embodiment, at least one of the electrodes is carried in a co-extruded lumen in a wall of the tube. Another co-extruded lumen in a wall of the extruded tube is attachable to a fluid source and has an outlet to dispense fluid into heat conductive contact with tissue in the tissue region. Another co-extruded lumen in a wall of the extruded tube is attachable to an aspiration source and having an inlet t
Chin Jay
Edwards Stuart
Gaiser John
Utley David
West Scott
Curon Medical, Inc.
Peffley Michael
Ryan Kromholz & Manion SC
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