Uterus muscle controller

Details Uterus muscle controller Uterus muscle controller

2001-01-03

2004-02-17

Hoang, Tu Ba (Department: 3742)

Surgery: light, thermal, and electrical application

Light, thermal, and electrical application

Electrical energy applicator

C607S041000, C607S138000, C600S304000, C600S372000, C606S193000

Reexamination Certificate

active

06694192

ABSTRACT:

FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION
Preterm (or premature) labor is the second most important reason for fetal morbidity and mortality after fetal anomalies, occurring in about 10 percent of all pregnancies (8-12% of all labors in the US are premature. The total annual number of premature deliveries is about 400,000). Preterm labor is usually defined as the onset of labor before 37 weeks of pregnancy have been completed. The symptoms of preterm labor include uterine contractions at regular intervals that begin before the fetus is mature, usually before the due date of delivery, passage of bloody mucus, flow of fluid (amniotic fluid) from the uterus, that may occur with a gush or may be only a continuous watery discharge.
Main causes of preterm labor include premature rupture of the amniotic membranes (“water breaks”), illness of the mother, including pre-eclampsia, high blood pressure or diabetes, abnormal shape or size of the uterus, weak or short cervix, hormone imbalance, vaginal infection that spreads to the uterus, large fetus or more than one fetus, abnormalities of the placenta, such as placenta previa, and excessive amniotic fluid.
Tocolytic agents (medications used to inhibit labor), such as Beta-adrenergic agents, Magnesium sulfate, Prostaglandin inhibitors, Calcium channel blocker, are usually used to treat preterm labor and permit pregnancy to proceed so that the fetus can gain more size and maturity before delivery.
However, it was found that tocolytic agents are effective only in short term (up to 72 h) with efficacy of 40-50%. Moreover, they present severe adverse effects for both mother and fetus.
Cervical cerclage, on the other hand, have long term efficacy, but is a relevant therapy for only 2-4% of all preterm labor cases, and comprises surgical intervention.
Itis not always possible to inhibit labor contractions and stop the labor process by drugs. Moreover, the efficiency of drugs on the inhibition of labor is low, and is associated with many adverse effects (even cervical cerclage in small percentage of patients).
Electric muscle control is not a new concept, dating back to Galvani's experiments, applying electrical field to a dead frog's leg and causing its twitching (Galvani himself thought it to be the result of the generation of electricity in the dead animal's leg). For example, PCT/IL97/00012 (Ben-Haim et al.), published as WO 97/25098 and titled ELECTRICAL MUSCLE CONTROLLER now U.S. Pat. No. 6,363,279) described an electrical muscle controller for applying non-excitatory electric stimulation of the cardiac muscle in order to gain enhanced contractility, all incorporated herein by reference. It is noted that by “non-excitatory electric stimulation” it is meant electric stimulation that does not initiate electrical activation signal. An activation signal is an electrical signal which, when it reaches an excitable cell, causes it to depolarize and perform its destined activity.
In PCT/IL97/00243 published as WO 99/03533, titled SMOOTH MUSCLE CONTROLLER, there was described a method of directly and locally controlling the contraction and the force of contraction of smooth muscles.
The uterus muscle is also a smooth muscle that contracts in response to electrical activation signals. The uterus wall is composed of myometrium tissue, which is excitable and suitable for excitable tissue control (ETC) therapy of motion modulation through electrical non-stimulatory signal. See: “Uterine Electromyography: A Critical Review”, by D. Deveduex et al., Am. J. Obstet Gynecol 1993, 169, 1636-53.
U.S. Pat. No. 5,447,526 (Karsdon), filed in 1992, titled TRANSCUTANEOUS ELECTRIC MUSCLE/NERVE CONTROLLER/FEEDBACK UNIT, described a transcutaneous device for inhibiting uterine contractions. It comprises a first plurality electrode positioned on an anterior side of an abdomen of a patient, extending laterally above an upper portion of the uterus, a second plurality electrode positioned on the anterior side of the abdomen of the patient, extending laterally on the mid to lower portion of the uterus. U.S. Pat. No. 5,964,789 (Karsdon) and U.S. Pat. No. 5,713,940 (Karsdon) describe similar versions of devices as in U.S. Pat. No. 5,447,526.
Karsdon explains that as opposed to prior art electrical control devices, which are generally aimed at stimulating or increasing muscle activity, his devices are aimed at inhibiting muscular activity. Karsdon explains that his devices employ relatively long electrical pulses with a plurality of wave patterns, and constant current output.
U.S. Pat. No. 5,991,649 (Garfield et al.), filed in 1996, titled METHODS FOR ACTIVATING THE MUSCLE CELLS OR NERVES OF THE UTERUS OR CERVIX, also described electrical control of uterus activity.
It is established that both Karsdon and Garfield suggest applying excitatory signals to the uterus (given the suggested length of the applied signals, as well as explicit mentioning—by Garfield—of the action potential propagation).
But although the concept of inhibiting labor contractions, using electrical signals, per se, is not entirely new, the present invention suggests an entirely novel approach to induction of labor using non-excitatory electrical stimulation.
Prior art methods of inducing labor included natural methods, such as rupturing the membranes, stripping the membranes during pelvic examination, nipple stimulation to release one's own natural oxytocin, administration of enema or drinking castor oil, and even just walking. Application of drugs that cause induced labor in the event of failure to commence spontaneous labor is carried out if these natural methods fail.
Commonly labor inducing drugs include oxytocin, pitocin (a synthetic form of oxytocin) given intravenously or Prostaglandin (usually in the form of gel or suppository).
Oxytocin causes prelabor contractions to increase both in amplitude and in rhythm. But although increased contraction amplitude is desirable, increased contraction rhythm may result in fetus stress. During strong contractions the fetus is pressed inside the uterus, its navel cord may be squeezed, and as a result the oxygen supply may be temporarily halted or severely reduced. In naturally rhythmic labor contractions the fetus is given enough time to recover, but if the pace of the contractions is speeded up serious irreversible damage may occur. Fetus stress can be monitored using commonly available monitoring devices (where usually the fetus heart rate as well as other parameters are tracked).
The correct dose of oxytocin is not initially known and varies from patient to patient. It depends, inter alia, on the readiness of the uterus for labor, and therefore administering over dose of oxytocin is not uncommon. Over dose of oxytocin may result in extreme cases in tearing of the uterus due to violent hypertonic contractions. As the duration of the oxytocin effect is determined by the given dose and the half life period (typically 3-5 minutes), the only way to cancel oxytocin effect before the wash-out period is by administering a tocolytic drug.
BRIEF DESCRIPTION OF THE INVENTION
The present invention seeks to provide novel method and device for inhibiting or enhancing and even initiating uterus contractions, i.e. inhibiting preterm labor or inducing or expediting labor in overdue pregnancy.
In our PCT/IL97/00243 published as WO 99/03533 there was disclosed (see also FIGS. 6-8 in that patent application) a device for inhibiting premature labor or stimulating labor contractions. It was stipulated that such device may provide more control over the process of labor than is possible by using drugs.
Several situations were considered:
a. stopping premature labor;
b. stopping a labor where a cesarean section is indicated;
c. situations where fine control of the force of contractions of the uterus is required;
d assisting a labor which is not advancing properly;
e. stopping labor from ever starting, where it is contra-indicated;
f dictating a preferred contraction profile during labor.
It is a main object of the present invention to provide uterus cont

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