Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2000-01-14
2004-06-15
Getzow, Scott M. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06751501
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to control of the heart, in particular defibrillation, pacing, and cardiac paralysis.
2. Background Art
Existing devices for treating cardiac arrhythmia require deployment of high voltages which can, and often do, cause injury to the patient. The present invention permits utilization of low voltages and greatly decrease the risk of further injury to the patient.
An arrhythmia is any abnormal electrical contraction of heart. Particular arrhythmias include: asystole—no beat at all or “flat-line” on monitor; bradycardia—slow beat, less than 60 beats per minute; tachycardia—fast beat, over 100 beats per minute; and fibrillation—life threatening chaotic heart action in which the heart twitches or quivers rapidly and is unable to pump efficiently.
During fibrillation, less blood is circulating and thus all systems of the human or animal body are at risk. The longer fibrillation continues unchecked the more likely death will occur. For every minute of fibrillation, a 10% reduction of life potential is subtracted, i.e., ten minutes results almost certain death. During fibrillation the electrical system of the heart is disorganized and erratic. The normal rhythmic beat is totally lost. Serious life threatening events begin to occur. Breathing becomes erratic and then stops as electrical failure begins. Shortly the inadequate circulation of blood causes organs and tissues to be oxygen starved and cell death begins. When brain and heart muscle oxygen starvation reach crisis points they begin to die and hence the entire body begins to die. At some point the heart fibrillations are not reversible and death of the human or animal occurs. It is important to stop fibrillation and to restart or regain the same level of heart contractions to oxygenate the entire body properly.
Fibrillation is currently typically treated by an electronic defibrillator which delivers a shock via two hand-held paddles. This process is familiar to those who view medical television shows and witness a shock so great that the entire body jumps. This shock is about 2,000 to 5,600 volts for external shocks and 310 to 750 volts for internal defibrillators. Repeated use of such large electrical shocks likely may damage the nervous system to such an extent that disabilities shall be present even if the patient lives. The popular conception is that a defibrillator “puts” a heart beat into a stopped heart. Actually, a defibrillator stops the quivering heart, after which, but not always, the heart may resume a slow beat (bradycardia). Paramedics then can use medications to speed up the heart and/or administer an emergency external pacemaker while transporting the victim to a hospital.
In the science of electromyography there is a graphical presentation of fibrillation on a visual monitor of a heart muscle being affected by a monophasic, biphasic or triphasic spike usually of 25 to 100 microvolts in amplitude and each less than 2 milliseconds in duration. These represent uncoordinated contractions of heart muscle (myocardium) fibers. This is a degrading and dangerous state and does require electrical intervention plus oxygen and cardiac medications in an effort to stabilize or regain a normal heart beat. Perhaps 40% of heart attack victims are in fibrillation when a paramedic arrives. Another 40% might be in bradycardia, tachycardia or asystolic status. The other 20% might have plugged heart blood vessels, bleeding, or other conditions that are not related to the electrical function of the heart muscle.
The present invention provides devices and methods whereby substantially lower voltages and currents may be used to successfully treat heart muscle arrhythmias.
All individual organs of the body are electrochemical in nature and operate on something approximating one volt to conduct their respective duties. Certainly the action of the myocardium (muscular contractile body of the heart) which contracts about one billion times in a life span, also conducts its business of pumping blood utilizing only about one volt of electricity at any point in time. Each beat is a cascading flow of myocardial contractile motions that squeeze blood from the four chambers of the heart and then accept a refilling of blood for the next cycle.
The heart is a pump with a closed system of arteries and veins with a natural duty to circulate oxygenated blood over the entire network of blood vessels. Oxygenated blood is red when it is rich with oxygen loaded into its red cells, called erythrocytes. Blood turns blue as carbon dioxide (CO2) and other waste products are loaded into its red cells, not now called “blue cells”. The returning blue blood is pumped to the lungs to release the CO2 and other gaseous waste products. The red cells immediately uptake oxygen and continue their journey via the heart and into the blood vessels, to cyclicly do it all over again.
State of the art application of electricity for medical therapy to stop the fibrillation or quivering that is often encountered when a paramedic arrives on the scene of a heart attack victim, uses from 1,800 to 5,600 volts with 27 to 75 amps of current. The actual voltage and amperage that reaches the heart varies under Ohm's law by the resistance of the human or animal body and the integrity of electrode contacts to the body. Ohm's law states that voltage (V) equals the product of current (I) and resistance (R), or V=IR. Hydration of the skin under the electrodes also plays into the efficiency of the electrical therapy. There is approximately 50 to 150 ohms of resistance in the body depending on the hydration of live tissues. However, the most outer thin layer of dry skin can be 1000 ohms or higher. But high voltage can bust through that skin layer. Obviously the tissue is not as good a conductor as a metallic wire. However, because of the ionic nature of human or animal bodies it is possible to generate a specific waveform and cause it to enter the biological tissue and have an effect. Designers of external defibrillators anticipate a 50-ohm resistance load, but they know it could be somewhat higher.
Despite public perception, most of the people collapsing with heart failure, are not reached in time by paramedics to save them. Those that live because they received early defibrillation are often impaired from the cardiopulmonary resuscitation (CPR) process or by the high-voltage energy applied to their chest. The use of voltages that re in the range of 1,800 to 5,600 volts applied to the closed-bare chest of a human is a risky event. It is also risky to the medical personnel who must stop all contact with the patient or potentially be an electrocution victim themselves. The patient must sustain the large shock which conducts all over the body, with risk of burning out peripheral nerves and injuring any organ or system. There is a question of why such large voltage electric shock therapeutically even makes a positive outcome in the small minority of heart attack victims it saves.
The human body runs on small voltage within all of its systems including the brain and the heart yet all electric shock therapy consists of explosive bursts that are a risk to patient and treatment personnel. “Stand-Clear” is used by medical personnel to mean keep away or risk dangerous electrocution.
The usual action of the heart electrically begins by the sinoatrial node (SA node) firing a signal that then travels through known conductive pathways while activating contraction events as it goes. The SA node is actually a strip of electrochemical cells located on the radius between the vena cava and the right atrial chamber. Explained in simplicity, the conducted bioelectrical pulse activates in turn the atrioventricular node (AV node) and then respectively to various branches of the cardiac conductive pathways to complete a cardiac cycle from the top atrial chambers of the heart onward to the powerful ventricular chambers. The SA note repeats itself for the next round of activation of the electrical ci
Schuler Eleanor L.
Scott Dale L.
Barnes & Thornburg
Getzow Scott M.
Science Medicus Inc.
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