ELECTRO-STIMULATOR

ELECTRO-STIMULATOR

GLOSSARY

• Muscle contraction is the physiological process in which muscles develop tension and shorten or stretch (or may remain of the same length) due to a stimulus of previous extension. 
• Endorphin: One of several substances that the body makes that can relieve pain and give a feeling of well-being. Endorphins are peptides (small proteins) that bind with the opioid receptors of the central nervous system. An endorphin is a type of neurotransmitter. 
• Neurotransmitters: chemical substances generated by the body that are responsible for emitting signals (information) from one neuron to another through a process called synapsis.

The electrostimulation is applied by means of an apparatus called 'electro-stimulator' in the most problematic areas, either for the purpose of improving muscular or therapeutic performance. This electrical current causes a contraction in the muscle very similar to the impulses that the central nervous system emits to control the muscular actions.

Muscle electrostimulation devices work depending on the objective pursued when using them, so it is important to choose well the intensity of the discharges that are applied and the area where the electrodes that are directly attached to the skin are placed. The membranes of the cells of the organism are polarized, since there is an unequal distribution of electrical charges between the outside of the cell (positive) and the inside of the cell (negative), where the energy of electrotherapy tries to act precisely. 

Thus, the type of frequency selected in the electrostimulation devices is the key to indicate to our body what type of muscle fiber is being activated or excited, according to the training phase in which we find ourselves, or the health problem that is attempted solve by this technique. 

The lower frequencies are indicated to achieve a relaxation of both the muscle and the person, with an increase in blood circulation and the release of endorphins, but as the band of the electric frequency is raised, the muscle from a typical aspect of aerobic exercise, through a combination of aerobic-anaerobic until reaching anaerobic metabolism, with the highest frequencies, above 50 Hz.

The frequency ranges that can be used in electrostimulation: 

• Range 2-4 hertz: it is a very gentle electrostimulation session, with which the muscle is relaxed, both in case it is overloaded and painful. This band promotes blood circulation and the elimination of toxic substances from the body. 
• Range 4-8 hertz: the session continues to be very smooth, but the body also responds to this electrostimulation. Thus, the organism generates endorphinic substances that contribute to raising the threshold of pain and, therefore, the ability to resist before it. 
• Range 8-12 hertz: although the session is still quite smooth, we begin to notice how the muscle contracts when this frequency range is applied. It is a kind of massage and, therefore, it is accompanied by the benefits of a local massage: intense relaxation in the area, improvement of local blood circulation and muscle oxygenation, as well as a decrease in toxic substances. 
• Range 12-40 hertz: with this intensity the slower muscle fibers are activated, just as it is done with a smooth continuous stroke. It begins, therefore, to work the aerobic capacity of the organism, but without hardly deficit of oxygen.
•  Range 40-60 hertz: this range works mostly intermediate slow fibers, although it can reach some fast, depending on the amplitude. It is one more step of the previous range because it achieves the same effect but expanded: greater muscular resistance and better level of oxygenation. 
• Range 60-80 hertz: this is already a work of strength and development of musculature itself, since both intermediate and rapid muscle fibers are activated.
•  Range 80-120 hertz: fast fibers are activated with great intensity, which improves strength, speed, and also a combination of both.

The electro-stimulator that was developed in practice had a voltage wave, with frequencies from 4 Hz to 14 Hz.

The TENS waves are indicated to reduce pain based on the theory of "GATE CONTROL", that is, the control of the entrance door, which consists of sending the brain a large amount of sensitive sensitive information so that this, the brain, do not receive the information corresponding to the pain. 

The TENS do not make contraction, just a tickling because, when used, they only excite sensory fibers.

    

Frecuencia	Resistencia(K)	Corriente	Voltaje
14	3,10E+05	3,58E-04	2,5
12	3,58E+05	3,74E-04	2,5
10	4,19E+05	3,68E-04	2,5
8	5,32E+05	3,50E-04	2,5
6	6,57E+05	3,58E-04	2,5
4	9,60E+05	3,00E-04	2,5

Electronic diagram and signal 

We use the following electronic diagram to obtain the signal with the desired amplitude and frequency

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We put the electrodes in the arm and obtained the output of our signal as shown below:  

DEFIBRILLATOR AND PACEMAKER

DEFIBRILLATOR AND PACEMAKER 

GLOSSARY

• Heart rate: number of times the heart beats for one minute.
• Arrhythmias: It is a disorder of the heart rate (pulse) or heart rate. The heart may beat too fast (tachycardia), too slow (bradycardia) or irregularly.
•  Defibrillation: is used in cases of cardiorespiratory arrest, with the patient unconscious, with ventricular fibrillation or ventricular tachycardia without a pulse. They are deadly without treatment. 
• The electrical cardioversion: It is used to reverse all types of reentrant arrhythmias, except ventricular fibrillation. The electric shock is synchronized with the electrical activity of the heart. It can be administered electively or urgently, if the situation compromises the patient's life.

Defibrillation is based on the abrupt and brief application of a high voltage electric current to stop and reverse the rapid cardiac arrhythmias (sustained ventricular tachycardia, ventricular fibrillation); situations in which the number of heartbeats increases excessively or a disorganized electrical activity occurs, because some area or focus of the heart 'triggers' impulses in an uncontrolled manner, which are not effective or produce a hemodynamic instability (deterioration of the vital signs) that can lead a person to cardiac arrest.

The defibrillator is indicated in patients with cardiac arrest, loss of consciousness and ventricular fibrillation. When the heart beats so many times and so disorganized, it can not pump blood and therefore its activity 'stops'. Under these conditions, death ensues in a few minutes if the arrhythmia does not stop. The only measure that can prevent this outcome is electrical defibrillation.

 It is also indicated in patients with a history of myocardial infarction or dilated cardiomyopathy who have poor ventricular function who have not suffered any cardiac arrest, but who are at high risk of suffering from a dangerous cardiac arrhythmia (primary prevention).

The pacemaker is an electronic device that sends impulses to the heart to maintain the normal rhythm. An artificial pacemaker is an electronic device designed to produce electrical impulses in order to stimulate the heart when physiological or normal stimulation fails. These impulses, once generated, need a conductor cable (or electrocatheter) that stands between them to reach their goal. In this way, a cardiac stimulation system consists of a generator of electrical impulses (or pacemaker itself) and a cable.

Pacemakers, in general, are indicated for heart rhythm disorders with abnormal decrease in heart rate. And there are two main causes of an abnormal fall in heart rate:

• The inability of the sinus node (cell group where the electrical impulse that gives rise to a heartbeat originates) to produce a sufficient number of impulses per minute: also called 'sick sinus syndrome or sinus node disease'. When the nodule fails, its trigger frequency decreases (number of pulses / minute) and sometimes there are long pauses in which the heart stops beating for a few seconds. Pacemaker implantation is indicated if symptoms such as syncope (loss of consciousness), heart failure (difficulty in breathing, swelling in the legs) or angina (chest pain) occur, as long as these symptoms are secondary to bradycardia.
• The failure of the conduction of the impulses produced by the sinus node to the heart muscle: if atrioventricular AV node disorders occur (cardiac cells specialized in the formation and conduction of cardiac electrical impulses) and of the distal conduction system, The indication of implanting a pacemaker depends on the severity of the disorder and the patient's symptoms. If there is a complete atrio-ventricular block (no conduction of any of the impulses produced by the sinus node), the pacemaker is indicated; if it is of the second degree (there is no conduction of some of the impulses produced by the sinus node), it will only be applied if there are symptoms, and if it is of the first degree (all impulses are driven but with a decrease in the transmission speed) , it is not implanted. There are other circumstances in which its use is indicated.

Types of pacemakers 

Temporary pacemaker: the generator is not implanted in the patient, and can be:

•  Transcutaneous (usually included in some defibrillators): the electrodes are placed on the skin, one in the anterior part of the chest (negative electrode) and another in the back (positive electrode). 
• Intravenous (endocavitary): the electrodes are placed through a central vein to contact the endocardium. Permanent pacemaker: the generator is implanted subcutaneously.

Permanent pacemaker: the generator is implanted subcutaneously.

Pacemaker and Defibrillator code

we declared the pin of input of a button and the size of arrays 

when the button is pressed, we set a discharge of 500 ms according to the value of voltage that the person selected.

In the circuit, we show the correct connection of capacitors from where we get the voltage.

To perform the defibrillation voltage multipliers are used, these are electronic circuits composed of rectifier diodes and capacitors to raise an AC voltage to a DC voltage. The voltages used were: 18, 140 and 260 V.

For show the vector of ECG that we read from signal generator, we did with the next code where we read 80 data in total where the time between data is 1 ms, and the sampling frequency was 125 Hz.