Therapeutic equipments

Therapeutic equipments
Unit-IV Therapeutic equipments Need of Physiological and electrotherapy equipment, Cardiac pacemaker, Cardiac defibrillators, Nerve and Muscle stimulators, Diathermy- Short-wave, Microwave, Ultrasonic VM Umale Dept. of Electronics and Telecommunication Engineering

Unit-IV: Therapeutic equipments
Need of physiological equipments and Electrotherapy equipments Nerve and muscle stimulators Cardiac pacemakers Cardiac defibrillators Diathermy Short wave Diathermy Microwave Diathermy Ultrasonic diathermy VM Umale Dept. of Electronics and Telecommunication Engineering

Need of physiological equipments Need of Electrotherapy equipments
Lecture-23 Physiotherapy Need of physiological equipments Need of Electrotherapy equipments VM Umale Dept. of Electronics and Telecommunication Engineering

Physiotherapy Need of physiological equipments Physiotherapy
Lecture-23 Physiotherapy Need of physiological equipments Physiotherapy Physical stimulus in the form of heat Simple heat radiation Application of high frequency Shortwave therapy Microwave Ultrasonic wave Principle of HF heat therapy- a) dipole molecules of the body are placed randomly b) they rotate or align according to the polarity of their charge in the direction of the field lines VM Umale Dept. of Electronics and Telecommunication Engineering

Merits of physiotherapy-
when the HF energy is utilized to get physical stimulus in the form of heat than that sort of physiotherapy is referred as thermotherapy Merits of physiotherapy- Considerable penetration of heat as compared with simple heat applications. Uniform heating of deeper lying tissues i.e deep heating directly in the tissues of the body ( Muscles, bones, internal organs) No burning of skin, No injury, Non traumatic VM Umale Dept. of Electronics and Telecommunication Engineering

Permits localization of the heat to the region that has to be treated
Merits of physiotherapy- No discomfort and skin burns even before adequate heat has penetrated to the deeper tissues like conventional techniques such as hot towels, IR lamps, heating pads Treatment can be controlled precisely by controlling amount of heat to be required. Permits localization of the heat to the region that has to be treated HF energy for heating is obtained by various equipments HF of MHz(27.12MHz, 11m) VM Umale Dept. of Electronics and Telecommunication Engineering

DIATHERMY ‘Diathermy' means 'through heating' or producing deep heating directly in the tissues of the body. Externally applied sources of heat like hot towels, infrared lamps and electric heating pads often produce discomfort and skin burns long before adequate heat has penetrated to the deeper tissues. In diathermy technique, the subject's body becomes a part of the electrical circuit and the heat is produced within the body and not transferred through the skin VM Umale Dept. of Electronics and Telecommunication Engineering

Electrotherapy Need of Electrotherapy equipments
The biological reactions produced due to Low volt, low freq. Impulse currents The biological reactions are adopted in this therapy for the management of many diseases affecting muscles and nerves. The technique is used for- The treatment of paralysis with totally or partially degenerated muscles The treatment of pain, muscular spasm, peripheral circulatory disturbances VM Umale Dept. of Electronics and Telecommunication Engineering

Electrotherapy Typical i-t curves of a normal muscle and degenerated muscle. The curve shows that decreasing excitability with progressive degeneration requires extended stimulation times and increased current strength for achieving successful stimulation The chronaxie and rheobase can be easily read from the i-t curves. The rheobase is the minimum intensity of current that will produce a response if the stimulus is of infinite duration, in practice an impulse of 100 ms being adequate for estimating this. The chronaxie is the min. duration of impulse that will produce a response with a current of double the rheobase. For example if the rheobase is 6 mA, the chronaxie is the duration of the shortest impulse that will produce a muscle contraction with a current of 12 mA. VM Umale Dept. of Electronics and Telecommunication Engineering

Electrotherapy Different types of current impulses used in
Galvanic current Interrupted Galvanic current Faradic current Surging or faradic surge currents Exponentially progressive current Biphasic stimulation VM Umale Dept. of Electronics and Telecommunication Engineering

Electrotherapy: Current waveforms
Current waveforms normally employed in electrodiagnosis and electrotherapy: galvanic Faradic Exponential Rectangular pulse with adjustable slope Surged Faradic. VM Umale Dept. of Electronics and Telecommunication Engineering

The most commonly used pulse waveforms are discussed below.
1. Galvanic Current: : A steady flow of direct current is passed through a tissue, its effect is primarily chemical. It causes the movement of ions and their collection at the skin areas lying immediately beneath the electrodes. The effect is manifested most clearly in a bright red coloration. It is an expression of hyperaemia (increased blood flow). Galvanic current / direct current/ galvanism/ continuous current / constant current. Used for the – Preliminary treatment of atonic paralysis Treatment of disturbance in the blood flow. Iontophores Int. of drugs into the body thr. the skin by electrolytic means.) The intensity of the current passed thr any part of the body < 0.3 to 0.5 ma/cm 2. The duration of the treatment is generally 10–20 minutes. VM Umale Dept. of Electronics and Telecommunication Engineering

2. Faradic Current: : Faradic Current: It is a sequence of pulses with a defined shape and current intensity The pulse duration is about 1 ms with a triangular waveform Interval = 20msec Duration of about 20 minutes. It acts upon muscle tissue and upon the motor nerves to produce muscle contractions. There is no ion transfer and consequently, no chemical effect. Used for the treatment of muscle weakness after lengthy immobilization Used in Disuse atrophy. VM Umale Dept. of Electronics and Telecommunication Engineering

3. Surged Faradic Current: : Surging Current: The resulting shape of the current waveform is called a surging current when The peak current intensity applied to the patient increases and decreases rhythmically along with the rate of increase and decrease of the peak amplitude is slow Application of the Faradic surge current – The treatment of functional paralysis. The treatment of spasm and pain. The surge rate is usually from 6-60 surges/min. in most of the inst. The ratio of interval to the duration of the surging is also adjustable so that graded exercise may be administered VM Umale Dept. of Electronics and Telecommunication Engineering

4. Exponentially Progressive Current: : Useful for the treatment of severe paralysis for the treatment of the paralysed muscles The main advantage of this method lies in the possibility of providing selective stimulation. This means that the surrounding healthy tissues even in the immediate neighbourhood of the diseased muscles are not stimulated The slope of the exponential pulse is kept variable. VM Umale Dept. of Electronics and Telecommunication Engineering

Biphasic Stimulation:
Other type of pulse Biphasic Stimulation: : The cell recovery from the effect of a stimulus current can be hastened by the passage of a lower intensity current of opposing polarity over a longer period so that the net quantity of electricity is zero. Combination of positive and negative pulses is called biphasic stimulation. The stimulating pulse may be followed by a pulse of opposite polarity of one-tenth the amplitude and 10 times the width. Biphasic stimulation also helps to neutralize the polarization of the recording electrodes in case silver-silver chloride electrodes are not used. This means that there are no electrolytic effects, nor are any macroscopic changes affecting either the skin or the electrodes observed. Also, there is reduced muscle fatigue, since each current pulse is immediately followed by an opposite current phase of the same magnitude. The stimulation current intensity required during treatment is less as compared with monophasic currents. VM Umale Dept. of Electronics and Telecommunication Engineering

Features of Electrotherapy:
To manage many diseases affecting muscles and nerves For the treatment of paralysis with totally or partially degenerated muscles Used for the treatment of pain, muscular spasm Widely used with availability of safe and simplified equipments Apparatus are either of constant voltage or constant current types Several types of commercial units are available which gives specific output waveforms for specific applications VM Umale Dept. of Electronics and Telecommunication Engineering

Devices produce output current waveforms to cover the
Cont….. Devices produce output current waveforms to cover the whole range of electro-diagnostic and therapeutic possibilities Modern electro-therapy units are up/uc controlled with automatic self test, automatic settings of the basic programs and also possible to indicate operating errors on the visual display VM Umale Dept. of Electronics and Telecommunication Engineering

Stimulators refers to an external influence
Electrical, mechanical or chemical All cells are sensitive to some degree to artificial electrical stimulation(Cells may depolarized and repolarised) The physiological action of stimulation depends on the passage of current across the cell membrane Stimulators are the devices- To stimulate innervated, denervated muscles and nerves For the treatment of paralysis with totally or partially denervated muscles For the treatment of pain, muscular spasms and peripheral circulatory disturbances VM Umale Dept. of Electronics and Telecommunication Engineering

Interrupted galvanic current Faradic current Surged faradic current
Stimulators TYPES OF STIMULATORS The applied voltage & current are the important parameters and which are related with source and load impedance Stimulators are classified based on the different types of current waveforms Galvanic current Interrupted galvanic current Faradic current Surged faradic current Exponential current VM Umale Dept. of Electronics and Telecommunication Engineering

Constant current circuit, both poles earth-free.
Electrotherapy The typical specifications of an electro-diagnostic therapy unit are as follows: Galvanic current up to 80 mA, ripple less than 0.5% as constant current or surging current with adjustable surge frequency from 6 to 30 surges per minute Exponentially progressive current pulse sequences with continuously variable pulse duration from 0.01 to 1000 ms and independently adjustable interval duration of 1 to 10,000 ms. The pulse form can be set continuously between triangular and rectangular forms; Faradic surging current with 25 surges per minute, up to 80 mA. Precision and constancy of the values set better than ±10%; peak current measurement facility. Constant current circuit, both poles earth-free. VM Umale Dept. of Electronics and Telecommunication Engineering

Schematic diagram of a diagnostic/therapeutic stimulating unit
Stimulators 1.Versatile electro diagnostic therapeutic stimulator it covers whole range of electro diagnostic and therapeutic possibilities BLOCK DIAGRAM – Schematic diagram of a diagnostic/therapeutic stimulating unit VM Umale Dept. of Electronics and Telecommunication Engineering

Stimulators BLOCK DIAGRAM – 2. Nerve stimulator-
VM Umale Dept. of Electronics and Telecommunication Engineering

Stimulators Other stimulators 3. Transcutaneous electrical Nerve stimulator(TENS) Transcutaneous electrical nerve stimulation (TENS) therapy involves the use of low-voltage electric currents to treat pain. Electrodes or mediums for electricity to travel to the body, placed on the body at the site of pain deliver electricity that travels through the nerve fibers. The electric currents block the pain receptors from being sent from the nerves to the brain. A patient will receive a small, battery operated TENS machine to use at home. In most cases, a doctor, physical therapist, or acupuncturist adjusts the machine to the correct settings. The provider shows the patient how to use the machine before sending him or her home with the TENS device. VM Umale Dept. of Electronics and Telecommunication Engineering

Osteoporosis-related joint, bone, or muscle problems
Stimulators TENS therapy can be used to treat both chronic (long lasting) and acute (short-term) pain. The most common conditions that TENS therapy is used to treat are: Osteoporosis-related joint, bone, or muscle problems Fibromyalgia-related joint, bone, or muscle problems Tendinitis (muscle tissue inflammation) Bursitis (inflammation of the fluid-filled pads that cushion the joints) Neck pain Labor pain Cancer pain VM Umale Dept. of Electronics and Telecommunication Engineering

4. Spinal cord stimulator 5. Magnetic stimulator 6. Bladder stimulator
Stimulators Other stimulators 4. Spinal cord stimulator 5. Magnetic stimulator 6. Bladder stimulator 7. Cerebellar stimulator VM Umale Dept. of Electronics and Telecommunication Engineering

THANKS A LOT Therapeutic Devices :

Diathermy VM Umale Dept. of Electronics and Telecommunication Engineering

SHRI SANT GAJANAN MAHARAJ COLLEGE OF ENGINEERING, SHEGAON
: VM Umale Dept. of Electronics and Telecommunication Engineering

Cont… In diathermy technique, the subject's body becomes a part of the electrical circuit and the heat is produced within the body and not transferred through the skin Draw back of externally applied sources of heat like hot towels, infrared lamps and electric heating pads often produce discomfort and skin burns long before adequate heat has penetrated to the deeper tissues, get eliminated in diathermy technique VM Umale Dept. of Electronics and Telecommunication Engineering

Advantages of Diathermy:
SHRI SANT GAJANAN MAHARAJ COLLEGE OF ENGINEERING, SHEGAON Advantages of Diathermy: Considerable penetration of heat as compare to conventional techniques Deeper lying tissues, muscles, bones, internal organs gets uniform heat The treatment can be controlled precisely Careful placement of the electrodes permits the localization of the heat to the region to be treated The amount of heat can be closely adjusted by means of circuit parameters HF currents do not stimulate motor/sensory nerves, nor they produce any muscle contraction No discomfort is caused to the subject. VM Umale Dept. of Electronics and Telecommunication Engineering

Diathermy Short wave Diathermy Microwave Diathermy Ultrasonic diathermy VM Umale Dept. of Electronics and Telecommunication Engineering

Diathermy Short wave Diathermy
Unit-IV: Therapeutic equipments Diathermy Short wave Diathermy VM Umale Dept. of Electronics and Telecommunication Engineering

O/P of RF Osc. Ckt 27.12MHz, 11m, 20min Continuous, pulsed
SHRI SANT GAJANAN MAHARAJ COLLEGE OF ENGINEERING, SHEGAON : O/P of RF Osc. Ckt 27.12MHz, 11m, 20min Continuous, pulsed VM Umale Dept. of Electronics and Telecommunication Engineering

Isolation Transformer
SHRI SANT GAJANAN MAHARAJ COLLEGE OF ENGINEERING, SHEGAON : Power Supply RF Oscillator Monitor Control Panel Isolation Transformer To patient electrodes RF energy heats the tissues and promotes healing of injured tissues and inflammations VM Umale Dept. of Electronics and Telecommunication Engineering

Patient’s resonator ckt
SHORT-WAVE DIATHERMY An Oscillating Circuit(HF Ckt) A patient Circuit Tank circuit + Ve FB Patient’s resonator ckt Simplified circuit diagram of a short wave diathermy unit Intensity of Current regulates by Controlling-1. Anode Voltage(4KV), 2. Filament I (ma), 3. adj. the grid bias thr Rg, 4. adj. position of the resonator coil wrt the osc. coil VM Umale Dept. of Electronics and Telecommunication Engineering

Application Techniques of Short-wave Therapy:
SHORT-WAVE DIATHERMY Application Techniques of Short-wave Therapy: Methods of applying electrodes in shortwave diathermy treatment (a) condenser method VM Umale Dept. of Electronics and Telecommunication Engineering

SHORT-WAVE DIATHERMY Application Techniques of Short-wave Therapy: Methods of applying electrodes in shortwave diathermy treatment (c )Shortwave diathermy (with capacitive electrodes) in use VM Umale Dept. of Electronics and Telecommunication Engineering

SHORT-WAVE DIATHERMY Application Techniques of Short-wave Therapy: Methods of applying electrodes in shortwave diathermy treatment (a) Inductive method VM Umale Dept. of Electronics and Telecommunication Engineering

SHORT-WAVE DIATHERMY Application Techniques of Short-wave Therapy: Methods of applying electrodes in shortwave diathermy treatment (d) Inductive heating by a coil housed in a drum. VM Umale Dept. of Electronics and Telecommunication Engineering

Pulsed Shortwave Therapy
Peak power vs mean power in a pulsed shortwave therapy machine Pulsed shortwave diathermy machine with monode applicator VM Umale Dept. of Electronics and Telecommunication Engineering

2. Microwave Diathermy: VM Umale Dept. of Electronics and Telecommunication Engineering

Set up of a Microwave Diathermy Unit:

2. Microwave Diathermy: Simple Block Diagram:

Schematic Diagram of a Microwave Diathermy Unit:
The magnetron Cylindrical cathode surrounded by anode, -- Resonator systems by means of a coupling loop -- the central conductor of a coaxial output tube through a glass seal to a director (radiating element of antenna and reflector witch directs the energy for application the patient) circuit diagram of a microwave diathermy The output power of a magnetron depends upon : 1. anode voltage, 2. magnetic field, 3. magnitude and phase of the ZL to which the magnetron o/p power is delivered, Efficiency of magnetron is % VM Umale Dept. of Electronics and Telecommunication Engineering

2. Microwave Diathermy: The main supply voltage is a applied to an interference suppression filter it by pass the high frequency pickup generated by the magnetron The fan is used to cool the magnetron, which is directly connected to the mains supply. Deal circuit: delay of 3-4 minutes before power may be derived from magnetron is necessary to warm up the magnetron The magnetron circuit: the magnetron filament heating voltage is obtained directly from a separate secondary winding of the transformer. The filament cathode circuit contains interference suppression filters The anode supply to the magnetron can be either DC or AC. A DC voltage is a obtained by a FWR followed by a voltage doubler circuit Safety circuit: the magnetron may damage due to excessive flow of current and which may be protected by inserting a fuse (500ma) in the anode supply circuit of the magnetron VM Umale Dept. of Electronics and Telecommunication Engineering

2. Microwave Diathermy: The magnetron consists of cylindrical cathode surrounded by anode structure that contains cavities opening into the cathode-anode space by means of slots The output energy is derived from the resonator systems by means of a coupling loop The energy picked up on the coupling loop is carried out of the magnetron of the central conductor of a coaxial output tube through a glass seal to a director Director consist of a radiating element of antenna and reflector witch directs the energy for application the patient The output power of a magnetron depends upon 1. anode voltage, 2. magnetic field, 3. magnitude and phase of the load impedance to which the magnetron output power is delivered Efficiency of magnetron is % VM Umale Dept. of Electronics and Telecommunication Engineering

2. Microwave Diathermy: The main supply voltage is a applied to an interference suppression filter it by pass the high frequency pickup generated by the magnetron The fan is used to cool the magnetron, which is directly connected to the mains supply. Deal circuit: delay of 3-4 minutes before power may be derived from magnetron is necessary to warm up the magnetron The magnetron circuit: the magnetron filament heating voltage is obtained directly from a separate secondary winding of the transformer. The filament cathode circuit contains interference suppression filters The anode supply to the magnetron can be either DC or AC. A DC voltage is a obtained by a FWR followed by a voltage doubler circuit Safety circuit: the magnetron may damage due to excessive flow of current and which may be protected by inserting a fuse (500ma) in the anode supply circuit of the magnetron VM Umale Dept. of Electronics and Telecommunication Engineering

Comparision Application Techniques of Short-wave Therapy: Comparison of the heat distribution in the body tissues with the shortwave inductive diathermy, capacitive plate of diathermy applicator and microwave diathermy. (Adapted from Cameron, 2009) VM Umale Dept. of Electronics and Telecommunication Engineering

ULTRASONIC THERAPY UNIT
An ultrasonic therapy unit Block Diagram The output of the osc. can be controlled by: Using a transformer with a primary winding having multi-tapped windings and switching the same as per requirement; Controlling the firing angle of a triac placed in the primary circuit of the transformer, and thereby varying the output of the transformer. Dosage Control: The dosage can be controlled by varying any of the following variables. Frequency of ultrasound; Intensity of ultrasound; or Duration of the exposure. VM Umale Dept. of Electronics and Telecommunication Engineering

The thermal effects of ultrasound are dependant on the The amount of energy absorbed The length of time of the ultrasound application Frequency of the ultrasound generator Ultrasonic generator are constructed on the piezo-electric effect High frequency of 0.75 – 3 Mhz current is applied to a crystal Dose control The doses can be controlled by varying any of the following Frequency of ultrasound Intensity of ultrasound Duration of the exposur Out put power of an ultrasonic diathermy can be continuously varied between 0-3 watt/cm2 Application technique The probe can be put in direct contact with body through a couplet provided the part to be treaded is sufficiently smooth and un injured Incase of logh area is to be treated, the probe is moved up and down and for small area it is given a circular motion. VM Umale Dept. of Electronics and Telecommunication Engineering

: 1 VM Umale Dept. of Electronics and Telecommunication Engineering

Application Techniques
ULTRASONIC DIATHERMY Application Techniques Ultrasonic therapy in use VM Umale Dept. of Electronics and Telecommunication Engineering

Application Techniques
DIATHERMY Application Techniques VM Umale Dept. of Electronics and Telecommunication Engineering

THANKS A LOT Therapeutic Devices :

Necessity of CARDIAC PACEMAKER NSR: Normal sinus rhythm
Therapeutic Devices CARDIAC PACEMAKER Necessity of CARDIAC PACEMAKER NSR: Normal sinus rhythm In abnormal condition: Disturbances in NSR Either temporary or permanent failure in natural pacemaker( SA Node) Arrhythmia Bradycardia Tachycardia Heart Block I degree II degree III degree VM Umale Dept. of Electronics and Telecommunication Engineering

Pacemaker pulses followed by QRS complex of the heart
CARDIAC PACEMAKER : Pacemaker pulses followed by QRS complex of the heart VM Umale Dept. of Electronics and Telecommunication Engineering

Types of CARDIAC PACEMAKER
Based on Implantation or location- External Cardiac Pacemaker Internal (Implantable) Cardiac Pacemaker Programmable Cardiac Pacemaker Based on pacing modes- competitive Non-Competitive Based on output impulse waveform- Constant current type Constant Voltage type limited current constant voltage type VM Umale Dept. of Electronics and Telecommunication Engineering

A pacemaker basically consists of two parts:
CARDIAC PACEMAKER A pacemaker basically consists of two parts: An electronic unit- Pulse generator Generates stimulating impulses of controlled rate and amplitude i.e. The impulse-forming circuit determines- The frequency and duration of the impulses. This is usually a multi-vibrator circuit with adjustable rate and fixed pulse width. The output circuit determines the shape and amplitude of the impulse. (ii) Patient Circuit: (iii) The lead -Carries the electrical pulses from the pulse generator to the heart. -Includes the termination which connects to the pulse generator and the insulated conductors, -Interface with electrodes and terminate within the heart. : VM Umale Dept. of Electronics and Telecommunication Engineering

Can be in the form of bipolar or unipolar system.
CARDIAC PACEMAKER : (iv)The electrode : Can be in the form of bipolar or unipolar system. In the bipolar system, two electrodes are placed on the heart for myocardial stimulation. In the unipolar system, one electrode is placed on the heart and the other electrode is positioned elsewhere in the body. The waveforms used for pacing: Round-topped rectangular pulses- Duration 1–3 ms Rates pulses/minute(adjustable). VM Umale Dept. of Electronics and Telecommunication Engineering

Block diagram of external pacemaker
CARDIAC PACEMAKER : Block diagram of external pacemaker VM Umale Dept. of Electronics and Telecommunication Engineering

CARDIAC PACEMAKER : Impulses from three different types of pacemakers as seen on oscilloscope: (a) constant current type pacemaker (b) current limited voltage pacemaker (c) voltage pacemaker VM Umale Dept. of Electronics and Telecommunication Engineering

The implantable pacemaker placed inside the human body
CARDIAC PACEMAKER : The implantable pacemaker placed inside the human body VM Umale Dept. of Electronics and Telecommunication Engineering

Various pacing modalities in demand pacemakers
CARDIAC PACEMAKER : Various pacing modalities in demand pacemakers ventricular demand inhibited : VVI (b) A-V sequential VM Umale Dept. of Electronics and Telecommunication Engineering

Various pacing modalities in demand pacemakers
CARDIAC PACEMAKER : Various pacing modalities in demand pacemakers (c) atrial synchronous (ventricular inhibited), (VD T/I, (d) fully automatic DDD) VM Umale Dept. of Electronics and Telecommunication Engineering

CARDIAC PACEMAKER : Fixed Rate Pacemaker: This type of pacemaker is intended for patients having permanent heart blocks. The rate is pre-set, say at 70 bpm. The rate can be varied externally in implanted units by magnetically actuating a built-in relay. Since the fixed rate pacemaker functions regardless of the patients' natural heart rhythm, it poses a potential danger because of competition between the patients' rhythm and that of the pacemaker. Demand Pacemaker: These pacemakers have gradually almost replaced the fixed rate pacemakers because they avoid competition between the heart's natural rhythm and the pacemaker rhythm. The demand unit functions only when the R-R intervals of the natural rhythm exceed a pre-set limit. R wave Triggered Pacemaker: The ventricular synchronized demand type (R wave triggered) pacemaker is meant for patients who are generally in heart block with occasional sinus rhythm. The pacemaker detects ventricular activity (R wave of ECG) and stimulates the ventricles after a very short delay time of some milliseconds. If there is sinus rhythm, the stimulating impulse will occur in the ventricular de-polarization. If there is asystole, the unit will stimulate the heart after a pre-set time. VM Umale Dept. of Electronics and Telecommunication Engineering

CARDIAC PACEMAKER : Ventricular Inhibited or R Wave Blocked Pacemaker: The ventricular inhibited type (R wave blocked) pacemaker is meant for patients who generally have sinus rhythm with occasional heart block. The circuitry detects spontaneous R wave potentials at the electrodes and the pacemaker provides a stimulus to the heart after pre-set asystole. However, in the case of ventricular activity, the R-wave does not trigger the output circuit of the pacemaker but blocks the output circuit and no stimulation impulse is given to the heart. Atrial Triggered Pacemaker: This is a R wave triggered or atrial triggered pacemaker. The pacemaker detects the atrial de-polarization and starts the pulse forming circuits after a delay so that the impulse to the ventricles is delivered after a suitable PR interval. The major advantage of this pacemaker is its ability to provide maximum augmentation of cardiac output at changing atrial rates to meet various physiological requirements. Dual Chamber Pacemakers: These devices are capable of treating the majority of those patients who suffer from diseases of the sino-atrial node by providing atrial stimulation whenever needed. In these devices, both the atria and the ventricles are sensed and stimulated as needed while maintaining proper synchronization of the upper and lower chambers. Rate–adaptive features available with dual chamber pacemakers include the automatic adjustment of stimulus intensity and gains for the various sensing channels. VM Umale Dept. of Electronics and Telecommunication Engineering

Block diagram of a ventricular synchronous demand pacemaker
CARDIAC PACEMAKER : Block diagram of a ventricular synchronous demand pacemaker VM Umale Dept. of Electronics and Telecommunication Engineering

Functional block diagram of programming interface
CARDIAC PACEMAKER : Magnetic—an electromagnet placed on the surface of the body establishes a magnetic field which penetrates the skin and operates the pacemaker's reed switch, Radio-frequency waves—the information can be transmitted over high frequency electromagnetic waves which are received inside the body by an antenna. The antenna is usually in the shape of a coil housed within the pacemaker, Acoustic-ultrasonic pressure waves from a suitable transducer placed over the skin, can penetrate the human body. They are received by a suitable receiver in the pacemaker which carries out the desired function. Functional block diagram of programming interface VM Umale Dept. of Electronics and Telecommunication Engineering

CARDIAC DEFIBRILLATORS
Therapeutic Devices CARDIAC DEFIBRILLATORS Necessity of CARDIAC DEFIBRILLATOR NSR: Normal sinus rhythm In abnormal condition: Disturbances in NSR VM Umale Dept. of Electronics and Telecommunication Engineering

Defibrillator is a device that deliver a therapeutic dose of electrical energy (electric shock) to the affected heart (fibrillated heart or other shockable rhythm) to force the heart to produce more normal cardiac rhythm. VM Umale Dept. of Electronics and Telecommunication Engineering

Defibrillation is a common treatment for life threatening Cardiac dysrhythmias, Ventricular fibrillation, Pulse less ventricular tachycardia. VM Umale Dept. of Electronics and Telecommunication Engineering

Arrhythmias Bradycardia Ventricular Tachycardia VM Umale Dept. of Electronics and Telecommunication Engineering

NEED FOR A DEFIBRILLATOR
Ventricular fibrillation is a serious cardiac emergency resulting from asynchronous contraction of the heart muscles. Due to ventricular fibrillation, there is an irregular rapid heart rhythm. Fig. Ventricular fibrillation Fig. Normal heart beat VM Umale Dept. of Electronics and Telecommunication Engineering

Ventricular fibrillation can be converted into a more
Cont… Ventricular fibrillation can be converted into a more efficient rhythm by applying a high energy shock to the heart. This sudden surge across the heart causes all muscle fibres to contract simultaneously. Possibly, the fibres may then respond to normal physiological pace making pulses. The instrument for administering the shock is called a DEFIBRILLATOR. VM Umale Dept. of Electronics and Telecommunication Engineering

Purpouse of defibillation
Defibrillation is performed to correct life-threatening fibrillations of the heart, which could result in cardiac arrest. It should be performed immediately after identifying that the patient is experiencing a cardiac emergency, has no pulse, and is unresponsive. VM Umale Dept. of Electronics and Telecommunication Engineering

Principle Of Defibrillation
Energy storage capacitor is charged at relatively slow rate from AC line. Energy stored in capacitor is then delivered at a relatively rapid rate to chest of the patient. Simple arrangement involve the discharge of capacitor energy through the patient’s own resistance. VM Umale Dept. of Electronics and Telecommunication Engineering

AC DEFIBRILLATION CARDIAC DEFIBRILLATORS Applying a brief(.25 to 1 sec) burst of 50 HZ ac at an intensity of around 6 A. This application of an electrical shock to resynchronize the heart is sometimes called counter shock. If the patient does not respond, the burst is repeated until defibrillation occurs. this method is known as ac defibrillation. VM Umale Dept. of Electronics and Telecommunication Engineering

DC Defibrillation CARDIAC DEFIBRILLATORS In this method a capacitor is charged to a high dc voltage and then rapidly discharged. The amount of energy discharged by the capacitor may range between 2 to 400joules with peak value of current 20A. A corrective shock of volts is applied within a tenth of a second . VM Umale Dept. of Electronics and Telecommunication Engineering

CIRCUIT OF DC DEFIBRILLATOR

External Defibrillator
power supply energy storage patient ECG monitor timing circuitry gate charge discharge standby switch is under operator control applies shock about 20 ms after QRS complex, avoids T-wave VM Umale Dept. of Electronics and Telecommunication Engineering

PRINCIPLE OF DEFIBRILLATOR
Energy storage capacitor is charged at relatively slow rate from AC line. Energy stored in capacitor is then delivered at a relatively rapid rate to chest of the patient. Simple arrangement involve the discharge of capacitor energy through the patient’s own resistance. VM Umale Dept. of Electronics and Telecommunication Engineering

Cont….. The discharge resistance which the patient represents is roughly a ohmic resistance of 50 – 100 ohms for a typical electrode size of 80cm2. The particular wave form is called “Lown” wave form. The pulse width of this waveform is 10ms. VM Umale Dept. of Electronics and Telecommunication Engineering

Manual external defibrillator Electrodes placed directly around the heart area of chest. Higher Voltage required than internal defibrillator. Classified as Monophasic Biphasic VM Umale Dept. of Electronics and Telecommunication Engineering

Monophasic waveform Defibrillators
Deliver current of one polarity. Current travels in one direction through the patients heart from one paddle to another. 2 types :- The monophasic damped sinusoidal waveform (MDS) returns to zero gradually Monophasic truncated exponential waveform (MTE) current is abruptly returned to baseline (truncated) to zero current flow VM Umale Dept. of Electronics and Telecommunication Engineering

MDS v/s MTE wave form VM Umale Dept. of Electronics and Telecommunication Engineering

Biphasic waveform Defibrillators Current travels towards the +ve paddle & then reverses back. Reversing of polarity, depolarizes all cells – called “burping” response. Classified into – Biphasic truncated exponential waveform (BTE) Rectilinear biphasic waveform (RBL) RBL is better than BTE. VM Umale Dept. of Electronics and Telecommunication Engineering

Biphasic truncated exponential waveform (BTE) v/s Rectilinear biphasic waveform (RLB)
RBL VM Umale Dept. of Electronics and Telecommunication Engineering

Classes of discharge waveform Fig:- Generation of bi-phasic waveform VM Umale Dept. of Electronics and Telecommunication Engineering

Advantages of Biphasic over Monophasic Less power – Less trauma – Less battery. Defibrillation more effective at low energy. Fewer burns. Less myocardial damage. 1st shock success rate in cardiac arrest due to shockable rhythm – Monophasic 60% Biphasic increases to 90% VM Umale Dept. of Electronics and Telecommunication Engineering

Types of Defibrillators
Manual external defibrillator Manual internal defibrillator Semi-Automated External Defibrillator Automated external defibrillator (AED) Implantable cardioverter-defibrillator (ICD) {automatic internal cardiac defibrillator (AICD)} 6. Wearable cardiac defibrillator VM Umale Dept. of Electronics and Telecommunication Engineering

Defibrillator Strength Duration Curve
energy (joules) current (amps) pulse duration defibrillation occurs Defibrillator Strength Duration Curve no defibrillation charge (coulombs)

Strength Duration Curve
minimum defibrillation energy occurs for pulse durations of ms (for most pulse shapes). pulse amplitude in tens of amperes (few thousand volts). VM Umale Dept. of Electronics and Telecommunication Engineering

Strength Duration Curve
operator selects energy delivered: joules, depends on: intrinsic characteristics of patient patient’s disease duration of arrhythmia patient’s age type of arrhythmia (more energy required for v. fib.) VM Umale Dept. of Electronics and Telecommunication Engineering

POWER OF DEFIBRILLATION
Higher voltages are required for external defibrillation than for internal defibrillation. A corrective shock of volts is applied within a tenth of a second. That is the same voltage as no of AA batteries! VM Umale Dept. of Electronics and Telecommunication Engineering

DEFIBRILLATOR ELECTRODES
Types of Defibrillator electrodes:- Spoon shaped electrode Applied directly to the heart. Paddle type electrode Applied against the chest wall Pad type electrode Applied directly on chest wall VM Umale Dept. of Electronics and Telecommunication Engineering

Fig.- Pad electrode VM Umale Dept. of Electronics and Telecommunication Engineering

ELECTRODE PLACEMENT OF AED
Anterior electrode pad Apex electrode pad Fig: anterior –apex scheme of electrode placement VM Umale Dept. of Electronics and Telecommunication Engineering

TYPES OF DEFIBRILLATORS
Internal defibrillator Electrodes placed directly to the heart e.g..-Pacemaker External defibrillator Electrodes placed directly on the heart e.g..-AED VM Umale Dept. of Electronics and Telecommunication Engineering

External Defibrillators
For each minute elapsing between onset of ventricular fibrillation and first defibrillation, survival decreases by 10%. defibrillators should be portable, battery operated, small size. energy in defibrillators usually stored in large capacitors. total energy stored in capacitor: Vc = capacitor voltage VM Umale Dept. of Electronics and Telecommunication Engineering

AUTOMATIC EXTERNAL DEFIBRILLATOR
AED is a portable electronic device that auto- matically diagnoses the ventricular fibrillation in a patient. Automatic refers to the ability to autonomously analyse the patient's condition. AED is a type of external defibrillation process. AEDs require self-adhesive electrodes instead of hand held paddles. The AED uses voice prompts, lights and text messages to tell the rescuer what steps have to take next. VM Umale Dept. of Electronics and Telecommunication Engineering

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