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Therapeutic and Prosthetic
Devices
Part I : Cardiac Pacemaker
Dr. Mohamad O. Diab
Assistant ProfessorCollege of Engineering
Hariri Canadian University (HCU)
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Outline
Introduction
Physiology of the heart
Pacemaker Asynchronous
Synchronous
Demand type
Aterial synchronous type
Variable rate type
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Therapeutic and prosthetic
Instruments Electrically stimulate different parts of the body to relief pain,
cure diseases, or replace damaged biological organ in thebody.
Examples of Therapeutic and prosthetic devices:
Cardiac Pacemakers
Ventilators
Heart-Lung machines
Artificial Kidney Diathermy Devices
Electrosurgical Instrument
Cochlear Implant
Eye Bionic
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Physiology of the heart
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Electrical conduction system
of the heart
http://fr.wikipedia.org/wiki/Image:ECG_Principle_fast.gif8/4/2019 Pacemaker Presentation
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Cardiac Pacemakers
Cardiac Pacemaker:
An electric stimulator that produces periodic electric pulses that are
conducted to electrode on the surface of the heart, within the heart
muscle, or within the cavity of the heart.
Two Type of Pacemakers:
1) Asynchronous cardiac pacemaker2) Synchronous cardiac pacemaker
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Types of pacemakers
Pacemakers
Asychronous Sychronous
Atrial sychronous Demand type Variable rate
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Asynchronous Cardiac PacemakersPower Supply: Lithium iodide
Cathode reaction: Li Li+
+ e-
Anode reaction at the Anode: I2 + 2e- 2I-
Timing Circuit: pulse rate is 70 to 90 pulse per minute
Output Circuit:
Constant-Voltage Amplitude pulses: 5.0 to 5.5 V with duration of 0.5
to 0.6 msec.
Constant-current amplitude pulses: 8 to 10 mA with pulse duration
from 1.0 to 1.2 ms.
Block diagram of an asynchronous cardiac pacemaker
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Figure 1. Two of the more commonly applied cardiac pacemaker electrodes
(a) Bipolar intraluminal electrode. (b) Intramyocardial electrode.
Lead Wires and Electrodes
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Synchronous Pacemakers
Provide electric stimulus when the cardiac normal rhythm is stopped.
Two type of synchronous pacemakers
1) The demand pacemaker (Irregular SA node firing)
2) The atrial-synchronous pacemaker (AV node is not working)
Figure 2. A demand-type synchronous pacemaker
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Figure 3. An atrial-synchronous cardiac pacemaker, which detects
electric signals corresponding to the contraction of the atria and uses
appropriate delays to activate a stimulus pulse to the ventricles. Figure
13.5 shows the waveforms corresponding to the voltages noted.
Atrial-Synchronous Pacemaker
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Rate-Responsive Pacemaker
Physiological Variable SensorRight-ventricle blood temperature Thermistor
Venous blood oxygen saturation Optical Oximeter
Respiratory rate and/or volume Thoracic electric-
impedance
Physiological variables are used to control the pulse rate of the
rate-responsive pacemakers
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Any Questions