PACEMAKER

NEED FOR CARDIAC PACEMAKERRhythmic beating of heart originates from SA

nodeIf SA node doesn’t function properly results

in decreased heart rate & change in ECG waveform

PACEMAKER CONSIST OF 2 PARTSElectronic unitLead

ELECTRODESUNIPOLARBIPOLAR

TYPES OF PACEMAKEREXTERNAL PACEMAKER Used in cases of cardiac standstill Applied through metal electrode placed on surface of body It applies upto 80mA of pulses through 50sq.cm electrode on

chest

DISADVANTAGE Requires maximum of 150V pulses Electrodes tend to burn skin Electric pulses become painful Each impulse causes uncomfortable contraction of thoracic

muscles around the area under electrodes

INTERNAL PACEMAKERStimulating pulses can be applied to a heart

through a catheter passing through a vein & connected to heart

ADVANTAGESPacing current required is lessVoltage o/p of internal PM is about 0-15V

POWER SOURCELife of PM is determined by the current

consumption of electronic circuit and availability energy in the unit

Hg batteries, biological batteries, nuclear batteries, li cells.

Lithium iodide battery most commonly usedLife span:5-8 yrs

IMPLANTABLE PACEMAKERElectrodes are implanted beneath the skino/p leads are connected directly to the heart

musclePulse generator is powered by small batteries

PACEMAKERASYNCHRONOUSFixed rateImpulse produced at a set rateNo relation to patients intrinsic cardiac

activity

SYNCHRONOUSDemand modeSensing circuit searches for instrinsic

depolarization potentialIf absent, pacing response is generated

LEADSSUTURELESSPOROUS

REFERENCESwww.google.comWikipedia

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