NEED FOR CARDIAC PACEMAKER Rhythmic beating of heart originates from SA node If SA node doesn’t function properly results in decreased heart rate & change in ECG waveform

PACEMAKER CONSIST OF 2 PARTS  Electronic unit  Lead

ELECTRODES  UNIPOLAR  BIPOLAR

TYPES OF PACEMAKER EXTERNAL 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 PACEMAKER  Stimulating pulses can be applied to a heart through a catheter passing through a vein & connected to heart  ADVANTAGES  Pacing current required is less  Voltage o/p of internal PM is about 0-15V

POWER SOURCE Life 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 used Life span:5-8 yrs

IMPLANTABLE PACEMAKER Electrodes are implanted beneath the skin o/p leads are connected directly to the heart muscle Pulse generator is powered by small batteries

PACEMAKER ASYNCHRONOUS  Fixed rate  Impulse produced at a set rate  No relation to patients intrinsic cardiac activity

SYNCHRONOUS  Demand mode  Sensing circuit searches for instrinsic depolarization potential  If absent, pacing response is generated

LEADS SUTURELESS POROUS

REFERENCES Wikipedia

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