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CHART CCDS Review > Pacing System Components > Flashcards

Pacing System Components Flashcards

1
Q

Resistor

A

Resists the flow of electrical charge (measured in Ohms).

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2
Q

Capacitor

A

Stores and releases electrical charge (measured in Farad).

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3
Q

Transistor

A

Electrical switch within a circuit. One pulse generator has billions of individual transistors.

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4
Q

Diode

A

Allows electrical current to flow in an exclusively unidirectional manner.

Protects PG circuitry from high external voltages.

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5
Q

Rectifier

A

Converts biphasic signal to a signal with only positive components. Used for sensing.

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6
Q

Complementary Metal Oxide Semiconductor (CMOS)

A

Elements of microscopic electrical circuitry and creates the channel for the PG being most susceptible to radiation.

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7
Q

Transformer

A

Converts the input of electrical flow to an output electrical flow of higher voltage and lower current.

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8
Q

What kind of core do high voltage conductor leads typically have?

A

Silver or platinum due to low resistance

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9
Q

Anode (definition and location)

A

Positive polarity and signals flow AWAY. Anode is located at ring/can.

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10
Q

Cathode (definition and location)

A

Negative polarity and signals flow TOWARD. Cathode is located at lead tip in the tissue.

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11
Q

What are the pros to unipolar pacing leads?

A
  1. Smaller diameter lead, using a single set screw
  2. Reliable and more durable
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12
Q

What are the pros to bipolar pacing leads?

A
  1. Less chance of extracardiac stimulation at the PG.
  2. Less chance of myopotential or far-field oversensing.
  3. Can act as unipolar if so programmed.
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13
Q

What are the materials that compose lead electrodes?

A
  1. Platinum with 10% Iridium
  2. Elgiloy- an alloy of several metals
  3. Silver and stainless steel
  4. Activated carbon
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14
Q

What are the two primary forms of lead insulation?

A

Silicone and polyurethane

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15
Q

What are the advantages of silicone?

A

Inert, durable, and reliable

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16
Q

What are the advantages of polyurethane?

A

Smaller lead diameter, easy maneuverability, high tear strength

17
Q

Coulomb (C)

A

the fundamental unit of battery capacity

18
Q

Ampere-hours (A-hr)

A

A way to express battery capacity. Represents the charge carried by a current of one ampere flowing for one hour.

1 ampere-hour = 3600 coulumbs

19
Q

What is the purpose of the capacitor in an ICD?

A

allow the device to deliver a therapeutic, high-voltage, high-energy shock to the myocardium over a few milliseconds. This is something the battery itself could NOT do.

20
Q

What are pacemaker batteries made of?

A

Lithium iodine

21
Q

What are ICD batteries made of?

A

Lithium silver oxide

22
Q

Why is lithium silver oxide used in ICDs over lithium iodine?

A

Supports higher current drains for capacitor charging to deliver ATP and ICD shocks.

23
Q

What is the approximate voltage at the beginning of life of a lithium iodine (pacemaker) battery?

A

2.8 V

24
Q

Resistance (Ohms)

A

the opposition of flow of electrical current in a conductor. Relates ONLY to electrical components.

25
Q

Impedance (R)

A

The total resistance to the flow of current through a conductor including both body tissue and electrical components

26
Q

Ohms Law

A

V = IR

V = voltage
I = current
R = resistance (impedance)

27
Q

Automaticity

A

The capacity for spontaneous initiation of rhythm beating

28
Q

Excitability

A

having a resting membrane potential that is able to undergo rapid, transient reversal in polarity upon activation

29
Q

In a pacing system, current is determined by ____?

A

number of electrons that move through a circuit at any given time

30
Q

In a pacing system, impedance is a function of what?

A

The conductor (wire), electrode (tip), and myocardium (tissue)

31
Q

Polarization impedance

A

accumulation of charges of opposite polarity in the myocardium at the electrode-tissue interface.

32
Q

Other than a lead fracture, what is another reason that impedance may be high?

A

the lead is not appropriately seated in the pacemaker header (usually an acute problem).

33
Q

What factors create impedance within the pacing system?

A

Lead resistance, tissue impedance, polarization resistance

34
Q

Current drain (microamperes)

A

Average amount of current drawn from a battery by the external load

35
Q

How much current drain do pacemakers usually produce?

A

10-30 micramperes

CHART CCDS Review (7 decks)

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