CRM IBHRE EXAM QUESTIONS AND
ANSWERS LATEST UPDATED
, Rheobase - ANSWERthe lowest point on a strength duration curve at an infinitely long
pulse duration
Chronaxie time - ANSWERthe pulse width at twice the rheobase value. It approximates
the most efficient stimulation pulse duration
Charge (formula) - ANSWERCharge= I(current) x T(time)
Energy (formula) - ANSWEREnergy(microjoules)= I(current)xVxT
Functional Refractory Period - ANSWERthe coupling interval which first results in a
measurable degree of delay in impulse conduction
Effective Refractory Period - ANSWERthe longest coupling interval to be associated
with block
Devices with NO interaction with pacers - ANSWER1. microwave oven, 2. CT
scan/Ultrasound 3. X-rays (diagnostic)
Devices that cause transient or 1 beat inhibition - ANSWER1. EAS 2. Cellphones 3. Arc
Welding 4. airport metal detector 5. TENS 6. Electric appliances such as electric blanket
& power tools
Devices that may damage the pacemaker - ANSWER1. MRI 2. Defibrillator 3.
Cardioversion 4. Cautery/RF Ablation 5. Radiation Therapy
Resistance in Series - ANSWERSeries means the beginning of one resistance is
connected to another
Sum the resistances: R1+R2= total resistance. EX: A LEAD FRACTURE (fractures
INCREASE impedance)
Resistance in Parallel - ANSWERParallel means all the resistances are connected to
the same point.
(R1xR2)/(R1+R2)= total resistance
EX: LEAD INSULATION DEFECTS (insulation defects DECREASE impedance)
Permanent pacemakers are constant voltage or constant current? - ANSWERALL
permanent pacemakers are constant voltage devices.
ANSWERS LATEST UPDATED
, Rheobase - ANSWERthe lowest point on a strength duration curve at an infinitely long
pulse duration
Chronaxie time - ANSWERthe pulse width at twice the rheobase value. It approximates
the most efficient stimulation pulse duration
Charge (formula) - ANSWERCharge= I(current) x T(time)
Energy (formula) - ANSWEREnergy(microjoules)= I(current)xVxT
Functional Refractory Period - ANSWERthe coupling interval which first results in a
measurable degree of delay in impulse conduction
Effective Refractory Period - ANSWERthe longest coupling interval to be associated
with block
Devices with NO interaction with pacers - ANSWER1. microwave oven, 2. CT
scan/Ultrasound 3. X-rays (diagnostic)
Devices that cause transient or 1 beat inhibition - ANSWER1. EAS 2. Cellphones 3. Arc
Welding 4. airport metal detector 5. TENS 6. Electric appliances such as electric blanket
& power tools
Devices that may damage the pacemaker - ANSWER1. MRI 2. Defibrillator 3.
Cardioversion 4. Cautery/RF Ablation 5. Radiation Therapy
Resistance in Series - ANSWERSeries means the beginning of one resistance is
connected to another
Sum the resistances: R1+R2= total resistance. EX: A LEAD FRACTURE (fractures
INCREASE impedance)
Resistance in Parallel - ANSWERParallel means all the resistances are connected to
the same point.
(R1xR2)/(R1+R2)= total resistance
EX: LEAD INSULATION DEFECTS (insulation defects DECREASE impedance)
Permanent pacemakers are constant voltage or constant current? - ANSWERALL
permanent pacemakers are constant voltage devices.
