CCDS IBHRE Exam UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS
Rheobase - CORRECT ANSWER the lowest point on a strength duration curve at an
infinitely long pulse duration
Chronaxie time - CORRECT ANSWER the pulse width at twice the rheobase value. It
approximates the most efficient stimulation pulse duration
Charge (formula) - CORRECT ANSWER Charge= I(current) x T(time)
Furman's formula - CORRECT ANSWER Energy(microjoules)=
I(current)xV(voltage)xT(pulse width)
Ohms law formula - CORRECT ANSWER Voltage(electromotive force)=
I(current/flow of electrons) x R(resistance to current flow in ohms)
Functional Refractory Period - CORRECT ANSWER the coupling interval which first
results in a measurable degree of delay in impulse conduction
Effective Refractory Period - CORRECT ANSWER the longest coupling interval to be
associated with block
Devices with NO interaction with pacers - CORRECT ANSWER 1. microwave oven,
2. CT scan/Ultrasound 3. X-rays (diagnostic)
Devices that cause transient or 1 beat inhibition - CORRECT ANSWER 1. 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 - CORRECT ANSWER 1. MRI 2.
Defibrillator 3. Cardioversion 4. Cautery/RF Ablation 5. Radiation Therapy
,Resistance in Series - CORRECT ANSWER Series 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 - CORRECT ANSWER Parallel 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? - CORRECT
ANSWER ALL permanent pacemakers are constant voltage devices.
SOME temp pacemakers are constant voltage, most are constant current.
LOAD - CORRECT ANSWER Load refers to impedance (or resistance) applied to a
circuit.
A system with a SMALL load (low impedance) applied to the circuit is said to be a constant
current device
A system with LARGE load is said to be a constant voltage device
Guidelines for Permanent Pacing - CORRECT ANSWER 1. Patient is symptomatic
2. The heart rate is less than 40 bpm
3. Asystole of greater than 3 seconds is documented
,NOTE: Pt may be asymptomatic with 2 or 3
Slew Rate - CORRECT ANSWER Slew rate = peak slope of an electrogram
slew rate= change in voltage/ change in time
Normal slew rate in atrium - CORRECT ANSWER >.3 V/s
Normal slew rate in ventricle - CORRECT ANSWER >.5V/s
Steroid used in electrodes - CORRECT ANSWER dexamethasone sodium phosphate in
the silicone core(a corticosteriod)
Steroid-Eluting Electrodes - CORRECT ANSWER 1. The acute threshold is relatively
flat compared to non-steroid electrodes
2. The initial capture threshold is similar to non-steroid leads
Silicone Rubber lead insulation Pros - CORRECT ANSWER 1. Can easily be repaired
2. Flexible
3. Proven performance history
4. Easy to make
Silicone Rubber lead insulation cons - CORRECT ANSWER 1. high friction
coefficient
2. Absorbs lipids
3. More thrombogenic and fibrotic
4. Cuts easily
5. Tears easily if suture tied too tightly
6. Large diameter
, Polyurethane 80A - CORRECT ANSWER BAD
Polyurethane 55D - CORRECT ANSWER GOOD
polyurethane lead insulation pros - CORRECT ANSWER 1. relatively
nonthrombogenic/fibrotic
2. thin walls
3. high tear friction
4. resists cutting
5. low friction coefficient
polyurethane lead insulation cons - CORRECT ANSWER 1. cannot be repaired
2. relatively stiff
3. hard to make
Pacemaker Syndrome Causes - CORRECT ANSWER 1. Loss of AV synchrony
2. Sustained retrograde conduction
3. A single ventricular rate when rate modulation is required for exercise
Approx 25% of patients only paced from the ventricle may have some level of severity
related to pacemaker syndrome
Pacemaker syndrome diagnosis - CORRECT ANSWER 1. Observe fluctuation in the
peripheral blood pressure
2. Cannon "A" wave in the neck
3. History alone
Pacemaker syndrome management - CORRECT ANSWER Restore AV synchrony
QUESTIONS AND CORRECT ANSWERS
Rheobase - CORRECT ANSWER the lowest point on a strength duration curve at an
infinitely long pulse duration
Chronaxie time - CORRECT ANSWER the pulse width at twice the rheobase value. It
approximates the most efficient stimulation pulse duration
Charge (formula) - CORRECT ANSWER Charge= I(current) x T(time)
Furman's formula - CORRECT ANSWER Energy(microjoules)=
I(current)xV(voltage)xT(pulse width)
Ohms law formula - CORRECT ANSWER Voltage(electromotive force)=
I(current/flow of electrons) x R(resistance to current flow in ohms)
Functional Refractory Period - CORRECT ANSWER the coupling interval which first
results in a measurable degree of delay in impulse conduction
Effective Refractory Period - CORRECT ANSWER the longest coupling interval to be
associated with block
Devices with NO interaction with pacers - CORRECT ANSWER 1. microwave oven,
2. CT scan/Ultrasound 3. X-rays (diagnostic)
Devices that cause transient or 1 beat inhibition - CORRECT ANSWER 1. 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 - CORRECT ANSWER 1. MRI 2.
Defibrillator 3. Cardioversion 4. Cautery/RF Ablation 5. Radiation Therapy
,Resistance in Series - CORRECT ANSWER Series 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 - CORRECT ANSWER Parallel 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? - CORRECT
ANSWER ALL permanent pacemakers are constant voltage devices.
SOME temp pacemakers are constant voltage, most are constant current.
LOAD - CORRECT ANSWER Load refers to impedance (or resistance) applied to a
circuit.
A system with a SMALL load (low impedance) applied to the circuit is said to be a constant
current device
A system with LARGE load is said to be a constant voltage device
Guidelines for Permanent Pacing - CORRECT ANSWER 1. Patient is symptomatic
2. The heart rate is less than 40 bpm
3. Asystole of greater than 3 seconds is documented
,NOTE: Pt may be asymptomatic with 2 or 3
Slew Rate - CORRECT ANSWER Slew rate = peak slope of an electrogram
slew rate= change in voltage/ change in time
Normal slew rate in atrium - CORRECT ANSWER >.3 V/s
Normal slew rate in ventricle - CORRECT ANSWER >.5V/s
Steroid used in electrodes - CORRECT ANSWER dexamethasone sodium phosphate in
the silicone core(a corticosteriod)
Steroid-Eluting Electrodes - CORRECT ANSWER 1. The acute threshold is relatively
flat compared to non-steroid electrodes
2. The initial capture threshold is similar to non-steroid leads
Silicone Rubber lead insulation Pros - CORRECT ANSWER 1. Can easily be repaired
2. Flexible
3. Proven performance history
4. Easy to make
Silicone Rubber lead insulation cons - CORRECT ANSWER 1. high friction
coefficient
2. Absorbs lipids
3. More thrombogenic and fibrotic
4. Cuts easily
5. Tears easily if suture tied too tightly
6. Large diameter
, Polyurethane 80A - CORRECT ANSWER BAD
Polyurethane 55D - CORRECT ANSWER GOOD
polyurethane lead insulation pros - CORRECT ANSWER 1. relatively
nonthrombogenic/fibrotic
2. thin walls
3. high tear friction
4. resists cutting
5. low friction coefficient
polyurethane lead insulation cons - CORRECT ANSWER 1. cannot be repaired
2. relatively stiff
3. hard to make
Pacemaker Syndrome Causes - CORRECT ANSWER 1. Loss of AV synchrony
2. Sustained retrograde conduction
3. A single ventricular rate when rate modulation is required for exercise
Approx 25% of patients only paced from the ventricle may have some level of severity
related to pacemaker syndrome
Pacemaker syndrome diagnosis - CORRECT ANSWER 1. Observe fluctuation in the
peripheral blood pressure
2. Cannon "A" wave in the neck
3. History alone
Pacemaker syndrome management - CORRECT ANSWER Restore AV synchrony
