CCDS IBHRE UPDATED ACTUAL Exam
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
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
