CCDS IBHRE Exam Test Questions and Answers Graded A+
the lowest point on a strength duration curve at an infi-
Rheobase
nitely long pulse duration
the pulse width at twice the rheobase value. It approxi-
Chronaxie time
mates the most eflcient stimulation pulse duration
Charge (formula) Charge= I(current) x T(time)
Energy(microjoules)= I(current)xV(voltage)xT(pulse
Furman's formula
width)
Voltage(electromotive force)= I(current/flow of electrons)
Ohms law formula
x R(resistance to current flow in ohms)
the coupling interval which first results in a measurable
Functional Refractory Period
degree of delay in impulse conduction
Ettective Refractory Period the longest coupling interval to be associated with block
1. microwave oven, 2. CT scan/Ultrasound 3. X-rays (diag-
Devices with NO interaction with pacers
nostic)
1. EAS 2. Cellphones 3. Arc Welding 4. airport metal detec-
Devices that cause transient or 1 beat inhibition tor 5. TENS 6. Electric appliances such as electric blanket
& power tools
1. MRI 2. Defibrillator 3. Cardioversion 4. Cautery/RF Ab-
Devices that may damage the pacemaker
lation 5. Radiation Therapy
Series means the beginning of one resistance is connect-
ed to another
Resistance in Series
Sum the resistances: R1+R2= total resistance. EX: A LEAD
FRACTURE (fractures INCREASE impedance)
Parallel means all the resistances are connected to the
same point.
Resistance in Parallel
(R1xR2)/(R1+R2)= total resistance
, CCDS IBHRE Exam Test Questions and Answers Graded A+
EX: LEAD INSULATION DEFECTS (insulation defects DE-
CREASE impedance)
ALL permanent pacemakers are constant voltage devices.
Permanent pacemakers are constant voltage or constant
current? SOME temp pacemakers are constant voltage, most are
constant current.
Load refers to impedance (or resistance) applied to a
circuit.
A system with a SMALL load (low impedance) applied to
LOAD
the circuit is said to be a constant current device
A system with LARGE load is said to be a constant voltage
device
1. Patient is symptomatic
2. The heart rate is less than 40 bpm
Guidelines for Permanent Pacing 3. Asystole of greater than 3 seconds is documented
NOTE: Pt may be asymptomatic with 2 or 3
Slew rate = peak slope of an electrogram
Slew Rate
slew rate= change in voltage/ change in time
Normal slew rate in atrium >.3 V/s
Normal slew rate in ventricle >.5V/s
dexamethasone sodium phosphate in the silicone core(a
Steroid used in electrodes
corticosteriod)
1. The acute threshold is relatively flat compared to
Steroid-Eluting Electrodes
non-steroid electrodes
,CCDS IBHRE Exam Test Questions and Answers Graded A+
2. The initial capture threshold is similar to non-steroid
leads
1. Can easily be repaired
2. Flexible
Silicone Rubber lead insulation Pros
3. Proven performance history
4. Easy to make
1. high friction coeflcient
2. Absorbs lipids
3. More thrombogenic and fibrotic
Silicone Rubber lead insulation cons
4. Cuts easily
5. Tears easily if suture tied too tightly
6. Large diameter
Polyurethane 80A BAD
Polyurethane 55D GOOD
1. relatively nonthrombogenic/fibrotic
2. thin walls
polyurethane lead insulation pros 3. high tear friction
4. resists cutting
5. low friction coeflcient
1. cannot be repaired
polyurethane lead insulation cons 2. relatively stitt
3. hard to make
1. Loss of AV synchrony
2. Sustained retrograde conduction
3. A single ventricular rate when rate modulation is re-
quired for exercise
Pacemaker Syndrome Causes
Approx 25% of patients only paced from the ventricle may
have some level of severity related to pacemaker syn-
drome
, CCDS IBHRE Exam Test Questions and Answers Graded A+
1. Observe fluctuation in the peripheral blood pressure
Pacemaker syndrome diagnosis 2. Cannon "A" wave in the neck
3. History alone
Restore AV synchrony
in ventricular only PM -->lower the pacing rate to minimize
Pacemaker syndrome management
ventricular only pacing
DO NOT increase the pacing rate
1. Decouples atrial & ventricular events at the upper rate
limit
2. The ventricular inhibited pacing rate then gradually
Fallback decrements to a programmed lower or "fallback" rate over
a programmed duration
3. When the fallback rate is reached, atrial synchrony is
restored
1. Eliminated large cycle to cycle variations by preventing
paced rate from changing more than a certain percentage
(3%, 6%, 12%, etc) from one V-V interval to the next
Rate smoothing 2. Eliminates large fluctuations in rate during fixed-ratio or
psuedo-Wenckebach block
FOUND IN GDT devices
if the sinus rate is faster than the sensor indicated rate, P
synchronous pacing occurs
if the sensor indicated rate is faster, AV pacing at the sensor
indicated rate occurs
sensor upper rate behavior mixed scenario: when the device is sensor driven AV pac-
ing for a few cycles and a sinus rate sudden emerges
faster than the sensor indicated rate. The sensor driven
atrial output will be inhibited, a PR interval started, and a
ventricular output will occur at the end of the sensor AV
the lowest point on a strength duration curve at an infi-
Rheobase
nitely long pulse duration
the pulse width at twice the rheobase value. It approxi-
Chronaxie time
mates the most eflcient stimulation pulse duration
Charge (formula) Charge= I(current) x T(time)
Energy(microjoules)= I(current)xV(voltage)xT(pulse
Furman's formula
width)
Voltage(electromotive force)= I(current/flow of electrons)
Ohms law formula
x R(resistance to current flow in ohms)
the coupling interval which first results in a measurable
Functional Refractory Period
degree of delay in impulse conduction
Ettective Refractory Period the longest coupling interval to be associated with block
1. microwave oven, 2. CT scan/Ultrasound 3. X-rays (diag-
Devices with NO interaction with pacers
nostic)
1. EAS 2. Cellphones 3. Arc Welding 4. airport metal detec-
Devices that cause transient or 1 beat inhibition tor 5. TENS 6. Electric appliances such as electric blanket
& power tools
1. MRI 2. Defibrillator 3. Cardioversion 4. Cautery/RF Ab-
Devices that may damage the pacemaker
lation 5. Radiation Therapy
Series means the beginning of one resistance is connect-
ed to another
Resistance in Series
Sum the resistances: R1+R2= total resistance. EX: A LEAD
FRACTURE (fractures INCREASE impedance)
Parallel means all the resistances are connected to the
same point.
Resistance in Parallel
(R1xR2)/(R1+R2)= total resistance
, CCDS IBHRE Exam Test Questions and Answers Graded A+
EX: LEAD INSULATION DEFECTS (insulation defects DE-
CREASE impedance)
ALL permanent pacemakers are constant voltage devices.
Permanent pacemakers are constant voltage or constant
current? SOME temp pacemakers are constant voltage, most are
constant current.
Load refers to impedance (or resistance) applied to a
circuit.
A system with a SMALL load (low impedance) applied to
LOAD
the circuit is said to be a constant current device
A system with LARGE load is said to be a constant voltage
device
1. Patient is symptomatic
2. The heart rate is less than 40 bpm
Guidelines for Permanent Pacing 3. Asystole of greater than 3 seconds is documented
NOTE: Pt may be asymptomatic with 2 or 3
Slew rate = peak slope of an electrogram
Slew Rate
slew rate= change in voltage/ change in time
Normal slew rate in atrium >.3 V/s
Normal slew rate in ventricle >.5V/s
dexamethasone sodium phosphate in the silicone core(a
Steroid used in electrodes
corticosteriod)
1. The acute threshold is relatively flat compared to
Steroid-Eluting Electrodes
non-steroid electrodes
,CCDS IBHRE Exam Test Questions and Answers Graded A+
2. The initial capture threshold is similar to non-steroid
leads
1. Can easily be repaired
2. Flexible
Silicone Rubber lead insulation Pros
3. Proven performance history
4. Easy to make
1. high friction coeflcient
2. Absorbs lipids
3. More thrombogenic and fibrotic
Silicone Rubber lead insulation cons
4. Cuts easily
5. Tears easily if suture tied too tightly
6. Large diameter
Polyurethane 80A BAD
Polyurethane 55D GOOD
1. relatively nonthrombogenic/fibrotic
2. thin walls
polyurethane lead insulation pros 3. high tear friction
4. resists cutting
5. low friction coeflcient
1. cannot be repaired
polyurethane lead insulation cons 2. relatively stitt
3. hard to make
1. Loss of AV synchrony
2. Sustained retrograde conduction
3. A single ventricular rate when rate modulation is re-
quired for exercise
Pacemaker Syndrome Causes
Approx 25% of patients only paced from the ventricle may
have some level of severity related to pacemaker syn-
drome
, CCDS IBHRE Exam Test Questions and Answers Graded A+
1. Observe fluctuation in the peripheral blood pressure
Pacemaker syndrome diagnosis 2. Cannon "A" wave in the neck
3. History alone
Restore AV synchrony
in ventricular only PM -->lower the pacing rate to minimize
Pacemaker syndrome management
ventricular only pacing
DO NOT increase the pacing rate
1. Decouples atrial & ventricular events at the upper rate
limit
2. The ventricular inhibited pacing rate then gradually
Fallback decrements to a programmed lower or "fallback" rate over
a programmed duration
3. When the fallback rate is reached, atrial synchrony is
restored
1. Eliminated large cycle to cycle variations by preventing
paced rate from changing more than a certain percentage
(3%, 6%, 12%, etc) from one V-V interval to the next
Rate smoothing 2. Eliminates large fluctuations in rate during fixed-ratio or
psuedo-Wenckebach block
FOUND IN GDT devices
if the sinus rate is faster than the sensor indicated rate, P
synchronous pacing occurs
if the sensor indicated rate is faster, AV pacing at the sensor
indicated rate occurs
sensor upper rate behavior mixed scenario: when the device is sensor driven AV pac-
ing for a few cycles and a sinus rate sudden emerges
faster than the sensor indicated rate. The sensor driven
atrial output will be inhibited, a PR interval started, and a
ventricular output will occur at the end of the sensor AV
