CCDS IBHRE Exam with Verified Answers Graded A+
1. Rheobase the lowest point on a strength du-
ration curve at an infinitely long
pulse duration
2. Chronaxie time the pulse width at twice the
rheobase value. It approximates
the most efficient stimulation
pulse duration
3. Charge (formula) C...
CCDS IBHRE Exam with Verified Answers Graded A+
1. Rheobase the lowest point on a strength du-
ration curve at an infinitely long
pulse duration
2. Chronaxie time the pulse width at twice the
rheobase value. It approximates
the most efficient stimulation
pulse duration
3. Charge (formula) Charge= I(current) x T(time)
4. Furman's formula Energy(microjoules)= I(cur-
rent)xV(voltage)xT(pulse width)
5. Ohms law formula Voltage(electromotive force)=
I(current/flow of electrons) x R(re-
sistance to current flow in ohms)
6. Functional Refractory Period the coupling interval which first re-
sults in a measurable degree of
delay in impulse conduction
7. Effective Refractory Period the longest coupling interval to be
associated with block
8. Devices with NO interaction with pac- 1. microwave oven, 2. CT scan/Ul-
ers trasound 3. X-rays (diagnostic)
9. Devices that cause transient or 1 beat 1. EAS 2. Cellphones 3. Arc Weld-
inhibition ing 4. airport metal detector 5.
TENS 6. Electric appliances such
as electric blanket & power tools
, CCDS IBHRE Exam with Verified Answers Graded A+
10. Devices that may damage the pace- 1. MRI 2. Defibrillator 3. Cardiover-
maker sion 4. Cautery/RF Ablation 5. Ra-
diation Therapy
11. Resistance in Series Series means the beginning of
one resistance is connected to an-
other
Sum the resistances: R1+R2= to-
tal resistance. EX: A LEAD FRAC-
TURE (fractures INCREASE im-
pedance)
12. Resistance in Parallel Parallel means all the resistances
are connected to the same point.
(R1xR2)/(R1+R2)= total resis-
tance
EX: LEAD INSULATION DE-
FECTS (insulation defects DE-
CREASE impedance)
13. Permanent pacemakers are constant ALL permanent pacemakers are
voltage or constant current? constant voltage devices.
SOME temp pacemakers are con-
stant voltage, most are constant
current.
14. LOAD Load refers to impedance (or re-
sistance) 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
, CCDS IBHRE Exam with Verified Answers Graded A+
15. Guidelines for Permanent Pacing 1. Patient is symptomatic
2. The heart rate is less than 40
bpm
3. Asystole of greater than 3 sec-
onds is documented
NOTE: Pt may be asymptomatic
with 2 or 3
16. Slew Rate Slew rate = peak slope of an elec-
trogram
slew rate= change in voltage/
change in time
17. Normal slew rate in atrium >.3 V/s
18. Normal slew rate in ventricle >.5V/s
19. Steroid used in electrodes dexamethasone sodium phos-
phate in the silicone core(a corti-
costeriod)
20. Steroid-Eluting Electrodes 1. The acute threshold is relatively
flat compared to non-steroid elec-
trodes
2. The initial capture threshold is
similar to non-steroid leads
21. Silicone Rubber lead insulation Pros 1. Can easily be repaired
2. Flexible
3. Proven performance history
4. Easy to make
22. Silicone Rubber lead insulation cons 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
23. Polyurethane 80A BAD
24. Polyurethane 55D GOOD
25. polyurethane lead insulation pros 1. relatively nonthrombogenic/fi-
brotic
2. thin walls
3. high tear friction
4. resists cutting
5. low friction coefficient
26. polyurethane lead insulation cons 1. cannot be repaired
2. relatively stiff
3. hard to make
27. Pacemaker Syndrome Causes 1. Loss of AV synchrony
2. Sustained retrograde conduc-
tion
3. A single ventricular rate when
rate modulation is required for ex-
ercise
Approx 25% of patients only
paced from the ventricle may have
some level of severity related to
pacemaker syndrome
28. Pacemaker syndrome diagnosis 1. Observe fluctuation in the pe-
ripheral blood pressure
2. Cannon "A" wave in the neck
3. History alone
29. Pacemaker syndrome management Restore AV synchrony
in ventricular only PM -->lower the
pacing rate to minimize ventricular
only pacing
DO NOT increase the pacing rate
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