CCDS PRACTICE 18 FULL SOLUTION STUDY
GUIDE
◉ Permanent pacemakers are constant voltage or constant current?
Answer: ALL permanent pacemakers are constant voltage devices.
SOME temp pacemakers are constant voltage, most are constant
current.
◉ LOAD.
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.
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.
Answer: Slew rate = peak slope of an electrogram
slew rate= change in voltage/ change in time
◉ Normal slew rate in atrium.
Answer: >.3 V/s
◉ Normal slew rate in ventricle.
Answer: >.5V/s
◉ Steroid used in electrodes.
Answer: dexamethasone sodium phosphate in the silicone core(a
corticosteriod)
◉ Steroid-Eluting Electrodes.
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.
Answer: 1. Can easily be repaired
2. Flexible
3. Proven performance history
4. Easy to make
◉ Silicone Rubber lead insulation cons.
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.
Answer: BAD
◉ Polyurethane 55D.
Answer: GOOD
◉ polyurethane lead insulation pros.
, Answer: 1. relatively nonthrombogenic/fibrotic
2. thin walls
3. high tear friction
4. resists cutting
5. low friction coefficient
◉ polyurethane lead insulation cons.
Answer: 1. cannot be repaired
2. relatively stiff
3. hard to make
◉ Pacemaker Syndrome Causes.
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.
Answer: 1. Observe fluctuation in the peripheral blood pressure
GUIDE
◉ Permanent pacemakers are constant voltage or constant current?
Answer: ALL permanent pacemakers are constant voltage devices.
SOME temp pacemakers are constant voltage, most are constant
current.
◉ LOAD.
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.
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.
Answer: Slew rate = peak slope of an electrogram
slew rate= change in voltage/ change in time
◉ Normal slew rate in atrium.
Answer: >.3 V/s
◉ Normal slew rate in ventricle.
Answer: >.5V/s
◉ Steroid used in electrodes.
Answer: dexamethasone sodium phosphate in the silicone core(a
corticosteriod)
◉ Steroid-Eluting Electrodes.
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.
Answer: 1. Can easily be repaired
2. Flexible
3. Proven performance history
4. Easy to make
◉ Silicone Rubber lead insulation cons.
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.
Answer: BAD
◉ Polyurethane 55D.
Answer: GOOD
◉ polyurethane lead insulation pros.
, Answer: 1. relatively nonthrombogenic/fibrotic
2. thin walls
3. high tear friction
4. resists cutting
5. low friction coefficient
◉ polyurethane lead insulation cons.
Answer: 1. cannot be repaired
2. relatively stiff
3. hard to make
◉ Pacemaker Syndrome Causes.
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.
Answer: 1. Observe fluctuation in the peripheral blood pressure
