CCDS IBHRE Exam Questions & Answers 2023/2024
Rheobase - ANSWER-the lowest point on a strength duration curve at an infinitely long pulse duration
Chronaxie time - ANSWER-the pulse width at twice the rheobase value. It approximates the most efficient stimulation pulse duration
Charge (fo...
CCDS IBHRE Exam Questions & Answers 2023/2024
Rheobase - ANSWER-the lowest point on a strength duration curve at an infinitely long pulse duration
Chronaxie time - ANSWER-the pulse width at twice the rheobase value. It approximates the most efficient stimulation pulse duration
Charge (formula) - ANSWER-Charge= I(current) x T(time)
Furman's formula - ANSWER-Energy(microjoules)= I(current)xV(voltage)xT(pulse width)
Ohms law formula - ANSWER-Voltage(electromotive force)= I(current/flow of electrons) x R(resistance to
current flow in ohms)
Functional Refractory Period - ANSWER-the coupling interval which first results in a measurable degree of delay in impulse conduction
Effective Refractory Period - ANSWER-the longest coupling interval to be associated with block
Devices with NO interaction with pacers - ANSWER-1. microwave oven, 2. CT scan/Ultrasound 3. X-rays (diagnostic)
Devices that cause transient or 1 beat inhibition - 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 - ANSWER-1. MRI 2. Defibrillator 3. Cardioversion 4. Cautery/RF Ablation 5. Radiation Therapy Resistance in Series - 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 - 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? - 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
2. Cannon "A" wave in the neck
3. History alone
Pacemaker syndrome management - ANSWER-Restore AV synchrony
in ventricular only PM -->lower the pacing rate to minimize ventricular only pacing DO NOT increase the pacing rate
Fallback - ANSWER-1. Decouples atrial & ventricular events at the upper rate limit
2. The ventricular inhibited pacing rate then gradually decrements to a programmed lower or "fallback" rate over a programmed duration
3. When the fallback rate is reached, atrial synchrony is restored
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Bensuda. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.99. You're not tied to anything after your purchase.
