IBHRE Exam Questions And All Correct Answers
A function of pacemaker circuitry that allows the pacemaker output pulse to be dissipated quickly
maximizing both the output and sensing capabilities.
a) circuit resistors
b) charge dump
c) pulse neutralizer
d) current consumption - Correct answer-B. Charge Dump
AV sequentially paced patients with frequent ventricular ectopy should have the following pacemaker
parameters programmed to decrease the chance of competition:
a) short blanking period
b) slower base rate
c) increased ventricular refractory period
d) none of the above - Correct answer-A. Short Blanking Period
Low threshold electrode materials include each of the following EXCEPT:
,a) iridium oxide
b) elgiloy
c) platinized platinum
d) titanium nitride - Correct answer-B. Elgiloy
Voltage is?
The electromotive force pushing on electrons
If the PM output voltage is 5v and the measured lead resistance is 330 ohms, then the current that flows
out of the pacemaker into the heart is?
15.15
I=V/R=5V/.33 k ohm
If a unipolar lead wire has an insulation break one would expect the resistance to?
decrease
for a wire fracture the resistance?
increases
if the output vlotage of the pacemaker is programmed from 5 volts to 2.5 volts, the energy delivered to
the heart is?
quartered
Which of the following affect the longevity of the PM?
output voltage, resistance of lead and amount % pacing
Which Pt's PM will last longer?
#1: AMP=5V, L.R.=90, resistance 500ohms, PW=.5ms, 100%pacing
#2: AMP=5V, L.R.=60, resistance 500ohms, PW=.5ms, 100%pacing
#3: AMP=2.5V, L.R.=60, resistance 330ohms, PW=.5ms, 100% pacing
(#4: AMP=2.5v, L.R.=60, resistance 500ohms, PW=.5ms, 50%pacing)
The strength duration curve is dependent on the?
,Cell's membrane capacitance, intracellular and extracellular resistance and threshold voltage.
A patient on flecainide should?
Have their threshold checked
The acute threshold peaking is due to?
Trauma and inflammation
An advantage of bipolar leads is?
They are less susceptible to EMI
The two parameters that are important for ventricular sensing and should be measured are?
R-wave amplitude and slew rate
If an external PM is set to a sensitivity setting of 5mV and some R-waves go unsensed, then you should
do the following
Increase sensing by lowering sensitivity to 2.5mV.
Typical acceptable R-wave amplitude values for an acute ventricular lead is?
7-15mV
Typical acceptable P wave amplitude values for an acute atrial lead is?
greater than 2mV
The slew rate is?
Change in voltage divided by time or the slope of the EGM
Typical lead resistance range measured in ohms is?
300-2000 ohms
At the time of implant we want a threshold?
at .5ms to be less than 1 volt for ventricle
When connecting a unipolar PM to the lead in the patient?
place the PM in the pocket to check pacing
The formula for calculating rate?
60,000 ms/min - time period in ms.
Hysterisis is?
The interval the PM waits after a sensed beat before pacing
A SSI PM is one that?
, senses and pace in either the atrium or ventricle and inhibits
You should always check which of the following when programming a unipolar pacemaker to bipolar
configuration?
Bipolar lead is implanted
Which of the following is likely to happen during the lead maturation process?
Encapsulation of electrode with fibrin tissue
Which of the following is/are NOT factor (s) which influence PM longevity?
Output voltage
lead resistance
pulse duration
(X) blanking
Cardiac stimulation thresholds are expressed in terms of?
Voltage, current, and energy.
Which of the following combinations of variables interact to determine stimulation threshold?
Voltage and pulse width
A PM that paces and sense only in the ventricle and is inhibited by spontaneous ventricular activity is
designated?
VVI
As pulse duration is shortened below .3mse., stimulation threshold increases as described by all of the
following, except?
Energy
(x) Charge
Volts
Current
Current PM's employ which of the following chemical batteries?
Lithium-iodide
All of the following functions are programmable in both VVI and DDD PM's, except?
(X) AV interval duration
Sensitivity
Refractory
A function of pacemaker circuitry that allows the pacemaker output pulse to be dissipated quickly
maximizing both the output and sensing capabilities.
a) circuit resistors
b) charge dump
c) pulse neutralizer
d) current consumption - Correct answer-B. Charge Dump
AV sequentially paced patients with frequent ventricular ectopy should have the following pacemaker
parameters programmed to decrease the chance of competition:
a) short blanking period
b) slower base rate
c) increased ventricular refractory period
d) none of the above - Correct answer-A. Short Blanking Period
Low threshold electrode materials include each of the following EXCEPT:
,a) iridium oxide
b) elgiloy
c) platinized platinum
d) titanium nitride - Correct answer-B. Elgiloy
Voltage is?
The electromotive force pushing on electrons
If the PM output voltage is 5v and the measured lead resistance is 330 ohms, then the current that flows
out of the pacemaker into the heart is?
15.15
I=V/R=5V/.33 k ohm
If a unipolar lead wire has an insulation break one would expect the resistance to?
decrease
for a wire fracture the resistance?
increases
if the output vlotage of the pacemaker is programmed from 5 volts to 2.5 volts, the energy delivered to
the heart is?
quartered
Which of the following affect the longevity of the PM?
output voltage, resistance of lead and amount % pacing
Which Pt's PM will last longer?
#1: AMP=5V, L.R.=90, resistance 500ohms, PW=.5ms, 100%pacing
#2: AMP=5V, L.R.=60, resistance 500ohms, PW=.5ms, 100%pacing
#3: AMP=2.5V, L.R.=60, resistance 330ohms, PW=.5ms, 100% pacing
(#4: AMP=2.5v, L.R.=60, resistance 500ohms, PW=.5ms, 50%pacing)
The strength duration curve is dependent on the?
,Cell's membrane capacitance, intracellular and extracellular resistance and threshold voltage.
A patient on flecainide should?
Have their threshold checked
The acute threshold peaking is due to?
Trauma and inflammation
An advantage of bipolar leads is?
They are less susceptible to EMI
The two parameters that are important for ventricular sensing and should be measured are?
R-wave amplitude and slew rate
If an external PM is set to a sensitivity setting of 5mV and some R-waves go unsensed, then you should
do the following
Increase sensing by lowering sensitivity to 2.5mV.
Typical acceptable R-wave amplitude values for an acute ventricular lead is?
7-15mV
Typical acceptable P wave amplitude values for an acute atrial lead is?
greater than 2mV
The slew rate is?
Change in voltage divided by time or the slope of the EGM
Typical lead resistance range measured in ohms is?
300-2000 ohms
At the time of implant we want a threshold?
at .5ms to be less than 1 volt for ventricle
When connecting a unipolar PM to the lead in the patient?
place the PM in the pocket to check pacing
The formula for calculating rate?
60,000 ms/min - time period in ms.
Hysterisis is?
The interval the PM waits after a sensed beat before pacing
A SSI PM is one that?
, senses and pace in either the atrium or ventricle and inhibits
You should always check which of the following when programming a unipolar pacemaker to bipolar
configuration?
Bipolar lead is implanted
Which of the following is likely to happen during the lead maturation process?
Encapsulation of electrode with fibrin tissue
Which of the following is/are NOT factor (s) which influence PM longevity?
Output voltage
lead resistance
pulse duration
(X) blanking
Cardiac stimulation thresholds are expressed in terms of?
Voltage, current, and energy.
Which of the following combinations of variables interact to determine stimulation threshold?
Voltage and pulse width
A PM that paces and sense only in the ventricle and is inhibited by spontaneous ventricular activity is
designated?
VVI
As pulse duration is shortened below .3mse., stimulation threshold increases as described by all of the
following, except?
Energy
(x) Charge
Volts
Current
Current PM's employ which of the following chemical batteries?
Lithium-iodide
All of the following functions are programmable in both VVI and DDD PM's, except?
(X) AV interval duration
Sensitivity
Refractory
