, IBHRE Prep Exam (2024) || With
Questions & Solutions (Rated A+)
Voltage is? - ANSWER - 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? - ANSWER - 15.15
I=V/R=5V/.33 k ohm
If a unipolar lead wire has an insulation break one would expect the resistance to? -
ANSWER - decrease
for a wire fracture the resistance? - ANSWER - increases
if the output vlotage of the pacemaker is programmed from 5 volts to 2.5 volts, the
energy delivered to the heart is? - ANSWER - quartered
Which of the following affect the longevity of the PM? - ANSWER - output voltage,
resistance of lead and amount % pacing
The strength duration curve is dependent on the? - ANSWER - Cell's membrane
capacitance, intracellular and extracellular resistance and threshold voltage.
A patient on flecainide should? - ANSWER - Have their threshold checked
The acute threshold peaking is due to? - ANSWER - Trauma and inflammation
An advantage of bipolar leads is? - ANSWER - They are less susceptible to EMI
The two parameters that are important for ventricular sensing and should be
measured are? - ANSWER - 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 - ANSWER - Increase sensing by
lowering sensitivity to 2.5mV.
Typical acceptable R-wave amplitude values for an acute ventricular lead is? -
ANSWER - 7-15mV
Typical acceptable P wave amplitude values for an acute atrial lead is? - ANSWER -
greater than 2mV
, The slew rate is? - ANSWER - Change in voltage divided by time or the slope of the
EGM
Typical lead resistance range measured in ohms is? - ANSWER - 300-2000 ohms
At the time of implant we want a threshold? - ANSWER - at .5ms to be less than 1
volt for ventricle
When connecting a unipolar PM to the lead in the patient? - ANSWER - place the
PM in the pocket to check pacing
The formula for calculating rate? - ANSWER - 60,000 ms/min - time period in ms.
Hysterisis is? - ANSWER - The interval the PM waits after a sensed beat before
pacing
A SSI PM is one that? - ANSWER - 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? - ANSWER - Bipolar lead is implanted
Which of the following is likely to happen during the lead maturation process? -
ANSWER - Encapsulation of electrode with fibrin tissue
Which of the following is/are NOT factor (s) which influence PM longevity? -
ANSWER - Output voltage
lead resistance
pulse duration
(X) blanking
Cardiac stimulation thresholds are expressed in terms of? - ANSWER - Voltage,
current, and energy.
Which of the following combinations of variables interact to determine stimulation
threshold? - ANSWER - Voltage and pulse width
A PM that paces and sense only in the ventricle and is inhibited by spontaneous
ventricular activity is designated? - ANSWER - VVI
As pulse duration is shortened below .3mse., stimulation threshold increases as
described by all of the following, except? - ANSWER - Energy
(x) Charge
Volts
Current
Current PM's employ which of the following chemical batteries? - ANSWER -
Lithium-iodide
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