IBHRE PREP EXAM QUESTIONS AND ANSWERS

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 Which Pt's PM will last longer? - Answer-#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? - 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 Typic