IBHRE Practice Test Questions with Answers

The relative refractory period of the ventricular myocardium corresponds to which of the following phases of the action potential 3 small subendocardial structure located with the interatrial septum Av node the propagation through the AV Node and HIS-Purkinje fibers. PR interval - Depolarization of neighboring cells occurs as a result of intercellular connections are called Gap Junctions Chemistry Used in the vast majority of ICD's today. Optimized for pulses of high current to charge the defibrillation capacitor quickly. Known as the "High-Rate" battery. Lithium silver vanadium oxide (Levi) Abnormal QT interval is 0.43 sec or 430 milliseconds. • Rule of thumb: QT than ½ the R-R interval is abnormal). What is the most frequent mechanism in unexplained syncope: Brady arrhythmias thickened left ventricular septum and lateral wall resulting in poor cardiac output with intrinsic ventricular conduction HOCM Antiarrhythmics: • Moderate reduction in phase 0 slope; increase APD, increase ERP Class 1A Antiarrhythmics: • Small reduction in phase 0 slope; reduce Action Potential Duration (APD's) decrease ERP. Class 1B Antiarrhythmics: • Pronounced reduction in phase 0 slope; no effect on APD or ERP Class 1C Antiarrhythmics: • Beta Blockers block sympathetic activity; reduce rate and conduction, decreases slope of Phase 4 in the action potential. Class 2 Antiarrhythmics: • Potassium Channel Blockers, delay repolarization (phase 3) and thereby increase action potential duration and effective refractory period. •proarrhythmia Class 3 Antiarrhythmics: • Slow Calcium Channel Blockers decrease systemic vascular resistance and prolong phase 2 of the action potential. Class 4 - May increase or decrease defibrillation thresholds. - Variable response due to class 1 and 3 actions - May slow VT rates Class 3 (Amiodarone, pacerone, cordarone) - May decrease defibrillation thresholds. - May slow VT rates. - Alter cycle lengths. Class 2 (beta blockers) - Slow ventricular conduction velocity and may increase DFT. Class 1 7) Li/cFx: Lithium poly carbon monofluoride is new for devices requiring more/less energy? More energy 1 HZ = how many bpm 60 switch activated by a magnet causing asynchronous pacing, now a solid state magnet detector. Reed switch restrics current flow to one direction Diode restricts current flow. Resistor converts a biphasic signal to all positive or negative Rectifier semiconductor used for switching and amplification Transistor