front 1 A normal ECG shows a small positive deflection just before atrial systole begins. This wave most directly reflects: A. atrial depolarization | back 1 A. atrial depolarization |
front 2 In a healthy heart, the QRS complex is generated by: A. atrial recovery potentials | back 2 C. ventricular depolarization |
front 3 A normal T wave is produced when the ventricles: A. begin isovolumic contraction | back 3 D. repolarize |
front 4 During ventricular depolarization, how does the electrical charge across the cell membrane change? A. Inside negative, outside positive | back 4 C. Inside positive, outside negative |
front 5 The normal monophasic action potential of ventricular muscle lasts about: A. 0.25 to 0.35 second | back 5 A. 0.25 to 0.35 second |
front 6 The ventricular T wave normally occurs approximately how long after ventricular depolarization? A. 0.05 to 0.10 second | back 6 B. 0.25 to 0.35 second |
front 7 No potential is recorded on the ECG when ventricular muscle is: A. partly polarized only | back 7 D. completely polarized or depolarized |
front 8 The P wave occurs at the beginning of contraction of the: A. ventricles | back 8 D. atria |
front 9 The QRS complex occurs at the beginning of contraction of the: A. atria | back 9 B. ventricles |
front 10 The ventricles normally remain contracted until after the end of the: A. P wave | back 10 D. T wave |
front 11 Atrial repolarization usually occurs approximately how long after termination of the P wave? A. 0.15 to 0.20 second | back 11 A. 0.15 to 0.20 second |
front 12 The atrial repolarization wave is usually not seen because it is obscured by the larger: A. P wave | back 12 C. QRS complex |
front 13 The atrial repolarization wave is also called the: A. atrial Q wave | back 13 B. atrial T wave |
front 14 Standard ECG paper runs at a speed of: A. 10 mm/sec | back 14 C. 25 mm/sec |
front 15 On standard ECG paper, each 5-mm segment represents: A. 0.04 second | back 15 B. 0.20 second |
front 16 Which statement best explains why the ECG is electrically silent during fully uniform ventricular depolarization? A. no current gradient exists | back 16 A. no current gradient exists |
front 17 On standard ECG paper run at 25 mm/sec, each small 1-mm box represents: A. 0.02 second | back 17 B. 0.04 second |
front 18 The interval from the beginning of the P wave to the beginning of the QRS complex is the: A. Q-T interval | back 18 D. P-Q interval |
front 19 The normal P-Q interval is closest to: A. 0.16 second | back 19 A. 0.16 second |
front 20 The interval representing ventricular contraction, measured from the beginning of Q (or R if Q absent) to the end of T, is the: A. P-Q interval | back 20 C. Q-T interval |
front 21 The normal Q-T interval is approximately: A. 0.16 second | back 21 D. 0.35 second |
front 22 In a normal adult, the interval between two successive QRS complexes is closest to: A. 0.83 second | back 22 A. 0.83 second |
front 23 A patient has an R-R interval of about 0.83 second. The heart rate is closest to: A. 60 beats/min | back 23 B. 72 beats/min |
front 24 When one portion of the ventricles depolarizes before the rest, that depolarized region becomes relatively: A. electropositive | back 24 C. electronegative |
front 25 During ventricular depolarization, current flows from the depolarized area toward the: A. polarized area | back 25 A. polarized area |
front 26 The cardiac impulse first arrives in the ventricles in the: A. apex | back 26 D. septum |
front 27 Shortly after first entering the septum, the impulse next spreads to the: A. epicardial surfaces first | back 27 C. inner ventricular surfaces |
front 28 If all ventricular current vectors are averaged algebraically early in depolarization, negativity is directed toward the: A. apex | back 28 B. base |
front 29 In that same averaged vector, positivity is directed toward the: A. base | back 29 D. apex |
front 30 An electrode placed nearer the base of the heart during this phase would record as relatively: A. negative | back 30 A. negative |
front 31 An electrode placed nearer the apex of the heart during this phase would be relatively: A. negative | back 31 B. positive |
front 32 With one electrode near the base and one near the apex under these conditions, the ECG meter will show a: A. negative deflection | back 32 C. positive deflection |
front 33 A standard limb lead is recorded with the negative electrode on the right arm and the positive electrode on the left arm. Which lead is this? A. Lead I | back 33 A. Lead I |
front 34 A patient’s ECG lead has a negative electrode on the right arm and a positive electrode on the left leg. Which lead is being recorded? A. Lead I | back 34 D. Lead II |
front 35 In standard limb lead III, the negative terminal is attached to the: A. right arm | back 35 B. left arm |
front 36 Simultaneous recording of all three standard limb leads shows that Lead I plus Lead III equals: A. aVR | back 36 C. Lead II |
front 37 Einthoven’s law states that the sum of the potentials in leads I and III equals the potential in: A. Lead II | back 37 A. Lead II |
front 38 How many standard chest leads are usually recorded from the anterior chest wall? A. Four | back 38 D. Six |
front 39 A normal ECG shows a predominantly negative QRS in a chest lead placed near the base of the heart. Which lead pair most fits this pattern? A. V5 and V6 | back 39 B. V1 and V2 |
front 40 Why are the QRS complexes in V1 and V2 usually mainly negative in a normal heart? A. They face the left ventricle | back 40 C. They are near the base |
front 41 In a normal ECG, the chest leads with mainly positive QRS complexes because they are nearer the apex are: A. V4 V5 V6 | back 41 A. V4 V5 V6 |
front 42 A chest electrode is placed farther leftward and more apically, producing a mainly positive QRS in a normal patient. Which lead is most likely? A. V1 | back 42 D. V5 |
front 43 In an augmented unipolar limb lead, a positive terminal on the left arm produces: A. aVR | back 43 B. aVL |
front 44 Which augmented limb lead has its positive electrode on the left leg? A. aVR | back 44 C. aVF |
front 45 A positive electrode placed on the right arm creates which augmented limb lead? A. aVR | back 45 A. aVR |
front 46 Which augmented limb lead is classically inverted in the normal ECG? A. aVL | back 46 D. aVR |
front 47 A student says all augmented limb leads are upright because they are “positive leads.” Which lead is the classic exception? A. aVF | back 47 B. aVR |
front 48 A patient has brief palpitations and near-syncope that occur unpredictably during routine daily activities, but the office ECG is normal. The most appropriate next test is: A. Signal-averaged ECG | back 48 C. Ambulatory ECG monitoring |
front 49 Ambulatory ECG monitoring is most useful when symptoms are suspected to result from: A. transient arrhythmias | back 49 A. transient arrhythmias |
front 50 A Holter monitor is prescribed because symptoms occur outside the clinic while the patient is walking around normally. This form of ECG monitoring is called: A. stress ECG | back 50 D. ambulatory ECG monitoring |