ECG Questions
The nurse is caring for a patient who is on a cardiac monitor. The nurse realizes that the sinus node is the pacemaker of the heart because it is: a. the fastest pacemaker cell in the heart. b. the only pacemaker cell in the heart. c. the only cell that does not affect the cardiac cycle. d. located in the left side of the heart.
A.
The patient is having premature ventricular contractions (PVCs). The nurse's greatest concern should be: a. the proximity of the R wave of the PVC to the T wave of a normal beat. b. the fact that PVCs are occurring, because they are so rare. c. if the number of PVCs are decreasing. d. if the PVCs are wider than 0.12 seconds.
A. The peak of the T wave through the downslope of the T wave is considered the vulnerable period, which coincides with partial repolarization of the ventricles. If a PVC occurs during the T wave, ventricular tachycardia may occur. When the R wave of PVC falls on the T wave of a normal beat, it is referred to as the R-on-T phenomenon.
Which of the following are common causes of sinus tachycardia? (Select all that apply.) a. Hyperthyroidism b. Hypovolemia c. Hypothyroidism d. Heart Failure e. Sleep
A, B, D Common causes of sinus tachycardia include hyperthyroidism, hypovolemia, heart failure, anemia, exercise, use of stimulants, fever, and sympathetic response to fear or pain and anxiety.
The normal width of the QRS complex is which of the following? (Select all that apply.) a. 0.06 to 0.10 seconds. b. 0.12 to 0.20 seconds. c. 1.5 to 2.5 small boxes. d. 3.0 to 5.0 small boxes. e. 0.04 seconds or greater.
A, C
The normal rate for the SA node when the patient is at rest is: a. 40 to 60 beats per minute. b. 60 to 100 beats per minute. c. 20 to 40 beats per minute. d. more than100 beats per minute.
B
The patient is admitted with sinus pauses causing periods of loss of consciousness. The patient is asymptomatic, awake and alert, but fatigued. He answers questions appropriately. When admitting this patient, the nurse should first: a. prepare the patient for temporary pacemaker insertion. b. prepare the patient for permanent pacemaker insertion. c. assess the patient's medication profile. d. apply transcutaneous pacemaker paddles.
C. AV nodal blocking medications (such as beta-blockers, calcium channel blockers, and digoxin) and increased vagal tone may cause sinus exit block. Causes are explored, and prescribed medications may need to be adjusted or discontinued. If patients are symptomatic, significant numbers of pauses may require treatment, including temporary (including transcutaneous) and permanent implantation of a pacemaker.
The nurse is working on the night shift when she notices sinus bradycardia on the patient's cardiac monitor. The nurse should: a. give atropine to increase heart rate. b. begin transcutaneous pacing of the patient. c. start a dopamine infusion to stimulate heart function. d. assess for hemodynamic instability.
D.
Electrocardiogram (ECG) paper contains a standardized grid where the horizontal axis measures time and the vertical axis measures voltage or amplitude. The nurse must understand that each horizontal box indicates: a. 200 milliseconds or 0.20 seconds duration. b. 40 milliseconds or 0.04 seconds duration. c. 3 seconds duration. d. millivolts of amplitude.
B
The nurse notices ventricular tachycardia on the heart monitor. When the patient is assessed, the patient is found to be unresponsive with no pulse. The nurse should: a. treat with intravenous amiodarone or lidocaine. b. begin cardiopulmonary resuscitation and advanced life support. c. provide electrical cardioversion. d. ignore the rhythm since it is benign.
B. If a pulse is present and the blood pressure is stable, the patient can be treated with intravenous amiodarone or lidocaine. Cardioversion is used as an emergency measure in patients who become hemodynamically unstable but continue to have a pulse.
The rhythm on the cardiac monitor is showing numerous pacemaker spikes, but no P waves or QRS complexes following the spikes. The nurse realizes this as: a. normal pacemaker function. b. failure to capture. c. failure to pace. d. failure to sense.
B. When the pacemaker generates an electrical impulse (pacer spike) and no depolarization is noted, it is described a failure to capture. On the ECG, a pacer spike is noted, but it is not followed by a P wave (atrial pacemaker) or a QRS complex (ventricular pacemaker)
The QT interval is the total time taken for ventricular depolarization and repolarization. Prolongation of the QT interval: a. decreases the risk of lethal dysrhythmias. b. usually occurs when heart rate increases. c. increases the risk of lethal dysrhythmias. d. can only be measured with irregular rhythms.
C.
The nurse notices that the patient has a first-degree AV block. Everything else about the rhythm is normal. The nurse should: a. prepare to place the patient on a transcutaneous pacemaker. b. give the patient atropine to shorten the PR interval. c. monitor the rhythm and patient's condition. d. give the patient an antiarrhythmic medication.
C.
The patient has a permanent pacemaker inserted. The provider has set the pacemaker to the demand mode at a rate of 60 beats per minute. The nurse realizes that: a. the pacemaker will pace only if the patient's intrinsic heart rate is less than 60 beats per minute. b. the demand mode often competes with the patient's own rhythm. c. the demand mode places the patient at risk for the R-on-T phenomenon. d. the fixed rate mode is safer and is the mode of choice.
A. Pacemakers can be operated in a demand mode or a fixed rate (asynchronous) mode. The demand mode paces the heart when no intrinsic or native beat is sensed. For example, if the rate control is set at 60 beats per minute, the pacemaker will only pace if the patient's heart rate drops to less than 60.
The patient is in chronic junctional escape rhythm with no atrial activity noted. Studies have demonstrated normal AV node function. This patient may be a candidate for which type of pacing? a. Atrial pacing b. Ventricular pacing c. Dual-chamber pacing d. Transcutaneous pacing
A. Pacemakers may be used to stimulate the atrium, ventricle, or both chambers (dual- chamber pacemakers). Atrial pacing is used to mimic normal conduction and to produce atrial contraction, thus providing atrial kick.
One of the functions of the atrioventricular (AV) node is to: a. pace the heart if the ventricles fail. b. slow the impulse arriving from the SA node. c. send the impulse to the SA node. d. allow for ventricular filling during systole.
B
The nurse is calculating the rate for a regular rhythm. There are 20 small boxes between each P wave and 20 small boxes between each R wave. What is the ventricular rate? a. 50 beats/min b. 75 beats/min c. 85 beats/min d. 100 beats/min
B
The patient's heart rate is 70 beats per minute, but the P waves come after the QRS complex. The nurse correctly determines that the patient's heart rhythm is: a. a normal junctional rhythm. b. an accelerated junctional rhythm. c. a junctional tachycardia. d. atrial fibrillation.
B. An accelerated junctional rhythm has a rate between 60 and 100 beats per minute, and the rate for junctional tachycardia is greater than 100 beats per minute. If P wave precedes QRS, it is inverted or upside down; the P wave may not be visible, or it may follow the QRS. If a P wave is present before the QRS, the PR interval is shortened less than 0.12 milliseconds.
The patient is admitted with a fever and rapid heart rate. The patient's temperature is 103° F (39.4° C).The nurse places the patient on a cardiac monitor and finds the patient's atrial and ventricular rates are above 105 beats per minute. P waves are clearly seen and appear normal in configuration. QRS complexes are normal in appearance and 0.08 seconds wide. The rhythm is regular, and blood pressure is normal. The nurse should focus on providing: a. medications to lower heart rate. b. treatment to lower temperature. c. treatment to lower cardiac output. d. treatment to reduce heart rate.
B. Sinus tachycardia results when the SA node fires faster than 100 beats per minute. Sinus tachycardia is a normal response to stimulation of the sympathetic nervous system. Sinus tachycardia is also a normal finding in children younger than 6 years. The dysrhythmia itself is not treated, but the cause is identified and treated appropriately.
The nurse understands that in a third-degree AV block: a. every P wave is conducted to the ventricles. b. some P waves are conducted to the ventricles. c. none of the P waves are conducted to the ventricles. d. the PR interval is prolonged.
C. Third-degree block is often called complete heart block because no atrial impulses are conducted through the AV node to the ventricles.
The patient has an irregular heart rhythm. To determine an accurate heart rate, the nurse first: a. identifies the markers on the ECG paper that indicate a 6-second strip. b. counts the number of large boxes between two consecutive P waves. c. counts the number of small boxes between two consecutive QRS complexes. d. divides the number of complexes in a 6- second strip by 10.
A
The nurse is caring for a patient who has atrial fibrillation. Sequelae that place the patient at greater risk for mortality/morbidity include which of the following? (Select all that apply.) a. Stroke b. Ashman beats c. Pulmonary emboli d. Prolonged PR interval e. Decreased cardiac output
A, C, E One complication of atrial fibrillation is thromboembolism. The blood that collects in the atria is agitated by fibrillation, and normal clotting is accelerated. Small thrombi, called mural thrombi, begin to form along the walls of the atria. These clots may dislodge, resulting in pulmonary embolism or stroke. The ineffectual contraction of the atria results in loss of "atrial kick." If too many impulses conduct to the ventricles, atrial fibrillation with rapid ventricular response may result and compromise cardiac output. Ashman beats are not clinically significant. No recognizable or discernible P waves are present; therefore, PR interval is absent.
The patient's heart rhythm shows an inverted P wave with a PR interval of 0.06 seconds. The heart rate is 54 beats per minute. The nurse recognizes the rhythm as a junctional escape rhythm, and understands that the rhythm is due to the: a. loss of sinus node activity. b. increased rate of the AV node. c. increased rate of the SA node. d. decreased rate of the AV node.
A. Junctional escape rhythm occurs when the dominant pacemaker, the SA node, fails to fire. The normal heart rate of the AV node is 40 to 60 beats per minute, so the AV node rate has neither increased nor decreased.
The nurse is talking with the patient when the monitor alarms and shows a wavy baseline without a PQRST complex. The nurse should: a. defibrillate the patient immediately. b. initiate basic life support. c. initiate advanced life support. d. assess the patient and the electrical leads.
D.
The patient is admitted with a condition that requires cardiac rhythm monitoring. To apply the monitoring electrodes, the nurse must first: a. apply a moist gel to the chest. b. make certain that the electrode gel is dry. c. avoid soaps to avoid skin irritation. d. clip chest hair if needed.
D.
When assessing the 12-lead electrocardiogram (ECG) or a rhythm strip, it is helpful to understand that the electrical activity is viewed in relation to the positive electrode of that particular lead. When an electrical signal is aimed directly at the positive electrode, the inflection will be: a. negative. b. upside down. c. upright. d. equally positive and negative.
C. When an electrical signal is aimed directly at the positive electrode, an upright inflection is visualized. If the impulse is going away from the positive electrode, a negative deflection is seen; and if the signal is perpendicular to the imaginary line between the positive and negative poles of the lead, the tracing is equiphasic, with equally positive and negative deflection.
Sinus bradycardia is a symptom of which of the following? (Select all that apply.) a. Calcium channel blocker medication b. Beta-blocker medication c. Athletic conditioning d. Hypothermia e. Hyperthyroidism
A, B, C, D Vasovagal response; medications such as digoxin or AV nodal blocking agents, including calcium channel blockers and beta-blockers; myocardial infarction; normal physiological variant in the athlete; disease of the sinus node; increased intracranial pressure; hypoxemia; and hypothermia may cause sinus bradycardia.
The patient is asymptomatic but is diagnosed with second-degree heart block Mobitz I. The patient is on digitalis medication at home. The nurse should expect that: a. the patient has had an anterior wall myocardial infarction. b. the physician will order the digitalis to be continued in the hospital. c. a digitalis level would be ordered upon admission. d. the patient will require a transcutaneous pacemaker.
C. Digitalis toxicity is a major cause of this rhythm, and further digitalis doses should not be given until a digitalis level is obtained. Other causes of Mobitz I include AV nodal blocking drugs, acute inferior wall myocardial infarction or right ventricular infarction, ischemic heart disease, and excess vagal response.
The patient's heart rate is 165 beats per minute. His cardiac monitor shows a rapid rate with narrow QRS complexes. The P waves cannot be seen, but the rhythm is regular. The patient's blood pressure has dropped from 124/62 to 78/30. His skin is cold and diaphoretic and he is complaining of nausea. The nurse prepares the patient for: a. administration of beta-blockers. b. administration of atropine. c. transcutaneous pacemaker insertion. d. emergent cardioversion.
D. If an abnormal P wave cannot be visualized on the ECG but the QRS complex is narrow, the term supraventricular tachycardia (SVT) is often used. This is a generic term that describes any tachycardia that is not ventricular in origin; it is also used when the source above the ventricles cannot be identified, usually because the rate is too fast. Treatment is directed at assessing the patient's tolerance of the tachycardia. If the rate is higher than 150 beats per minute and the patient is symptomatic, emergent cardioversion is considered. Cardioversion is the delivery of a synchronized electrical shock to the heart by an external defibrillator. Beta-blockers are a possibility if the patient is not symptomatic. Atropine is used in the treatment of bradycardia. If atropine is not effective in increasing heart rate, then transcutaneous pacing is implemented.
Because of the location of the AV node, the possible P waveforms that are associated with junctional rhythms include which of the following? (Select all that apply.) a. No P wave b. Inverted P wave c. Shortened PR interval d. P wave after the QRS complex e. Normal P wave and PR interval
A, B, C, D Because of the location of the AV node—in the center of the heart—impulses generated may be conducted forward, backward, or both. With the potential of forward, backward, or bidirectional impulse conduction, three different P waveforms may be associated with junctional rhythms: When the AV node impulse moves forward, P waves may be absent because the impulse enters the ventricle first. The atria receives the wave of depolarization at the same time as the ventricles; thus, because of the larger muscle mass of the ventricles, there is no P wave. When the AV node impulse is conducted backward, the impulse enters the atria first. When depolarization occurs backward, an inverted P wave is created. Once the atria have been depolarized, the impulse moves down the bundle of His and depolarizes both ventricles normally. A short PR interval (<0.12 second) is noted. When the impulse is conducted both forward and backward, P waves may be present after the QRS complex.
The patient is in third-degree heart block (complete heart block) and is symptomatic. The treatment for this patient is which of the following? (Select all that apply.) a. transcutaneous pacemaker. b. atropine IV. c. temporary transvenous pacemaker. d. permanent pacemaker. e. amiodarone IV.
A, C, D Treatments include transcutaneous or transvenous pacing and implanting a permanent pacemaker. Atropine reduces vagal tone, but that is not a cause of complete heart block and will produce more P waves, but the P waves will still not be associated with the QRS complexes. It is important to note that the only treatment is pacing.
The nurse is reading the cardiac monitor and notes that the patient's heart rhythm is extremely irregular and there are no discernible P waves. The ventricular rate is 90 beats per minute, and the patient is hemodynamically stable. The nurse realizes that the patient's rhythm is: a. atrial fibrillation. b. atrial flutter. c. atrial flutter with rapid ventricular response. d. junctional escape rhythm
A. Atrial fibrillation arises from multiple ectopic foci in the atria, causing chaotic quivering of the atria and ineffectual atrial contraction.
Which of the following is true about a patient diagnosed with sinus arrhythmia? a. The heart rate varies, dependent on vagal tone and respiratory pattern. b. Immediate treatment is essential to prevent death. c. Sinus arrhythmia is not well tolerated by most patients. d. PR and QRS interval measurements are prolonged.
A. Sinus arrhythmia is a cyclical change in heart rate that is associated with respiration. The heart rate increases slightly during inspiration and slows slightly during exhalation because of changes in vagal tone. The ECG tracing demonstrates an alternating pattern of faster and slower heart rate that changes with the respiratory cycle. Interval measurements are normal. This rhythm is tolerated well, and no treatment is required.
The nurse is examining the patient's cardiac rhythm strip in lead II and notices that all of the P waves are upright and look the same except one that has a different shape and is inverted. The nurse realizes that the P wave with the abnormal shape is probably: a. from the SA node since all P waves come from the SA node. b. from some area in the atria other than the SA node. c. indicative of ventricular depolarization. d. normal even though it is inverted in lead II.
B
The patient has a permanent pacemaker in place with a demand rate set at 60 beats/min. The cardiac monitor is showing a heart rate of 44 beats/min with no pacemaker spikes. The nurse realizes this as: a. normal pacemaker function. b. failure to capture. c. failure to pace. d. failure to sense.
C. Failure to pace or fire occurs when the pacemaker fails to initiate an electrical stimulus when it should fire. The problem is noted by absence of pacer spikes on the rhythm strip. Causes of failure to pace include battery or pulse generator failure, fracture or displacement of a pacemaker wire, or loose connections.
The patient is scheduled to have a permanent pacemaker implanted. The patient asks the nurse, "How long will the battery in this thing last?" The nurse should answer, a. "Life expectancy is about 1 year. Then it will need to be replaced." b. "Pacemaker batteries can last up to 25 years with constant use." c. "Battery life varies depending on usage, but it can last up to 10 years." d. "Pacemakers are used to treat temporary problems so the batteries don't last long."
C. Implanted permanent pacemakers are used to treat chronic conditions. These devices have a battery life of up to 10 years, which varies based on the manufacturer's recommendations.
