Critical Care - Chapter 08: Dysrhythmia Interpretation and Management

ANS: A The cardiac cycle begins with an impulse that is generated from a small concentrated area of pacemaker cells high in the right atria called the sinoatrial node (sinus node or SA node). The SA node has the fastest rate of discharge and thus is the dominant pacemaker of the heart. The AV node has pacemaker properties and can discharge an impulse if the SA node fails. The ventricles have pacemaker capabilities if the sinus node or the AV node ceases to generate impulses.

1. Why is the sinus node identified as the pacemaker of the heart? a. It contains the fastest pacemaker cell in the heart. b. It has the only pacemaker cell in the heart. c. It contains the only cell that does not affect the cardiac cycle. d. It is located in the left side of the heart.

ANS: B The rule of 1500 is used to calculate the exact rate of a regular rhythm. The number of small boxes between the highest points of two consecutive R waves is counted, and that number of small boxes is divided into 1500 to determine the ventricular rate. 1500/20 is 75 beats/min. This method is accurate only if the rhythm is regular.

10. 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

ANS: 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. Both atrial and ventricular rates are greater than 100 beats per minute, up to 160 beats per minute, but may be as high as 180 beats per minute. Sinus tachycardia is regular or essentially regular. PR interval is 0.12 to 0.20 seconds. QRS interval is 0.06 to 0.10 seconds. P and QRS waves are consistent in shape. P waves are small and rounded. A P wave precedes every QRS complex, which is then followed by a T wave. The fast heart rhythm may cause a decrease in cardiac output because of the shorter filling time for the ventricles. Lowering cardiac out further may complicate the situation. The dysrhythmia itself is not treated, but the cause is identified and treated a

11. The patient is admitted with a fever and rapid heart rate and a temperature of 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. What should be the nurse's initial focus? a. Medications to lower heart rate b. Treatment to lower temperature c. Treatment to lower cardiac output d. Treatment to reduce heart rate

ANS: D Sinus bradycardia may be a normal heart rhythm for some individuals such as athletes, or it may occur during sleep. Assess for hemodynamic instability related to the bradycardia. If the patient is symptomatic, interventions include administration of atropine. If atropine is not effective in increasing heart rate, then transcutaneous pacing, dopamine infusion, or epinephrine infusion may be administered. Atropine is avoided for treatment of bradycardia associated with hypothermia.

12. The nurse working on the night shift when notices sinus bradycardia on the patient's cardiac monitor. What initial action should the nurse take? 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.

ANS: 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.

13. Which statement 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.

ANS: 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.

14. The patient is admitted with sinus pauses causing periods of loss of consciousness. The patient is currently asymptomatic, awake and alert, but fatigued and answers questions appropriately. When admitting this patient, what should be the nurse's initial action? 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.

ANS: 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.

15. The patient's heart rate is 165 beats per minute and the 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; skin is cold and diaphoretic and the patient is reporting nausea. The nurse prepares the patient for what intervention? a. Administration of beta-blockers b. Administration of atropine c. Transcutaneous pacemaker insertion d. Emergent cardioversion

ANS: A Atrial fibrillation arises from multiple ectopic foci in the atria, causing chaotic quivering of the atria and ineffectual atrial contraction. The AV node is bombarded with hundreds of atrial impulses and conducts these impulses in an unpredictable manner to the ventricles. The atrial rate may be as high 700 and no discernible P waves can be identified, resulting in a wavy baseline and an extremely irregular ventricular response. Atrial flutter arises from a single irritable focus in the atria. The atrial focus fires at an extremely rapid, regular rate, between 240 and 320 beats per minute. The P waves are called flutter waves and may have a sawtooth appearance. The ventricular response may be regular or irregular based on how many flutter waves are conducted through the AV node. Atrial flutter with rapid ventricular response occurs when atrial impulses cause a ventricular response greater than 100 beats per m

16. 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 is demonstrating what rhythm? a. Atrial fibrillation b. Atrial flutter c. Atrial flutter with rapid ventricular response d. Junctional escape rhythm

ANS: 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. An increased SA node rate would override the AV node.

17. 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 what cause? 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

ANS: B The normal intrinsic rate for the AV node and junctional tissue is 40 to 60 beats per minute, but rates can accelerate. 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. Atrial fibrillation arises from multiple ectopic foci in the atria, causing chaotic quivering of the atria and ineffectual atrial contraction. The AV node is bombarded with hundreds of atrial impulses and conducts these impulses in an unpredictable manner to the ventricles.

18. The patient's heart rate is 70 beats per minute with the P waves coming after the QRS complex. The nurse correctly determines that the patient is demonstrating what heart rhythm? a. A normal junctional rhythm b. An accelerated junctional rhythm c. A junctional tachycardia d. Atrial fibrillation

ANS: 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. PVCs may occur in healthy individuals and usually do not require treatment. The nurse must determine if PVCs are increasing in number by evaluating the trend. If PVCs are increasing, the nurse should evaluate for potential causes such as electrolyte imbalances, myocardial ischemia or injury, and hypoxemia. Runs of nonsustained ventricular tachycardia may be a precursor to development of sustained ventricular tachycardia. Because the stimulus depolarizes the ventricles in a slower, abnormal way, the QRS complex appears widened and has a bizarre shape. The QRS complex is wider than 0.

19. The patient is having premature ventricular contractions (PVCs). What is the nurse's greatest concern? 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.

ANS: B The impulse from the SA node quickly reaches the atrioventricular (AV) node located in the area called the AV junction, between the atria and the ventricles. Here the impulse is slowed to allow time for ventricular filling during relaxation or ventricular diastole. The AV node has pacemaker properties and can discharge an impulse if the SA node (not the ventricle) fails. The electrical impulse is then rapidly conducted through the bundle of His to the ventricles (not the SA node) via the left and right bundle branches.

2. What is one of the functions of the atrioventricular (AV) node? a. Pacing the heart if the ventricles fail b. Slowing the impulse arriving from the SA node c. Sending the impulse to the SA node d. Allowing for ventricular filling during systole

ANS: B Ventricular tachycardia (VT) is a rapid, life-threatening dysrhythmia originating from a single ectopic focus in the ventricles. Determine whether the patient has a pulse. If no pulse is present, provide emergent basic and advanced life-support interventions, including defibrillation. 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. It also may be used in nonemergency situations, such as when a patient has asymptomatic VT.

20. 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 take what action immediately? 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.

ANS: D Ventricular fibrillation (VF) is a chaotic rhythm characterized by a quivering of the ventricles, which results in total loss of cardiac output and pulse. VF is a life-threatening emergency, and the more immediate the treatment is, the better the survival will be. VF produces a wavy baseline without a PQRST complex. Because a loose lead or electrical interference can produce a waveform similar to VF, it is always important to immediately assess the patient for pulse and consciousness.

21. The nurse is talking with the patient when the monitor alarms and shows a wavy baseline without a PQRST complex. The nurse should take what action immediately? a. Defibrillate the patient immediately. b. Initiate basic life support. c. Initiate advanced life support. d. Assess the patient and the electrical leads.

ANS: C First-degree AV block is a common dysrhythmia in the elderly and in patients with cardiac disease. As the normal conduction pathway ages or becomes diseased, impulse conduction becomes slower than normal. It is well tolerated. No treatment is required. Continue to monitor the patient and the rhythm.

22. The nurse notices that a patient is in first-degree AV block but everything else about the rhythm is normal. The nurse should be prepared to take what action? a. Placing the patient on a transcutaneous pacemaker. b. Giving the patient atropine to shorten the PR interval. c. Monitor the rhythm and patient's condition. d. Giving the patient an antiarrhythmic medication.

ANS: C In first-degree AV block, a P wave precedes every QRS complex, which is followed by a T wave indicating complete conduction. It is represented on the ECG as a prolonged PR interval. Second-degree heart block refers to AV conduction that is intermittently blocked. Therefore, some P waves are conducted and some are not. Third-degree block is often called complete heart block because no atrial impulses are conducted through the AV node to the ventricles.

23. The nurse understands what to be true of 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

ANS: 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. This type of block is usually well tolerated and no treatment is indicated unless the dropped beats occur frequently.

24. 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 action to be taken? 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.

ANS: 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.

25. The patient scheduled to have a permanent pacemaker implanted asks the nurse, "How long will the battery in this thing last?" What answer should the nurse provide? 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."

ANS: 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. This is the case in the scenario provided. Ventricular pacing stimulates ventricular depolarization and is commonly used in emergency situations or when pacing is required infrequently. Dual-chamber pacing allows for stimulation of both atria and ventricles as needed to synchronize the chambers and mimic the normal cardiac cycle. However, with this patient, ventricular and AV function are normal.

26. 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

ANS: 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 fixed rate mode paces the heart at a set rate, independent of any activity the patient's heart generates. The fixed rate mode may compete with the patient's own rhythm and deliver an impulse on the T wave (R-on-T phenomenon), with the potential for producing ventricular tachycardia or fibrillation. The demand mode is safer and is the mode of choice.

27. 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. How does the nurse interpret this? 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.

ANS: 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. This is not normal pacemaker function. 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). Common causes of failure to capture include output (milliamperes) set too low, or displacement of the pacing lead wire from the myocardium (transvenous or epicardial leads). Other causes of failure to capture include battery failure, fracture of the pacemaker wire, or increased pacing threshold as

28. 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. How does the nurse interpret this? a. Normal pacemaker function b. Failure to capture c. Failure to pace d. Failure to sense

ANS: 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). Common causes of failure to capture include output (milliamperes) set too low, or displacement of the pacing lead wire from the myocardium (transvenous or epicardial leads). Other causes of failure to capture include battery failure, fracture of the pacemaker wire, or increased pacing threshold as a result of medication or electrolyte imbalance. This is not normal pacemaker function. 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 displa

29. 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 what? a. Normal pacemaker function b. Failure to capture c. Failure to pace d. Failure to sense

ANS: B The sinus node reaches threshold at a rate of 60 to 100 times per minute. Because this is the fastest pacemaker in the heart, the SA node is the dominant pacemaker of the heart. The AV node has an inherent rate of 40 to 60 beats per minute and the His-Purkinje system can fire at a rate of 20 to 40 beats per minute. Sinus tachycardia results when the SA node fires faster than 100 beats per minute.

3. What is the normal rate for the SA node when the patient is at rest? a. 40 to 60 beats per minute b. 60 to 100 beats per minute c. 20 to 40 beats per minute d. More than 100 beats per minute

ANS: A Normal sinus rhythm (NSR) reflects normal conduction of the sinus impulse through the atria and ventricles. Atrial and ventricular rates are the same and range from 60 to 100 beats per minute. Rhythm is regular or essentially regular. PR interval is 0.12 to 0.20 seconds. QRS interval is 0.06 to 0.10 seconds. P and QRS waves are consistent in shape. Sinus tachycardia results when the SA node fires faster than 100 beats per minute. Bradycardia is defined as a heart rate less than 60 beats per minute. Sinus arrhythmia is a cyclical change in heart rate that is associated with respiration. The heart rate slightly increases during inspiration and slightly slows during exhalation because of changes in vagal tone.

30. Interpret the following rhythm: a. Normal sinus rhythm b. Sinus bradycardia c. Sinus tachycardia d. Sinus arrhythmia

ANS: C Normal sinus rhythm (NSR) reflects normal conduction of the sinus impulse through the atria and ventricles. Atrial and ventricular rates are the same and range from 60 to 100 beats per minute. Rhythm is regular or essentially regular. PR interval is 0.12 to 0.20 seconds. QRS interval is 0.06 to 0.10 seconds. P and QRS waves are consistent in shape. Sinus tachycardia results when the SA node fires faster than 100 beats per minute. Bradycardia is defined as a heart rate less than 60 beats per minute. Sinus arrhythmia is a cyclical change in heart rate that is associated with respiration. The heart rate slightly increases during inspiration and slightly slows during exhalation because of changes in vagal tone.

31. Interpret the following rhythm: a. Normal sinus rhythm b. Sinus bradycardia c. Sinus tachycardia d. Sinus arrhythmia

ANS: B Normal sinus rhythm (NSR) reflects normal conduction of the sinus impulse through the atria and ventricles. Atrial and ventricular rates are the same and range from 60 to 100 beats per minute. Rhythm is regular or essentially regular. PR interval is 0.12 to 0.20 seconds. QRS interval is 0.06 to 0.10 seconds. P and QRS waves are consistent in shape. Sinus tachycardia results when the SA node fires faster than 100 beats per minute. Bradycardia is defined as a heart rate less than 60 beats per minute. 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.

32. Interpret the following rhythm: a. Normal sinus rhythm b. Sinus bradycardia c. Sinus tachycardia d. Sinus arrhythmia

ANS: A The underlying rhythm is identified first. Following this step, the dysrhythmia that is occurring to disrupt the underlying rhythm is then determined. A premature atrial contraction (PAC) is a single ectopic beat arising from atrial tissue, not the sinus node. The PAC occurs earlier than the next normal beat and interrupts the regularity of the underlying rhythm. The P wave of the PAC has a different shape than the sinus P wave because it arises from a different area in the atria; it may follow or be in the T wave of the preceding normal beat. If the early P wave is in the T wave, this T wave will look different from the T wave of a normal beat. Normal sinus rhythm (NSR) reflects normal conduction of the sinus impulse through the atria and ventricles. Atrial and ventricular rates are the same and range from 60 to 100 beats per minute. Rhythm is regular or essentially regular. PR interval is 0.12 to 0.20 second

33. Interpret the following rhythm: a. Sinus rhythm with PACs b. Normal sinus rhythm c. Sinus tachycardia d. Sinus bradycardia

ANS: B Atrial flutter arises from a single irritable focus in the atria. The atrial focus fires at an extremely rapid, regular rate, between 240 and 320 beats per minute. The P waves are called flutter waves and may have a sawtooth appearance. The ventricular response may be regular or irregular based on how many flutter waves are conducted through the AV node. The number of flutter waves to each QRS complex is called the conduction ratio. The conduction ratio may remain the same or vary depending on the number of flutter waves that are conducted to the ventricles. The description of atrial flutter might be constant at 2:1, 3:1, 4:1, 5:1, and so forth, or it may be variable. Because this patient's rhythm has varying P waves for each QRS, the ventricular conduction (rate) varies from 2:1 to 6:1. Atrial flutter with RVR occurs when atrial impulses cause a ventricular response greater than 100 beats per minute. Atrial f

34. Interpret the following rhythm: a. Atrial flutter with variable conduction b. Ventricular fibrillation c. Atrial fibrillation d. Atrial flutter with RVR (rapid ventricular response)

ANS: A Atrial fibrillation arises from multiple ectopic foci in the atria, causing chaotic quivering of the atria and ineffectual atrial contraction. The AV node is bombarded with hundreds of atrial impulses and conducts these impulses in an unpredictable manner to the ventricles. The atrial rate may be as high 700 and no discernible P waves can be identified, resulting in a wavy baseline and an extremely irregular ventricular response. Atrial flutter arises from a single irritable focus in the atria. The atrial focus fires at an extremely rapid, regular rate, between 240 and 320 beats per minute. The P waves are called flutter waves and may have a sawtooth appearance. The ventricular response may be regular or irregular based on how many flutter waves are conducted through the AV node. Atrial flutter with RVR occurs when atrial impulses cause a ventricular response greater than 100 beats per minute. A junctional esc

35. Interpret the following rhythm: a. Atrial Fibrillation b. Atrial Flutter c. Atrial flutter with RVR d. Junctional escape rhythm

ANS: A The normal intrinsic rate for the AV node and junctional tissue is 40 to 60 beats per minute, but rates can accelerate. 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 to less than 0.12 milliseconds. Atrial fibrillation arises from multiple ectopic foci in the atria, causing chaotic quivering of the atria and ineffectual atrial contraction. The AV node is bombarded with hundreds of atrial impulses and conducts these impulses in an unpredictable manner to the ventricles.

36. Interpret the following rhythm: a. Junctional rhythm b. An accelerated junctional rhythm c. A junctional tachycardia d. Atrial fibrillation

ANS: A A single ectopic focus produces PVC waveforms that look alike, called unifocal PVCs. Waveforms of PVCs arising from multiple foci are not identical and are called multifocal PVCs. PVCs may occur in a predictable pattern, such as every other beat (bigeminal), every third beat (trigeminal), or every fourth beat (quadrigeminal). PVCs can also occur sequentially. Two PVCs in a row are called a pair, and three or more in a row are called nonsustained ventricular tachycardia.

37. Interpret the following rhythm: a. Sinus rhythm with multifocal premature ventricular contractions b. Sinus rhythm with unifocal premature ventricular contractions c. Sinus rhythm with bigeminal premature ventricular contractions d. Sinus rhythm with paired premature ventricular contractions (couplets)

ANS: B A single ectopic focus produces PVC waveforms that look alike, called unifocal PVCs. Waveforms of PVCs arising from multiple foci are not identical and are called multifocal PVCs. PVCs may occur in a predictable pattern, such as every other beat (bigeminal), every third beat (trigeminal), or every fourth beat (quadrigeminal). PVCs also can occur sequentially. Two PVCs in a row are called a pair, and three or more in a row are called nonsustained ventricular tachycardia. atrioventricular node, and the ventricles. TOP: Nursing Process Step: Assessment

38. Interpret the following rhythm: a. Sinus rhythm with multifocal premature ventricular contractions b. Sinus rhythm with unifocal premature ventricular contractions c. Sinus rhythm with bigeminal premature ventricular contractions d. Sinus rhythm with paired premature ventricular contractions (couplets)

ANS: C A single ectopic focus produces PVC waveforms that look alike, called unifocal PVCs. Waveforms of PVCs arising from multiple foci are not identical and are called multifocal PVCs. PVCs may occur in a predictable pattern, such as every other beat (bigeminal), every third beat (trigeminal), or every fourth beat (quadrigeminal). PVCs can also occur sequentially. Two PVCs in a row are called a pair (couplet), and three or more in a row are called nonsustained ventricular tachycardia.

39. Interpret the following rhythm: a. Sinus rhythm with multifocal premature ventricular contractions b. Sinus rhythm with unifocal premature ventricular contractions c. Sinus rhythm with bigeminal premature ventricular contractions d. Sinus rhythm with paired premature ventricular contractions (couplets)

ANS: 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.

4. 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. What is the effect on the inflection when an electrical signal is aimed directly at the positive electrode? a. Negative b. Upside down c. Upright d. Equally positive and negative

ANS: D A single ectopic focus produces PVC waveforms that look alike, called unifocal PVCs. Waveforms of PVCs arising from multiple foci are not identical and are called multifocal PVCs. PVCs may occur in a predictable pattern, such as every other beat (bigeminal), every third beat (trigeminal), or every fourth beat (quadrigeminal). PVCs can also occur sequentially. Two PVCs in a row are called a pair (couplet), and three or more in a row are called nonsustained ventricular tachycardia.

40. Interpret the following rhythm: a. Sinus rhythm with multifocal premature ventricular contractions b. Sinus rhythm with unifocal premature ventricular contractions c. Sinus rhythm with bigeminal premature ventricular contractions d. Sinus rhythm with paired premature ventricular contractions (couplets)

ANS: 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 a PVC falls on the T wave of a normal beat, it is referred to as the R-on-T phenomenon. PVCs may occur in healthy individuals and usually do not require treatment. The nurse must determine if PVCs are increasing in number by evaluating the trend. If PVCs are increasing, the nurse should evaluate for potential causes, such as electrolyte imbalances, myocardial ischemia or injury, and hypoxemia. Runs of nonsustained ventricular tachycardia may be a precursor to development of sustained ventricular tachycardia. Because the stimulus depolarizes the ventricles in a slower, abnormal way, the QRS complex appears widened and has a bizarre shape. The QRS complex is wider than

41. Interpret the following rhythm: a. R-on-T phenomenon b. Sinus rhythm with multifocal premature ventricular contractions c. Nonsustained ventricular tachycardia d. Sinus rhythm with bigeminal premature ventricular contractions

ANS: D Ventricular tachycardia (VT) is a rapid, life-threatening dysrhythmia originating from a single ectopic focus in the ventricles. It is characterized by at least three PVCs in a row. VT occurs at a rate greater than 100 beats per minute, but the rate is usually around 150 beats per minute and may be up to 250 beats per minute. Depolarization of the ventricles is abnormal and produces a widened QRS complex. The patient may or may not have a pulse. Determine whether the patient has a pulse. If no pulse is present, provide emergent basic and advanced life-support interventions, including defibrillation. If a pulse is present and the blood pressure is stable, the patient can be treated with intravenous amiodarone or lidocaine.

42. The patient is alert and talking when the nurse notices the following rhythm. The patient's blood pressure is 90/44 mm Hg. The nurse should take what action? a. Defibrillate immediately. b. Begin basic life support. c. Begin advanced life support. d. Treat with intravenous amiodarone or lidocaine.

ANS: B Ventricular fibrillation (VF) is a chaotic rhythm characterized by a quivering of the ventricles, which results in total loss of cardiac output and pulse. VF is a life-threatening emergency, and the more immediate the treatment, the better the survival will be. VF produces a wavy baseline without a PQRST complex. Because a loose lead or electrical interference can produce a waveform similar to VF, it is always important to immediately assess the patient for pulse and consciousness. If no pulse is present, provide emergent basic and advanced life-support interventions, including defibrillation.

43. The nurse notes the following rhythm on the heart monitor. The patient is unresponsive and not breathing. The nurse should be prepared to implement what action? a. Treat with intravenous amiodarone or lidocaine. b. Provide emergent basic and advanced life support. c. Provide electrical cardioversion. d. Ignore the rhythm because it is benign.

ANS: A Idioventricular rhythm is an escape rhythm that is generated by the Purkinje fibers. This rhythm emerges only when the SA and AV nodes fail to initiate an impulse. The Purkinje fibers are capable of an intrinsic rate of 20 to 40 beats per minute. Because this last pacemaker is located in the ventricles, the QRS complex appears wide and bizarre with a slow rate. No P waves are present. If the rate is between 40 and 100 beats per minute, this rhythm is called accelerated idioventricular rhythm (AIVR). Ventricular tachycardia (VT) is a rapid, life-threatening dysrhythmia originating from a single ectopic focus in the ventricles. It is characterized by at least three PVCs in a row. VT occurs at a rate greater than 100 beats per minute, but the rate is usually around 150 beats per minute and may be up to 250 beats per minute. VF produces a wavy baseline without a PQRST complex. Because a loose lead or electrical in

44. Interpret the following rhythm: a. Idioventricular rhythm b. Accelerated idioventricular rhythm c. Ventricular tachycardia d. Ventricular fibrillation

ANS: D In first-degree block, P and QRS waves are consistent in shape. P waves are small and rounded. A P wave precedes every QRS complex, which is followed by a T wave. PR interval is prolonged and is greater than 0.20 seconds. QRS complex and QT/QTc measurements are normal. Normal sinus rhythm (NSR) reflects normal conduction of the sinus impulse through the atria and ventricles. Atrial and ventricular rates are the same and range from 60 to 100 beats per minute. Rhythm is regular or essentially regular. PR interval is 0.12 to 0.20 seconds.

45. Interpret the following rhythm: a. Normal sinus rhythm b. Sinus rhythm with second-degree AV block c. Complete heart block d. Sinus rhythm with first-degree AV block

ANS: B Also called a Mobitz I or Wenckebach phenomenon, second-degree AV block type I is represented on the ECG as a progressive lengthening of the PR interval until there is a P wave without a QRS complex. In first-degree AV block, a P wave precedes every QRS complex, and every P wave is followed by a QRS. Second-degree AV block type II (Mobitz II) is a more critical type of heart block that requires early recognition and intervention. There is no progressive lengthening of the PR interval, which remains the same throughout with the exception of the dropped beat(s). Third-degree block is often called complete heart block because no atrial impulses are conducted through the AV node to the ventricles. In complete heart block, the atria and ventricles beat independently of each other because the AV node is completely blocked to the sinus impulse and it is not conducted to the ventricles. One hallmark of third-degree he

46. Interpret the following rhythm: a. First-degree AV block b. Second-degree AV block Mobitz I (Wenckebach phenomenon) c. Second-degree AV block Mobitz II d. Third-degree AV block (complete heart block)

ANS: C Second-degree AV block type II (Mobitz II) is a more critical type of heart block that requires early recognition and intervention. There is no progressive lengthening of the PR interval, which remains the same throughout with the exception of the dropped beat(s). Also called a Mobitz I or Wenckebach phenomenon, second-degree AV block type I is represented on the ECG as a progressive lengthening of the PR interval until there is a P wave without a QRS complex. In first-degree AV block, a P wave precedes every QRS complex, and every P wave is followed by a QRS. Third-degree block is often called complete heart block because no atrial impulses are conducted through the AV node to the ventricles. In complete heart block, the atria and ventricles beat independently of each other because the AV node is completely blocked to the sinus impulse and it is not conducted to the ventricles. One hallmark of third-degree he

47. Interpret the following rhythm: a. First-degree AV block b. Second-degree AV block Mobitz I (Wenckebach phenomenon) c. Second-degree AV block Mobitz II d. Third-degree AV block (complete heart block)

ANS: D Third-degree block is often called complete heart block because no atrial impulses are conducted through the AV node to the ventricles. In complete heart block, the atria and ventricles beat independently of each other because the AV node is completely blocked to the sinus impulse and it is not conducted to the ventricles. One hallmark of third-degree heart block is that the P waves have no association with the QRS complexes and appear throughout the QRS waveform. Second-degree AV block type II (Mobitz II) is a more critical type of heart block that requires early recognition and intervention. There is no progressive lengthening of the PR interval, which remains the same throughout with the exception of the dropped beat(s). Also called a Mobitz I or Wenckebach phenomenon, second-degree AV block type I is represented on the ECG as a progressive lengthening of the PR interval until there is a P wave without a QR

48. Interpret the following rhythm: a. First-degree AV block b. Second-degree AV block Mobitz I (Wenckebach phenomenon) c. Second-degree AV block Mobitz II d. Third-degree AV block (complete heart block)

ANS: 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. This is the case in the scenario provided. Ventricular pacing stimulates ventricular depolarization and is commonly used in emergency situations or when pacing is required infrequently. Dual-chamber pacing allows for stimulation of both atria and ventricles as needed to synchronize the chambers and mimic the normal cardiac cycle. However, with this patient, ventricular and AV function are normal.

49. Interpret the following rhythm: a. Atrial pacing b. Ventricular pacing c. Dual-chamber pacing d. Transcutaneous pacing

ANS: D Adequate skin preparation of electrode sites requires clipping the hair, cleansing the skin, and drying vigorously (moisture gels are not applied). Cleansing includes washing with soap and water, or alcohol, to remove skin debris and oils. Before application, the electrodes are checked to ensure that the gel is moist. It is difficult for electrodes to adhere to the chest in the presence of chest hair. Clipping, not shaving, is recommended since shaving may create small nicks that can become a portal for infection.

5. The patient is admitted with a condition that requires cardiac rhythm monitoring. To apply the monitoring electrodes, the nurse must first take what action? 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.

ANS: B 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. This is the case in the scenario provided. Ventricular pacing stimulates ventricular depolarization and is commonly used in emergency situations or when pacing is required infrequently. Dual-chamber pacing allows for stimulation of both atria and ventricles as needed to synchronize the chambers and mimic the normal cardiac cycle. However, with this patient, ventricular and AV function are normal.

50. Interpret the following rhythm: a. Atrial pacing b. Ventricular pacing c. Dual-chamber pacing d. Transcutaneous pacing

ANS: C 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. This is the case in the scenario provided. Ventricular pacing stimulates ventricular depolarization and is commonly used in emergency situations or when pacing is required infrequently. Dual-chamber pacing allows for stimulation of both atria and ventricles as needed to synchronize the chambers and mimic the normal cardiac cycle. However, with this patient, ventricular and AV function are normal.

51. Interpret the following rhythm: a. Atrial pacing b. Ventricular pacing c. Dual-chamber pacing d. Transcutaneous pacing

ANS: 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. This is not normal pacemaker function. 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). Common causes of failure to capture include output (milliamperes) set too low, or displacement of the pacing lead wire from the myocardium (transvenous or epicardial leads). Other causes of failure to capture include battery failure, fracture of the pacemaker wire, or increased pacing threshold as

52. Interpret the following rhythm: a. Normal pacemaker function b. Failure to capture c. Failure to pace d. Failure to sense

ANS: D Failure to sense manifests as pacer spikes that fall too closely to the patient's own rhythm, earlier than the programmed rate. The most common cause is displacement of the pacemaker electrode wire. This is not normal pacemaker function. 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). Common causes of failure to capture include output (milliamperes) set too low, or displacement of the pacing lead wire from the myocardium (transvenous or epicardial leads). Other causes of failure to capture include battery failure, fracture of the pacemaker wire, or increased pacing threshold as a result of medication or electrolyte imbalance. Failure to pace or fire occurs when the pacemaker fails to initiate an

53. Interpret the following rhythm: a. Normal pacemaker function b. Failure to capture c. Failure to pace d. Failure to sense

ANS: B ECG paper contains a standardized grid where the horizontal axis measures time and the vertical axis measures voltage or amplitude. Horizontally, the smaller boxes denote 0.04 seconds each or 40 milliseconds; the larger box contains five smaller boxes and thus equals 0.20 seconds or 200 milliseconds.

6. 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 what? a. 200 milliseconds or 0.20 seconds duration b. 40 milliseconds or 0.04 seconds duration c. 3 seconds duration d. Millivolts of amplitude

ANS: B Normally a P wave indicates that the SA node initiated the impulse that depolarized the atrium. However, a change in the shape of the P wave may indicate that the impulse arose from a site in the atria other than the SA node. The P wave represents atrial depolarization. It is usually upright in leads I and II and has a rounded, symmetrical shape. The amplitude of the P wave is measured at the center of the waveform and normally does not exceed three boxes, or 3 millimeters, in height.

7. 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 result of what? a. Originating from the SA node since all P waves come from the SA node. b. Originating from some area in the atria other than the SA node. c. Ventricular depolarization. d. Normal firing even though it is inverted in lead II.

ANS: C The QT interval is measured from the beginning of the QRS complex to the end of the T wave. This interval measures the total time taken for ventricular depolarization and repolarization. Abnormal prolongation of the QT interval increases vulnerability to lethal dysrhythmias, such as ventricular tachycardia and fibrillation. Normally, the QT interval becomes longer with slower heart rates and shortens with faster heart rates, thus requiring a correction of the value (QTc). Generally, the QT interval is less than half the RR interval. QTc accuracy is based on a regular rhythm. In irregular rhythms such as atrial fibrillation, an average QTc may be necessary because the QT varies from beat to beat.

8. The QT interval is the total time taken for ventricular depolarization and repolarization. Prolongation of the QT interval will result in what outcome? a. Decreased risk of lethal dysrhythmias b. Increase in heart rate c. Increase in the risk of lethal dysrhythmias. d. Will only be measured with irregular rhythms.

ANS: A Six-second method: A quick and easy estimate of heart rate can be accomplished by counting the number of P waves or QRS waves within a 6-second strip to obtain atrial and ventricular heart rates per minute. This is the optimal method for irregular rhythms. Identify the lines above the ECG paper that represent 6 seconds, and count the number of P waves within the lines; then add a zero (multiply by 10) to identify the atrial heart rate estimate for 1 minute. Next, identify the number of QRS waves in the 6-second strip and again add a zero to identify the ventricular rate. Large box method: In this method, two consecutive P and QRS waves are located. The number of large boxes between the highest points of two consecutive P waves is counted, and that number of large boxes is divided into 300 to determine the atrial rate in beats per minute. The number of large boxes between the highest points of two consecutive Q

9. The patient has an irregular heart rhythm. To determine an accurate heart rate, the nurse will take what action first? a. Identify the markers on the ECG paper that indicate a 6-second strip. b. Count the number of large boxes between two consecutive P waves. c. Count the number of small boxes between two consecutive QRS complexes. d. Divide the number of complexes in a 6-second strip by 10.

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

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

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

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

The nurse is caring for a patient diagnosed with 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

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