Exam 2 Practice Questions

List three potential sites of origin of ectopic beats:

1. Atria (PACs) 2. AV junction (PJCs) 3. ventricles (PVCs)

Depending on the severity of the patient's signs and symptoms, management of slow rhythms originating from the AV junction may require intervention including _____. a. defibrillation b. intravenous atropine c. synchronized cardioversion d. vagal maneuvers or adenosine, or both

ANS: B Atropine, administered intravenously, is the drug of choice for symptomatic bradycardia. Defibrillation, synchronized cardioversion, vagal maneuvers, and adenosine are not indicated in the treatment of slow cardiac rhythms.

If seen, the P wave of a rhythm originating in the AV junction will appear _____ in lead II. a. upright b. inverted c. tall and peaked d. wide and notched

ANS: B If the AV junction paces the heart, the electrical impulse must travel in a backward (retrograde) direction to activate the atria. If a P wave is seen, it will be inverted in leads II, III, and aVF because the impulse is traveling away from the positive electrode.

To determine whether the ventricular rhythm on an ECG tracing is regular or irregular, compare _____ intervals. a. PR b. R to R c. TP d. P to P

ANS: B To evaluate the rhythmicity of the ventricular rhythm on a rhythm strip, the interval between two consecutive R waves is measured. The distance between succeeding R-R intervals is measured and compared. If the ventricular rhythm is regular, the R-R intervals will measure the same.

The usual rate of nonparoxysmal junctional tachycardia is _____ beats/min. a. 50 to 80 b. 80 to 120 c. 101 to 140 d. 150 to 300

ANS: C Nonparoxysmal (i.e., gradual onset) junctional tachycardia usually starts as an accelerated junctional rhythm, but the heart rate gradually increases to more than 100 beats/min. The usual ventricular rate for nonparoxysmal junctional tachycardia is 101 to 140 beats/min.

Common causes of junctional dysrhythmias may include acute coronary syndromes and _____. a. hyperthyroidism b. hypovolemia c. digitalis toxicity d. hypoxia

ANS: C Toxicity or excess of digitalis is a common cause of junctional dysrhythmias.

The most common type of supraventricular tachycardia (SVT) is _____. a. atrial tachycardia b. atrial flutter c. AV reentrant tachycardia (AVRT) d. AV nodal reentrant tachycardia (AVNRT)

ANS: D AVNRT is the most common type of SVT. It is caused by reentry in the area of the AV node.

Which of the following may cause a sinus bradycardia? a. Stress or anxiety b. Increased sympathetic tone c. Fever d. Hypothermia

ANS: D Causes of sinus bradycardia include: disease of the SA node; hyperkalemia; hypokalemia; hypothermia; hypothyroidism; hypoxia; increased intracranial pressure; inferior myocardial infarction (MI); medications such as calcium channel blockers, digitalis, beta-blockers, amiodarone, and sotalol; obstructive sleep apnea; post heart transplant; posterior MI; and vagal stimulation.

The rate of sinus tachycardia is _____ beats/min. a. slower than 60 b. 40 to 80 c. 60 to 100 d. faster than 100

ANS: D The rate of sinus tachycardia is between 101 and 180 beats/min.

(T/F) Most patients with type I atrial flutter develop atrial fibrillation.

False Patients with type II atrial flutter, which is also called atypical or very rapid atrial flutter, often develop atrial fibrillation. The precise mechanism of type II atrial flutter has not been defined. In type II atrial flutter, the atrial rate ranges from 350 to 450 beats/min.

(T/F) Delivery of an electrical current timed for delivery during the QRS complex is called defibrillation.

False Synchronized cardioversion is the delivery of a shock to the heart by means of a defibrillator to terminate a rapid dysrhythmia. A synchronized shock means that the shock is timed to avoid the relative refractory period of the cardiac cycle. On the ECG, this period occurs during the peak of the T wave to approximately the end of the T wave. Defibrillation is the delivery of an electrical current across the heart muscle over a very brief period to terminate an abnormal heart rhythm. Defibrillation is also called unsynchronized countershock or asynchronous countershock, because the delivery of current has no relationship to the cardiac cycle.

(T/F) An escape rhythm is initiated by a lower pacemaker site when the sinoatrial (SA) node slows or fails to initiate an impulse.

True

(T/F) In atrial fibrillation, fibrillatory waves are referred to as f waves.

True

(T/F) Individuals with preexcitation syndrome are predisposed to tachydysrhythmias.

True

PACs associated with a wide QRS complex are called _____ _____ PACs, indicating that conduction through the ventricles is abnormal.

aberrantly conducted

What is the name given to polymorphic VT that occurs in the presence of a long QT interval?

torsades de pointes

List four reasons why the ventricles may assume responsibility for pacing the heart.

1. if the sinoatrial (SA) node fails to discharge 2. an impulse from the SA node is generated but blocked as it exits the SA node 3. the rate of discharge of the SA node is slower than that of the ventricles 4. an irritable site in either ventricle produces an early beat or rapid rhythm

Indicate the ventricular rates for each of the following junctional dysrhythmias: A. Junctional bradycardia B. Junctional tachycardia C. Accelerated junctional rhythm D. Junctional rhythm

A. Slower than 40 beats/min B. 101 to 180 beats/min C. 61 to 100 beats/min D. 40 to 60 beats/min

What is meant by the term controlled atrial fibrillation? a. The overall ventricular rate is less than 100 beats/min. b. The atrial rate is less than 100 beats/min. c. The overall ventricular rate is greater than 100 beats/min. d. The atrial rate is greater than 100 beats/min.

ANS: A Atrial flutter or atrial fibrillation that has a ventricular rate of less than 100 beats/min is described as controlled. A controlled ventricular rate may be the result of a healthy atrioventricular (AV) node protecting the ventricles from very fast atrial impulses or medications used to control (block) conduction through the AV node, decreasing the number of impulses reaching the ventricles.

List three significant signs and/or symptoms that, if observed with a sinus bradycardia, would require management of this dysrhythmia.

Clinical signs and symptoms of hemodynamic compromise can include: - acute changes in mental status - chest pain or discomfort - cold, clammy skin - fall in urine output - heart failure - low blood pressure - pulmonary congestion - shock - shortness of breath

(T/F) A macroreentrant circuit is one that involves a small area of heart tissue, usually a few centimeters or less.

False Macroreentry circuits and microreentry circuits are two main types of reentry circuits. If the reentry circuit involves conduction through a large area of the heart, such as the entire right or left atrium, it is called a macroreentry circuit. A reentry circuit involving conduction within a small area is called a microreentry circuit.

(T/F) Multifocal atrial tachycardia is another name for atrial fibrillation.

False When a wandering atrial pacemaker rhythm is associated with a ventricular rate of more than 100 beats/min, the dysrhythmia is called multifocal atrial tachycardia (MAT) or chaotic atrial tachycardia.

(T/F) An idioventricular (ventricular escape) rhythm has an intrinsic rate of 40 to 60 beats/min.

False An idioventricular rhythm (IVR), which is also called a ventricular escape rhythm, exists when three or more ventricular escape beats occur in a row at a rate of 20 to 40 beats/min (i.e., the intrinsic firing rate of the Purkinje fibers).

(T/F) Adenosine is the drug of choice when treating a symptomatic patient with a junctional rhythm at a rate of 40 beats/min.

False Atropine (not adenosine) is the drug of choice when treating a symptomatic patient with a junctional rhythm at a rate of 40 beats/min.

(T/F) Transcutaneous pacing is the treatment of choice for pulseless ventricular tachycardia or ventricular fibrillation.

False Cardiopulmonary resuscitation and defibrillation are the treatments of choice for pulseless ventricular tachycardia or ventricular fibrillation.

(T/F) The ventricular rhythm in atrial fibrillation is usually "irregularly irregular."

True

An accessory pathway that has one end attached to normal conductive tissue is called a(n) _____ _____.

bypass tract

A beat originating from the AV junction that appears later than the next expected sinus beat is called a(n) _____ _____ _____.

junctional escape beat

A(n) _____ pause often follows a PJC and represents the delay during which the SA node resets its rhythm for the next beat.

noncompensatory

Sometimes, when a premature atrial complex (PAC) occurs very prematurely and close to the T wave of the preceding beat, only a P wave may be seen with no QRS after it (appearing as a pause). This type of PAC is termed a(n) _____ PAC.

nonconducted (blocked)

Delivery of an electrical current timed for delivery during the QRS complex is called _____ _____.

synchronized cardioversion

List four reasons why the AV junction may assume responsibility for pacing the heart:

(1) the SA node fails to discharge (such as sinus arrest) (2) an impulse from the SA node is generated but blocked as it exits the SA node (such as SA block) (3) the rate of discharge of the SA node is slower than that of the AV junction (such as a sinus bradycardia or the slower phase of a sinus arrhythmia) (4) an impulse from the SA node is generated and is conducted through the atria but is not conducted to the ventricles (such as an AV block)

List four common causes of premature ventricular complexes:

- acid-base imbalance - acute coronary syndromes - cardiomyopathy - digitalis toxicity - electrolyte imbalance (e.g., potassium, magnesium) - exercise - heart failure - hypoxia - an increase in catecholamines and sympathetic tone (e.g., emotional stress, anxiety) - medications (e.g., sympathomimetic drugs) - normal variant - stimulants (e.g., caffeine, tobacco) - valvular heart disease - ventricular aneurysm

In a junctional rhythm viewed in lead II, where is the location of the P wave on the ECG if atrial depolarization precedes ventricular depolarization? a. Before the QRS complex b. During the QRS complex c. After the QRS complex

ANS: A If the AV junction paces the heart and the atria depolarize before the ventricles, an inverted P wave will be seen before the QRS complex and the PR interval will usually measure 0.12 seconds or less. The PR interval is shorter than usual because an impulse that begins in the AV junction does not have to travel as far to stimulate the ventricles.

The rate of a sinus bradycardia is _____ beats/min. a. slower than 60 b. 60 to 100 c. 80 to 120 d. faster than 100

ANS: A If the SA node fires at a rate that is slower than normal for the patient's age, the rhythm is called sinus bradycardia. The rhythm starts in the SA node and then travels the normal conduction pathway, resulting in atrial and ventricular depolarization. In adults and adolescents, a sinus bradycardia has a heart rate of less than 60 beats/min. The term severe sinus bradycardia is sometimes used to describe a sinus bradycardia with a rate of less than 40 beats/min.

A beat originating from the AV junction that appears later than the next expected sinus beat is called a _____. a. junctional escape beat b. period of SA block c. premature junctional complex (PJC) d. premature atrial complex (PAC)

ANS: A Junctional complexes may come early (before the next expected sinus beat) or late (after the next expected sinus beat). If the complex is early, it is called a premature junctional complex. If the complex is late, it is called a junctional escape beat. To determine whether a complex is early or late, you need to see at least two sinus beats in a row to establish the regularity of the underlying rhythm.

The rate of an idioventricular rhythm is _____ beats/min. a. 20 to 40 b. 41 to 60 c. 61 to 100 d. 101 to 180

ANS: A The intrinsic rate of an idioventricular rhythm, which is also called a ventricular escape rhythm, is 20 to 40 beats/min (i.e., the intrinsic firing rate of the Purkinje fibers).

Management of a patient with a sinus tachycardia might include _____. a. identification and treatment of the underlying cause b. administration of atropine c. use of a pacemaker d. vagal maneuvers, such as carotid sinus pressure

ANS: A Treatment for sinus tachycardia is directed at correcting the underlying cause (i.e., fluid replacement, relief of pain, removal of offending medications or substances, reducing fever or anxiety). Sinus tachycardia in a patient experiencing an acute myocardial infarction (MI) may be treated with medications to slow the heart rate and decrease myocardial oxygen demand (e.g., beta-blockers), provided there are no signs of heart failure or other contraindications.

Atrial fibrillation is characterized by _____. a. one P wave before each QRS and a regular ventricular rate of 60 to 100 beats/min b. an erratic, wavy baseline and irregular ventricular rhythm c. "saw-tooth"- or "picket-fence"-shaped waveforms preceding each QRS d. P waves occurring before, during, or after the QRS complex; when seen, they are inverted

ANS: B

How would you differentiate a junctional escape rhythm at 40 beats/min from a ventricular escape rhythm at the same rate? a. It is impossible to differentiate a junctional escape rhythm from a ventricular escape rhythm. b. The junctional escape rhythm will have a narrow QRS complex; the ventricular escape rhythm will have a wide QRS complex. c. The rate (40 beats/min) would indicate a junctional escape rhythm, not a ventricular escape rhythm. d. The junctional escape rhythm will have a wide QRS complex; the ventricular escape rhythm will have a narrow QRS complex.

ANS: B Although junctional and ventricular rhythms are ectopic pacemaker sites, their rhythms can generally be differentiated by the width of their QRS complexes. The junctional escape rhythm will have a narrow QRS complex; the ventricular escape rhythm will have a wide QRS complex.

A 77-year-old woman is complaining of a sudden onset of palpitations. The cardiac monitor reveals atrial fibrillation with a ventricular response of 144 to 210 beats/min while the patient is at rest. In this situation, the ventricular rate associated with this rhythm is considered to be _____. a. controlled b. uncontrolled

ANS: B Atrial flutter or atrial fibrillation that has a ventricular rate of less than 100 beats/min is described as controlled. A controlled ventricular rate may be the result of a healthy AV node protecting the ventricles from very fast atrial impulses or medications used to control (block) conduction through the AV node, decreasing the number of impulses reaching the ventricles.

Which of the following medications increases heart rate by accelerating the SA node discharge rate and blocking the vagus nerve? a. Digitalis b. Atropine c. Amiodarone d. Beta-blocker

ANS: B Atropine is a vagolytic drug that is used to increase the heart rate. Vago refers to the vagus nerves (right and left), which are the main nerves of the parasympathetic division of the autonomic nervous system. Lytic refers to "lyse," which means "to interfere with." Atropine works by blocking acetylcholine at the endings of the vagus nerves. The vagus nerves innervate the heart at the SA and AV nodes. Thus, atropine is most effective for narrow-QRS bradycardia. By blocking the effects of acetylcholine, atropine allows more activity from the sympathetic division of the autonomic nervous system. As a result, the rate at which the SA node can fire is increased. Areas of the heart that are not innervated or that are minimally innervated by the vagus nerves (e.g., the ventricles) will not respond to atropine. Thus, atropine is usually ineffective for the treatment of wide-QRS bradycardia. Atropine also increases the rate at which an impulse is conducted through the AV node. It has little or no effect on the force of contraction.

Which of the following are possible causes of sinus bradycardia? a. Elevated temperature, pain b. Increased intracranial pressure, beta-blocker overdose c. Hypoxia, fright, caffeine-containing beverages d. Hypovolemia, administration of sympathomimetics

ANS: B Causes of sinus bradycardia include: disease of the SA node; hyperkalemia; hypokalemia; hypothermia; hypothyroidism; hypoxia; increased intracranial pressure; inferior myocardial infarction (MI); medications such as calcium channel blockers, digitalis, beta-blockers, amiodarone, and sotalol; obstructive sleep apnea; post heart transplant; posterior MI; and vagal stimulation.

Which of the following correctly reflects the ECG criteria for a sinus rhythm? a. More P waves than QRS complexes b. P waves that look alike and upright in lead II, one before each QRS complex c. Irregular atrial and ventricular rhythm d. PR interval exceeding 0.20 seconds

ANS: B Characteristics of sinus rhythm: Rhythm R-R and P-P intervals are regular Rate 60 to 100 beats/min P waves Positive (upright) in lead II; one precedes each QRS complex; P waves look alike PR interval 0.12 to 0.20 seconds and constant from beat to beat QRS duration 0.11 seconds or less unless abnormally conducted

In a junctional rhythm viewed in lead II, where is the location of the P wave on the ECG if atrial and ventricular depolarization occur simultaneously? a. Before the QRS complex b. During the QRS complex c. After the QRS complex

ANS: B If the atria and ventricles depolarize at the same time, a P wave will not be visible because it will be hidden in the QRS complex.

What is meant by the term pulseless electrical activity (PEA)? a. A chaotic rhythm that is likely to degenerate into cardiac arrest b. An organized rhythm on the cardiac monitor (other than VT), although a pulse is not present c. A slow rhythm with a wide QRS complex d. A flat line on the cardiac monitor

ANS: B If the patient is not breathing and has no pulse despite the appearance of organized electrical activity on the cardiac monitor (other than VT), pulseless electrical activity (PEA) exists.

In sinus arrhythmia, a gradual increasing of the heart rate is usually associated with _____. a. expiration b. inspiration c. excessive caffeine intake d. early signs of heart failure

ANS: B Sinus arrhythmia that is associated with the phases of breathing and changes in intrathoracic pressure is called respiratory sinus arrhythmia. The rhythm is irregular; the heart rate increases gradually during inspiration (R-R intervals shorten) and decreases with expiration (R-R intervals lengthen).

The rate of a sinus rhythm is ____ beats/min. a. slower than 60 b. 60 to 100 c. 80 to 120 d. faster than 100

ANS: B The rate of a sinus rhythm is between 60 and 100 beats/min.

An ECG rhythm strip shows a ventricular rate of 46 bpm, a regular rhythm, a PR interval of 0.14 seconds, a QRS duration of 0.06 seconds, and one upright P wave before each QRS. This rhythm is _____. a. sinus rhythm b. sinus bradycardia c. sinus arrest d. sinoatrial block

ANS: B The rhythm described fits the ECG criteria for a sinus bradycardia.

Which of the following best describes an idioventricular rhythm? a. Rapid, chaotic rhythm with no pattern or regularity b. Gradual alteration in the amplitude and direction of the QRS; atrial rate indiscernible; ventricular rate 150 to 250 beats/min c. Essentially regular ventricular rhythm with QRS complexes measuring 0.12 seconds or greater; atrial rate not discernible; ventricular rate 20 to 40 beats/min d. Regular ventricular rhythm with QRS complexes measuring less than 0.10 seconds; P waves may occur before, during, or after the QRS; ventricular rate 40 to 60 beats/min

ANS: C An idioventricular rhythm (IVR), which is also called a ventricular escape rhythm, exists when three or more ventricular escape beats occur in a row at a rate of 20 to 40 beats/min (i.e., the intrinsic firing rate of the Purkinje fibers). The QRS complexes seen in IVR are wide and bizarre because the impulses begin in the ventricles, bypassing the normal conduction pathway. When the ventricular rate slows to a rate of less than 20 beats/min, some practitioners refer to the rhythm as an agonal rhythm or dying heart.

Which of the following are possible causes of sinus tachycardia? a. Hypothermia, hypovolemia b. Hypoxia, calcium channel blocker overdose c. Fever, pain, anxiety d. Vomiting, vagal maneuvers

ANS: C Causes of sinus tachycardia include: acute myocardial infarction; caffeine-containing beverages; dehydration, hypovolemia; drugs such as cocaine, amphetamines, ecstasy, cannabis; exercise; fear and anxiety; fever; heart failure; hyperthyroidism; hypoxia; infection; medications such as epinephrine, atropine, and dopamine; nicotine; pain; pulmonary embolism; shock; sympathetic stimulation.

How are frequent PACs usually managed? a. Defibrillation b. Synchronized cardioversion c. Correcting the underlying cause d. Administration of medications such as atropine or epinephrine

ANS: C PACs usually do not require treatment if they are infrequent. The patient may complain of a "skipped beat" or occasional "palpitations" if PACs are frequent or may be unaware of their occurrence. In susceptible individuals, frequent PACs may induce episodes of atrial fibrillation or paroxysmal supraventricular tachycardia (PSVT). Frequent PACs are treated by correcting the underlying cause (e.g., correcting electrolyte imbalances, reducing stress, reducing or eliminating stimulants, treating heart failure). If the patient is symptomatic, frequent PACs may be treated with beta-blockers, such as atenolol or metoprolol.

The atrioventricular (AV) junction consists of the _____. a. SA and AV nodes b. AV node and the Purkinje fibers c. AV node and nonbranching portion of the bundle of His d. AV node, bundle of His, and the right and left bundle branches

ANS: C The AV node and the nonbranching portion of the bundle of His are called the AV junction. The bundle of His has pacemaker cells that are capable of discharging at a rhythmic rate of 40 to 60 beats/min.

A junctional escape rhythm occurs because of _____. a. severe chronic obstructive pulmonary disease b. multiple irritable sites firing within the AV junction c. slowing of the rate of the heart's primary pacemaker d. intrathoracic pressure changes associated with the normal respiratory cycle

ANS: C The atrioventricular (AV) junction may assume responsibility for pacing the heart if (1) the sinoatrial (SA) node fails to discharge (such as sinus arrest), (2) an impulse from the SA node is generated but blocked as it exits the SA node (such as SA block), (3) the rate of discharge of the SA node is slower than that of the AV junction (such as a sinus bradycardia or the slower phase of a sinus arrhythmia), and (4) an impulse from the SA node is generated and is conducted through the atria, but is not conducted to the ventricles (such as an AV block).

Which of the following best describes an accelerated idioventricular rhythm (AIVR)? a. Rapid, chaotic rhythm with no pattern or regularity b. Gradual alteration in the amplitude and direction of the QRS; atrial rate indiscernible, ventricular rate 150 to 250 beats/min c. Regular ventricular rhythm with QRS complexes measuring 0.10 seconds or less; P waves may occur before, during or after the QRS; ventricular rate 41 to 60 beats/min d. Essentially regular ventricular rhythm with QRS complexes measuring 0.12 seconds or greater; atrial rate not discernible; ventricular rate 41 to 100 beats/min

ANS: D

Which of the following correctly describes multifocal atrial tachycardia? a. Atrial rhythm is regular. b. Ventricular rhythm is irregular. c. Atrial and ventricular rhythms are regular. d. Atrial and ventricular rhythms are irregular.

ANS: D

A wandering atrial pacemaker rhythm with a ventricular rate of 60 to 100/min may also be referred to as _____. a. atrial flutter b. atrial fibrillation c. multifocal atrial tachycardia d. multiformed atrial rhythm

ANS: D Multiformed atrial rhythm is an updated term for the rhythm formerly known as wandering atrial pacemaker. When a wandering atrial pacemaker rhythm is associated with a ventricular rate of more than 100 beats/min, the dysrhythmia is called multifocal atrial tachycardia (MAT) or chaotic atrial tachycardia.

An ECG rhythm strip shows a ventricular rate of 128 bpm, a regular rhythm, a PR interval of 0.16 seconds, a QRS duration of 0.08 seconds, and one upright P wave before each QRS. This rhythm is sinus _____. a. arrhythmia b. bradycardia c. rhythm d. tachycardia

ANS: D The rhythm described fits the ECG criteria for a sinus tachycardia.

If the AV junction paces the heart, the electrical impulse must travel in a backward direction to activate the atria. This is called _____ conduction.

Retrograde

(T/F) In atrial fibrillation, the AV node attempts to protect the ventricles from the hundreds of impulses bombarding it per minute by blocking many of the impulses generated by the irritable sites in the atria.

True

(T/F) Medications to suppress an idioventricular rhythm should generally be avoided.

True

(T/F) Sustained monomorphic VT is often associated with underlying heart disease, particularly myocardial ischemia, and rarely occurs in patients without underlying structural heart disease.

True

(T/F) The AV junction consists of the AV node and the nonbranching portion of the bundle of His.

True

(T/F) The pacemaker cells in the AV junction are located near the nonbranching portion of the bundle of His.

True

(T/F) The presence of an accessory pathway should be considered in atrial fibrillation with a ventricular rate faster than 180 beats/min.

True

(T/F) The term premature ventricular complex is technically more correct than premature ventricular contraction.

True

(T/F) Upon conversion of atrial fibrillation to sinus rhythm, the patient should be observed for signs of a possible stroke.

True