Question 1

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

Accepted Answer

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.

Question 2

Identify the following rhythm (lead II). 
A) Sinus arrhythmia
B) Sinus rhythm with junctional escape beats
C) Sinus tachycardia with premature atrial complexes
D) Sinus tachycardia with premature junctional complexes

Accepted Answer

The rhythm strip shows a sinus tachycardia with premature junctional complexes.

Question 3

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

Accepted Answer

junctional escape beat

Question 4

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

Accepted Answer

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.

Question 5

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)

Accepted Answer

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.

Question 6

The pacemaker cells in the AV junction are located near the nonbranching portion of the bundle of His.

Accepted Answer

The pacemaker cells in the AV junction are located near the nonbranching portion of the bundle of His, which is true.

Question 7

Identify the following rhythm (lead II). 
A) Accelerated junctional rhythm
B) Sinus rhythm
C) Junctional rhythm
D) Sinus arrhythmia

Accepted Answer

The rhythm strip shows an accelerated junctional rhythm.

Question 8

Identify the following rhythm (lead II). 
A) Junctional tachycardia
B) Sinus rhythm with PACs
C) Sinus rhythm with PJCs
D) Accelerated junctional rhythm

Accepted Answer

The rhythm strip shows an accelerated junctional rhythm. The rate is 60 to 100 and inverted P wave in lead II.

Question 9

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

Accepted Answer

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.

Question 10

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

Accepted Answer

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 second 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.

Question 11

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

Accepted Answer

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.

Question 12

The AV junction consists of the AV node and the nonbranching portion of the bundle of His.

Accepted Answer

The AV junction includes both the AV node and the nonbranching portion of the bundle of His.

Question 13

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

Accepted Answer

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

Question 14

Common causes of junctional dysrhythmias may include acute coronary syndromes and _____.
A) hyperthyroidism
B) hypovolemia
C) digitalis toxicity
D) hypoxia

Accepted Answer

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

Question 15

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

Accepted Answer

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). Junctional escape rhythm does not occur because of severe chronic obstructive pulmonary disease, although EKG changes can occur due to desaturation of oxygenation. Multiple irritable sites firing within the AV junction would most likely result in atrial issues. Intrathoracic pressure changes associated with the normal respiratory cycle should not cause any rhythm changes within an EKG.

Question 16

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

Accepted Answer

This is correct. An escape rhythm occurs when a lower pacemaker site takes over the pacing of the heart because the SA node is not providing sufficient impulses.

Question 17

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

Accepted Answer

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.

Question 18

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

Accepted Answer

The answer of Completion
-If the AV junction paces the heart,...

Question 19

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

Accepted Answer

The answer of Completion
-A(n) _____ pause often follows a PJC...

Question 20

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

Accepted Answer

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.

Quiz 5: Junctional Rhythms

The atrioventricular (AV) junction consists of the _____.

Identify the following rhythm (lead II) .

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

If seen, the P wave of a rhythm originating in the AV junction will appear _____ in lead II.

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

The pacemaker cells in the AV junction are located near the nonbranching portion of the bundle of His.

Identify the following rhythm (lead II) .

Identify the following rhythm (lead II) .

Which of the following medications increases heart rate by accelerating the SA node discharge rate and blocking the vagus nerve?

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?

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?

The AV junction consists of the AV node and the nonbranching portion of the bundle of His.

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

Common causes of junctional dysrhythmias may include acute coronary syndromes and _____.

A junctional escape rhythm occurs because of _____.

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

Depending on the severity of the patient's signs and symptoms, management of slow rhythms originating from the AV junction may require intervention including _____.

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

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

The usual rate of nonparoxysmal junctional tachycardia is _____ beats/min.