Chapter 3

Question 1

Why do P waves have to look the same in a regular rhythm?

Answer 1

Impulse created in SA node will be in same place, take same path, they’re always going to look alike

The time will also be the same

Taking same steps (in a sense) so a QRS will always follow

Question 2

What characteristics does a rhythm that begins in the SA node have?

Answer 2

1. Positive (upright) P wave before each QRS complex (always)
2. P waves that look a like
3. A constant PR interval
4. A regular arterial and ventricular rhythm (usually)

Question 3

What can affect the electrical impulse of the SA node?

Answer 3

1. Medications
2. Diseases or conditions that cause the heart rate to speed up, slow down, or beat irregularly.
3. Diseases or conditions that delay or block the impulse from leaving the SA node
4. Diseases or conditions that prevent an impulse from being generated in the SA node

SA node has the ability to change rate to the situation. Need more blood? Moving more? Less?

Question 4

Normal Sinus Rhythm (NSR)

Answer 4

Reflects normal electrical activity - that is, the rhythm starts in the SA node and then heads down the normal conduction pathway through the aria, arioventricular (AV) node and bundle, right and left bundle branches, and purkinje fibers.

In adults and adolescents, the SA node usually fires at a regular rate of 60-100bpm

Question 5

How do you recognize NSR?

Answer 5

1. P waves look the same. Spacing is the same. Upright.
2. Following after P wave will always be a QRS.
3. R-R regular / P-P regular
4. PRI measurement is the same
5. 60-100bpm

Question 6

Sinus Bradycardia (SB)

Answer 6

If SA node fires at a rate slower than normal for the patient’s age, the rhythm is called sinus bradycardia

In adults and adolescents, SB has a heart rate of less than 60bpm

Severe SB is less than 40bpm

Question 7

What causes SB?

Answer 7

1. Occurs in adults and children during sleep
2. Common in well-conditioned athletes
3. Vagus nerve stimulation (makes everything go slow - parasympathetic stimulation)

-coughing
-vomiting
-straining to have a bowel movement
-sudden exposure of the face to cold water

Question 8

Examples of what causes SB

Answer 8

-diseases in SA node
-hyperkalemia
-hypokalemia
-hypothermia
-hypothyroidism
-hypoxia
-increased intracranial pressure
-inferior myocardial infraction (MI)
-medications
-obstructive sleep apnea
-post heart transplant
-posterior MI
-tracheal suctioning
-vagal stimulation

Question 9

What can be done to treat SB?

Answer 9

1. No treatment if asymptomatic
2. If symptomatic because of the slow rate, treatment may include

-pulse oximeter
-supplemental oxygen, if indicated
-vascular access
-12 - lead ECG
-Atropine

Question 10

Atropine

Answer 10

Given to patients with low (severe) heart rate

Blocks chemicals at endings of vagus nerves

Allows more sympathetic activity
-rate at which the SA node can fire is increased
-increases rate of impulse conduction through AV node

Question 11

Sinus Tachycardia (ST)

Answer 11

If the SA node fires at a rate faster than normal for the patients age

Sinus tachycardia begins and ends GRADUALLY (no spikes, goes up at a constant pace)

Over 100bpm

Question 12

What causes ST?

Answer 12

-acute myocardial infection
-caffeine-containing beverages
-dehydration, hypovolemia
-drugs such as cocaine, amphetamines, ecstasy, cannabis
-exercise
-fear and anxiety
-fever
-heart failure
-hyperthyroidism
-hypoxia
-infection
-medications (epinephrine, atropine, dopamine)
-nicotine
-pain
-pulmonary embolism
-shock
-sympathetic stimulation

Question 13

Inappropriate Sinus Tachycardia (IST)

Answer 13

1. Occurs for no apparent physiological cause
2. Heart rate may rapidly increase to more than 100bpm with minimal exertion, at rest or both
3. Accompanying symptoms are usually nonspecific
4. Mechanisms responsible for IST are not entirely understood
5. Diagnosis is made only after other causes for the tachycardia have been ruled out

Question 14

What to do about ST?

Answer 14

1. Physiological ST:
   -directed at correcting the underlying cause
   _fluid replacement
   _relief of pain
   _removal of offending medications or substances
   _reducing fever or anxiety
2. Inappropriate ST:
   -Lifestyle modifications
   -pharmacological treatment may be tried
   -surgical ablation may be performed in severe causes

Question 15

Sinus Arrhythmia (SA)

Answer 15

When SA node fires IRREGULARLY, the resulting rhythm is called sinus arrhythmia

Respiratory SA - associated with the phases of breathing and changes in intrathoracic pressure

Non-respiratory SA - not related to the ventilatory cycle

Question 16

How do you recognize SA?

Answer 16

1. Doesn’t have the same patter - IRREGULAR
2. Normal P wave followed by QRS

IRREGULAR rhythm, but has all the other normal characteristics of NSR

Question 17

What causes sinus arrhythmia?

Answer 17

Non respiratory SA

Can be seen in people with normal hearts, but is more likely to be found in older individuals and in those with heart disease

Common after inferior wall MI

May be seen with increased intracranial pressure

May be a result of the effects of medications or carotid sinus pressure

Question 18

What to do about sinus arrhythmias?

Answer 18

Does not usually require treatment unless accompanied by a slow heart rate that causes hemodynamic compromise
-if hemodynamic compromise is present as a result of slow rate, IV atropine may be indicated

Question 19

Sinoatrial (SA) Block

Answer 19

Disorder of impulse conduction

SA node generates impulses

Impulses are blocked as they exit the SA node

Results in periodically absent PQRST complexes

Question 20

How to recognize sinoatrial block?

Answer 20

Skips a beat

Skips PQRST

Has all NSR characteristics

Irregular

Question 21

What causes sinoatrial block?

Answer 21

1. Hypoxia
2. Damage or disease to the SA node from coronary artery disease, myocarditis, or acute MI
3. Carat old sinus sensitivity
4. Increased vagal tone on the SA node
5. Medications
   -digitalis, quinidine, procainamide, or salicylates

Question 22

What to do about sinoatrial block?

Answer 22

No treatment if episodes are transient and there are no significant signs or symptoms

If hemodynamic compromise is present
-possible atropine
-possible temporary pacing or permanent pacemaker

Question 23

Sinus Arrest

Answer 23

Disorder of impulse formation

1. The SA node’s pacemaker cells do not initiate an electrical impulse for one or more beats
2. Results in absent PQRST complex’s (more than 1)
3. Double skip
4. The next one comes late
5. Irregular

Question 24

What causes Sinus Arrest

Answer 24

1. Damage to or disease of the SA node
   -coronary artery disease
   -myocardial infraction
   -rheumatic disease
2. Carotid sinus pressure
3. Sudden increase in parasympathetic activity on SA node
4. Stimulation of pharynx
5. Obstruction of sleep apnea
6. Hypothermia
7. Reactions to medication

Question 25

What to do about sinus arrest?

Answer 25

1. No treatment if episodes are transient and there are no significant signs or symptoms 2. If hemodynamic compromise is present -possible atropine -possible temporary pacing 3. If episodes are frequent and prolonged or a result of SA node disease, insertion of a permanent pacemaker is generally warranted

Question 26

Sick Sinus Syndrome (SSS)

Answer 26

More often affects adults over the age of 70 Usually related to degenerative SA node tissue changes On the ECG, SSS can appear as alternating patterns of bradycardia and tachycardia (bradycardia - tachycardia syndrome) or skipped beats caused by episodes of SA block or sinus arrest Patients may be asymptomatic, have subtle or nonspecific symptoms, or experience syncope, dizziness or lightheadedness, palpitations, or confusion Diagnosis usually requires holter monitoring or the use of an event recorder Placement of a permanent dual-chamber pacemaker may be necessary

Question 27

Characteristics of rhythms that begin in the SA node include which of the following? A. P waves that look alike B. A constant PR interval C. A QRS duration of 0.10 sec or longer D. A positive P wave before each QRS complex E. A regular atrial and ventricular rhythm (usually)

Answer 27

A, B, D, E A rhythm that begins in the SA node has the following characteristics: A positive (upright) P wave before each QRS P waves that look alike A constant PR interval A regular atrial and ventricular rhythm

Question 28

Which of the following are possible causes of sinus tachycardia? A. Pain B. Fever C. Exercise D. Beta blockers, digitalis E. Obstructive sleep apnea F. Increased intracranial pressure

Answer 28

A, B, C There are many causes of sinus tachycardia including pain, fever, and exercise. Medications such as calcium blockers, digitalis, beta blockers, amiodarone, and sotalol, obstructive sleep apnea, and increased intracranial pressure are possible causes of sinus bradycardia

Question 29

A lead II rhythm strip obtained from a 38 year old woman with difficulty breathing reveals a regular atrial and ventricular rhythm, a ventricular rate of 120bpm, an upright P wave before each QRS complex and a normal PR interval and QRS duration. This rhythm is: A. Sinus rhythm B. Sinus arrhythmia C. Sinus tachycardia D. Sinoatrial (SA) block

Answer 29

C A sinus tachycardia is differentiated from other rhythms that originate in the SA node by its rate (after than 100bpm; max rate about 220 minus the patients age in years)

Question 30

Which of the following dysrhythmias is/are associated with one or more absent PQRST complexes? A. SA block B. Sinus arrest C. Sinus rhythm D. Sinus arrhythmia E. Sinus tachycardia F. Sinus bradycardia

Answer 30

A, B Sinus arrest and SA block are associated with one or more absent PQRST complexes

Question 31

Which of the following is true regarding respiratory sinus arrhythmia? A. Every other electrical impulse is blocked as it leaves the SA node B. This rhythm is often associated with heart failure symptoms and dizziness C. This rhythm is typically the result of degenerative changes in SA node tissue D. The rhythm is irregular because the heart increases with inspiration and decreases with expiration

Answer 31

D Respiratory sinus arrhythmia, which is the most common type of sinus arrhythmia, is a normal phenomenon that occurs when phases of breathing and changes in intrathoacic pressure. The heart rate increases with inspiration (the R-R interval shorten) and decreases with expiration (the R-R interval lengthen). Sinus arrhythmia is most commonly observed in children and young adults

Question 32

A 35 year old man has been experiencing nausea, vomiting, and diarrhea for the past 48hrs. His blood pressure is 112/70 mm Hg. The cardiac monitor reveals a sinus tachycardia at 124bpm. Management of this patients dysrhythmia should include: A. Administering atropine B. Preparing for temporary pacing C. Replacing fluids and electrolytes D. Scheduling the patient for surgical ablation

Answer 32

C Based on the information provided, the most likely cause of the patients sinus tachycardia cardia is dehydration/hypovolemia, which is best managed by replacing fluids and electrolytes

Question 33

A lead II rhythm strip reveals a regular atrial and ventricular rhythm, a ventricular rate of 46bpm, an upright P wave before each QRS complex, a PR interval of 0.16sec, and a QRS duration of 0.08sec. This rhythm is: A. Sinus rhythm B. Sinoatrial block C. Sinus arrhythmia D. Sinus bradycardia

Answer 33

D A sinus bradycardias characteristics are the same as those of NSR with one exception — the rate. A NSR rate is 60 to 100bpm; sinus bradycardia rate is less than 60bpm

Question 34

SA block is a disorder of __________, whereas sinus arrest is a disorder of ________. A. Impulse formation, impulse conduction B. Impulse conduction, impulse formation

Answer 34

B With SA block, the SA nodes pacemaker cells initiate an impulse but it is blocked as it exits the SA node, resulting in periodically absent PQRST complexes. SA block is thought to occur because of the failure of the transitional cells in the SA node to conduct the impulse from the pacemaker cells to the surrounding atrium. Thus, SA block is a disorder of impulse conduction. With sinus arrest, the SA nodes pacemaker cells fail to initiate an electrical impulse for one or more beats, resulting in absent PQRST complexes on the ECG. Thus, sinus arrest is a disorder of impulse formation

Question 35

Differentiating between a P wave and a T wave is most likely to be difficult with which of the following rhythms? A. SA block B. Sinus arrest C. Sinus tachycardia D. Sinus bradycardia

Answer 35

C With sinus tachycardia, it maybe be hard to tell the difference between a P wave and a T wave at very fast rates

Question 36

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. The patients blood pressure is 75/40mm Hg, pulse is 44bpm and ventilations 16. A bradycardia is present when the heart rate is less than: A. 60bpm B. 75bpm C. 85bpm D. 100bpm

Answer 36

A In adults, a bradycardia exists if the rate is less than 60bpm

Question 37

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. You prepare to apply electrodes and lead wires to the patient for continuous ECG monitoring in lead II. Lead II views the A. Lateral surface of the left ventricle B. Inferior surface of the left ventricle C. Anterior surface of the left ventricle D. Posterior surface of the right ventricle

Answer 37

B Lead II viewed the inferior surface of the left ventricle

Question 38

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. You are examining the waveforms on this patients ECG. What is the name given to thee first negative deflection observed after the P wave? A. Q wave B. R wave C. S wave D. T wave

Answer 38

A A QRS complex normally follows each P wave. The QRS complex begins as a downward deflection, the Q wave, and represents depolarization of the interventricular septum

Question 39

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. As you measure the intervals on this patients rhythm strip, you recall that the PR intervals normal duration is ________ second A. 0.04 to 0.10 B. 0.06 to 0.14 C. 0.12 to 0.20 D. 0.16 to 0.24

Answer 39

C The PR interval changes with heart rate but typically measures 0.12 to 0.29 seconds in adults. As the heart rate increases, the duration of the PRI shortens. A PRI is considered short if it is less than 0.12sec and long if it is more than 0.20sec

Question 40

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. Analysis of the patients ECG reveals ST segment depression in lead II. The presence of ST segment depression suggests A. Myocardial injury B. Myocardial ischemia C. Death of a portion of the left ventricular tissue D. Death of a portion of the cardiac conduction system

Answer 40

B ST segment depression of 0.5mm or more in patients experiencing an acute coronary syndrome is suggestive of myocardial ischemia

Question 41

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. For the ST segment depression seen in lead II to be considered clinically significant, this finding would also need to be seen in which of the following anatomically contiguous leads? A. I or III B. I or VL C. V3 or V4 D. III or aVF

Answer 41

D For the ST segment depression seen in lead II to be considered clinically significant, this finding would also need to be seen in lead III or aVF. Leads II, III and aVF view the inferior wall of the left ventricle

Question 42

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. Supplemental oxygen is being administered because the patients oxygen saturation level was 89% on room air. The patient reports that he continues to feel weak and lightheaded. The cardiac monitor continues to display sinus bradycardia and a second set of vital signs are essentially unchanged. Which of the following statements is true about this patients situation? A. The patient is asymptomatic B. A 12 lead ECG should be obtained C. Vascular access should be established D. The patient is showing signs of hemodynamic compromise E. Continuous observation is the only intervention necessary at this time

Answer 42

B, C, D The term symptomatic bradycardia is used to describe a patient who experiences signs and symptoms of hemodynamic compromise related to a slow heart rate. Because this patient is complaining of weakness and lightheadedness and is hypotension, he is clearly symptomatic with his slow heart rate. Treatment of symptomatic bradycardia should include applying a pulse oximeter and administering supplemental oxygen if indicated,, which have already been done. Next, establish IV access and obtain a 12 lead ECG

Question 43

A 75 year old man presents with weakness and “feeling lightheaded.” His symptoms began about 30 min ago. The patients symptoms persist, and his vital signs are essentially unchanged. The cardiac monitor shows a sinus bradycardia with ST segment depression. You should prepare to administer A. Atropine B. Atenolol C. Adenosine D. Amiodarone

Answer 43

A Atropine, administered intravenously, is the drug of choice for symptomatic bradycardia. Reassess the patients response to the therapeutic interventions provided and continue monitoring the patient. Adenosine is used to slow the ventricular rate. Atenolol, a beta blocker, would further slow the heart rate. Although amiodarone is anti-arrhythmic used to treat many atrial and ventricular dysrhythmias, its not used to treat a sinus bradycardia