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122 Cards in this Set

  • Front
  • Back
What is an accessory pathway?
Additional or abnormal electrical conduction pathway
What is an example of an accessory pathway?
The bundle of Kent (Kent bundle)
What is antegrade?
Downward movement of an electrical impulse from atria to ventricles
What is an atrial dysrhythmia?
Rhythm that is initiated from any pacemaker site in the atria, when the sinoatrial (SA) node fails to initiate an electrical impulse
What is bradycardia?
Heart rate slower than 60 electrical impulses per minute
What is a compensatory pause?
A pause in the rhythm that measures 2 times the R to R interval of the underlying rhythm
What is a delta wave?
Extra “bump” seen in the slurred section at the beginning of a QRS complex
When is a delta wave seen?
In Wolff-Parkinson-White syndrome
What is an inherent heart rate?
Normal rate at which electrical impulses are generated
What is the inherent heart rate for the sinoatrial node?
60 to 100 heartbeats per minute
What is a noncompensatory pause?
A pause in the rhythm that measures less than 2 times the R to R interval of the underlying rhythm
What is the normal electrical conduction pathway?
Sinoatrial (SA) node to atrioventricular (AV) node, through the bundle of His and bundle branches, to the Purkinje's fibers, ending in the ventricular muscle
What is paroxysmal?
Sudden, intermittent start and stop of symptoms or dysrhythmias
What does the term paroxysmal usually used to describe?
A type of atrial tachycardia
What is a premature complex?
A complex that occurs earlier than expected in the underlying rhythm
What is the Sinoatrial (SA) Node?
Pacemaker of the heart; it usually initiates the electrical impulses that travel through the electrical conduction pathway of the heart
What is the Sinus Rhythm?
Cardiac rhythm that shows the movement of an electrical impulse traveling from the sinoatrial node to the ventricles, following the normal electrical conduction pathway
What is tachycardia?
Heart rate faster than 100 electrical impulses per minute
Where is the sinoatrial node located?
Upper portion of the right atrium
What happens if the SA node fails to generate an electrical impulse?
Any other pacemaker cell within the atria can generate the impulse
What does the P wave represent?
Atrial depolarization
What does the QRS complex represent?
Ventricular depolarization
What is the normal range of the PR interval (PRI)?
0.12 to 0.20 second
What is the normal QRS complex?
Less than 0.12 second
What rhythms originate from the SA node?
1. Normal sinus rhythm

2. Sinus dysrhythmia
What rhythms originate from all other atrial sites?
Atrial dysrhymias

**anything but a normal sinus rhythm is considered a dysrhythmia
What signs and symptoms indicate that a patient is medically unstable?
1. Weakness
2. Faintness
3. Sudden decrease in blood pressure
4. Chest pain
5. Confusion
6. Unresponsiveness
7. Any other sign or symptom of poor cardiac output
What are the characteristics of a normal sinus rhythm?
1.Electrical impulse follows the normal conduction pathway

2. There is an upright P wave preceding every QRS complex

3. All PR intervals range from 0.12 to 0.20 second, and the QRS complex is less than 0.12 second

4. All P waves look alike, and all QRS complexes are the same size and shape

5. Both the atria and the ventricles depolarize at regular intervals

6. The P to P intervals and R to R intervals are regular

7. The P to P intervals are the same length as the R to R intervals

8. The rhythm is very regular and the rate is 60 to 100 electrical impulses per minute
What are the characteristics of sinus bradycardia?
1. All electrical impulses originate from the SA node and follow the normal conduction pathway

2. An upright P wave occurs before every QRS complex

3. The PR intervals remain within the normal range of 0.12 to 0.20 second, and the QRS complexes are less than 0.12 second

4. All P waves look alike, and QRS complexes are the same size and shape

5. The P to P intervals and the R to R intervals are regular and equal in length, so the rhythm is regular

6. The rate can vary, but it is less than 60 electrical impulses per minute
When is sinus bradycardia considered normal?
In conditioned athletes and sleeping individuals
When is sinus bradycardia considered a dangerous dysrhythmia?
If the rate falls significantly or if the patient begins to show signs of poor cardiac output
What are the signs and symptoms of sinus bradycardia?
1. Pale, cool, clammy skin
2. Cyanosis
3. Dyspnea
4. Confusion or disorientation
5. Dizziness
6. Weakness or faintness
7. Sudden decrease in blood pressure
8. Shortness of breath
9. Nausea or vomiting
10. Decreased urinary output
11. Mild or severe chest pain
12. Unresponsiveness
What are the common causes of sinus bradycardia?
Vomiting and/or drugs such as digitalis, morphine, and sedatives
What is sinus tachycardia?
A rate between 101 and 150 beats per minute
When is sinus tachycardia considered a dysrhythmia?
When the patient becomes medically unstable (poor cardiac output)
What are the causes of sinus tachycardia?
1. Pain
2. Fever
3. Anemia
4. Dehydration
5. Hemorrhage
6. Exercise
7. Fear
8. Sudden excitement
9. Anxiety
10. The effects of drugs such as atropine, nicotine, caffeine, or some street drugs
When does a sinus arrhythmia occur?
1. When the SA node initiates all the electrical impulses but at irregular intervals

2. The P to P intervals and the R to R intervals change with respirations, producing an irregular rhythm

(**the horizontal measurement varies)
When is a sinus arrhythmia considered normal?
For infants and young children
When is a sinus arrhythmia considered in adults?
It may be a warning of a diseased SA node or coronary artery disease in the adult patient
When is sinus arrhythmia considered serious?
Sinus arrhythmia is usually not serious unless the patient's cardiac output decreases and the patient becomes medically unstable
What is a sinus exit block?
A dysrhythmia that occurs when the SA node initiates an electrical impulse that is blocked and not conducted to the atria, so the atria and ventricles do not depolarize, and a P wave will not be seen until the next conducted complex

(** no P wave or QRS complex)
What is a sinus arrest?
A dysrhythmia that occurs when the SA node does not initiate an electrical impulse, so depolarization will not occur and the next expected complex will not be seen

(** no P wave or QRS complex)
What is the difference between a sinus exit block and a sinus arrest?
The pause of a sinus exit block is equal to exactly two or more previous cardiac cycles of the underlying rhythm. For example, the P to P interval of the underlying rhythm will fit into the pause of a sinus exit block exactly 2 times, or exactly 3 times, and so forth. The SA node continues to fire at its normal rate, so the rhythm will usually be regular except where the pause occurs.

The pause of a sinus arrest is not equal to exactly two or more cardiac cycles of the underlying rhythm. It will be more than 2 times the cardiac cycle of the underlying rhythm. For example, the P to P interval of the underlying rhythm will not fit into the pause of a sinus arrest exactly 2 times, or exactly 3 times, and so forth.
What causes a sinus exit block or a sinus arrest?
Both dysrhythmias may be caused by myocardial infarction (MI), ischemia, hypoxia, or drugs such as digitalis or quinidine
How do atrial dysrhythmias affect ventricular depolarization?
In atrial dysrhythmias, the electrical impulse travels through the atria to the AV node, continues through the bundle of His and bundle branches to the Purkinje's fibers, and ends in the ventricular muscle, so the ventricles usually depolarize in a NORMAL manner.
What is a premature atrial complex (PAC)?
An individual complex that occurs earlier than the next expected complex of the underlying rhythm
Where does a premature atrial complex originate?
From any atrial site outside the SA node
What types of pauses can follow a premature atrial complex (PAC)?
1. Noncompensatory pause

2. Compensatory pause
What is a noncompensatory pause?
A pause that causes the measurement from the R and R wave after the PAC to be less than 2 times the R to R interval of the underlying (original) rhythm
What is a noncompensatory pause indicative of?
The development of increased irritability in the SA node, causing it to generate an impulse sooner than expected in response to the premature beat
What can a noncompensatory pause cause?
Increase in irritability could lead to sinus tachycardia
What is a compensatory pause?
A pause that does not affect the measurement of the R and R interval after the PAC and this interval will still equal at least 2 times the R to R interval of the underlying (original) rhythm
What is a compensatory pause indicative of?
In a compensatory pause, the SA node does not respond to the premature beat. Therefore there is no change in the rate or regularity of the underlying rhythm.
What type of pause usually follows a premature atrial complex (PAC)?
A noncompensatory pause
What does a premature atrial complex (PAC) represent?
Increased irritability of the atria
What does increased irritability of the atria indicate?
The cardiac cells are able to respond to even a mild electrical stimulus and may depolarize in an unpredictable rate or manner
What causes premature atrial complex (PAC)?
1. Pain
2. Fever
3. Fear
4. Anxiety
5. Sudden excitement
6. Exercise
7. The effects of drugs such as digitalis, atropine, nicotine, caffeine, and some street drugs
Why are PACs frequently monitored?
Because they may lead to a more serious dysrhythmia, such as paroxysmal atrial tachycardia (even though the PAC itself is not a serious dysrhythmia)
What is a paroxysmal atrial tachycardia (PAT)?
The sudden onset of a tachycardia with a rate greater than 150 electrical impulses per minute
What is the most recent term for a paroxysmal atrial tachycardia?
Paroxysmal supraventricular tachycardia (PSVT)
What triggers a paroxysmal atrial tachycardia/paroxysmal supraventricular tachycardia (PAT/PSVT)?
A premature atrial complex (PAC)
What are the characteristics of a paroxysmal atrial tachycardia/paroxysmal supraventricular tachycardia (PAT/PSVT)?
1. A P-wave occurs before every QRS complex

2. However, because of the rapid rate of PAT/PSVT, the P wave may be hidden in the T wave of the preceding complex

3. If P waves are seen, the PR intervals range from 0.12 to 0.20 second and the QRS complexes are usually less than 0.12 second

4. The rhythm is regular because the P to P intervals and R to R intervals are regular and equal in length

5. The rate may vary from 151 to 250, or more, electrical impulses per minute

6. Because the rate is so rapid, the ventricles do not have time to fill completely before each contraction, causing a decrease in cardiac output
What are the effects of a paroxysmal atrial tachycardia/paroxysmal supraventricular tachycardia (PAT/PSVT)?
1. Decreased cardiac output

2. Most of the blood flow through the coronary arteries occurs between heartbeats, the rapid heart rate of a PAT/PSVT may also decrease the amount of oxygenated blood circulated to the heart muscle
What are the symptoms of a paroxysmal atrial tachycardia/paroxysmal supraventricular tachycardia (PAT/PSVT)?
1. Weakness
2. Dizziness
3. Palpitations
4. A feeling that the heart is doing “flip-flops”
What causes a paroxysmal atrial tachycardia/paroxysmal supraventricular tachycardia (PAT/PSVT)?
1. Caffeine
2. Nicotine
3. Some street drugs
What is a supraventricular tachycardia?
A dysrhythmia that fits all the characteristics of a PAT/PSVT but the beginning of the dysrhythmia is not seen
What are the characteristics of a supraventricular tachycardia?
1. Originates from an irritable site above the bundle of His

2. Has a rate greater than 150

3. A P wave usually occurs before every QRS complex

4. However, the P wave may be hidden in the T wave of the preceding complex because of the rapid rate of the SVT

5. If P waves are seen, the PR intervals usually range from 0.12 to 0.20 second, and the QRS complexes usually measure less than 0.12 second

6. Any P waves that can be seen usually look alike, and the QRS complexes are usually the same size and shape

7. The P to P intervals and R to R intervals are regular and equal in length, and the rhythm is regular

8. The rate of the SVT varies from 151 to 250, or more, electrical impulses per minute

9. A rhythm resembling SVT but with a heart rate less than 151 is called sinus tachycardia
What is a rhythm resembling an SVT but with a heart rate less than 151 called?
Sinus tachycardia
What triggers a supraventricular tachycardia (SVT)?
An irritable site within the atria
What causes a supraventricular tachycardia (SVT)?
1. Caffeine
2. Nicotine
3. Some street drugs
What is an atrial flutter?
Dysrhythmia that occurs when a single irritable site in the atria initiates many electrical impulses at a rapid rate. The electrical impulses are conducted throughout the atria so rapidly that normal P waves are not produced, and instead, flutter waves (F waves) are formed.
What are the characteristics of the flutter (F) waves?
1. Atypical “saw-toothed” or jagged appearance on the rhythm strip

2. They may not all look exactly the same, because some F waves may be buried in the QRS complex, ST segment, or T wave
What happens during an atrial flutter?
1. The atria depolarize more rapidly than normal, but the AV node delays some of the electrical impulses, allowing the ventricles to depolarize at a normal rate

2. Therefore, every atrial impulse cannot be conducted to the ventricles, and a QRS complex is not present for every F wave
What are the characteristics of an atrial flutter?
1. The ventricles usually depolarize and repolarize at regular intervals, allowing them to respond to the atrial impulse at a regular rate, which may result in a regular ventricular rhythm

2. The QRS complexes typically measure less than 0.12 second and usually occur at regular intervals

3. The ventricular rate, as measured by the number of QRS complexes, is usually 60 to 100 electrical impulses per minute

4. However, the atrial rate (F waves) usually ranges from 250 to 350 impulses per minute
What is an atrial flutter with a ventricular rate of less than 60 impulses per minute called?
Atrial flutter with a slow ventricular response
What is an atrial flutter with a ventricular rate between 101 to 150 impulses per minute called?
Atrial flutter with a rapid ventricular response
What is a 2:1 block/ratio?
Two F waves with one QRS complex
What is a 3:1 block/ratio?
Three F waves with one QRS complex
What is a 4:1 block/ratio?
Four F waves with one QRS complex
What is a 5:1 block/ratio?
Five F waves with one QRS complex
What is an atrial flutter with a variable ventricular response?
A rhythm in which the number of F waves before each QRS complex varies, the R to R interval is irregular
What causes atrial flutters?
1. Heart disease
2. Myocardial infarction
3. Drug toxicity
What is an atrial fibrillation (A fib)?
1. A dysrhythmia in which an increased irritability of all the cardiac cells in the atria exists

2. Because of this increased atrial irritability, many sites within the atria attempt to initiate electrical impulses at the same time
What are the characteristics of an atrial fibrillation (A Fib)?
1. Because so many electrical impulses are initiated, most of the impulses are not conducted; therefore the atria are not completely depolarized with each impulse

2. The atria do not contract forcefully; only a quivering movement (fibrillatory waves) occurs

3. These fibrillatory waves (fib waves) appear on the rhythm strip or monitor screen as a wavy baseline between each QRS complex

4. No true P waves or PR intervals exist

5. At irregular intervals, one electrical impulse is conducted through the AV junction and ventricles, resulting in ventricular depolarization and a QRS complex

6. QRS complexes usually remain within the normal range of less than 0.12 second, and the R to R intervals are irregular throughout the rhythm strip

7. Frequently, one of the first clues that a dysrhythmia might be atrial fibrillation is seeing R to R intervals that are irregularly irregular (with no pattern to the irregularity)

8. The atrial heart rate is usually 350 to 500, or more, electrical impulses per minute
What is a controlled atrial fibrillation?
Atrial fibrillation in which the AV node delays some of the electrical impulses, allowing the ventricular heart rate to usually remain within the normal limits of 60 to 100 impulses per minute
What is an atrial fibrillation with a slow ventricular response?
Atrial fibrillation with a ventricular rate of less than 60 impulses per minute
What is an atrial fibrillation with rapid ventricular response?
Atrial fibrillation with a ventricular rate of 101 to 150 impulses per minute
What is an uncontrolled atrial fibrillation?
Atrial fibrillation with a ventricular rate greater than 150 impulses per minute
What are the signs and symptoms of a patient who is medically unstable during atrial fibrillation?
1. Pale, cool, clammy skin
2. Nausea and vomiting (N/V)
3. Dizziness, weakness, faintness
4. Shortness of breath
5. Hypotension
6. Dyspnea
7. Tachycardia
8. Diaphores
9. Mild to severe chest pain
10. Confusion or disorientation
11. Cyanosis
12. Decreased urinary output
13. Unresponsiveness
What causes atrial fibrillation?
1. Severe heart disease
2. Myocardial infarction
3. Excessive use of alcohol or caffeine
What is the Wolff-Parkinson-White (WPW) syndrome?
A dysrhythmia that occurs when an electrical impulse follows an additional or abnormal electrical conduction pathway, called the bundle of Kent (Kent bundle). Although the normal conduction pathway is working, the impulse from the different pathway, known as an accessory pathway, also reaches the ventricles after bypassing the AV node.
How can electrical impulses travel through the accessory pathway (bundle of Kent)?
1. Downward from the atria to the ventricles (antegrade)

2. Upward from the ventricles to the atria (retrograde)

3. Both downward and upward, in a continuous cycle
What are the characteristics of the Wolff-Parkinson-White (WPW) syndrome?
1. PR interval shorter than 0.12 second, if a P wave is present

2. Usually a widened QRS complex, greater than 0.12 second

3. Delta wave
Why is the PR interval shorter than normal in Wolff-Parkinson-White (WPW) syndrome?
Because the electrical impulse does not travel through the AV node, but goes directly from the atria to the ventricles
What happens to the QRS complex in the Wolff-Parkinson-White (WPW) syndrome?
1. The QRS is usually widened if the electrical impulse travels in a retrograde manner, or in a continuous cycle

2. The QRS complex is usually within the normal limits of 0.04 to 0.12 second when the electrical impulse travels from the atria to the ventricles

3. The R wave of the QRS complex usually is “slurred,” or curved, at the beginning of the R wave
What is a delta wave?
1. An extra “bump” seen in the slurred section of the QRS complex

2. The delta wave is formed by depolarization of the ventricles through the accessory pathway, before the normally conducted electrical impulse can reach the ventricles
What is the heart rate in Wolff-Parkinson-White syndrome?
1. The P to P intervals and R to R intervals of WPW syndrome vary, depending on the underlying rhythm

2. The rate of WPW syndrome may also vary, depending on the underlying rhythm. However, because the ventricles are receiving impulses from both the normal and accessory pathways, the ventricles usually depolarize quickly, causing tachycardia
When is the Wolff-Parkinson-White syndrome considered life-threatening?
If the ventricular rate increases to 200 to 300 beats per minute or greater
What are the signs and symptoms of Wolff-Parkinson-White syndrome?
1. The patient may have no symptoms

OR

2. May complain of palpitations; racing heart; dizziness, weakness, or faintness; SOB; and/or chest pain
What are the complications of Wolff-Parkinson-White syndrome, atrial flutter, and especially atrial fibrillation?
1. Clots may form in the atria

2. The rapid atrial rate may not allow either atrial chamber to empty completely. This could lead to stroke, pulmonary emboli (blockage of an artery in the lungs), and/or MI.
True or False:

The SA node normally generates 60 to 100 electrical impulses per minute.
True
True or False:

Sinus bradycardia may become dangerous if the heart rate decreases significantly or the patient becomes medically unstable.
True
True or False:

The complex that ends a sinus arrest can only be initiated from the SA node.
False

(Complex may be either atrial, junctional, or ventricular)
True or False:

A PAC is an atrial complex that occurs later than the next expected complex of the underlying rhythm.
False

(Occurs sooner than expected)
True or False:

In a sinus arrhythmia, the heart rate increases with inspirations and decreases with expirations.
True
What is the number of electrical impulses in sinus tachycardia?
101-150
What is the usual measurement of the QRS complexes in atrial fibrillation?
0.12 second
Sinus exit block occurs when the SA node fails to initiate an electrical impulse for a length of time equal to ______ previous cardiac cycles.
Two or more
If the onset of PAT/PSVT is not seen, the dysrhythmia is called

a. sinus tachycardia
b. supraventricular tachycardia
c. premature atrial tachycardia
d. atrial tachycardia
b. Supraventricular tachycardia
SVT is a dysrhythmia that originates from an irritable site located

a. above the bundle of His
b. within the ventricles
c. within the bundle branches
d. below the bundle of His
a. Above the bundle of His
Wolff-Parkinson-White syndrome can be identified by a shortened PR interval and the presence of a(n)

a. alpha wave
b. P wave
c. delta wave
d. beta wave
c. Delta wave
Atrial flutter has

a. P waves
b. Q waves
c. F waves
d. T waves
c. F waves
Atrial fibrillation has fib waves that are

a. distinct and regular
b. notched and regular
c. wavy and irregular
d. absent
c. Wavy and irregular
What is a “variable ventricular response” in atrial flutter?
Variable ventricular response occurs when the impulse that depolarized the ventricle is conducted from the atria at irregular intervals. This results in changing blocks/ratios, such as 3:1, 4:1, 2:1, etc.
What is the path of an electrical impulse from the SA node to the ventricular muscle?
SA node to atria (by the intraatrial pathways) and to the AV node (by the internodal pathways), to the bundle of His and bundle branches, to the Purkinje's fibers, to the ventricular muscle cells
Describe the components and intervals of a complex in normal sinus rhythm, including measurements as seen on a rhythm strip.
Upright P wave before each QRS; all P waves look alike; PR interval measuring 0.12-0.20 second; QRS measuring 0.04-0.12 second, follows each P wave; all QRS complexes look alike; upright T waves; QT intervals less than half the R to R intervals; all P to P intervals and R to R intervals are equal; and the heart rate is between 60 to 100 per minute.
What is the heart rate usually found in sinus bradycardia?
Less than 60 pulses per minute
What is the heart rate usually found in SVT?
Greater than 150 pulses per minute
What is the heart rate usually found in sinus arrhythmia?
Varies; usually 60-100 pulses per minute
What is the atrial heart rate in atrial flutter?
250-350 per minute
What is the atrial heart rate in atrial fibrillation?
350-500 or more per minute
What is the difference between the pause of a sinus exit block and a sinus arrest, including the length of the pause?
The pause of a sinus exit block is exactly two or more cardiac cycles of the underlying rhythm. The pause would fit into exactly two, three, four, or more cardiac cycles of the underlying rhythm. The pause of a sinus arrest is more than two or more cardiac cycles. It will not fit exactly into two, three, or four cardiac cycles of the underlying rhythm.