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EKG Certification > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

Atrioventricular Block

A

Depolarization and repolarization are slow in the AV node, which makes this area vulnerable to blocks in conduction

AV block is a delay or interruption in impulse conduction from the atria to the ventricles which occurs as a result of a temporary or permanent anatomical or functional impairment

Anatomic - structure
Functional - internal “software”

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2
Q

PR interval in AV block

A

Assess PR intervals to detect conduction disturbances

Normal PR interval measures 0.12 to 0.20

PRI will be longer in AV block

ALWAYS measure PRI

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3
Q

What are the classifications of AV blocks?

A

First degree AV block - will look like NSR with long PRI

Second degree AV block
-Type I (Mobitz I or wenchebach phenomenon)
-Type II (Mobitz II)
-2:1
-Advanced second degree AV block (high grade)

Third degree AV block

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4
Q

First degree AV block

A

Will have normal sinus rhythm characteristics, but a more than normal (over 0.20 PRI)

PRI will be constant

Causes: Acute myocardial infraction, acute myocarditis or endocarditis, cardiomyopathy, degenerative fibrosis and sclerosis of the conduction system, drug effects, etc

What to do about it: monitor patient

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5
Q

Second degree AV block type I

A

Type I, Mobitz I, wenchebach phenomenon

PRI will progressively get longer over time, followed by a “drop” (P wave with no QRS) and a reset of the rhythm.

Gradual shortening of R-R intervals

Causes: blockage of the right coronary artery (inferior myocardial infraction, right ventricular infraction), can also occur in healthy individuals during sleep or in athletes. Other possible causes - aortic valve disease, atrial septal defect, medications, etc.

What to do about it: monitor and normal pulse oximeter, oxygen, 12 lead ECG, IV access, etc

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6
Q

Second degree AV block type II

A

At least 2 beats in a row
Constant PRI
Fewer QRS
More P waves (P waves occur on time)
Atrial rate regular
Ventricular rate irregular

Causes: left coronary artery disease, anterior MI, acute myocarditis, aortic valve disease, cardiomyopathy, etc.

What to do about it: same as others monitor

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7
Q

Second degree AV block 2:1

A

One conducted P wave followed by a block P wave; thus 2 P waves for every QRS (2:1). P-P ratio will be higher than R-R ratio

Need at least TWO beats in a row to classify as a type I or type II. If there is only one beat, it’ll be most likely a 2:1

normal beat, “drop”, normal beat, “drop”, normal beat, “drop”

Always look at PRI and measure

Can be indications of pacemaker

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8
Q

Advanced second degree AV block

A

AV block high grade

Three or more consecutive P waves that are not conducted (multiple consecutive blocks “drops”)

Regular rhythm then “drops” (heart stops)

P waves are constant (sinus P waves)

PRI constant

P-P regular / R-R irregular

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9
Q

Third degree AV block

A

Complete heart block (CHB) - complete block in impulse conduction between the atria and ventricles (neither side knows what the other is doing)

P waves and QRS are completely dissociated - atria and ventricles are not communicating). P waves are constant

PRI inconsistent (long, short)

SA node creating atrial depolarization while ventricular depolarization happening, but neither is connected or working together

Causes: acute MI, acute myocarditis, drug effect, fibrosis of the conduction systems

What to do about it: same as others, monitor. IV access, pulse oximeter, medications, etc.

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10
Q

Which of the following dysthymias may be a normal finding in individuals with no history of cardiac disease?
A. Atrial fibrillation
B. First degree AV block
C. Third degree AV block
D. Ventricular tachycardia

A

B

First degree AV block may be a normal finding an individuals with no history of cardiac disease, especially in athletes. Some people, mild prolongation of the PR interval maybe a normal variant, especially with sinus bradycardia during rest or sleep. Second-degree AV block type 1 can also occur in athletes, related to an increased resting, vagal tone, and in healthy individuals during sleep

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11
Q

Which of the following ECG components is used to detect AV conduction disturbances?
A. P wave
B. PR interval
C. QT interval
D. ST segment

A

B

When analyzing a rhythm strip assess PR intervals to detect AV conduction disturbances

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12
Q

The term second degree AV block type I is synonymous with:
A. Mobitz I
B. Mobitz II
C. Wenchebach
D. AV dissociation
E. High grade AV block
F. Wolf parkinson white pattern

A

A, C

Second-degree AV block type 1 is also known as type 1 block, Mobitz I or wenchebach

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13
Q

Identify the ECG characteristics of 2:1 AV block:
A. The ventricular rate is twice the atrial rate
B. Atrial and ventricular rhythms are regular
C. Every other P wave is not followed by a QRS complex
D. PR intervals progressively lengthen until a P wave appears without a QRS after it

A

B, C

Characteristics of 2:1 APB can be summarized as follows:
Rhythm: ventricular regular; atrial regular
Rate: atrial rate is twice the ventricular rate
P wave: normal size and shape; every other P-wave is not followed by a QRS complex
PR interval: constant
QRS duration: may be narrow or wide; complexes are absent after every other P wave

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14
Q

A key difference between second degree type I and type II AV block is that with:
A. Type I the P wave occurs irregularly
B. Type I the ventricular rhythm is regular
C. Type II the QRS duration is consistently more than 0.12sec in duration
D. Type II the PR intervals before and after a blocked P wave are constant

A

D

With both second-degree type I and II AV blocks, P waves occur regularly, and the ventricular rhythm is irregular. With second-degree type II, the QRS duration is within normal limits if the block occurs above or within the bundle of his and It is greater than 0.11 second if the block occurs below the bundle of his. QRS complexes are periodically absent after P waves. With second-degree AV block type II the PR intervals After a non-conducted P wave is shorter than the interval preceding the nonconductive beat

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15
Q

With third degree AV block, the PR interval:
A. shortens
B. Is absent
C. Lengthens
D. Remains constant

A

B

Third degree AV block is characterized by regular P to P intervals (regular atrial rhythm) and regular R to R intervals (regular ventricular rhythm); however, because there is no relationship between the atrial and ventricular rhythms there is no true PR interval

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16
Q

Which of the following dysthymias is more commonly seen with an inferior wall myocardial infraction?
A. Sinus arrhythmia
B. Second degree AV block type I
C. Second degree AV block type II
D. Third degree AV block with wide QRS

A

B

Remember that the RCA supplies, the AV node in 90% of the population . The RCA also supplies, the inferior wall of the left ventricle and the right ventricle in most individuals. Blockage of the RCA, resulting in an inferior myocardial infarction or right ventricular infarction, can also result in conduction delays such as first-degree AV block and second-degree AV block type I

17
Q

An ECG rhythm strip reveals an irregular ventricular rhythm at a rate of 46 to 54bpm, more P waves than QRS complexes with regular P-P intervals, PR intervals after nonconducted P waves are shorter than the interval preceding the nonconducted beats, and a QRS duration of 0.08sec. This rhythm is:
A. 2:1 AV block
B. Third degree AV block
C. Second degree AV block type I
D. Second degree AV block type II

A

C

With second-degree AV block type I the ventricular rhythm is irregular. There are more P waves then QRS complexes and the P-P interval is regular. P waves are normal in size shape but some P waves are not followed by a QRS complex. PR intervals are inconstant. The PR interval after a non-conducted P wave is shorter than the interval preceding the nonconductive beat. The QRS duration is usually 0.11 seconds or less the QRS complexes are periodically dropped.

18
Q

An ECG rhythm strip reveals an irregular ventricular rhythm at a rate of 28 to 40bpm, more P waves than QRS complexes, regular P-P intervals, a constant PR interval of 0.16sec, and a QRS duration of 0.14sec. This rhythm is:
A. 2:1 AV block
B. Third degree AV block
C. Second degree AV block type I
D. Second degree AV block type II

A

D

What second-degree AV blocked type II, ventricular rhythm is irregular. There are more P waves than QRS complexes and the P-P interval is regular. P waves are normal in size and shape but some P waves are not followed by QRS complex. The interval may be within normal limits or prolonged, but it is constant for the conducted beats; the intervals before, and after a blocked P wave our constant. The QRS duration is within normal limits if the block occurs above or within the bundle of his; it is greater than 0.11 seconds if the block occurs below the bundle of his. QRS complexes are periodically absent after P waves

19
Q

A 67 year old man presents with a blood pressure of 64/42mm HG, a heart rate of 38bpm, and an oxygen saturation on room air of 90%. The cardiac monitor reveals a type II AV block. Interventions to consider in the management of this patient include:
A. Administer oxygen
B. Administering atropine
C. Establishing IV access
D. Obtaining a 12 lead ECG
E. Obtaining a cardiology consult
F. Preparing for temporary pacing

A

A, C, D, E, F

This patient is clearly symptomatic with this dysrhythmia. Treatment should include applying a pulse oximeter, administration oxygen (when indicated), obtaining the patient’s vital signs and establishing IV access. Obtain a 12 lead ECG any cardiology consult. Temporary or permanent pacing may be necessary. Reports exist of occasional worsened AB conduction and or hemodynamic compromise following atropine administration patients with AV block and a wide QRS complex.

20
Q

ECG characteristics of third degree AV block include:
A. Regular atrial and ventricular rhythm
B. A QRS that may appear narrow or wide
C. An atrial rate is greater than the ventricular rate
D. PR intervals that are constant before each QRS

A

A, B, C

21
Q

An ECG rhythm strip shows a regular ventricular rhythm at a rate of 128bpm, one upright P wave before each QRS, a regular atrial rate, a constant PR interval of 0.24sec and a QRS duration of 0.08sec. This rhythm is:
A. Third degree AV block
B. Second degree AV block type I
C. Sinus tachycardia with first degree AV block
D. Junctional tachycardia with first degree AV block

A

C

Sinus tachycardia is present when there is a 1:1 relationship between P waves and QRS complexes and the ventricular rate is faster than 100 bpm. Firstdegree AV block is present when there is a 1:1 relationship between P waves and QRS complexes and the PR interval is prolonged (more than 0.20 sec) and constant

EKG Certification (12 decks)

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