[MCQ] The Bradyarrhythmias- Part 1

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The Bradyarrhythmias- Part 1

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Question 1

Which of the following is false about nodal cells ?

A	Less negative resting membrane potential
B	Most rapid phase 4 depolarization
C	Slow action potential upstrokes (phase 0)
D	Action potential mediated by Na+ rather than Ca++

Question 1 Explanation:

In nodal cells, action potential mediated by Ca++ rather than Na+ current.

Question 2

Nodal cell action potentials exhibit which of the following ?

A	More depolarized resting membrane potentials
B	Slower phase 0 upstrokes
C	Slower phase 4 diastolic depolarization
D	All of the above

Question 2 Explanation:

Nodal cell action potentials exhibit more depolarized resting membrane potentials, slower phase 0 upstrokes, and phase 4 diastolic depolarization.

Question 3

Which of the following is not a feature of SA nodal cells ?

A	Fewer myofibrils
B	No intercalated disks
C	Well developed sarcoplasmic reticulum
D	No T-tubules

Question 3 Explanation:

SA nodal cells have fewer distinct myofibrils than surrounding atrial myocardium, no intercalated disks, poorly developed sarcoplasmic reticulum, and no T-tubules.

Question 4

In majority, SA nodal artery arises from ?

A	Right coronary artery
B	Left anterior descending artery
C	Left circumflex artery
D	Posterior descending artery

Question 4 Explanation:

SA nodal artery arises from RCA in 55 - 60% and left circumflex artery in 40 - 45% of persons

Question 5

Membrane potential of SA nodal cells is ?

A	–20 to –40 mV
B	–40 to –60 mV
C	–60 to –80 mV
D	–80 to –100 mV

Question 5 Explanation:

The action potentials of SA nodal cells are characterized by a relatively depolarized membrane potential of –40 to –60 mV, slow phase 0 upstroke, and relatively rapid phase 4 diastolic depolarization compared to the action potentials recorded in cardiac muscle cells

Question 6

Cushing’s response is best related to ?

A	Visual blurring
B	Accelerated hypertension
C	Accelerated hypertension
D	Dermopathy

Question 6 Explanation:

Increased intracranial pressure producing SA nodal dysfunction is called Cushing’s response

Question 7

Which of the following neuromuscular disease produce SA node disease ?

A	Myasthenia gravis
B	Botulism
C	Lambert-Eaton syndrome
D	Kearns-Sayre syndrome

Question 7 Explanation:

Neuromuscular diseases like Kearns-Sayre syndrome (ophthalmoplegia, pigmentary degeneration of retina & cardiomyopathy) & myotonic dystrophy produce conducting system & SA node disease.

Question 8

Sinus bradycardia is associated with all except ?

A	Hypothyroidism
B	Advanced liver disease
C	Trypnosomiasis
D	Brucellosis

Question 9

Sinus bradycardia is associated with all except ?

A	Sinus bradycardia is associated with all except ?
B	Acute hypertension
C	Hypercapnia
D	Alkalosis

Question 10

Sinus arrest means ?

A	Failure of sinus impulse formation
B	Block of conduction of sinus impulses to atrial tissue
C	Block of conduction of sinus impulses at AV node
D	Block of conduction of sinus impulses beyond AV node

Question 11

Sinus exit block means ?

A	Failure of sinus impulse formation
B	Failure of conduction of sinus impulses to surrounding atrial tissue
C	Failure of conduction of sinus impulses at AV node
D	Failure of conduction of sinus impulses beyond AV node

Question 11 Explanation:

Sinus pauses & sinus arrest result from failure of SA node to discharge, causing a pause without P waves visible on ECG. Intermittent failure of conduction from SA node produces sinus exit block

Question 12

Electrocardiographic manifestations of SA node dysfunction include ?

A	Sinus pauses
B	Sinus exit block
C	Tachycardia
D	All of the above

Question 12 Explanation:

Electrocardiographic manifestations of SA node dysfunction include sinus bradycardia, sinus pauses, sinus arrest, sinus exit block, tachycardia (in SSS), and chronotropic incompetence.

Question 13

Intermittent absence of P waves on ECG is due to ?

A	Second-degree SA block
B	Sinus exit block
C	Sinus arrest
D	Sick sinus syndrome

Question 14

A prolongation of conduction time from SA node to surrounding atrial tissue is called ?

A	First-degree sinoatrial exit block
B	Second-degree sinoatrial exit block
C	Third-degree sinoatrial exit block
D	None of the above

Question 15

The intermittent failure of conduction of sinus impulses to the surrounding atrial tissue is called ?

A	First-degree sinoatrial exit block
B	Second-degree sinoatrial exit block
C	Third-degree sinoatrial exit block
D	None of the above

Question 16

Lack of atrial activity or the presence of an ectopic subsidiary atrial pacemaker is called ?

A	First-degree sinoatrial exit block
B	Second-degree sinoatrial exit block
C	Third-degree sinoatrial exit block
D	None of the above

Question 16 Explanation:

Type I second-degree SA block results from progressive prolongation of SA node conduction with intermittent failure of the impulses originating in the sinus node to conduct to the surrounding atrial tissue. Second-degree SA block appears on the ECG as an intermittent absence of P waves. In type II second-degree SA block, there is no change in SA node conduction before the pause. Complete or third-degree SA block results in no P waves on the ECG.

Question 17

Sick sinus syndrome refers to a combination of all except ?

A	Sinus bradycardia
B	Sinoatrial block
C	Sinus arrest
D	Sinus arrhythmia

Question 17 Explanation:

ECG manifestations of SA node dysfunction include sinus bradycardia, sinus pauses, sinus arrest, sinus exit block, tachycardia (in SSS), and chronotropic incompetence (inability to increase heart rate in response to exercise or other stress appropriately).

Question 18

In sinus arrest and in sinus exit block, atrial asystole is of what duration ?

A	> 1 seconds
B	> 1.5 seconds
C	> 2.5 seconds
D	> 3 seconds

Question 18 Explanation:

Sinus pauses of up to 3 seconds are common in the awake athlete, & pauses of this duration or longer may be observed in asymptomatic elderly subjects

Question 19

In Tachycardia-bradycardia syndrome, which of the following is the most common tachycardia ?

A	Atrial tachycardia
B	Atrial flutter
C	Atrial fibrillation
D	Atrial fibrillation

Question 19 Explanation:

Tachycardia-bradycardia syndrome manifests as alternating sinus bradycardia & atrial tachyarrhythmias. Although atrial tachycardia, atrial flutter, and atrial fibrillation may be observed, the latter is the most common tachycardia

Question 20

Which of the following is false about Mobitz type I SA nodal exit block ?

A	Regularly irregular heart rhythm
B	Decreasing P-P intervals before the pause
C	Pause < twice the cycle length of last sinus interval
D	None of the above

Question 20 Explanation:

In Mobitz type I SA nodal exit block, there is grouped beating producing a regularly irregular heart rhythm. SA node rate is constant with progressive delay in exit from the node and activation of atria. This produces subtly decreasing P-P intervals before the pause, and the pause is less than twice the cycle length of the last sinus interval

Question 21

Chronotropic incompetence is failure to reach what percentage of predicted maximal heart rate at peak exercise?

A	55 %
B	65 %
C	75 %
D	85 %

Question 21 Explanation:

Exercise testing is useful in discriminating chronotropic incompetence from resting bradycardia. Failure to increase the heart rate with exercise is called chronotropic incompetence. Alternatively defined as a failure to reach 85% of predicted maximal heart rate at peak exercise or failure to achieve a heart rate >100 beats/minute with exercise or a maximal heart rate with exercise less than two standard deviations below that of an age-matched control population

Question 22

Normal values of intrinsic heart rate are calculated by the formula ?

A	118.1 - (0.37 x age) beats per minute
B	118.1 - (0.47 x age) beats per minute
C	118.1 - (0.57 x age) beats per minute
D	118.1 - (0.67 x age) beats per minute

Question 23

Normal values of intrinsic heart rate are calculated by the formula ?

A	116.2 – (0.53 x age) beats per minute
B	117.2 – (0.53 x age) beats per minute
C	118.2 – (0.53 x age) beats per minute
D	119.2 – (0.53 x age) beats per minute

Question 23 Explanation:

Determining the intrinsic heart rate (IHR) may distinguish SA node dysfunction from slow heart rates resulting from high vagal tone. Normal IHR after administration of 0.2 mg/kg propranolol & 0.04 mg/kg atropine is 117.2 – (0.53 x age) in beats/minute. Low IHR is indicative of SA disease.

Question 24

Which of the following is a sensitive and specific indicator of intrinsic SA node disease ?

A	Sinus node recovery time (SNRT)
B	Sinoatrial conduction time (SACT)
C	Low intrinsic heart rate (IHR)
D	All of the above

Question 24 Explanation:

Sinus node recovery time (SNRT) is defined as the longest pause after cessation of overdrive pacing of right atrium near SA node (normal <1500 mseconds or, corrected for sinus cycle length, <550 mseconds). Sinoatrial conduction time (SACT) is defined as one-half the difference between intrinsic sinus cycle length and a noncompensatory pause after a premature atrial stimulus (normal <125 mseconds). Combination of an abnormal SNRT, an abnormal SACT, and a low IHR is a sensitive and specific indicator of intrinsic SA node disease.

Question 25

In susceptible individual, SA node dysfunction may become manifest in the presence of which of the following ?

A	Cardiac glycosides
B	Amiodarone
C	Calcium channel blockers
D	All of the above

Question 25 Explanation:

Cardiac glycosides, beta-blockers, calcium channel blockers, amiodarone may unmask evidence of sinus node dysfunction in susceptible individuals.

Question 26

Which of the following pharmacologic agents may improve SA node function ?

A	Class I Antiarrhythmics
B	Class III Antiarrhythmics
C	Calcium channel blockers
D	Digitalis

Question 26 Explanation:

Beta blockers and calcium channel blockers increase SNRT in patients with SA node dysfunction, and antiarrhythmic drugs with class I and III action may promote SA node exit block. Digitalis shortens SNRT in SA node dysfunction. Isoproterenol or atropine administered IV may increase sinus rate acutely. Theophylline increases heart rate

Question 27

The AV node lies at the ?

A	Base of interatrial septum just above tricuspid annulus and anterior to coronary sinus
B	Base of interatrial septum just below tricuspid annulus and anterior to coronary sinus
C	Base of interatrial septum just above tricuspid annulus and posterior to coronary sinus
D	Base of the interventricular septum just above tricuspid annulus and anterior to coronary sinus

Question 28

Normal AV node in vivo possesses ?

A	Automaticity always
B	Automaticity sometimes
C	No automaticity
D	None of the above

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See all quizzes of the The Bradyarrhythmias at here:

The Bradyarrhythmias- Part 1 | The Bradyarrhythmias- Part 2 | The Bradyarrhythmias- Part 3

1.Which of the following is false about nodal cells ?
A. Less negative resting membrane potential
B. Most rapid phase 4 depolarization
C. Slow action potential upstrokes (phase 0)
D. Action potential mediated by Na+ rather than Ca++
In nodal cells, action potential mediated by Ca++ rather than Na+ current.

2. Nodal cell action potentials exhibit which of the following ?
A. More depolarized resting membrane potentials
B. Slower phase 0 upstrokes
C. Slower phase 4 diastolic depolarization
D. All of the above

3. Which of the following is not a feature of SA nodal cells ?
A. Fewer myofibrils
B. No intercalated disks
C. Well developed sarcoplasmic reticulum
D. No T-tubules

4. In majority, SA nodal artery arises from ?
A. Right coronary artery
B. Left anterior descending artery
C. Left circumflex artery
D. Posterior descending artery

5. Membrane potential of SA nodal cells is ?
A. –20 to –40 mV
B. –40 to –60 mV

C. –60 to –80 mV
D. –80 to –100 mV

6. Cushing’s response is best related to ?
A. Visual blurring
B. Accelerated hypertension
C. Increased intracranial pressure
D. Dermopathy

7. Which of the following neuromuscular disease produce SA node disease ?
A. Myasthenia gravis
B. Botulism
C. Lambert-Eaton syndrome
D. Kearns-Sayre syndrome

8. Sinus bradycardia is associated with all except ?
A. Hypothyroidism
B. Advanced liver disease
C. Trypnosomiasis
D. Brucellosis

9. Sinus bradycardia is associated with all except ?
A. Typhoid fever
B. Acute hypertension
C. Hypercapnia
D. Alkalosis

10. Sinus arrest means ?
A. Failure of sinus impulse formation
B. Block of conduction of sinus impulses to atrial tissue
C. Block of conduction of sinus impulses at AV node
D. Block of conduction of sinus impulses beyond AV node

11. Sinus exit block means ?
A. Failure of sinus impulse formation
B. Failure of conduction of sinus impulses to surrounding atrial tissue
C. Failure of conduction of sinus impulses at AV node
D. Failure of conduction of sinus impulses beyond AV node

12. Electrocardiographic manifestations of SA node dysfunction include ?
A. Sinus pauses
B. Sinus exit block
C. Tachycardia
D. All of the above

13. Intermittent absence of P waves on ECG is due to ?
A. Second-degree SA block
B. Sinus exit block
C. Sinus arrest
D. Sick sinus syndrome

14. A prolongation of conduction time from SA node to surrounding atrial tissue is called ?
A. First-degree sinoatrial exit block
B. Second-degree sinoatrial exit block
C. Third-degree sinoatrial exit block
D. None of the above

15. The intermittent failure of conduction of sinus impulses to the surrounding atrial tissue is called ?
A. First-degree sinoatrial exit block
B. Second-degree sinoatrial exit block
C. Third-degree sinoatrial exit block
D. None of the above

16. Lack of atrial activity or the presence of an ectopic subsidiary atrial pacemaker is called ?
A. First-degree sinoatrial exit block
B. Second-degree sinoatrial exit block
C. Third-degree sinoatrial exit block
D. None of the above

17. Sick sinus syndrome refers to a combination of all except ?
A. Sinus bradycardia
B. Sinoatrial block
C. Sinus arrest
D. Sinus arrhythmia

18. In sinus arrest and in sinus exit block, atrial asystole is of what duration ?

A. > 1 seconds
B. > 1.5 seconds
C. > 2.5 seconds
D. > 3 seconds

19. In Tachycardia-bradycardia syndrome, which of the following is the most common tachycardia ?
A. Atrial tachycardia
B. Atrial flutter
C. Atrial fibrillation
D. Any of the above

20. Which of the following is false about Mobitz type I SA nodal exit block ?
A. Regularly irregular heart rhythm
B. Decreasing P-P intervals before the pause
C. Pause < twice the cycle length of last sinus interval
D. None of the above

21. Chronotropic incompetence is failure to reach what percentage of predicted maximal heart rate at peak exercise?
A. 55 %
B. 65 %
C. 75 %
D. 85 %

22. Normal values of intrinsic heart rate are calculated by the formula ?
A. 118.1 – (0.37 x age) beats per minute
B. 118.1 – (0.47 x age) beats per minute
C. 118.1 – (0.57 x age) beats per minute
D. 118.1 – (0.67 x age) beats per minute

23. Normal values of intrinsic heart rate are calculated by the formula ?
A. 116.2 – (0.53 x age) beats per minute
B. 117.2 – (0.53 x age) beats per minute
C. 118.2 – (0.53 x age) beats per minuteD. 119.2 – (0.53 x age) beats per minute

24. Which of the following is a sensitive and specific indicator of intrinsic SA node disease ?
A. Sinus node recovery time (SNRT)
B. Sinoatrial conduction time (SACT)
C. Low intrinsic heart rate (IHR)
D. All of the above

25. In susceptible individual, SA node dysfunction may become manifest in the presence of which of the following ?
A. Cardiac glycosides
B. Amiodarone
C. Calcium channel blockers
D. All of the above

26. Which of the following pharmacologic agents may improve SA node function ?
A. Class I Antiarrhythmics
B. Class III Antiarrhythmics
C. Calcium channel blockers
D. Digitalis

27. The AV node lies at the ?
A. Base of interatrial septum just above tricuspid annulus andanterior to coronary sinus
B. Base of interatrial septum just below tricuspid annulus and anterior to coronary sinus
C. Base of interatrial septum just above tricuspid annulus and posterior to coronary sinus
D. Base of the interventricular septum just above tricuspid annulus and anterior to coronary sinus

28. Normal AV node in vivo possesses ?
A. Automaticity always
B. Automaticity sometimes
C. No automaticity
D. None of the above

The Bradyarrhythmias

[MCQ] The Bradyarrhythmias- Part 1

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The Bradyarrhythmias- Part 1

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