Cardiac Rhythm Monitors and
Equipment Review Exam Question
and answers verified to pass
2026/2027
The normal QT interval is:
A. 0.10 seconds.
B. 0.25 seconds.
C. 0.40 seconds.
D. 0.55 seconds. - correct answer *C. 0.40 seconds*
Explanation:
Key facts about the QT interval:
• It extends from the beginning of the Q wave (or R wave if there is no Q wave) through the end of the T
wave.
• It corresponds with the beginning of ventricular depolarization to the end of repolarization.
• Hypercalcemia makes it shorter.
• Hypocalcemia makes it longer.
• It is inversely related to heart rate (faster heart rate = shorter QT interval).
• Normal value = 0.35 - 0.45 seconds.
• When it exceeds 0.5 seconds, there is an increased risk of torsades de pointes.
How do you determine the axis or direction of the mean electrical vector? - correct answer Look at the
QRS complex in *lead I and aVF*
, Normal = both positive
Left axis deviation = lead I is positive, aVF is negative
Right axis deviation = lead I is negative, aVF is positive
Extreme right axis deviation = both negative
All of the following are true of sinus arrhythmia EXCEPT:
A. it is a consequence of the Bainbridge reflex.
B. it is caused by an ectopic pacemaker
C. increased venous return increases heart rate.
D. inhalation increases heart rate. - correct answer *B. It is caused by an ectopic pacemaker*
Explanation:
Sinus arrhythmia occurs when the SA node's pacing rate varies with respiration.
• Inhalation → increased heart rate
• Exhalation → decreased heart rate
Remember the Bainbridge reflex? This is the one where an increased venous return stretches the right
atrium and SA node causing the heart rate to increase. It should also make sense that the Bainbridge
reflex causes sinus arrhythmia.
• Inhalation → decreased intrathoracic pressure → increased venous return → increased heart rate
• Exhalation → increased intrathoracic pressure → decreased venous return → decreased heart rate
Sinus arrhythmia is usually benign.
Equipment Review Exam Question
and answers verified to pass
2026/2027
The normal QT interval is:
A. 0.10 seconds.
B. 0.25 seconds.
C. 0.40 seconds.
D. 0.55 seconds. - correct answer *C. 0.40 seconds*
Explanation:
Key facts about the QT interval:
• It extends from the beginning of the Q wave (or R wave if there is no Q wave) through the end of the T
wave.
• It corresponds with the beginning of ventricular depolarization to the end of repolarization.
• Hypercalcemia makes it shorter.
• Hypocalcemia makes it longer.
• It is inversely related to heart rate (faster heart rate = shorter QT interval).
• Normal value = 0.35 - 0.45 seconds.
• When it exceeds 0.5 seconds, there is an increased risk of torsades de pointes.
How do you determine the axis or direction of the mean electrical vector? - correct answer Look at the
QRS complex in *lead I and aVF*
, Normal = both positive
Left axis deviation = lead I is positive, aVF is negative
Right axis deviation = lead I is negative, aVF is positive
Extreme right axis deviation = both negative
All of the following are true of sinus arrhythmia EXCEPT:
A. it is a consequence of the Bainbridge reflex.
B. it is caused by an ectopic pacemaker
C. increased venous return increases heart rate.
D. inhalation increases heart rate. - correct answer *B. It is caused by an ectopic pacemaker*
Explanation:
Sinus arrhythmia occurs when the SA node's pacing rate varies with respiration.
• Inhalation → increased heart rate
• Exhalation → decreased heart rate
Remember the Bainbridge reflex? This is the one where an increased venous return stretches the right
atrium and SA node causing the heart rate to increase. It should also make sense that the Bainbridge
reflex causes sinus arrhythmia.
• Inhalation → decreased intrathoracic pressure → increased venous return → increased heart rate
• Exhalation → increased intrathoracic pressure → decreased venous return → decreased heart rate
Sinus arrhythmia is usually benign.
