CRAT Sinus Rhythm Interpretation 3

Question 1

Sinoatrial (SA) exit block type II is distinguished from sinus arrest by which feature?

Accepted Answer

SA exit block produces pauses that are exact multiples of the basic P-P cycle length

Answer

SA exit block produces pauses that are random and not related to cycle length

Answer

SA arrest produces pauses that are multiples of the P-P interval

Answer

SA exit block produces wide QRS complexes

Question 2

Sinus node dysfunction presenting with alternating bradycardia and tachycardia (typically AFib with rapid ventricular response alternating with sinus pauses) is called what syndrome?

Accepted Answer

Sick sinus syndrome (bradycardia-tachycardia syndrome)

Answer

Wolff-Parkinson-White syndrome

Answer

Long QT syndrome

Answer

Brugada syndrome

Question 3

Which physiological mechanism causes increased sinus rate during exercise?

Accepted Answer

Sympathetic nervous system activation releasing norepinephrine which increases SA node automaticity

Answer

Decreased blood pressure stimulating baroreceptors

Answer

Increased serum potassium during exercise

Answer

Mechanical stretching of the SA node

Question 4

Which respiratory pattern produces the most pronounced sinus arrhythmia?

Accepted Answer

Slow, deep breathing

Answer

Rapid shallow breathing

Answer

Breath-holding at end expiration

Answer

Mechanical ventilation at high PEEP

Question 5

A patient's ECG shows a P wave in every beat, upright in lead II, with a constant PR interval of 220 ms and a rate of 72 bpm. What is the correct interpretation?

Accepted Answer

Normal sinus rhythm with first-degree AV block

Answer

Normal sinus rhythm without any abnormality

Answer

Sinus bradycardia with first-degree AV block

Answer

Junctional rhythm

Question 6

Hyperthyroidism most commonly affects sinus rhythm by causing which finding?

Accepted Answer

Sinus tachycardia or atrial fibrillation

Answer

Sinus bradycardia

Answer

Third-degree AV block

Answer

Ventricular tachycardia