Sinus Rhythms

Question 1

Key Points of Normal Sinus Rhythm

Answer 1

HR: 60-100 bpm
Rhythm: Regular
P-wave upright in Lead II, precedes every QRS complex
PR Interval: 0.12-0.20s
QRS Complex: <0.12s

Question 2

Key Points of Sinus Arrhythmia

Answer 2

HR: 60 – 100 bpm, may be slower
Rhythm: IRREGULAR (R-R or P-P interval not consistent)
P-wave upright in lead II, precedes eachQRS
PR interval: 0.12 - 0.20 sec
QRS Complex: <0.12 sec

Question 3

Cause of Sinus Arrhythmia

Answer 3

Intrathoracic pressure changes that coincide with respirations (inhale= increased pressure, increased HR. exhale= decreased pressure, decreased HR)

Question 4

Sinus Arrhythmia is concerning and often treated. TRUE/FALSE

Answer 4

FALSE

Question 5

Requirement for Sinus Bradycardia

Answer 5

Heart Rate <60 bpm

Question 6

Excluding heart rate, normal sinus rhythm and sinus bradycardia share the same characteristics. TRUE/FALSE

Answer 6

TRUE

Question 7

Symptoms of sinus bradycardia

Answer 7

Fatigue

Dizziness

Question 8

SA node fails to fire – no depolarization – no p-wave

Answer 8

Sinus Pause

Question 9

What is it called when a sinus pause lasts longer than 3 seconds?

Answer 9

Sinus Arrest

Question 10

TRUE/FALSE

A sinus pause will reset the rhythm

Answer 10

TRUE

Question 11

Name 3 ways a sinus pause will terminate

Answer 11

1 - SA node fires again - another p-wave and normal QRS will result
2 - SA node fails - junctional escape beat or ventricle escape beat
3 - no beat generated - sinus arrest ensures

Question 12

Are sinus pauses regularly symptomatic? What length do they need to be to usually be noticeable?

Answer 12

Often asymptomatic. Pauses ~4 sec may be symptomatic. symptoms usually dizziness and syncope

Question 13

rhythm in sinus pause/arrest

Answer 13

Irregular d/t pause (underlying rhythm may be regular)

Question 14

normal rate in sinus pause/arrest

Answer 14

40-100 bpm

Question 15

Regular PR Interval

Answer 15

0.12-0.20s

Question 16

Difference between sinus pause and sinoatrial block

Answer 16

• pause initially looks the same
• SA node generates impulse but it is blocked from transmission to atrial tissue
• SA node continues to fire so when conduction resumes the rhythm will continue as NSR
• SA block: pause length will be a multiple of the R-R interval