1. Sinus Dysrhythmia
Same as NSR except for slight irregularity of the heart rhythm
Rate of impulse formation in SA node may vary with respirations
P-to-P and R-to-R intervals change with respirations
Increases with inspiration and decreases with expiration

2. Sinus Dysrhythmia
Should be a difference of at least 0.8 seconds between shortest and longest R-R intervals
Common and normal finding
Causes may include MI, Sick Sinus Syndrome, and administration of certain drugs, i.e., digitalis
Varies with respirations

3. Sinus Dysrhythmia

4. Sinus Dysrhythmia

5. Sinus Arrest Rhythm SA node fails to initiate an impulse
Absence of a PQRST complex is noted on rhythm strip
Causes a slight period of cardiac standstill
Lasts until sinus node continues its normal function

6. Sinus Arrest Rhythm
Causes include hypoxia, ischemia, damage to the SA node, or administration of certain drugs such as digitalis or salicylates
Also occurs as result of acute MI
These occurrences are infrequent
Patient assessment is imperative

7. Sinus Arrest Rhythm

8. Sinus Arrest Rhythm

9. Clinical Significance of Sinus Rhythms
Associated with assessment of patients
If patient is experiencing chest pains, dizziness, weakness, fainting, markedly decreased blood pressure, or altered level of consciousness = symptomatic or medically unstable

10. Sinus Bradycardia
If heart rate falls significantly, cardiac compromise may occur
Symptomatic
Signs of decreased cardiac output
Treatment
Oxygen, IV access line, administration of drugs (atropine), or TCP

11. Sinus Tachycardia
Cardiac output may fall < 150 due to inadequate ventricular filling time
Myocardial oxygen demand increases
Can precipitate myocardial ischemia or infarct
Treatment
Aimed at finding and treating cause

12. Sinus Dysrhythmia
Considered a normal alteration in heart rhythm, especially in young children and elderly adults
Usually does not require emergency treatment

13. Sinus Arrest
If patient is asymptomatic (medically stable) episodes occurring occasionally, observation may be done
If patient is bradycardic and symptomatic (medically unstable) may need oxygen, IV, drug therapy, and/or TCP

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