sinus rhythm
regular rhythm
Set by SA node at 60 to 100 bpm
P waves normal
normal qrs
PR 0.12 - 0.2
normal qrs less than 0.10
wide qrs is
greater than 0.12
Sinus Tachycardia
100-160 bpm
SA node
reduced time for ventricle filling
assess for SOB or chest pain
a prolonged QT ...
Cardiology Nursing 1 Humber Final exam 302 questions and answers(including diagrams)
sinus rhythm
regular rhythm
Set by SA node at 60 to 100 bpm
P waves normal
normal qrs
PR 0.12 - 0.2
normal qrs less than 0.10
wide qrs is
greater than 0.12
Sinus Tachycardia
100-160 bpm
SA node
reduced time for ventricle filling
assess for SOB or chest pain
a prolonged QT interval
more prone to arrhythmia NSR reflects the heart's
normal electrical activity, providing synchrony between the atria and the ventricles.
Sinus tachycardia occurs when the
sinus node discharges impulses too fast (100 - 160 beats/minute). All other parameters are normal
Facts about sinus tachycardia
Normal response of heart in certain circumstances (for example exercise)
•Begins and ends gradually in contrast to other tachycardias
•Usually benign arrhythmia that goes away when underlying cause is treated
•Common causes: Anxiety, hypoxia, hypovolemia, hypotension, heart failure, pain, drugs that increase sympathetic tone (epinephrine, norepinephrine, dopamine, dobutamine, isoproterenol, nitroprusside), and drugs that decrease parasympathetic tone (atropine)
•Persistent sinus tachycardia may result in decreased cardiac output due to a decrease in stroke volume. Cardiac output = stroke volume ×heart rate. A decrease in either stroke volume or heart rate may result in a decrease in cardiac output.
Sinus bradycardia occurs when
the sinus node discharges impulses too slow (40 - 60 beats/minute). All other parameters are normal.
Sinus bradycardia features
regular rhythm, rate 40-60 bpm
Normal p waves PR interval normal 0.12 to 0.2
QRS normal less than 0.1
Facts about sinus bradycardia
Normal response of heart in certain circumstances (for example relaxation, sleep)
•Most common arrhythmia associated with acute inferior wall myocardial infarction
•Other causes: Reperfusion rhythm following myocardial reperfusion procedures (thrombolytic administration, angioplasty); vagal stimulation; sleep apnea; hyperkalemia; increased intracranial pressure; disease of SA node; and administration of drugs, such as digitalis, calcium channel blockers, and beta blockers
•Persistent bradycardia may result in decreased cardiac output due to a decrease in heart rate. Cardiac output = stroke volume ×heart rate. A decrease in either stroke volume or heart rate may result in a decrease in cardiac output.
Treatment of sinus bradycardia
No treatment is necessary if patient is asymptomatic.
•Symptomatic bradycardia is initially treated with oxygen and atropine IV push. If unsuccessful, external pacing or transvenous pacing may be used.
•Chronic sinus bradycardia may require a permanent pacemaker.
Sinus arrhythmia occurs when
the sinus node discharges impulses irregularly. The heart rate may be normal range or slow. All other parameters are normal.
Sinus arrhythmia ECG features
irregular rhythm
rate normal or slow
P waves normal
PR interval normal 0.12 to 0.20
QRS normal less than 0.1 Facts about sinus arrhythmia
Normal phenomenon usually associated with phases of respiration (heart rate increases with inspiration and decreases with expiration)
•Most commonly observed in infants, children, and young adults, although it may occur in any age-group
•Frequently occurs along with sinus bradycardia, in which case it is usually called sinus arrhythmia with a bradycardic rate
•Treatment: Does not require intervention unless accompanied by symptomatic bradycardia (follow symptomatic bradycardia protocols)
Sinus pause
A broad term used to describe a sudden pause in the basic rhythm with one or more missing beats; two rhythms fall under this category:
Sinus arrest and Sinus exit block
sinus arrest
SA node fails to initiate impulse; represents a problem with SA node automaticity; basic rhythm does not resume on time following pause.
Sinus exit block
SA node initiates impulse, but impulse is blocked as it exits SA node; represents a problem with SA node conductivity; basic rhythm resumes on time following pause.
Sinus arrest and sinus exit block ECG
Rhythm: basic is regular with sudden pause with one or more missing beats, HR may slow for several beats after pause but then return to basic rate.
P waves: sinus with basic rhythm, absent during pause
PR interval: normal during basic, absent during pause
QRS normal during basic, absent during pause
Sinus block: basic rhythm resumes on time after pause
Sinus arrest: basic rhythm does not resume on time after pause
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