Chapter 7: Sinus Rhythms
What three things can cause an arrhythmia?
A disturbance in (1) automaticity (2) conduction (3) a combination of the 2
Is sinus arrhythmia normal?
A normal variation in heart rhythm (can happen during sleep and be perfectly fine) Everything normal but the rhythm
Besides medicine, what else manages sinus bradycardia?
A pacemaker -- if the sinus node is diseased they can put in a pacemaker
What interrupts the rhythm in a sinus block?
A pause
What is a sinus node rhythm?
A rhythm that begins in the SA node
In a sinus arrhythmia what causes an increase or decrease in heart rate?
Increase: with inspiration Decrease: with expiration
How can you tell the difference between a sinus block and sinus arrest?
R-R interval will fall where you expect it to if you continue it if it is a sinus block, it will not if it is an arrest
What is the cardinal rule?
REMEMBER!! Treat the patient, not the monitor.
What occurs in hypothermia to the heart?
Slows down the heart rate
Anytime you have a rhythm interrupted, what method do you want to use to get your rate?
Small or big box method
How should you check the rate of a sinus block?
Small or big box method
What can occur if the heart rate get above 140?
diastole shortens so there is less time for ventricular filling, we are depolarizing so quickly that there is less blood being filled up, less blood being ejected, and decreased cardiac output
If it originates in the atria,
it is not one of the back up pacemakers
What does NSR stand for as an EKG abbreviation?
normal sinus rhythm
Symptoms of a sinus block depend on the
number and length of pauses
Management of a sinus block depends on
number and length of pauses, s/s of decreased cardiac output can let you know
Initial management of a sinus block/arrest:
pacemaker
An arrhythmia is a disturbance in _______ or _________
rate or rhythm
Normal sinus rhythm (NSR) is the
standard against which all other rhythms are compared
In a NSR, the P wave is
upright in Lead II
In a NSR, the rate is
60 - 100
What is the rate in a sinus arrhythmia?
60 - 100
In NSR, the QRS is
< .12
Sinus bradycardia
<60 bpm
Sinus Tachycardia
>100 bpm
Which node is in control in sinus bradycardia?
The sinus node is the pacemaker
Arrhythmias are named according to their origin first and then the ____________ of the arrhythmia
"mechanism"
What are four characteristics of sinus node rhythms?
1. Positive (upright) P wave before each QRS 2. P waves that look alike 3. Constant PR intervals 4. Regular atrial and ventricular rhythm (usually)
Sinus tachycardia has ah heart rate of
101-160 (sinus node will not go above 160 on its own)
At rates > ______, diastole shortens so there is less time for ventricular filling
140
In NSR, the PRI is
.12 - .20
What is an arrhythmia?
Any disturbance in heart rate or heart rhythm
What causes the variation of sinus arrhythmias?
Associated with respiration
What three medications are given for sinus bradycardia?
Atropine Dopamine Epinephrine (Just need to know that there are medications, not which ones to give for what)
Sinus arrhythmias: Sinus ________________ Sinus _______________ Sinus _______________ Sinus ________/________
Bradycardia Tachycardia Arrhythmia Arrest/Block
What are the different "mechanisms"?
Bradycardia Tachycardia Fibrillation Flutter Premature beats Escape Beats
How do we know if a sinus bradycardia is hurting the patient?
Check for s/s of decreased cardiac output
Why is decreased urine output indicative of sinus bradycardia?
Decreased cardiac output --> low pressure to kidneys --> low filtering --> decreased output
________________ and arrhythmia are synonymous terms.
Dysrhythmia
Describe conduction in sinus tachycardia.
Each impulse is conducted normally to the ventricles
Describe the conduction of an impulse in sinus bradycardia.
Each impulse is conducted normally to the ventricles
Why is there an increase oxygen demand?
Heart is beating fast but not a lot of blood is being put out per beat
What are four causes of a sinus block/arrest?
Hypoxia, ischemia, medications, or diseased sinus node
What is the heart rhythm in sinus arrhythmias?
Initiates an impulse irregularly
What is the rate of a sinus bradycardia?
It initiates an impulse regularly at a rate of less than 60 times per minute.
What is the heart rate in sinus tachycardia?
It initiates an impulse regularly at a rate of more than 100 times per minute.
Signs/Symptoms of Decreased Cardiac Output: Changes in ________ Changes in skin _______/_______________ Diaphoresis Chest _______ ___________ of Breath Syncope _______tension Signs of _____
LOC color/temperature Pain Shortness Hypo HF
What are some of the common causes of arrhythmias?
Myocardial ischemia Autonomic nervous system imbalances Hypoxemia Electrolyte imbalances Electrocution Hypothermia Medications
What arrhythmia would stimulants cause?
Sinus tachycardia
Sinus arrhythmia: P wave: PRI: QRS:
P wave: upright in Lead II PRI: .12 - .20 QRS: < .12
Sinus Tachycardia: Rate: Rhythm: P wave: PRI: QRS:
Rate: 101 - 160 (150) Rhythm: Regular P wave: upright in Lead II PRI: .12 - .20 QRS: < .12
Sinus block: Rate: Rhythm: P wave: PRI: QRS:
Rate: 60 - 100 Rhythm: Regular but interrupted (by a pause) P wave: upright in Lead II PRI: .12 - .20 QRS: < .12
Sinus Bradycardia: Rate: Rhythm: P wave: PRI: QRS:
Rate: <60 Rhythm: Regular P wave: upright in Lead II PRI: .12 - .20 QRS: < .12
In a NSR, the rhythm is
Regular
What is the rhythm in a sinus arrhythmia?
Regularly irregular (irregular in a repetitive pattern rhythm)
Is a sinus arrhythmia associated with the rhythm or rate of the heart?
Rhythm
What are three signs of HF?
SOB, Pulmonary Congestion, 3rd and 4th heart sound, etc.
Where are the four different sites of origin?
Sinus Atrial Junctional Ventricular
What arrhythmia would hypothermia cause?
Sinus Bradycardia
What arrhythmia would parasympathetic (Vagal) stimulation cause?
Sinus Bradycardia
What are the four different sinus arrhythmias?
Sinus Bradycardia Sinus Tachycardia Sinus Arrhythmia Sinus Arrest/Block
What arrhythmia would a diseased SA node cause?
Sinus Bradycardia Sinus Block/arrest
What arrhythmia would medications cause?
Sinus Bradycardia Sinus Block/arrest
What arrhythmia would hypoxia cause?
Sinus Bradycardia Sinus Block/arrest (hypoxia around the SA node)
What arrhythmia would ischemia cause?
Sinus Bradycardia Sinus block/arrest
What does NSR mean?
Sinus node initiates regular impulses at a normal rate. Each impulse is conducted normally to the ventricles. Pacemaker: Sinus node Rate: 60-100 Regularity: regular Conduction: normal, each impulse is conducted through to the ventricles
What arrhythmia would anxiety/fear cause?
Sinus tachycardia
What arrhythmia would exercise cause?
Sinus tachycardia
What arrhythmia would hypovolemia cause?
Sinus tachycardia
What arrhythmia would infection cause?
Sinus tachycardia
What arrhythmia would pain cause?
Sinus tachycardia
Which node fires in a sinus arrhythmia?
The sinus node
Which node is the pacemaker in sinus tachycardia?
The sinus node
What causes a sinus block or sinus arrest?
The sinus node either fails to initiate an impulse or the impulse is blocked as it exits the sinus node
What is there a increased demand for in sinus tachycardia?
There is an increase in myocardial oxygen demand
What are arrhythmia classified according to FIRST?
To their site of origin (where it is firing from)
How is sinus tachycardia treated?
Treat the Cause
What do we want to find out if a patient is in sinus bradycardia?
What are the hemodynamic consequences of the arrhythmia? OR "Is it making the patient sick?" They may just be an athlete
Is decreased urine output indicative of sinus bradycardia?
Yes
An abnormal heart rhythm is called
an arrhythmia
