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Cardiac Rhythm
• “Until the day Jesus returns, I will live in a
body which does not function as God
originally intended. My brain, which is a key,
central, integral part of my body, will not
function correctly. Chemicals will become
imbalanced. Serotonin will not be properly
absorbed. Norepinephrine will be unevenly
distributed. Synapses won’t fire correctly. My
brain, just like every other part of my body, is
prone to illness.”
Sinus Rhythm
- 6 second strip
qrs times 10 = heart rayr
Sinus Rhythm
Atrial Fibrillation
A-Fib – no p wave
Atrial Flutter – fluttering of p waves
Supra Ventricular – heart is beating
fast and the heart can’t fill and the
heart can’t pump
First Degree
Atrioventricular block
1° AV Block – p waves are far away
from qrs
Third Degree
Atrio Ventricular Block
3° AV Block – p waves completely
dissociated from qrs complexes
Ventricular Tachycardia
V-Tach – qrs complexes are wide, one
ventricle must be stimulating the other
Ventricular Fibrillation
V-Fib
VF – no qrs complexes, common rhythm in cardiac
arrest
Cardiac Muscle Cell
• The cardiac muscle cell can repeatedly
contract or beat by itself
Cardiac Muscle Cell
• Na+ Ca2+ K+ Cl• The cardiac muscle cell requires these ions
and their membrane channel
Charged and Ready
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The Na+/K+ pump creates:
- sodium concentration gradient
- more outside than inside
- potassium concentration gradient
- more inside than outside
The Na/Ca pump creates
- calcium concentration gradient
Action Potential
• Step 1 sodium channels open
• Sodium rushes in, causing a voltage change
across the membrane
Action Potential
• Step 2 calcium channels open
• Calcium rushes in, causing muscle contraction
• Na channels are closing now
Action Potential
• Step 3 potassium channels open
• Potassium ‘resets’ the membrane by rushing
out until the membrane is charged and ready
for another action potential
Cardiac muscle cell
• Each separate cardiac muscle cell can
repeatedly contract or beat by itself, at it’s
own pace.
Fibrillation
• When the cells beat separately and on their
own, this is called fibrillation
Fibrillation
• When the ventricles, the main pumps, are
fibrillating there can be no heart beat
Synchrony
• It is important that the cells work together
Conduction Pathway
• Certain specialized heart muscles help
conduct the signals and maintain synchrony
Conducting System of the Heart
Picture
Atrio-Ventricular Node
R-Atrium Picture
• Sympathetic Neuron
• NE – norepinephrine
• Increased HR
• Parasympathetic Neuron
• Ach
• Decreased HR
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P wave – atrial excitation
- think of it as lighting the fuse
QRS wave – ventricular excitation
- think of it as the BANG!
T wave – ventricular repolarization
- think of it as the RESET
What do we do in V-fib?
• Chest compressions is the first round of
treatment for V-fib
• 100 beats/minute
Pulseless arrest
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BLS Algorithm: Call for help, give CPR
Give oxygen when available
Attach monitor/defibrillator when available
Allow for full recoil using chest compressions
• Oxygen is a drug
• - most important drug in pediatric arrhythmia
• Use Bag valve mask or ambu bag
Bag Valve
Ambu Bag
VF/VT – pulseless
• Give 1 shock
• Manual biphasic: device specific (typically 120
to 200J)
• AED: device specific – automatic external
defibrillator
• Monophasic: 360J
• Resume CPR immediately
• Stand clear
• Shock!
Fibrillation
• By applying a large electrical shock sometimes
we can convert fibrillation into a perfusing
rhythm – synchrony
• So must do chest compressions, oxygen,
electricity
Defibrillation
• Applying a shock to the heart is called
defibrillation
• V-fib – oxygen is one of the greatest antiarrhythmic drugs
• Resume CPR immediately after the shock
• When the IV is available, give vasopressin
during the procedure (before or after the
shock)
• Epinephrine 1mg IV
• Repeat every 3 to 5 mins or may give 1 dose of
vasopressin 40IV to replace first or second
dose of epinephrine
• Epinephrine produces beneficial effects in
patients during cardiac arrest primarily
because of it’s α-adrenergic stimulating
vasoconstrictive properties
• Vasopressin – is a nonadrenergic
vasoconstrictor
• Vasopressin is also called Anti-Diuretic
Hormone (ADH) and is released by the
posterior pituitary of the brain
• Resume CPR immediately after the shock
• Consider antiarrhythimics, give during CPR
(before or after the shock)
• - amiodarone
• - lidocaine
• Lidocaine is a “Class 1” antiarrhythmic
• It is a sodium channel blocker in heart muscle
slowing down heart contraction
• Amiodarone
• Is a “Class 3” antiarrhythmic
• It is a: sodium channel blocker, potassium
channel blocker, calcium channel blocker, α &
β adrenergic blocker
V-Fib interventions
• Chest compressions
• Oxygen
• Shock!
V-Fib Drugs
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Epinephrine
Vasopressin (ADH)
Lidocaine
Amiodarone
Do not confuse
• Ventricular fibrillation – cardiac arrest
• Atrial fibrillation – the ventricles are still
beating – will have a pulse, irregularly
irregular ECG, will have tachycardia – you may
call this as atrial fibrillation with rapid
response
A-fib
• Major cause of strokes
• Major reason to give coumadin
• Don’t want to convert A-fib to SR (sinus
rhythm) until we know there is no thrombus
A-Fib
• Stable
• Unstable
Digoxin Lanoxin
• Digitalis glycoside
• Blocks Na/K ATPase increasing calcium
availability
• Antiarrhythmic
• Positive Inotrope
• Negative Chronotrope
• Slows AV conduction
Digoxin Risks
• Arrythmia
• Toxicity with hypokalemia
Supra Ventricular Tachycardia ECG
Picture
SVT
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A-Fib RVR – rapid ventricular rate
- Control ventricular rate
- Β-blockers (Class 2)
- Calcium channel blokcers (Class 4)
- verapamil
- diltiazem
Adenosine
• Endogenous nucleotides which slows
conduction through the AV node
• IV antidysrythmic used in PSVT – paroxysmal
supra ventricular tachycardia
SVT
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Adenosine
- safe
- “reset” AV node
- stops heart beat for about 6 secs
- 6 very long seconds……
Will not reverse a-fib a-flut
• Atrial flutter – treat the same as a-fib
First Degree AV Block ECG Picture
Third Degree AV Block ECG Picture – p
waves completely dissociated from qrs
complexes
Bradycardia
• Bradycardia means low heart rate
• Bradycardia is heart rate less than 60
• Relative bradycardia means heart is beating
too slow just to keep up with demand
Bradycadia
• Stable
• Unstable
Bradycardia
• Atropine
• - cholinergic blocker
• Epinephrine
• - adrenaline
Procaine – similar to Lidocaine
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Procainamide
- sodium channel blocker
- watch for hypertension
- lupus-like adverse effects when taken
chronically