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Basic Dysrhythmias. Chemeketa Paramedic Program -Basic Anatomy of the Heart -Electrical Conduction of the Heart -A System of Defining 3-Lead EKG’s. What is an:. EKG? ECG? EEG? EGG? Isn’t School Great?. Heart A & P. Location Pieces, Parts Important Vessels Electrolyte Role - PowerPoint PPT Presentation
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Basic Dysrhythmias
Chemeketa Paramedic Program-Basic Anatomy of the Heart
-Electrical Conduction of the Heart
-A System of Defining 3-Lead EKG’s
What is an:
EKG? ECG? EEG? EGG?
Isn’t School Great?
Heart A & P
Location Pieces, Parts Important Vessels Electrolyte Role Pulling apart
waveforms
Valves & Vessels
Review of Important Vessels
A System of Checks & Balances
Baroreceptors (Pressoreceptors)– Found:
Internal carotid arteries Aortic Arch
Chemoreceptors– Found in same places
– Monitors pH, O2 & CO2
Respond by:– Stimulating sympathetic
Adrenergic response Alpha, Beta & Dopaminergic Norepi & Epi release
– Inhibiting Parasympathetic Acetylcholine
– Cholinergic Response
– Medulla Regulatory organ
Electrical Conduction System Sympathetic-Thoracic/Lumbar Nerve
– Norepinephrine HR, Contractility
Parasympathetic-Vagus Nerve– Acetylcholine
HR (Valsalva)
Chronotropic-HR
Inotropic-Contraction
Electrolytes & Conduction
“Excitable” cells of the Heart
Self-depolarizing cells (Automaticity)
Electrolytes of the Heart (Na+ / K+/ Ca++)
Electrolytes & Conduction
Membrane Potential (MP)– Slight difference between charge inside & out
Threshold– MP becomes high enough to depolarize
Action Potential– Ability of cells at a given time– Difference (mV) between inside & out
The Cardiac Cycle
Membrane Potential
Sodium-Potassium MP Rises
– Na+ Channels Open– Rapid Influx (Fast Channels)
Cell Attains + Charge– K+ Channels Open– Outflow
The Pump– ATP Transports:– 3 Na+ out & 2 K+ in– Restores Resting cellular
conditions
Calcium– Slow Channels– Selective Permeability
“The Wave”– One cell contraction
Spreads
Electrical Conduction System
Na+ - Depolarization K+ - Repolarization
– > = < Automaticity & Conduction– < = > Irritability
Ca++ - Depolarization and Contraction– > = > Contractility– < = < Contractility, > Irritability
Electrical Conduction System
Na+ in & K+ out = Depolarization K+ in & Na+ out = Repolarization
– Imbalances in K+ or Na+
Effects Automaticity & Conduction Hypo & hyperkalemia affects irritability
Ca++ - Depolarization and Contraction– Affects Contractility– Hypo & Hypercalcemia effects contractile force
I know what you’re thinking…Who gives a @#$% !!! You are caring for a patient with a rapid heart rate. You
follow protocols and administer 20mg of Diltiazem.– You’re patient responds by becoming:
Less responsive Bradycardic B/P drops to 72/40 Weak Pulse at wrist Not responding to fluid, time or positioning.
What now??? Calcium Gluconate 10%
– 500 – 1000 mg slow IV Push
@#$% = Dang
Phases
Phase 0 – Rapid Depolarization– Reached max potential -90mV– Fast Na+ Channels Open– Cell now positive +25mV
Phase 1 – Early Rapid Repolarization– Fast Na+ Channels Close– K+ still being lost– MP approaching 0mV
Phase 2 – Prolonged Slow Repolarization– Plateau Phase– Muscle finishing contraction– Beginning to relax– MP staying close to 0mV
Phases
Phase 3 – End of Rapid Repolarization– K+ returns to inside– Cell returns to -90mV– Almost ready
Phase 4– Na+ - K+ Pump turns on
Sends Na+ out Brings K+ in
Ready to do it all over again now
Refractory PeriodsExcuse me!!! I hate to interrupt again, but, who cares???
Absolute Refractory Period– Polarity of cell prohibits depolarization
Relative Refractory Period– Cell is returning to ready state for
depolarization– Impulse now is BAD!!!
R on T Phenomenon– Causes VT & VF– Treated with defibrillation
Can be caused by:– Frequent FLB’s– EMT-P not pushing the “sync”
button
The Electrocardiograph (ECG, EKG)
Electrical Activity– Not Heart Action
Records + and – impulses Paper runs at 25mm/s Counting Rates
– 300-150-100-75-60-50– 6 second strip x 10– 10 Second Strip x 6– The little number on the monitor
Lead Considerations
$25,000 mVoltmeter– Lead Views:
1 – Lateral 2 – Inferior 3 – Inferior
The Components
SA Node Internodal Pathways AV Junction AV Node Bundle of His L & R Bundle Branch Purkinje Network Purkinje Fibers
Ode to a Node
Have a heart, and have no fear,The SA node is over here.Beating at a constant rate,60 – 100 is really great.
The AV node can make a show,If SA node has gone too slow.
40 – 60 is not too badIf it’s all you’ve got, you will be glad.Should the whole thing drop it’s speed,
His and bundle branches will take the lead.And that, my friend is the whole and part,Of the conduction system of your heart.
– Flip and See ECG, Cohn/Gilroy-Doohan
Sino Atrial Node
The Natural “Pacemaker”– Connects directly
to atrial fibers
Fires 60-100 times per minute Wavelike Atrial Depolarization The P-Wave P-Wave
P-R Interval
Q-Wave
.04 Sec .04 Sec .04 Sec .04 Sec .04 Sec
0.20 Seconds per 5 Boxes
AV Junction
Receives impulses from SA Node via the Atrial Cells– An electrical funnel– Impulses hit at various times– Causes delay
PR-I
– Susceptible to blockage Path from A to V
– Delivers impulse to the AV Node
Atrio-Ventricular Node
Lies between the Atria and Ventricles
Collects impulses from above
Stimulates Ventricles If unstimulated
– Intrinsic rate 40-60
Bundle of His / Left and Right Bundle Branches
Distributes Impulses from the Node “The Ventricular Messengers”
Purkinje Network/Fibers
Direct connection with ventricular tissue
Intrinsic rate 20-40 if unstimulated
P-Wave
P-R Interval
QRS Complex
T-Wave
P-Wave
P-R Interval
QRS Complex
T-Wave
Q
R
S
PRI
Baseline
The Six Step Approach
What is the Rate? Is the Rhythm Regular? Are there P-Waves? Is the P-R Interval Normal? Is the QRS Complex Normal? Is There a P-Wave for Every QRS?
Step 1 = Rate
Is the rate between 60-100 (Sinus) Between 40-60 (Junctional/Bradycardic) Above 100 (Tachycardic) Between 20-40 (Ventricular)
Step 2 = Regularity
At-a-glance: Does it look regular? Are the P-Waves evenly spaced? Are the QRS Complexes evenly spaced?
Step 3 = P-Waves
Are P-Waves present? Are they upright and rounded? Are they irregular in any way: Notched /
Peaked / Depressed…? Are they all the same?
Step 4 = P-R Interval
Is the P-R Interval between 0.12-0.20? Is it too long / too short? (Block) Is it the same on every conduction? Is it absent?
Step 5 = QRS Complex
Is it there? Is it between 0.04 - 0.12? Does it have any abnormalities? (Notched /
Rabbit Eared / Wide / Bizarre)
Step 6 = P-QRS Married?
Is there a P-wave for every QRS? Are there more P-Waves than QRS? Are the P-Waves after or within the QRS?
Describe What You’ve Found!!!
IN GENERAL (underlying rhythms)!!! What are the abnormalities? Does it originate in the Sinus Node? Does it follow through from the Atria to the
ventricles? Are there abnormal delays? What are the exceptions to the underlying
rhythm? (Describe those also)
EKG INTERPRETATION CHART
RHYTHM RATE REGULARITY P-WAVE (U/R) P-RINTERVAL
QRS P-QRSMARRIED
NSR 60-100 Regular Normal/Upright/Rounded
0.12-0.20 sec. 0.04-0.12
Yes
SinusTachycardia
Above100
Regular Normal/Upright/Rounded
0.12-0.20 sec 0.04-0.12
Yes
SinusBradycardia
Below 60 Regular Normal/Upright/Rounded
0.12-0.20 sec 0.04-0.12
Yes
SinusArrhythmia
60-100 Irregular Normal/Upright/Rounded
0.12-0.20 sec 0.04-0.12
Yes
AtrialFibrillation
UsuallyTachy
Irregular Not Discernible Not Discernible 0.04-0.12
NotDiscernible
Atrial Flutter May beNormal /Tachy
Atria-regular/Ventricles-regular or irregular
Sawtooth pattern,2:1, 3:1, 4:1 ratios
0.12-0.20 on theconducting beat
0.04-0.12
On theconductingflutter wave
(P)SVT 140-220 Regular In QRS/T complexor not present
Shortened orabsent
0.04-0.12
No
1st DegreeBlock
Normal Regular Normal/ Upright/Rounded
Longer than0.20
0.04-0.12
Yes
2nd Degree(Type 1)Wenckebach
Normalor Brady
Irregular Normal/Upright/Rounded
Lengtheninguntil beat isdropped
0.04-0.12
No
2nd Degree(Type 2)Mobitz II
Brady Irregular Normal/Upright/Rounded 2:1, 3:1, 4:1
Normal or longon conductedbeats
0.04-0.12
On theconducting P-Wave
3rd DegreeCompleteHeart Block
40-60 Atria-RegularVent.-Regular
Normal/Upright/Rounded
Atriaindependent ofVentricles
Usuallygreaterthan0.12
No
Junctional(accel/tach)
40-60(60+/100+)
Regular Inverted/Retrograde/Absent
Short/ Normal/Absent
0.04-0.12
Yes-if P-waveis visible
VentricularTachycardia
100-220 Usually Regular Not Discernible(usually)
Not Discernible Greaterthan0.12
No
VentricularFibrillation
Rapid/Chaotic
Irregular Not discernible NotDeterminable
Wide/Bizarre
No
Asystole 0 N/A None None None NoAgonalIdioventricular
20-40 Irregular None None Wide No
-PVC-Wide, Bizarre QRS Complex, Look at underlying rhythm. Can appear in couplets, triplets, or short runs of VT. Canbe multi-focal or uni-focal. Caused by random firing within the ventricles. No atrial firing.-PAC-Conducted beat appearing in an otherwise normal rhythm. Stimuli originates within the atria, but not in the SA.-If Bundle Branch Block occurs, QRS will usually be wider than 0.12.
Normal Sinus Rhythm Rate: 60 - 100 Regularity: Very P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages
Sinus Arrhythmia Rate: 60 - 100 Regularity: Irregular P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages
Sinus Tachycardia Rate: Over 100 Regularity: Regular P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages
Sinus Bradycardia Rate: Less than 60 Regularity: Regular P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages
Atrial Fibrillation Rate: Usually tachy Regularity: Irregular (Irregularly irregular) P-Waves: Not Discernible P-R I: Undeterminable QRS: 0.04-0.12 sec Married: Undeterminable
Atrial Flutter Rate: Usually tachy Regularity: Atria Regular
• Ventricles May be Irregular
P-Waves: Sawtooth Pattern 2:1, 3:1, 4:1... P-R I: 0.12-0.20 sec on conducting beat QRS: 0.04-0.12 sec Married: P-waves outnumber QRS
(Picket fence)
(Paroxysmal) Supra Ventricular Tach Rate: 140-220
Regularity: Regular P-Waves: Usually falls within the QRS-T
complex ( sometimes not visible) P-R I: Shorter than 0.12, or absent QRS: 0.04-0.12 sec and Normal Married: Undeterminable
SVT WPW
– Usually based on Hx.– Delta wave on Q– Shortened PR-I– No Verapamil – Accessory Path use increase
1st Degree Heart Block Rate: 60 - 100 Regularity: Very P-Waves: Present and Normal P-R I: Longer than 0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages
2nd Degree Heart Block (Type 1) Wenkebach
Rate: Can be Normal, or usually brady Regularity: Irregular P-Waves: Present and Normal P-R I: Lengthens until beat is dropped QRS: 0.04-0.12 sec and Normal Married: P-wave present on conducting beats,
increased delay causes missed QRS
2nd Degree Heart Block (Type 2)Mobitz II Rate: Less than 60
Regularity: Irregular P-Waves: Present, 2:1, 3:1, 4:1 P-R I: 0.12-0.20 sec on conducting beat QRS: 0.04-0.12 sec, may begin to widen Married: P-wave for every QRS and extras
depending on conduction ratio
3rd Degree Heart Block (CHB)Complete Heart Block
Rate: Ventricular Rate 40-60 Regularity: Atria-Regular
• Vent-Regular P-Waves: Present and Normal P-R I: Atria independent of Ventricles QRS: Usually greater than 0.12 sec Married: P-waves completely unrelated to QRS
Complexes.
Complete Heart Block
Junctional Rhythm Rate: 40-60 Regularity: Regular P-Waves: Inverted, Retrograde or Absent P-R I: Shortened or absent QRS: 0.04-0.12 sec Married: P-wave for every QRS, sometimes not
visible
Junctional
Junctional Accelerated Rhythm
Rate: 60-100 Regularity: Regular P-Waves: Inverted, Retrograde or Absent P-R I: Shortened or absent QRS: 0.04-0.12 sec Married: P-wave for every QRS,
sometimes not visible
Accelerated Junctional
Junctional Tachycardia
Rate: 100-140 Regularity: Regular P-Waves: Inverted, Retrograde or Absent P-R I: Shortened or absent QRS: 0.04-0.12 sec Married: P-wave for every QRS,
sometimes not visible
Junctional Tachycardia
Ventricular Tachycardia Rate: 100-220 Regularity: Regular P-Waves: None P-R I: None QRS: Greater than 0.12 sec Married: NO
We’ll look at Torsades de Pointes in Lab
Ventricular Tachycardia
Ventricular Fibrillation Rate: No ventricular rate Regularity: Irregular P-Waves: No P-R I: No QRS: No, unorganized ventricular baseline Married: No
Ventricular Fibrillation
Asystole
Rate: 0 Regularity: N/A P-Waves: None P-R I: N/A QRS: None Married: No (verify a second lead)
Asystole
Agonal / Idioventricular
Rate: 20-40 Regularity: Irregular P-Waves: None P-R I: N/A QRS: Wider than 0.12 sec Married: NO (a dying heart)
Idioventricular
Less regular than this!
Exceptions / Disruptions
Premature Ventricular Contractions Premature Atrial Contractions Bundle Branch Blocks Pacer Considerations (Atrial, Ventricular or
Both)
Premature Ventricular Contractions
Wide, Bizarre QRS Complex Always identify the underlying rhythm first Can appear in couplets, triplets, short runs of
V-Tach, bigeminy and trigeminy Can be uni-focal or multi-focal Caused by random firing within the ventricles Not accompanied by a P-wave
PVC’s
PAC’s P-QRS Complex
appearing in an unexpected location
Caused by a stimulus from within the Atria, but not from the SA Node
PJC
Bundle Branch Block
Any rhythm having a BBB will have a widened twin peaked R-Wave
Paced Rhythms
Patients may have various types of pacemakers
Atrial Ventricular Both Vertical spike on monitor is an indicator
Paced Rhythms Various
Artifact
60 Cycle Interference
Loose Leads/Moving Ambulance
In Summary
Really Cool Physiology!!! GENERAL RULES to Interpretation
– Applicable to 3 – lead monitoring Practice, Practice, Practice… Remember the rules, NOT how it looks
coming from one patient or one rhythm generator!!!
Sources – In order of preference
Many of the pictures and info from:– Flip and See ECG, 2nd Edition
Cohn/Gilroy-Doohan– A great resource
– Paramedic Paramedic Textbook, Revised 2nd Edition Mick J. Sanders, Mosby
– ECG’s Made Easy, 2nd Edition Barbara Aehlert, RN, Mosby
– Basic Dysrhythmias, Interpretation and Management, 3rd Edition
Robert J. Huszar, Mosby