Name That Rhythm
EMT-Intermediate
W06
And you thought we wouldn’t review…..
Heart A & P
• Location• Pieces, Parts• Important
Vessels• Electrolyte Role• Pulling apart
waveforms
Valves & Vessels
Review of Important Vessels
The Components
• SA Node• Internodal
Pathways• AV Junction• AV Node• Bundle of His• L & R Bundle
Branch• Purkinje Network• Purkinje Fibers
The Route
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
Electrical Conduction System
• Sympathetic-Thoracic/Lumbar Nerve
– Norepinephrine
• HR, Contractility
• Parasympathetic-Vagus Nerve
– Acetylcholine
• HR (Valsalva)
• Chronotropic-HR
• Inotropic-Contraction
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
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 PVC’s– EMT-P not pushing the
“sync” button
QRS Complex
Lead Considerations
• $25,000 mVoltmeter– Lead Views:
• 1 – Lateral• 2 – Inferior• 3 – Inferior
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?
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)
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 (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
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
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