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