EKG Recognition for EMT’s (Part 2)
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EKG Recognition for EMT’s (Part 2). Scott S. Shadoin EMT-P Boca Raton Fire Rescue Boca Raton, Fl Emergency Medical Consultants Port St. Lucie, Fl. Professional Disclosures. None. Objectives. Discuss the anatomy of the heart Understand the components of an ECG
EKG Recognition for EMT’s (Part 2)
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EKG Recognition for EMT’s (Part 2) Scott S. Shadoin EMT-P Boca Raton Fire Rescue Boca Raton, Fl Emergency Medical Consultants Port St. Lucie, Fl
Professional Disclosures • None
Objectives • Discuss the anatomy of the heart • Understand the components of an ECG • Understand the following ECG’s • Ventricular Rhythms • AV Heart Blocks • Pacemaker Rhythms
Cardiac Anatomy Myocardium Muscle of the heart Should contract when stimulated Atria Upper chambers of the heart Ventricles Lower chambers of the heart
Cardiac Anatomy • Septum • Separates left and right sides of atria and ventricles • Cardiac Skeleton • Separates the atria from the ventricles • Impermeable to electricity • Electrical conduction system • Pathways through the heart for electricity
Electrical Conduction System • Electricity created in Sinoatrial Node travels through electrical system • Myocardium contracts in response to stimulation • Depolarization • Change in cells electrical potential • Muscle contracts in response • Repolarization • Cell resets to original electrical potential • Muscle is relaxed
Electrical Conduction System • Sinoatrial Node (SA Node) • Pacemaker of the heart • Sends electricity into atrium • Bachmann’s Bundle (intra-atrial pathway) • Delivers electricity to left atrium • Atrioventricular node (AV Node) • “Doorway” to ventricles • Pauses electrical flow
Electrical Conduction System • Bundle of His • Splits in L/R bundle branches • Connects AV node to Purkinje fibers • Bundle branches • Travel through ventricular septum • Left bundle splits into anterior/posterior fascicle • Purkinje fibers • Disseminate electricity through the ventricles
EKG Paper Left to right = TIME -Small box = .04 sec -Large box = .20 sec -3 second ticks/marks Up/down = DIRECTION -Up = Positive -Down = Negative Height = VOLTAGE -10 small boxes = 1mV
ECG Components • P wave • First part of the ECG complex • Atrial depolarization • QRS • Usually largest voltage • Ventricular depolarization • T Wave • Ventricular repolarization
ECG Pieces • P waves • Round (ish) • Upright • <.12 sec (3 small boxes wide) • <.25 mv (2 ½ small boxes high)
ECG Pieces • Q wave • If it occurs, first negative deflection after the P wave • Septal depolarization • < .04 sec (1 box wide) • < 1/3 total height of QRS
ECG Pieces • R wave • First positive deflection after the P wave • Usually largest voltage on ECG • Beginning phase of ventricular depolarization • Entire QRS .04 - .12 sec (1 to 3 small boxes)
ECG Pieces • S wave • Return to baseline after R wave • May be small or not present • Late or ending of ventricular depolarization
ECG Pieces • T wave • Positive (usually) deflection after the QRS • Ventricular repolarization
Electrode placement Lead I From Right arm to Left arm Lead 2 From Right arm to Left leg Lead 3 From Left arm to Left leg *Lead 2 is the typical monitoring lead
ECG Rules • What is the rate? • Is it regular? • How do the P waves look? • PR Interval? • QRS width? Interpretation? Clinical Significance?
Rate? • Ventricular Rate • R to R • 6 second rule • Number of R waves in 6 seconds x10 • Triplicate method • # of large boxes (5 small boxes) between R waves, divide into 300 • 1 box = 300, 2 box = 150, 3 box =100, etc
Regular? • Measure distances from R to R • Can be slightly irregular with breathing, etc
P waves and PR Interval? • Should be upright • Consistent in shape • QRS Relationship • From start of P wave to QRS <.20 sec (5 small boxes) • P in front of every QRS (consistent PR interval) • QRS after every P wave
QRS width? • Narrow • < .10 probably supraventricular (2 ½ small boxes) • Wide • >.12 Probably ventricular (3 small boxes)
Ventricular Tachycardia • Rate? • >100 • Regular? • Yes • P waves? • None • PR Interval? • None • QRS? • Wide >.12 sec • Same shape
Torsades de Pointes • Rate? • >100/min • Rhythm? • No • P waves? • None • PR Interval? • None • QRS width? • Wide > .12 sec • Polymorphic • Electrical rotation
Ventricular Fibrillation • Rate? • Atrial: None • Ventricular: Irregular and chaotic • Regular? • No • P waves? • None • PR Interval? • None • QRS width? • Wide >.12 sec
Ventricular Fibrillation Coarse Fib Fine Fib
Idioventricular • Rate? • < 40/min • Regular? • Yes • P waves? • None • PR Interval? • None • QRS width? • Wide > .12 sec
Accelerated Idioventricular • Rate? • 40 – 100/min • Regular? • Yes • P waves? • None • PR Interval? • None • Q waves? • Wide > .12 sec
Agonal • Rate? • Atrial: None • Ventricular <20/min • Regular? • Can be regular or irregular • P waves? • None • PR Interval? • None • QRS width? • Wide > .12 sec
1° AV block • Rate? • Atrial: 60 – 100/min • Ventricular: Same as atrial rate • Regular? • Yes • P waves? • Round, upright, uniform • PR Interval? • PR Interval >.20 sec • QRS width? • Narrow (M.B.W.W.A.C.)
2° AV block Type 1 (Wenckebach) • Rate? • Atrial: 40 – 60/min • Ventricular: < Atrial rate • Regular? • No (P’s are, QRS’s are not) • P waves? • Upright, round, consistent • P in front of every QRS • QRS does not always follow every P • PR Interval? • PR Interval gets progressively longer • QRS width? • Narrow (M.B.W.W.A.C.)
2°AV Block Type II • Rate? • Atrial: 60 – 100/min • Ventricular: < Atrial Rate • Regular? • Can be either (P’s are regular, QRS’s are not) • P waves? • Round, upright, consistent • P in front of every QRS • QRS does not follow every P • PR Interval? • PR Interval is always the same • QRS width? • Narrow (M.B.W.W.A.C.)
3°AV Block (CHB) • Rate? • Atrial: 60 – 100/min • Ventricular: 20 – 60/min • Regular? • Yes, but no • P to P is regular, R to R is regular (but not together) • P waves? • Round, upright, consistent • P – QRS relationship nonexistent • PR Interval? • PR Interval is always varied • QRS width? • Usually wide
Atrial Pacemaker • Rate? • Atrial: 60 – 100/min (ventricular follows atrial) • Regular? • Yes • May be irregular if demand pacemaker • P waves? • Round, upright, consistent • Small short pacemaker spike in front of P • PR Interval? • < .20 seconds • QRS width? • Narrow (M.B.W.W.A.C.)