ECG Interpretations
Course Objectives Proper Lead Placements Review the ECG print paper Review the mechanics of the Myocardium Review basics of ECG Rhythms
How Leads Work The ECG Leads we use are Bipolar When an electrical impulse moves towards the (+) lead Displays as an Upward Deflection When an electrical impulse moves toward the (-) lead Displays as a Downward Deflection Lead II is displayed on the monitor because it shows the most (+) moving activity
ECG Lead Placement Limb Leads If 3 Leads (RA, LA, LL) If 4 Leads (RA, LA, LL, RL) RA is ground for all leads (Including the 12 leads) If there is excess artifact or difficulty with display Replace the RA Lead with a fresh sticker Place Leads on muscle, not over bone When you can: Place the Leads on the Torso of the Patient
ECG Lead Placement RA (White) Negative (-) LA (Black) Negative (-) RL (Green) Positive (+) LL (Red) - Positive (+) Remember: Clouds over Grass, Smoke over Fire
Breakdown of the Cardiac Rhythm Strip:
ECG interpretations HOW TO READ THE PRINTOUT..
The ECG Paper Horizontally (Time) One small box - 0.04 sec One large box - 0.20 sec Vertically (Voltage) One large box - 0.5 mv
The ECG Paper (cont.) 3 sec 3 sec Every 3 seconds (15 large boxes) is marked by a vertical line. ECG Interpretations are based on 6 seconds
ECG interpretations THE MECHANICS OF THE MYOCARDIUM
Pacemakers of the Heart SA Node - Dominant pacemaker with an intrinsic rate of 60-100 beats/minute. AV Node - Back-up pacemaker with an intrinsic rate of 40-60 beats/minute. Ventricular cells - Back-up pacemaker with an intrinsic rate of 20-45 bpm.
Impulse Conduction & the ECG Sinoatrial node AV node Bundle of His Bundle Branches Purkinje fibers
The PQRST P wave - Atrial depolarization QRS - Ventricular depolarization T wave - Ventricular repolarization The Atria repolarizes at the same time that the Ventricles depolarize
ECG interpretations MEASUREMENTS OF ECG INTERPRETATIONS.
Option 1 Step 1: Calculate Rate 3 sec 3 sec Count the Number of complete QRS complexes in a 6 second rhythm strip, then multiply by 10. Reminder: all rhythm strips in the modules are 6 seconds in length. What is the Rate on this Strip? 9 x 10 = 90 bpm
Option 2 Step 1: Calculate Rate R wave Find an R wave that lands on a bold line. Count the number of large boxes to the next R wave. If the second R wave is 1 large box away the rate is 300, 2 boxes - 150, 3 boxes - 100, 4 boxes - 75, etc. (cont.)
Option 2 Step 1: Calculate Rate 3 0 0 1 5 0 1 0 0 7 5 6 0 5 0 Memorize the sequence: 300-150 - 100-75 - 60-50 What is the Rate on this Strip? Approx. 1 box less than 100 = 95 bpm
Step 2: Determine regularity R R Look at the R-R distances (using a caliper or markings on a pen or paper). Regular (are they equal distance apart)? Occasionally irregular? Regularly irregular? Irregularly irregular?
Step 3: Assess the P waves Are P waves present? Do the P waves all look the same? Do the P waves occur at a regular rate? Is there one P wave before each QRS complex? Normal P waves with 1 P wave for every QRS
Step 4: Determine PR interval Normal: 0.12-0.20 seconds. (3-5 boxes)
Step 5: QRS duration Normal: 0.04-0.12 seconds. (1-3 boxes)
ECG interpretations PUTTING IT ALL TOGETHER.
Rhythm Analysis Step 1: Step 2: Step 3: Step 4: Step 5: Calculate rate. Determine regularity. Assess the P waves. Determine PR interval. Determine QRS duration.
Normal Sinus Rhythm (NSR) Rate Regularity P waves PR interval QRS duration 60-100 bpm regular Before each QRS Complex 0.12-0.20 sec 0.04-0.12 sec
Sinus Rhythms: Sinus Tachycardia Sinus Bradycardia Sinus Arrhythmia
Sinus Tachycardia Rate Regularity P waves PR interval QRS duration between 100 and 150 bpm regular before each QRS Complex 0.12-0.20 sec 0.04-0.12 sec Remember: sinus tachycardia can be a response to physical or psychological stress, not a primary arrhythmia.
Sinus Bradycardia Rate Regularity P waves PR interval QRS duration less than 60 bpm regular before each QRS Complex 0.12-0.20 sec 0.04-0.12 sec
Sinus Arrhythmia Rate Regularity P waves PR interval QRS duration 60-100 bpm irregular normal 0.12-0.20 sec 0.04-0.12 sec Can be related to respirations, common in pediatrics
Atrial Rhythms Wandering Atrial Pacemaker Atrial Tachycardia Atrial Flutter Atrial Fibrillation
Wandering Pacemaker Rate Regularity P waves PR interval QRS duration 40-60 bpm slightly irregular change from beat to beat, may disappear completely 0.12-0.20 sec 0.04-0.12 sec
Atrial Tachycardia Rate Regularity P waves PR interval QRS duration more than 100 bpm regular normal, flat or inverted varies 0.04-0.12 sec
Atrial Flutter Rate Regularity P waves PR interval QRS duration Ventricle Rate - normal Atrial Rate - 250-320 bpm regular flutter wave Multiple per each QRS Complex not measurable 0.04-0.12 sec (Turning the strip upside down may make the saw tooth pattern more prominent)
Atrial Fibrillation Rate Regularity P waves PR interval QRS duration Atrial Rate can t be counted Ventricular Rate - varies irregularly irregular not distinguishable not measurable 0.04-0.12 sec
Junctional Rhythms Junctional Escape Junctional Bradycardia Accelerated Junctional SVT
Junctional Escape Rate Regularity P waves PR interval QRS duration 40-60 bpm regular inverted or flat < 0.12 - if before the QRS Complex usually <0.12 sec, but can be greater
Junctional Bradycardia Rate Regularity P waves PR interval QRS duration <40 bpm regular inverted or flat < 0.12 sec usually <0.12 sec, but can be greater
Accelerated Junctional Rate Regularity P waves PR interval QRS duration 60-100 bpm regular inverted or flat < 0.12 - if before the QRS Complex usually <0.12 sec, but can be greater
Junctional Tachycardia Rate Regularity P waves PR interval QRS duration more than 100 bpm regular inverted or flat 0.12-0.20 sec 0.04-0.12 sec
Supraventricular Tachycardia (SVT) Rate Regularity P waves PR interval QRS duration greater than 150 bpm regular unable to be read buried in previous QRS Complex 0.04-0.12 sec
Blocks 1 0 HB + Underlying Rhythm 2 0 Type I - Wenkebach 2 0 Type II - Classical 3 0 degree HB
1st Degree AV Block Prolonged conduction delay in the AV node or Bundle of His. PRI will be greater than 0.20 There will be one P wave in front of every QRS Complex The underlying rhythm is part of the interpretation
2 0 HB Mobitz I - Wenckebach Rate Regularity P waves PR interval QRS duration Atrial Rate normal Ventricular Rate Bradycardic regular normal progressively longer until the QRS is missed then recaptures 0.04-0.12 sec
20 HB Block, Type II - Classical Rate Regularity P waves PR interval Atrial Rate normal Ventricular Rate Bradycardic regular ratio of 2:1, 3:1 (P waves to QRS) normal or prolonged when followed by a QRS Complex (P-R Interval will always be the same) QRS duration 0.04-0.12 sec - P wave conduction is blocked in a consistent repeating pattern
3rd Degree AV Block Rate Regularity P waves PR interval QRS duration Atrial Rate normal Ventricular Rate Bradycardic Rate regular from P to P or QRS to QRS unrelated to QRS Complex unrelated to QRS Complex slower than 0.12 seconds The P waves are completely blocked in the AV junction; QRS complexes originate independently from below the AV junction.
Differentiating The Heart Blocks Look at the R to R intervals Are they regular or not Look at the PR intervals Are they consistent? If not, is there a pattern Heart Block R to R PR interval 2 0 Type I Wenckebach Irregular - Dropped QRS Irregular longer, longer, longer 2 0 Type II - Classical Regular if consistent degree of block Regular for PR interval; just more P s than QRS 3rd degree - complete Regular Irregular no pattern 45
Differentiating The Heart Blocks 46
Differentiating The Heart Blocks
Comparing Heart Blocks
Ectopic Beats Premature Atrial Contraction (PAC) Premature Junctional Contraction (PJC) Premature Ventricular Contraction (PVC) Uni-focal Multi-focal
Premature Atrial Contractions (PAC) Etiology: Excitation of an atrial cell forms an impulse that is then conducted normally through the AV node and ventricles.
Premature Junctional Contractions (PJC) Etiology: Excitation of cells in the AV Node. A pause is dependent on if the SA Node is depolarized when the impulse occurs.
Premature Ventricular Contraction (PVC) Ectopic beats originate in the ventricles resulting in wide and bizarre QRS complexes. Compare multiple premature beats: When multiple PVCs look alike, they are called uniform When multiple PVCs look different, they are called multifocal
Unifocal PVC Multifocal PVC
PVC Patterns Bigeminy: Every other beat is a PVC Trigeminy: Every third beat is a PVC Quadgeminy Every fourth beat is a PVC
Run of PVCs If 3 or more PVCs occur in a row: This is a Run of V-Tach (Ventricular Tachycardia)
Ventricular Rhythms Wolf Parkinson White (WPW) Ventricular Tachycardia (V-Tach) Torsade de pointes Ventricular Fibrillation (V-Fib) Asystole
Wolf Parkinson White (WPW) Congenital defect in conduction system Presence of abnormal electrical pathway that can cause tachycardia Episodes often begin occurring in teens and early 20 s Normal Conduction WPW Conduction 57
Wolf Parkinson White (WPW) The pacemaker impulse bypasses the AV Node Rate: 60-100 bpm Rhythm: regular P wave: less than 0.12 sec QRS: >.12 seconds (wide and bizarre) Only Rhythm with Delta Wave 58
Ventricular Tachycardia (monomorphic) Ventricular cells fire continuously due to a looping re-entrant circuit Rate usually regular, 100-250 bpm P wave: absent QRS: complexes bizarre, >.12 Rhythm: usually regular
Ventricular Tachycardia (polymorphic) Ventricular cells fire continuously due to a looping re-entrant circuit from multiple foci Rate usually regular, 100-250 bpm P wave: may be absent, inverted or retrograde QRS: complexes bizarre, >.12 Rhythm: usually regular
Torsade de Pointes A Multifocal V-Tach Escape rhythm (safety mechanism) to prevent ventricular standstill Bundle of HIS/Purkinje Fiber pacemaker take over Rhythm: varies from beat to beat P wave: absent QRS: >.12 seconds (wide and bizarre) *Can be caused by mixture of antiarrhythmic drugs and non-sedating antihistamines, anti fungal meds and certain antibiotics * Can be seen in alcoholic, anorexia and/or bulimic patients 61
Ventricular Fibrillation Rhythm: irregular (coarse or fine), wave form varies in size and shape Fires continuously from multiple foci No organized electrical activity No cardiac output
Asystole Ventricular standstill, no electrical activity, no cardiac output no pulse! Remember! No defibrillation with Asystole Rate: absent due to absence of ventricular activity. Occasional P wave may be identified Not productive
Other Rhythms Idioventricular Accelerated Idioventricular Paced PEA
Idioventricular Rhythm Escape rhythm (safety mechanism) to prevent ventricular standstill HIS/Purkinje system takes over as the heart s pacemaker Rhythm: regular Rate: 20-40 bpm P wave: absent QRS: >.12 seconds (wide and bizarre) 65
Accelerated Idioventricular Rhythm Escape rhythm (safety mechanism) to prevent ventricular standstill Bundle of HIS/Purkinje Fiber system takes over as the heart s pacemaker Rhythm: regular Rate: 60-100 bpm P wave: absent QRS: >.12 seconds (wide and bizarre) 66
Paced Rhythm Man made mechanical pacing device Rhythm: regular if continuous firing Irregular if pacing on demand Rate: Based on what is programmed P wave: dependent on where pacer is originating from QRS: >.12 seconds (wide and bizarre) The only thing to identify is that it is a Paced Rhythm 67
Pulseless Electrical Activity (PEA) Pick any rhythm that we have discussed and remove the pulse This is only electrical activity with no mechanical function That is why we treat the patient, not the monitor. NO PULSE Consider the H s and T s to improve the patient s out come: - Hypoxia - Hypovolemia - Tension Pneumothorax - Hypothermia - Hypo/Hyperkalemia - Tamponade Cardiac - Hydrogen Ion (Acidosis) - Thrombosis Pulmonary - Thrombosis - Cardiac 68
ECG interpretations INTERPRETATIONS
Normal Sinus Rhythm
Atrial Fibrillation Is the patient stable or unstable? Patients can walk around in this rhythm with no problems Watch for medication hx to include: Coumadin, Prodaxa, Eliquis, Xarelto or Lovenox
Sinus Rhythm w/ Run of V-Tach Is the patient stable or unstable? Are there multiple occurrences? Interventions: ASA (ACS SOP) and Amiodarone
2 0 HB Mobitz II (Classical) Is the patient stable or unstable Interventions: Dopamine, TCP
Sinus Rhythm w/1 0 Heart Block Not Normal Sinus Rhythm w/1 0 Heart Block
Monomorphic V-Tach Is the patient stable or unstable? Intervention: Amiodarone 150mg in 50 ml 0.9 NS drip Be ready for Synchronized Cardioversion
Torsades de Pointes Is the patient stable or unstable? Intervention: Magnesium 2 Gm w/16 ml 0.9 NS over 5 min or you may get the 2 Gm in 40 ml bag. Be ready for Defibrillation
Junctional Escape Is the patient stable or unstable? Interventions: Atropine, Dopamine, TCP
Artificial Paced Rhythm Is the patient stable or unstable?
NO PULSE Start CPR Pulseless Electrical Activity (PEA) Consider H s and T s Interventions: Epinephrine, Possibly Sodium Bicarbonate
REVIEW.. 80
Review For every strip we look at: Rate Regularity Determine P waves Measure PR interval Determine QRS duration Pacemaker Rates: SA Node Dominant pacemaker: 60 100 bpm AV Node Back-up pacemaker: 40-60 bpm Ventricular cells - Back-up pacemaker: 20-45 bpm 81
Review.. Each small square is 0.04 seconds and a large box is 0.20 seconds P wave - Atrial depolarization QRS Ventricular depolarization T wave - Ventricular repolarization * The Atria repolarizes at the same time that the Ventricles depolarize 82
Questions? 83