Electrophysiology Daymar College Lisa H. Young, RN, BSN, MAE 2011
Electrical Conduction Pathway
Chemical Basis for Impulse Formation
Cardiac Action Potential Phases http://www.youtube.com/watch?v=oqpffilde0e
Electrical Pathway ECG Waveforms
Systole and Diastole ECG Waveforms
Leads
Einthoven s Triangle
MCL1 and MCL6
Leadwire Systems
Common Monitor Problems Artifact False-high rate Weak signals Wandering baseline Fuzzy baseline (electrical interference) Baseline (no waveforms)
Common Arrhythmia Interferences
Normal Sinus Rhythm Rhythm: Regular Rate: 60 100 bpm P wave: Small, round, before QRS (sinus) PRI: 0.12 0.20 seconds QRS: < 0.12 seconds
ECG Paper Each small box is one millimeter (1mm) Each large box (5 small boxes) is 5 millimeters Standard paper speed is 25mm/second Each small box is 0.04 seconds Each large box is 0.20 seconds Convert seconds to milliseconds 1000 X number of boxes in seconds 0.04 sec. = 0.040 = 40 ms
Sinus Bradycardia Rhythm: Regular Rate: 40 60 bpm P wave: sinus PRI: 0.12 -.020 sec QRS: <0.12 sec Treatment Drugs: Atropine Epinephrine Intervention: Pacer
Sinus Tachycardia Rhythm: Regular Treatment Rate: 100 160 bpm Treat cause, i.e. fever P wave: sinus PRI: 0.12 0.20 sec QRS: < 0.12 sec
Sinus Arrhythmia Rhythm: Irregular Treatment Rate: 60 100 Usually not necessary. P wave: sinus PRI: 0.12 0.20 seconds QRS: <0.12 seconds
Sinus Arrest Rhythm: Irregular Treatment Rate: 60 100 or < 60 Pacemaker P wave: sinus, absent in pause PRI: 0.12 0.20 sec., absent in pause QRS: <0.12 sec., absent in pause
ESCAPE BEATS Sinus Escape Beat Junctional Escape Beat Ventricular Escape Beat
SINUS BLOCK Rhythm: Irregular Treatment Rate: 60 100 or < 60 None P wave: sinus, absent in pause PRI: 0.12 0.20 sec., absent in pause QRS: < 0.12 sec., absent in pause
WANDERING PACEMAKER Rhythm: Regular or Irregular Rate: 60 100 bpm P wave: Change size, shape & direction PRI: < 0.12 seconds, may vary slightly QRS: < 0.12 seconds Treatment: Not usually necessary
PREMATURE ATRIAL CONTRACTION (PAC) Rhythm: Regular and irregular because of PAC Rate: Underlying rhythm P wave: Abnormal size, shape and/or direction PRI: 0.12-0.20 or prolonged QRS: < 0.12 seconds Treatment: Not usually necessary
Non-conducted PAC Non-conducted P wave, which may occur before, during, or after the T wave preceding the pause. Possible distortion of the slope of the T wave preceding the pause; T wave difference in its height or shape. These are clues showing nonconducted P wave could be hidden in T wave
PAC Conduction EARLY A PAC occurring in the rhythm NON-CONDUCTED A premature, abnormally shaped P wave is seen without a QRS ABERRANTLY A PAC with a wide QRS
PAC Groupings Bigeminal every other beat is a PAC Trigeminal every third beat is a PAC Paroxsymal abruptly occurring in rhythm PAT Paroxysmal Atrial Tachycardia
ATRIAL TACHYCARDIA Rhythm: Regular Rate: 150 250 P wave: Abnormal, hidden in T wave PRI: 0.12-0.20 sec. if measurable QRS: < 0.12 sec. Treatment: Vagal maneuvers / Adenosine IV http://www.youtube.com/watch?v=ih5xpcb0eou
PSVT
ATRIAL FLUTTER Rhythm: Regular or irregular Rate: Varies P wave: Flutter waves PRI: Not measurable QRS: < 0.12 seconds Treatment: Coagulation, Cardioversion, Medications
ATRIAL FIBRILLATION Rhythm: Grossly irregular Rate: Controlled or Uncontrolled P wave: Fibrillatory waves; Coarse / Fine PRI: Not measurable QRS: < 0.12 seconds http://www.youtube.com/watch?v=dc_i8zuclmq
P wave features with AV rhythms P wave inverted in Lead II P wave immediately before QRS P wave immediately after QRS P wave hidden in QRS
Premature Junctional Contraction (PJC) Rhythm: Regular except premature beat Rate: Underlying rhythm P wave: inverted, before, during or after QRS PRI: Short, <.12 seconds QRS: < 0.12 seconds Treatment: Not required
JUNCTIONAL ESCAPE RHYTHM Rhythm: Regular Rate: 40 60 bpm P wave: inverted before, during or after QRS PRI: Short, <0.12 seconds QRS: <0.12 seconds Treatment: Symptomatic-atropine, pacing, tx cause
Accelerated Junctional Rhythm Rhythm: Regular Rate: 60 100 bpm P wave: inverted before, during or after QRS PRI: Short, < 0.12 seconds QRS: < 0.12 seconds Treatment: Correct the cause if necessary
Junctional Tachycardia Rhythm: Regular Rate: 100 180 bpm P wave: usually hidden in preceding T wave PRI: Short, < 0.12 seconds, if present QRS: < 0.12 seconds Treatment: Correct cause or adenosine if needed
First Degree AV Heart Block Rhythm: Underlying rhythm Treatment Rate: Usually sinus Monitor P wave: Sinus Review Drugs PRI: greater 0.20 seconds & constant QRS: < 0.12 seconds
2 nd Degree AV Heart Block (Mobitz I or Type I or Wenckebach) Rhythm: Irregular Treatment Rate: Less than Atrial rate Atropine P wave: Sinus Review Drugs PRI: Progressively lengthens until missing QRS (MIA) (PRI after missing QRS is shorter than the last PRI) QRS: < 0.12 seconds
2 nd Degree AV Heart Block (Mobitz II or Type II) Rhythm: Regular unless the conduction varies Rate: # impulses conducted (< 60 bpm) P wave: More than # QRS (ratio or variable) PRI: 0.12 sec. or prolonged, but CONSTANT QRS: < 0.12 seconds, but could be wide Treatment: Pacemaker, Dopamine or Epinephrine
3 rd Degree AV Heart Block (Complete Heart Block (CHB) ) Rhythm: Regular Rate: 30 60 bpm (usually) P wave: More p waves than QRS complexes PRI: Varies greatly, no relationship with QRS QRS: < 0.12 if junctional, > 0.12 sec. if ventricular focus Treatment: Pacemaker, atropine (if narrow QRS)
Intraventricular Conduction Defect Rhythm: Regular Rate: Usually sinus P wave: Sinus PRI: Normal QRS: Wide, greater than 0.10 sec Treatment: Not necessary
Premature Ventricular Contraction (PVC) Rhythm: Irregular due to premature beat Rate: Underlying rhythm P wave: None with PVC PRI: Not measurable QRS: Premature, wide, greater than 0.12 sec T wave is usually opposite direction of R wave Treatment: Not necessary or reversible causes
Idioventricular Rhythm (Ventricular Escape Rhythm) Rhythm: Usually regular Treatment Rate: 20 40 bpm or slower Atropine P wave: Absent Pacemaker PRI: Not measurable QRS: Wide, greater than 0.10
Accelerated Idioventricular Rhythm Rhythm: Regular Treatment Rate: 50 100 bpm No treatment needed P wave: Absent PRI: Not measurable QRS: Wide, greater than 0.10 seconds
Ventricular Tachycardia Rhythm: Regular, may be slightly irregular Rate: 150 250 bpm P wave: None PRI: Not measurable QRS: Wide, greater than 0.12 sec. (T opposite R) Treatment: CPR, Defibrillation, Amiodarone, Epinephrine, Lidocaine (cardioversion with pulse)
Torsades de Pointes
Ventricular Fibrillation Rhythm: Chaotic, irregular Rate: 0 P wave: Absent PRI: Not measurable QRS: Absent Treatment: CPR, Defibrillation, Epinephrine, Amiodarone, Lidocaine, causes.
Ventricular Flutter Rhythm: usually regular Rate: ventricular rate is 220 440 bpm P waves: None seen PRI: None measurable QRS complex: Very wide, regular Treatment Defibrillation CPR Antiarrhythmics
Ventricular Standstill Rhythm: None Rate: Atrial only P wave: Present PRI: Not measurable QRS: Absent Treatment CPR Epinephrine Atropine
Ventricular Asystole Rhythm: No rhythm Rate: 0 P wave: None PRI: None QRS: Wide fading until none Treatment CPR Epinephrine Atropine
Agonal Wicked Witch is MELTING
Pulseless Electrical Activity Rhythm: Fairly regular (not sinus) Rate: 60 100 bpm P wave: Usually present PRI: Normal QRS: Narrow or Wide Treatment: CPR, Epinephrine, Atropine
Indications for Pacing Complete Heart Block Symptomatic type II 2 nd degree AV block Sick sinus syndrome Symptomatic bradycardias with syncope 2 nd degree AV block with episodic ventricular arrhythmias Severe CHF and dilated cardiomyopathy Prevent Atrial fibrillation Hypersensitive carotid sinus syndrome Neurocardiogenic syncope (vasovagle syncope) Long QT syndrome Sleep Apnea
Components of Pacing System Pulse Generator Pacing Lead Pacing cable
Temporary Pacing Treat symptomatic bradycardia after AMI Treat symptomatic bradycardia after cardiac surgery Hyperkalemia Drug toxicity Before permanent pacemaker implantation in symptomatic patients Bacterial endocarditis Lyme disease Cardiac trauma
Types of Temporary Pacemakers Transvenous Epicardial Transcutaneous
Transvenous Pacemaker http://www.youtube.com/watch?v=5bi QQYjw6no
Epicardial Pacing Cardiac surgery Epicardium One or two atrial or ventricular leads
Transcutaneous Pacing http://www.youtube.com/watch?v=qksgajknqvg
Permanent Pacemakers http://www.youtube.com/watch?v=dlert3zh8fo http://www.youtube.com/watch?v=lsdl2jvfpxs
Types of Pacing Single-Chamber Pacing Dual-Chamber Pacing Biventricular Pacing
Pacemaker Operation Bipolar Unipolar Asynchronous (Fixed-Rate) Demand
Codes for Permanent Pacemakers
Pacemaker Functions Capture Strength of stimulus (ma) Pulse width Pacemaker spike Indicated by a wide QRS complex Temporary pulse generators
Pacemaker Functions Sensing Millivolts (mv) see intrinsic activity Increase sensitivity decrease mv Decrease sensitivity increase mv Sensitivity threshold testing with temporary pacemakers
Pacemaker Functions Stimulation Threshold Testing Temporary pacemakers Minimum pacemaker output for capture Peak threshold Chronic stable threshold Performed each shift
Ventricular Paced Rhythm
Atrial Pacmaker
AV Sequential Pacemaker
Pacemaker Malfunctions Loss of capture Inadequate stimulus strength Pacing lead out of position Pacing lead positioned in infarcted tissue Electrolyte imbalances or drug effects Delivery of a pacing stimulus during ventricle s refractory period
Undersensing Pacing Malfunctions Asynchronous pacing mode Pacing catheter out of position Intrinsic QRS voltage too low Break in connections, battery failure, or faulty pulse generator Intrinsic ventricular activity occurring during pacemaker s refractory period
Pacemaker Malfunctions
Pacemaker Malfunctions Oversensing Too sensitive Inhibits ouput Interference from internal and external signals
Problems with Pacing http://www.youtube.com/watch?v=vc9its8goqk
Analyzing Paced Rhythms
Paced Interval
Analyzing Paced Rhythms
Pacemaker Rhythm: Regular Rate: Set or own P wave: Present or spike PRI: Normal QRS: Present or spike
Sick Sinus Syndrome Rhythm: irregular with sinus pauses Rate: fast, slow or alternating; abrupt changes P wave; varies with changes; may be absent PRI: usually normal; varies with changes QRS: normal; varies with changes
Non-Sinus Atrial Rhythm Regular Rate: 60 100 P wave: inverted before each QRS complex PRI: 0.12 seconds or greater QRS: <0.12 seconds
ATRIAL TACHYCARDIA Rhythm: Regular Rate: 150 250 P wave: Abnormal, hidden in T wave PRI: 0.12-0.20 sec. if measurable QRS: < 0.12 sec. Treatment: Vagal maneuvers / Adenosine IV
Multifocal Atrial Tachycardia Irregular Rate 150 to 250 bpm P wave: changing shapes & mixed with T wave PRI: varies QRS: <0.12 Treatment: Adenosine
Supraventricular Arrhythmias Supraventricular Arrhythmias Atrial Fibrillation Paroxysmal supraventricular tachycardias (PSVT) AV nodal reentry tachycardia (AVNRT) AV reentry tachycardia (AVRT) -WPW -AV reentry over concealed bypass tract Atrial Tachycardia
Types of SVT
Arrhythmias from Abnormal Conduction Pathways Definition Clinical Implications
Physiology of the Accessory Pathway Kent Bundles James Bundle Mahaim s fibers Atriofascicular bypass tracts Concealed accessory pathway
Accessory Pathways
Location of Accessory Pathways
ECG Characteristics
Degrees of Preexcitation None Minimal Less than maximum Maximum preexcitation
Degrees of Preexcitation
Interpretation of Preexcitation Arrhythmia Obtain 12 Lead ECG Compare with resting or normal ECG Assess PR interval Look for delta wave ECG Characteristics Rate and regularity P waves (P ) PRI QRS
Accessory Pathway Arrhythmias RECIPROCATING TACHYCARDIA Circus-movement Tachycardia Reentry tachycardia Orthodromic reciprocating tachycardia
Reentry
AV Nodal Reentry Tachycardia (AVNRT) AVNRT Dual AV node physiology both fast and slow conduction pathways are present in the AV node rapidly conducting tissue has a long recovery time -fast boat, long wake slow-conducting pathway has a relatively short recovery time -slow boats can follow more closely
AVNRT: Initiation of tachycardia
AVNRT
ORTHODROMIC TACHYCARDIA
ANTIDROMIC TACHYCARDIA
LOWN-GANONG-LEVINE SYNDROME
3 Criteria for LGL Syndrome 1. Short PR interval (0.12second or less) 2. Normal QRS configuration 3. Recurrent paroxysmal tachycardia
WOLF-PARKINSON-WHITE
WOLF-PARKINSON-WHITE
WPW ECG CHARACTERISTICS OVERT WPW Regular, 60 100 bpm P wave: upright, normal, and appearing only before each QRS PRI: less than 0.12 seconds and constant QRS: great than 0.10 sec. in duration; a delta wave, slurred on the initial upstroke or downstroke of the QRS
WPW CHARACTERISTICS Non-evident WPW Regular, 60 100 bpm; tendency for unprovoked PSVT, atrial flutter, or A fib P wave: upright, normal, and appearing only before each QRS PRI: 0.12 0.20 second and constant QRS: 0.10 sec.
WPW CHARACTERISTICS CONCEALED WPW Regular, 60 100 bpm; tendency for unprovoked PSVT. P wave: upright, normal, and appearing only before each QRS PRI: 0.12 0.30 sec and constant QRS: 0.10 second in duration
Mahaim s Fibers Right sided muscular bridges Originate below AV node into the ventricular wall Normal PR interval with a delta wave
Clinical Significance of Arrhythmias of Abnormal Conduction Pathways ASSESSMENT: Leads I, II, III, V1 and V6 in PSVT Assess Heart Rates Assess Ventricular Rate Assess Ventricular Rhythm Assess for history of onset
Proposed Interventions for Arrhythmias of Abnormal Conduction Pathways. Avoid AV nodal blocking agents in preexcitation syndromes Consider Amiodarone and Magnesium Paroxysms of tachycardia: EP testing Consider surgery or transvenous radio frequency catheter ablation
Table of Accessory Pathways
Romano-Ward syndrome
Atrio-Ventricular Dissociation One P wave for each QRS P wave moves in and out of QRS complex
Aberrant Ventricular Conduction Abnormal conduction pathway QRS complex that has the appearance of PVC Seen with Atrial Fibrillation and MAT Single beat or as a run of beats MCL1 lead
Ashman s Phenomenon Rhythm: irregular Rate: reflects the underlying rhythm P wave: abnormal configuration; unchanged if in the underlying rhythm RPI: commonly changes on the premature beat; if measurable at all QRS: altered configuration with right bundle-branch block pattern
Bundle Branch Blocks QRS wider than.12 in duration V1 Incomplete vs Complete
Right & Left-sided PVCs Determined by the direction of the QRS complex ECG strip in MCL1 lead PVC negative right ventricle PVC positive left ventricle
Interpolated PVC PVC falls close to the middle of 2 sinus QRS complexes No change in R R interval
End-diastolic PVC PVC falls at the very end of the sinus p wave PVC will have a sinus p wave & short PRI
Hyperkalemia ECG Changes
Hyperkalemia EKG Tracing
Hypokalemia ECG Changes Flatten T waves U waves merge with T wave ST segment depressed
Hypokalemia EKG
Hypercalcemia ECG Changes
Hypocalcemia ECG Changes
ECG Effects of Digoxin
Induced Arrhythmias CAD: monomorphic VT and atrial fib. Inferior MI: Bradycardia, sinus block, JR, AJR, AV Blocks, AVR Acute MIs: AT, Aflutter, Vfib Myocardial Ischemia: Vfib, VT, Premature beats Ischemic heart disease: 2 nd AVB and PVCs Acute Anteroseptal MI: 2 nd AVB-type II, RBBB Coronary thrombus: PEA
Radiofrequency Ablation AV Node Ablation Pulmonary Vein Ablation http://www.youtube.com/watch?v=_d-pxk2nvcm
Arrhythmias Treated with Ablation AV Nodal Reentrant Tachycardia (AVNRT) Accessory Pathway Atrial fibrillation and atrial flutter Ventricular tachycardia
Ablation Procedure http://www.youtube.com/watch?v=ijxfsziqwcy
Surgical Ablation The Maze procedure http://www.youtube.com/watch?v=fhiv31xee5m Minimally invasive surgical ablation The modified Maze procedure
12 Lead EKG Introduction 10 leads = 12 views of the heart 3 Limb leads, 3 augmented leads and 6 chest leads Monitoring for ST segment, T wave and Q wave changes
Lecture Resources Huff, Jane. ECG Workout: Exercises in Arrhythmia Interpretation. 5 th edition. Lippincott Thaler, Malcom S. The Only EKG Book You ll Ever Need. Lippincott Williams & Wilkins. Walraven,Gail. Basic Arrhythmias. 6 th edition. Pearson/Prentice Hall. Aehlert, Barbara. ECGs Made Easy. 3 rd edition. Mosby; Elsevier. 2006. ECG Strip Ease; an arrhythmia interpretation Workbook, Lippincott Williams & Wiilkins. 2007. Lewis, Kathryn. ECG Practical Applications Pocket Reference Guide, Cengage Learning. 2010.