ECGS, ACLS, AND OTHER CARDIAC EMERGENCIES Drs. Rebecca Kruisselbrink, Zain Surgical Half Day August 3, 2011 Amaratunga Kassam, Kanchana Rebecca Kruisselbrink Critical Care Fellow, McMaster University McMaster University Hamilton, Canada Outline •  Hour one (and a bit): •  Brief Review of an Approach to ECGs •  Top Ten ECGs: Spot Diagnoses •  Hour two: •  Review/introduction to ACLS algorithms •  Practice scenarios •  Hour three: •  Your patient is having chest pain….the practical stuff •  ECGs – Brief Review CG BASICs •  Creating the ECG •  Principles •  Leads •  Anatomy •  Reading the ECG à approach •  Nomenclature: Waves, Segments, Intervals •  Rate, Rhythm, Axis •  Intervals – PR, QRS, QT •  Segments – ST, T wave •  Specific Pathologies and “Spot Diagnoses” Principles of ECGs….. •  Cardiac muscle contraction results from depolarization and repolarization of myocytes •  Depolarization = loss of the negative potential •  Repolarization = restoration of the negative resting potential •  ECG = electrical changes recorded via electrodes on chest wall and transcribed onto graph paper Cardiac conduction system •  Sino-atrial node •  Atrio-ventricular node •  His-Purkinje system •  Left and right bundle branches •  Depolarization vector: moves infero-laterally towards apex 12-Lead ECG •  Limb Leads (frontal plane) •  I, II, III •  aVL, aVR, aVF 12-Lead ECG •  Precordial Leads (transverse plane) •  V1, V2, V3 •  V4, V5, V6 12-Lead ECG •  Anterior Leads •  V1, V2, V3, V4 •  Left Lateral Leads •  I, aVL, V5, V6 •  Inferior Leads •  II, III, aVF 12-Lead ECG I aVR V1 V4 II aVL V2 V5 III aVF V3 V6 Rhythm Strip (II) Coronary Anatomy LAD – V1-V6 RCA – II, III, AVF Cx – I, AVL, V5, V6 I - Lateral aVR- V1 - septal V4 anterior II - Inferior aVL - lateral V2 - septal V5 lateral III – Inferior aVF Inferior V3 – anterior V6 lateral ECG Anatomy Waves and Complexes •  P wave •  Atrial depolarization •  Look at leads II (positive) and V1(biphasic) •  Less than 3 small squares in duration, less than 2.5 in amplitude •  QRS complex •  Ventricular depolarization •  Q = first negative deflection •  R = any positive deflection •  S = negative deflection following R •  Septal depolarization = small Q in lateral leads •  T wave •  Ventricular repolarization •  Begins in last area of repolarization and travels backwards •  orientation therefore = depolarization Normal 12-Lead ECG T Waves P Waves Lateral Q Waves QRS Complex APPROACH TO ECG 1.  2.  3.  4.  5.  Rate, Rhythm, Axis Segments and Intervals Enlargement/Hypertrophy Ischemia/Infarction Practice ECGs Rate •  Standard ECG – 25mm/sec ???sec/mm sec/mm – •  0.04 •  •  300, 150, 100, 75, 60, 50 Method 300 / # large squares Irregular rhythms •  •  ??? sec/5 0.2 sec/5 mm mm Regular rhythms •  •  == Count # QRS complexes over 10 seconds (= 1 full page at 25mm/sec) and multiply by 6 = beats per minute Normal rate = 60-100 bpm •  •  Tachycardia > 100 bpm Bradycardia < 60 bpm Rate – 300/150/100 Method 300 / 4 large squares = 75 bpm 300 150 100 ~75 bpm Rate – 10-Second Method 13/10sec x 6 = 78 bpm 1 2 3 4 5 6 7 8 9 10 11 12 13 Rhythm •  Is it Normal Sinus Rhythm? (origin = SA node) Are normal P waves present? 2.  Is there a P for every QRS, and a QRS for every P? 3.  Is the rhythm regular or irregular? 4.  (QRS complexes wide or narrow?) 1.  •  Normal P wave axis (i.e., upright in inferior leads II, III, aVF) Axis •  Normal QRS axis: -30 to +90 •  Check I and AVF: if positive, normal axis •  If I is negative: •  Right axis deviation •  If II is negative: •  Left axis deviation Axis Abnormalities L. axis deviation R. axis deviation •  L. anterior fascicular block •  L. posterior fasicular block •  Emphysema •  Children, thin adults •  Hyperkalemia •  RV hypertrophy •  Q waves of inferior MI •  Chronic lung disease •  Ostium primum ASD •  RV strain (ie. PE) •  ASD or VSD •  Anterior MI APPROACH TO ECG 1.  2.  3.  4.  5.  Rate, Rhythm, Axis Segments and Intervals Enlargement/Hypertrophy Ischemia/Infarction Practice ECGs Segments and Intervals •  PR < 0.2 seconds •  QRS < 0.12 seconds •  QTc = QT (sec) / sq.root RR (sec) •  0.35 – 0.46 seconds (less than half RR distance) PR Interval •  Widened PR interval… •  Suggests AV node conduction block •  Shortened PR interval… •  Suggests pre-excitation (AV accessory pathway – Wolf Parkinson White) QRS Widening •  QRS width helps locate origin of the impulse •  AVN required to synchronize conduction •  If QRS is narrow, suggests that focus is supraventricular = above the AVN •  If QRS is wide, this suggests either: •  Origin below the AVN •  Abnormal conduction pathway (SVT with aberrancy) Widened QRS •  Left Bundle Branch Block •  Widened QRS >0.12 •  V1 – QS complex •  V6 – RSR` complex •  No lateral Q waves (I, aVL, V6) Delayed LV Depolarization Widened QRS – LBBB Wide QRS Broad, deep S wave in R. precordial leads RSR` in L. precordial leads Abnormal septal depolarization (no Q laterally) Widened QRS – RBBB •  RBBB •  Widened QRS >0.12 •  V1 – tall R •  V1 – RSR` complex •  Wide terminal S in lateral leads (I, V6) Delayed RV Depolarization RSR’ in V1 Widened QRS – RBBB Wide QRS RSR` in R. precordial leads (positive in R. leads) Wide terminal S wave I, aVL Prolonged QT •  QTc = QT corrected for rate •  Normal = less than half of R-R •  Prolonged QT can precipitate malignant arrhythmias Causes: congenital vs acquired •  Electrolytes •  Hypothyroidism •  Myocardial ischemia •  Drugs •  Abx •  Anti-arrhythmics •  Antipsychotics •  Anti-neoplastic agents •  Diuretics QT Interval •  Important b/c of risk of Torsade de Pointes APPROACH TO ECG 1.  2.  3.  4.  5.  Rate, Rhythm, Axis Segments and Intervals Enlargement/Hypertrophy Ischemia/Infarction Practice ECGs Atrial Enlargement •  Reexamine the P waves •  First half of P wave represents R. atrial depolarization •  Second half represents L. atrial depolarization II V1 Right Atrial Enlargement •  Amplitude increase, esp. in the inferior leads as well as the positive portion of V1 •  >2.5 mm is suggestive of R. atrial enlargement Left Atrial Enlargement •  Duration of the P wave increases > 0.04 seconds •  Prominence of second portion of P wave Left Ventricular Hypertrophy •  Many criteria… try to remember a few: •  S in V1/2 + R V5/6 > 35 mm •  R in aVL > 11 mm (most sensitive) Right Ventricular Hypertrophy •  Many criteria… try to remember a few: - R. axis deviation > +110* - R wave > S wave in V1 - Persistent S waves in lateral leads APPROACH TO ECG 1.  2.  3.  4.  5.  Rate, Rhythm, Axis Segments and Intervals Enlargement/Hypertrophy Ischemia/Infarction Practice ECGs Ischemic Changes T-waves, ST-segment, and Q-waves 1.  T-waves •  Hyperacute (tall and peaked) •  Flattened •  Inverted (symmetrical) 2.  ST-segments •  Elevated (Infarct) •  Depressed (Ischemia or Infarct) 3.  Q-Waves •  Late change of Infarction Ischemia – T-Wave •  Peaked T-waves •  Ischemia, HyperK, LVH, LBBB Hyperacute T waves Ischemia – T-Wave •  Inverted T-waves •  Ischemia (deep, symmetrical) •  LVH, LBBB, myocarditis, pericarditis, contusion, high ICP, digoxin (asymmetrical) Ischemia LVH w/strain Ischemia – ST-Segment •  ST-segment Elevation •  A change of Infarction (concave down) •  DDx: Prinzmetal angina, Aneurysm, LBBB, Pericarditis, Hypothermia, Hyperkalemia, Benign early repolarization Benign Early Repolarization (concave up) Acute Infarction (concave down) Ischemia – ST-Segment •  ST-segment depression •  Ischemia or Infarction (horizontal or down-slope) •  DDx: Reciprocal Infarct changes, Digoxin, LVH, hypokalemia, LBBB/RBBB Ischemia – Q-Waves •  Q-waves •  Indicates infarction •  Occur several hours to days after infarct •  Persist lifelong •  Pathological Q •  Ensure there is no R wave! •  Should be > 0.04 s (1 small block) •  Should be > 25% of the R wave amplitude Q waves NOT Q waves (they are S waves) Ischemic Changes •  Remember the anatomical correlations •  Especially important when diagnosing ischemia or infarction I aVR V1 V4 II aVL V2 V5 III aVF V3 V6 Rhythm Strip (II) Ischemia – Examples Acute Anterior ST-elevation MI Reciprocal ST-depression II, III, aVF ST-segment elevation V1-V4 Ischemia – Examples Acute Inferior ST-elevation MI ST-elevation II, III, aVF Ischemia – Examples Old Inferior MI Q-waves III, aVF SUMMARY Approach to ECG •  Rate, Rhythm, Axis •  Intervals – PR, QRS, QT •  Segments – ST, T wave •  Ischemia, infarction, and anatomical correlations •  Now for some cases ECG Spot Diagnoses….a dozen or so 12. Sinus rhythm •  Rate 60-100 •  Rhythm: sinus •  P before each QRS •  QRS after each P •  P waves upright in inferior leads •  Normal axis •  Intervals: PR <200, QRS <120, QT <450 •  Normal voltage •  No ST-T changes 11. Long QT •  Definition: QT (QTc) >450 •  Roughly: should be < ½ R-R interval •  Causes: •  Congenital •  Electrolyte abnormalities •  Drug induced •  •  •  •  Cardiac: procainamide, quinidine, sotalol Antibiotics: erythromycin, sulfa, FQs, macrolides Antipsych: TCAs Ischemia 10. Afib with RVR •  No p waves •  Irregular atrial activity •  May see “f waves” (fibrillatory waves) 9. SVT •  Tachycardia •  Narrow complex •  Regular •  No visible ‘p’ waves Narrow complex tachycardia ddx •  Irregular: •  Afib •  Aflutter with variable block •  MAT •  Multiple PACs •  Regular •  SINUS tachycardia •  A flutter with regular block •  SVT (AVNRT, AVRT) •  Atrial tachycardia •  Diagnosis: •  Carotid sinus massage, vagal maneuvers, adenosine 8. (for comparison) Atrial flutter •  Typical atrial rate: 240-340 •  Conduction often 2:1, 3:1, 4:1 = rate of?? •  Narrow complex regular SVT with rate of 150? •  May see negative flutter waves (saw tooth in 2,3,AVF) 7. SVT??? A Fib?? •  WPW •  Accessory conduction via “Bundle of Kent” •  Narrow PR •  Delta wave •  Usually, narrow complex, regular…..but beware…. •  WPW (AVRT) n  Accessory Pathway (Bundle of Kent) –  Preexcitation: short PR, delta wave Delta Wave Atrial fibrillation with pre-excitation 6. Anterior MI •  Criteria for STEMI: •  ST elevation of >/= 1 mm in 2 contiguous leads •  Measure 2 small boxes past J point •  What is the baseline? •  What is….. •  Persistent ST elevation on serial ECGs over weeks/months? Reciprocal ST-depression II, III, aVF ST-segment elevation V1-V4 12-Lead ECG I aVR V1 V4 II aVL V2 V5 III aVF V3 V6 Rhythm Strip (II) 5. Inferior MI •  STE II, III, AVF •  Reciprocal changes? •  Additional investigation you would order (or perform)? •  Key management principles? Inferior MI •  15-lead EKG to look at lateral and posterior leads •  Avoid nitro •  Venodilation •  Drop in preload •  Hypotension •  Beware of a tall R wave in V1: •  Posterior MI/ RV infarct •  RVH •  RBBB •  WPW •  Dextrocardia •  Duchenes muscular dystrophy 15 lead ECG 4. Complete heart block •  AV dissociation •  Sinus rate: P waves •  QRS: ventricular escape rate •  Width of QRS suggests degree of block: •  Narrow - higher up – better prognosis •  Wide - lower down – worse prognosis 3. Hyperkalemia •  Sequence: •  Tall peaked T waves (10mm precordial, 6mm limb) •  1st degree AVB; flattening or widening of p wave •  Bundle branch block •  Sine wave pattern Hyperkalemia – sine waves 2. Pericarditis •  Stage 1: diffuse, concave, upward STE •  no reciprocal changes (except AVR) •  Also: early PR depression •  +/- sinus tach •  Low voltage (depending on etiology •  Stage 2: ST returns to baseline; T waves decrease •  Stage 3: T waves invert •  Stage 4: ECG returns to normal 1. Ventricular Tachycardia •  Ddx of wide complex tachycardia: •  VT •  SVT with Aberrancy •  Preexcitation •  Is it VT or SVT with aberrancy? •  Clinical, historical, and ECG information needed: •  Hx of CAD, MI, or known structual heart disease: PPV > 95% for VT •  On ECG: AVR axis and Brugada criteria One more…. Ventricular fibrillation •  Irregularly irregular contractions originating from ventricular foci •  NOT GOOD •  CODE BLUE •  And with that…… •  On to ACLS J