12 lead-lesson 4


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  • In this lesson I am going to teach you how you can uncover some things if you just dig a little.
  • In this lesson, we are going to perform the third and fourth steps of the six step method.
  • In this lesson, we will learn a few more pathologies which can be identified on a 12-lead ECG. All of these conditions listed can be identified by examining the intervals and morphologies. Lets learn how.
  • Brady et al. said it best in Electrocardiographic ST-segment elevation: correct identification of acute myocardial infarction (AMI) and non-AMI syndromes by emergency physicians (Acad Emerg Med 2001; 8(4):349-360): ST segment elevation was determined if the ST segment was elevated >1 mm in the limb leads or >2 mm in the precordial leads (in at least two anatomically contiguous leads).
  • RBBB due to difficulty in finding baseline with tachyarrhythmias. Paced rhythms not mentioned, possible nonspecific BBB.
  • RBBB due to difficulty in finding baseline with tachyarrhythmias. Paced rhythms not mentioned, possible nonspecific BBB.
  • Sejersten et al. Comparison of the Ability of Paramedics With That of Cardiologists in Diagnosing ST-Segment Elevation Acute Myocardial Infarction in Patients With Acute Chest Pain (Am J Cardiol 2002 Nov 1;90(9):995-8):
  • When looking for ST-elevation that indicates an MI, we look for changes in contiguous or associated leads. Contiguous leads look at the same area of the heart muscle.
  • Knowing to look for reciprocal changes will assist you in identifying a true myocardial infarction.
  • Left ventricular strain pattern may be identified on some ECGs that have LVH changes. The strain pattern is associated with asymmetrical ST-depression in the left precordial leads, and possibly ST-elevation in the right precordial leads. The ST-segments usually have a curved appearance, and T-wave discordance will be present. The deepest ST-depression will be combined with the tallest R-waves and the highest degree of ST-elevation will be coupled with the deepest S-wave.
  • The take home message is that T-Wave discordance can cause both ST-Depression and ST-Elevation. The trick is knowing that the amount of ST-elevation or depression is directly proportionate to the depth or height of the preceding wave.
  • Here is one of our LVH examples from Lesson 3. We noted that the QRS complexes have been cut short by the monitor to keep them from interfering with nearby leads. This example happens to have changes associated with LV-Strain. Take a look at the T-waves of the precordial leads. Notice the discordance? Every lead but V4 shows T-wave discordance. The transitional leads often have T-wave concordance like V4 on this example. The left precordial leads have obvious downwardly concave ST-depression, and V1 & V2 have slight upwardly concave ST-Elevation. This is a typical LV-Strain pattern, and there is no evidence of MI.
  • Here is another example of LVH. This particular 12-lead is formatted slightly differently. The 6 limb leads are on the left and the 6 precordial leads are on the right. Note the obvious strain pattern in the precordial leads. The downward concavity in the left precordial leads is the biggest clue of LV Strain. An ST-Elevation MI with reciprocal changes would have either a straight or convex ST-segment.
  • Lets take another look at this example of LV strain, and examine some of the classic findings. You might notice that the ST-elevation is greater when the preceding S-wave is deeper, and the ST-depression is deeper when the preceding R-wave is taller.
  • Lets take a look at the precordial leads. V1 has the deepest terminal S-Wave which
  • Chang AM, Shofer FS, Tabas JA, et al. Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients . Am J Emerg Med 2009;27:916-921.
  • Lets examine these findings closer
  • Lets examine these findings closer
  • The take home message is that T-Wave discordance can cause both ST-Depression and ST-Elevation. The trick is knowing that the amount of ST-elevation or depression is directly proportionate to the depth or height of the preceding wave.
  • Draw a line from the J-Point to the peak of the T-wave, if the ST-segment falls below that line it is convex and probably benign. If it falls on or above that line it is concave, and probably an indication of an MI
  • Not so common
  • A sine wave occurs when there is a straight line from the nadir, or tip of the S-wave to the peak of the T-Wave. This causes the QRS to appear wide, and the rhythm may appear ventricular. In fact if the QRS is wider than 200ms you should be very suspicious of hyperkalemia. The sine wave may only last a short while before the rhythm degrades into a ventricular rhythm. The peaked T-wave has a sharp peak, symmetrical T-wave, and is a sign of hyperkalemia as well.
  • This ECG is an example of peaked T-waves indicating hyperkalemia
  • Here is an example of a Sine Wave. Look at how it almost appears to be a straight line from the tip of the S-wave, the Nadir, to the peak of the T-Wave.
  • Not so common
  • Not so common
  • 12 lead-lesson 4

    1. 1. 12-LeadElectrocardiography a comprehensive course sson4 Le Adam Thompson, EMT-P, A.S.
    2. 2. Resourceshttp://www.ekgclub.com/
    3. 3. The 6-Step Method• 1. Rate & Rhythm• 2. Axis Determination• 3. Intervals• 4. Morphology• 5. STE-Mimics• 6. Ischemia, Injury, & Infarct
    4. 4. Lesson Four• STE-Mimics – Any cause of ST-Elevation or AMI-like patterns that is not associated with an actual MI.
    5. 5. Objectives• Learn what the different STE-Mimics are.• Learn how to identify a STE-Mimic.• Learn how to differentiate between a STE- Mimic and a STEMI – (ST-Segment Elevation Myocardial Infarction)
    6. 6. ST-Elevation• The most common cause of ST- elevation is not myocardial infarction.• Less than 50% of STEMI alerts called by paramedics are actually ACS patients
    7. 7. ST-Elevation TP-Segment• ST-Elevation is elevation of the J-Point which causes elevation of the following ST- Segment.• Elevation is defined as anything above the T P isoelectric line.• Find the isoelectric line by locating the TP- Segment.
    8. 8. ST-Elevation• The J-Point is where the QRS complex J-Point and the ST-Segment meet.
    9. 9. NERD ALERT!
    10. 10. The Research• Electrocardiographic ST-segment elevation: correct identification of acute myocardial infarction (AMI) and non- AMI syndromes by emergency physicians (Acad Emerg Med 2001; 8(4):349-360)• 902 patients were enrolled in the study. Of those, 202 patients (22.4%) had ST segment elevation on their initial 12 lead ECG. Of those, only 31 patients (15%) had a discharge diagnosis of STEMI. In other words, 171 patients (85%) had a non-AMI cause of ST segment elevation on their initial 12 lead ECG
    11. 11. Causes of ST-Elevation Listed from most common to least: • Left ventricular hypertrophy (LVH) • Left bundle branch block (LBBB) • Benign early repolarization (BER) • Right bundle branch block (RBBB) • Nonspecific BBB • Ventricular Aneurysm • Pericarditis • Undefined or unknown cause
    12. 12. Causes of ST-Elevation Easier way to remember: E - Electrolytes (hyperkalemia) L - LBBB E - Early repolarization V - Ventricular hypertrophy (LVH) A - Aneurysm T - Treatment (e.i. pericardiocentesis) I - Injury (AMI, contusion) O - Osborne waves (hypothermia) N - Non-occlusive vasospasm
    13. 13. More Research• “Paramedics diagnosed over half of patients as having ST elevation AMI, when in fact they did not. One reason for this may be that the paramedics were concerned about missing patients with this condition.”
    14. 14. Also From The Research• The incidence of poor quality ECGs recorded by the paramedics was calculated to determine the paramedics performance in electrocardiographic acquisition.• In 13 of 124 patients (10.5%), the ECGs were characterized as poor quality..."
    15. 15. Lead Placement • Poor ECG captures were noted as a common problem. • V3 is most commonly misplaced lead
    16. 16. Which Electrode is Causing Artifact? • Precordial leads are easy. V1 has artifact? Check V1 electrode. • If Leads I & III have artifact, check left shoulder. • If Leads I & II have artifact, check right shoulder. • Leads II & III? Check left leg electrode.
    17. 17. What are Contiguous Leads?Lead I aVR V1 V4 • Contiguous leads are leads that look at high lateral septal anterior the same area of the heart.Lead II aVL V2 V5 •inferior show up on the 12-lead proximal They high lateral septal low lateral to each other.Lead III aVF V3 V6 inferior inferior anterior low lateral
    18. 18. Reciprocal Changes Site Facing Reciprocal Septal V1, V2 V7, V8, V9• Reciprocal changesV4 changes like Anterior V3, are None ST-depression V1, V2, V3, V4 inversionV9 Anteroseptal or T-Wave V7, V8, in leads opposite to the site of injury. aVF Lateral I, aVL, V5, V6 II, III, Anterolateral I, aVL, V3, V4, V5, V6 II, III, aVF Inferior II, III, aVF I, aVL Posterior V7, V8, V9 V1, V2, V3, V4
    19. 19. Left Ventricular Hypertrophy • The “Strain Pattern” is a repolarization abnormality associated with LVH and may cause ST-Segment changes. • STEMI is more difficult, but still possible to identify in the presence of LVH.
    20. 20. LV Strain• "Strain" is a pattern of asymmetric ST segment depression and T wave inversion. LV strain is most commonly seen in one or more leads that look at the left ventricle (leads I, aVL, V4, V5, V6); less commonly it can be seen in inferior leads.
    21. 21. LV Strain Pattern Left Precordial Leads Right Precordial Leads V4, V5, V6 V1, V2, V3Normal Complex
    22. 22. LV Strain• Discordance means opposite. – T-Wave discordance means that the T- Wave is deflected in the opposite direction as the terminal (last) wave of the QRS. – T-Wave discordance is normal in every lead with Left or Right BBBs.
    23. 23. T-Wave Discordance
    24. 24. LVH Clues• QRS Duration < 120 ms (Not BBB)• T wave Discordance (widened QRS/T angle)• Concave ST-Segments with asymmetrical T waves• The height of STE and T waves are directly proportionate to the depth of the S waves.• The taller the R wave the deeper the ST depression.• STE in right precordial leads with depression in left precordial leads due to “strain pattern”.• Deep narrow dagger-like Q waves have been noted in lateral leads with hypertrophic cardiomyopathy.
    25. 25. LV-Strain
    26. 26. LV-Strain
    27. 27. LV-Strain
    28. 28. LV-Strain
    29. 29. LV-Strain
    30. 30. RV-Strain • Indicates a pathology of the rightI III ventricle. Inverted – R:S ratio > 1 in V1 or V2 T-Wave – S1Q3T3 Pattern • S-Wave in Lead I, Q-wave & Inverted T-wave in Lead III • This indicates acute cor pumonale or pulmonary embolism. Q-Wave S-Wave
    31. 31. RV-StrainV1/V2 • An R:S ratio of > 1 in V1 or V2 indicates RVH. – This means that the R-Wave is bigger than the S-Wave in V1 or V2. • May cause ST-Segment Elevation due to T-Wave discordance. • P-Pulmonale is also a common finding with RV-Strain
    32. 32. Left Bundle Branch Block• LBBB may also mimic a STEMI – Delayed conduction due to a block of both the Left Anterior Fascicle & Left Posterior Fascicle. – Atrial rhythm with QRS duration > 120 ms and negatively deflected QRS complex in V1. – May cause ST-elevation due to T-Wave discordance.
    33. 33. LBBB Research• The evidence shows that there is no correlation between a new LBBB and ACS despite what was previously believed. – Am J Emerg Med 2009;27:916-921.
    34. 34. STE due to LBBB• Like LVH, STE may be caused by the T wave discordance normally found with a LBBB.• Acute Myocardial Infarction can still be diagnosed in the presence of LBBB. – This is not a commonly known fact, and many texts teach that an AMI can not be identified in the presence of LBBB
    35. 35. LBBB
    36. 36. LBBB
    37. 37. LBBB
    38. 38. LBBB
    39. 39. LBBB
    40. 40. T-Wave Discordance
    41. 41. Benign Early Repolarization (BER)• BER may present with an appearance of ST- elevation.• Notched J points are the most commonly taught indicator of “early repol”.• The ST-segment morphology is the easiest way to determine malignancy of the finding.• LOOK for reciprocal changes!!!
    42. 42. Early Repolarization• If mean amplitude of R wave in V2-V4 > 5mm than BER is more likely.• Consequently if the mean amplitude of V2-V4 is < 5 mm, the probability the patient is suffering from an MI is almost 99%.• An MI is still possible even if the above criteria does not indicate so.
    43. 43. Early Repolarization
    44. 44. Early Repolarization
    45. 45. ST-Segment Morphology Concave• Concave ST-Elevation is generally Convex more benign. – However, an MI may present with concave ST-Elevation.• Convex ST-Elevation is almost always an indication of an MI. J-Point J-Point
    46. 46. Benign Early Repolarization • Notched J-Points are sure indicators of benign early repolarization
    47. 47. Early Repolarization
    48. 48. Early Repolarization
    49. 49. Early Repolarization
    50. 50. Right Bundle Branch Block• A conduction delay due to blockage of the only right fascicle.• ST-segment usually not altered by the normal T wave discordance of RBBB.• QRS duration > 120 ms with positive terminal QRS deflection in V1.
    51. 51. Right Bundle Branch Block
    52. 52. Right Bundle Branch Block• Identify your J point• Compare J point to leads above and below to make certain you have the correct spot.• Identify Isoelectric line• Compare J point to isoelectric line.• STE > 1mm in limb leads or 2mm in precordial leads = STEMI
    53. 53. Right Bundle Branch Block
    54. 54. Left Ventricular Aneurysm • Localized area of infarcted myocardium that bulges outward during both systole and diastole. • Due to old infarction • May cause varying degrees of persistent STE < 4mm. • No reciprocal changes present. • Deep Q waves in leads with STE. • Most common in V1-V3.
    55. 55. Acute Pericarditis• Inflammation of the pericardium (pericardial sac).• May present with global STE• STE may appear pronounced due to PR- depression. QuickTime™ and a decompressor are needed to see this picture.• Tip - STE will be present in leads I & II, even though these leads are reciprocal to each other in most patients.• aVR will present with ST-depression
    56. 56. Acute Pericarditis• Stage Ieverything is UP – ST elevation in almost all leads• Stage IITransition – "pseudonormalization"• Stage IIIEverything is DOWN – inverted T waves• Stage IV Normalization.
    57. 57. Acute PericarditisStage 1 Stage 2 Stage 3
    58. 58. Acute Pericarditis
    59. 59. Acute Pericarditis
    60. 60. Acute Pericarditis
    61. 61. Hyperkalemia• Peaked, usually narrow, symmetrical T waves• Severe hyperkalemia may present with straight line from tip of S wave (nadir) to peak of T wave, AKA Sine wave.• Sometimes presents with wide complexes, possibly lacking P waves. Z-Fold pattern is common with severe hyperkalemia.• Use medical history to help determine cause.
    62. 62. Hyperkalemia Peaked T-Wave• Hyperkalemia = High Potassium Level – Peaked T-Waves • May mimic an acute MI – Sine Waves • Sign of lethally high potassium level Sine Wave
    63. 63. Hyperkalemia
    64. 64. Hyperkalemia
    65. 65. Hyperkalemia
    66. 66. Hyperkalemia
    67. 67. Osborn Waves• Sometimes called “J-Waves”• Indicates HYPOTHERMIA• May be associated with bradycardia• Extra wave at the J-Point of the QRS- complex.
    68. 68. Osborn Waves Osborn Waves
    69. 69. Other STE-Mimics• Brugada Syndrome - AKA Sudden Unexpected Death Syndrome. RBBB morphology in V1.• Takotsubo Cardiomyopathy - non-ischemic cardiomyopathy in which there is a sudden temporary weakening of the myocardium. Because this weakening can be triggered by emotional stress, such as the death of a loved one, the condition is also known as broken heart syndrome
    70. 70. STE-Mimics• Take a big look at the entire clinical picture.• Often, a pathology has not read up on what it is suppose to look like on an ECG, and breaks all the rules.
    71. 71. Lesson 4• This is the end of Lesson 4• In Lesson 5 we will discuss ischemia, injury, and infarct.