ekg exam 2

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ekg exam 2
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  1. how is the P wave measured
    from the beginning of the P wave until the start of the PR segment, and also measured from iso-electric line to the highest point of the P wave
  2. what is the normal amplitude and duration of the P wave
    • amplitude: 0.5-2.5mm
    • duration: <0.11 seconds
  3. what are the abnormal amplitudes and duration of a P wave
    • amplitude >2.5 likely RAE
    • amplitude <0.5mm hyperkalemia
    • duration >0.12 seconds likely LAE
  4. how is the QRS complex measured
    measure from the beginning of the Q(or R if no Q) to the end of the complex.  Also measured from the iso-electric line to the top of the R wave and from the iso-electric line to the bottom of the S wave
  5. when is the Q wave defined as significant
    if it is > than 1/3 the depth of the R wave or >1 small box wide
  6. what is the normal duration and amplitude of the QRS complex
    • 0.05 seconds to 0.10 (0.12) seconds
    • wide variation in amplitude
    •    - upper limits
    •        - 30 in lead II
    •        - 30 in V1 and V6
  7. what is the abnormal amplitude and duration of the QRS complex
    • QRS duration >0.12 seconds (BBB)
    • between 0.10 and 0.12 seconds (pBBB)
    • total amplitude (voltage) <5mm (0.5mv)
    • total amplitude >30mm
    • significant Q waves
  8. how is the PR interval measured
    from the beginning of the P wave to the beginning of the Q wave (R wave if there is no Q)
  9. what is the normal duration of the PR interval
    duration: 0.12 to 0.20 seconds
  10. what are the abnormal durations of the PR interval
    • duration > 0.20 (prolonged): AV block, medication
    • duration < 0.12 (shortened): low atrial focus, accessory pathway (WPW,LGL)
  11. how is the QT interval measured
    from the beginning of the QRS complex to the end of the T wave
  12. what are the normal for a QT interval
    • corrected QT tables based on gender and HR
    • QTc=QT/√ of the RR interval
    • useful rule of thumb: QT should be half of RR
    • QTC for male: <0.42, female: <0.43
  13. what are the abnormal durations of the QT interval
    • >0.43: delayed repolarization
    • <0.3: short QT syndrome or electrolyte imbalance
  14. an impaired impulse through on or more of the divisions of the conduction system distal to the Bundle of HIS is known as what
    bundle branch block
  15. a QRS greater than 0.12 seconds (3 small boxes) is defined as a what
    BBB
  16. how is a BBB recongnized
    R,R′ in specific leads of a 12 lead ECG
  17. a QRS between 0.10 and 0.12 is defined only as a(n) what
    • intraventricular conduction delay (IVCD, pBBB, or IBBB).
    • if it can not be determined which bundle is involved, it is labeled non-specific
  18. what are the causes of a RBBB
    • idiopathic degenerative conduction system disease
    • ischemic heart disease
    • cardiomyopathy
    • massive PE
    • RVH
    • normal variant
  19. what is the ECG criteria for a RBBB
    • QRS duration >0.12 in any lead
    • RSR′ in V1-V3 (any one or more)
    • wide S wave in V4-V6 (any one or more)
    • ST depression in V1 and V2
    • inverted T wave in V1 and V2 (T wave discordance)
    • if RSR′ and QRS <0.12 then "incomplete" BBB or IVCD
  20. explain the P wave, PR interval, QRS complex, and characteristics of a RBBB
    • P wave: before each QRS, identical
    • PRI: 0.12 to 0.20 seconds
    • QRS complex: >0.12 seconds
    • characteristics: RSR′ in V1
  21. in a RBBB, how is it diagnosed and in which leads
    • slurred S waves in leads I and V6
    • leads V1 and V2 should have increased R:S ration and some semblance of an RSR′ or QR′ complex
  22. what are the causes of a LBBB
    • idiopathic degenerative conduction system disease
    • CAD/ischemic heart disease
    • dilated cardiomyopathy
    • aortic stenosis
    • HTN/LVH
    • hyperkalemia
    • MI
    • normal variant (much less often that RBBB)
  23. what is the ECG criteria for LBBB
    • QRS duration >0.12 in any lead
    • high voltage S waves in V1-V3 (any one or more)
    • tall R wave in V4-V6, I and aVL (any one or more)
    • slurred notch in any of the above (vice true RSR′)
    • ST depression in V5,V6,I and aVL
    • inverted T wave in V5, V6, I and aVL (T wave discordance)
    • if RSR′ and QRS <0.12 then "incomplete" BBB or IVCD
  24. explain the P wave, PRI, QRS complex, and characteristics of the LBBB
    • P wave: before each QRS, identical
    • PRI: 0.12-0.20 seconds
    • QRS complex: ≥0.12 seconds
    • characteristics: RR′ in V5
  25. an ECG containing a LBBB can not be evaluate for what
    • ischemia or infarct
    • ventricular hypertrophy
    • ST/T wave changes (except concordance)
  26. what are the diagnostic criteria for a complete LBBB
    • QRS duration ≥ 120 msec
    • broad, notched R waves in lateral precordial leads (V5 and V6) and usually leads I and aVL
    • small or absent initial r waves in right precordial leads (V1 and V2) followed by deep S waves
    • absent septal q waves in left-sided leads
    • prolonged intrinsicoid deflection (>60 msec) in V5 and V6
  27. what are the diagnostic criteria for a complete RBBB
    • QRS duration ≥ 120 msec
    • broad, notched R waves (rsr′, rsR′, or rSR′ patterns) in right precordial leads (V1 and V2)
    • wide and deep S waves in left precordial leads (V5 and V6)
  28. what are the causes of left anterior hemiblock (LAFB)
    • acute MI (up to 4% of acute MI)
    • HTN
    • aortic stenosis
    • dilated cardiomyopathy
    • consider LAD as source
  29. what are the ECG criteria for LAFB
    • left axis deviation (usually marked)
    • normal or slightly widened QRS (<0.12)
    • S wave larger than R wave in II, III, aVF
    • qR or R wave in lead I
    • rS wave in lead III (probably II and aVF)
    • Q1S3
  30. what are the causes of the left posterior hemiblock (LPFV)
    • rare
    • acute MI (up to 4% of acute MI)
    • consider RCA as source
  31. what are the ECG criteria for a LPFB
    • right axis deviation
    • normal or slightly widened QRS (<0.12)
    • q wave in lead III
    • s wave in lead I
    • S1Q3
  32. explain the bifascicular blocks
    • RBBB + anterior hemiblock
    • RRR + posterior hemiblock
    • anterior hemiblock + posterior hemiblock =LBBB
    • RBBB + LAFB + LPFB = third degree AV block
    • may be intermittent or rate related
    • compare old ECG
    • RBBB + LPFB usually progresses to complete heart block
  33. what are the etiologies of LAE
    • valvular heart disease (MS,MR,AS,AR)
    • LVH
    • HCM or HOCM
    • HTN
  34. what are the ECG criteria for LAE (P-mitrale)
    • a notched P wave in any lead (lead II)
    •    - >0.11 or peaks >0.04 apart
    • diphasic P in V1
    •    - terminal portion of P wave ≥ 1mm deep and ≥  0.04 wide (P terminal force)
  35. what are the etiologies of RAE
    • valvular heart disease (TS, PS, MR, MS)
    • COPD
    • pulmonary HTN
    • PE
  36. what are the ECG criteria for RAE (P-pulmonale)
    • tall, peaked P wave in any lead
    •    - ≥ 2.5mm
    • most prominent in leads I, II, aVF
    • biphasic P in V1 with initial force > terminal force
  37. what are the etiologies of LVH
    • HTN
    • valvular heart disease (AS, AR, MR, HCM)
    • coarctation of the aorta
    • patent ductus arteriosus
    • acromegaly
  38. what are the false positives in LVH
    • thin chest wall
    • s/p radical mastectomy
    • LBBB
    • acute MI
    • LAFB
    • WPW
  39. what are the ECG criteria for LVH
    • scott criteria:
    • - normal duration of QRS (<0.12)
    • - sum of S in V1 or V2 + R in V5 or V6 > 35mm (use deepest in V1/V2 and tallest in V5/V6)
    • R wave in aVL > 11mm (supportive)

    estes criteria
  40. what is the cornell voltage and voltage duration of LVH
    • voltage: R aVL + S V3 > 20mm (F), >25mm (M)
    • voltage duration: cornell voltage X QRS duration in ms
  41. what are the etiologies of RVH
    • COPD
    • pulmonary HTN
    • valvular disease (MS, MR, TR, PS)
    • PE
    • chronic left HF
    • ASD,VSD
    • tetralogy of Fallot
  42. what are the ECG criteria for RVH
    • RAD (must have)
    • normal QRS duration
    • reversal of R wave progression
    • may have strain pattern in V1,V2
    • must not have BBB
  43. "normal" Q waves indicate what
    activation of the intraventricular septum. They will appear in the leads that "look left"
  44. explain the septal Q's
    they are normal in I,aVL,V5 and V6 (left or lateral leads)

    Small Qs are also generally innocent in lead III and lead V1 if no other abnormality is seen
  45. when are Q waves significant
    if they are greater than 1 box in width (longer than 0.04 msec) OR are larger than 1/3 of the R wave
  46. what do significant Q waves indicate
    MI or obstructive septal hypertrophy (IHSS)
  47. in transmural myocardial infarction, significant Q waves (1 box wide or 1/3 the R) appear in which leads
    leads "looking at" the areas of infaction: II, III, aVF, for inferior infarct; I, aVL, and V5-V6 for lateral; etc
  48. what are the Q wave rules
    • a Q wave in lead III alone is not diagnostic of infarct, even if it is otherwise "significant" in size and width. Qs in III are ignored unless other abnormalities are seen
    • Q waves that occur in the setting of LBBB or LVH are less reliable for diagnosis of MI
    • the presence of ST or T wave abnormality in the same lead(s) as "borderline" Qs makes these Qs suspicious for infarct
  49. explain the Q waves in hypertrophic cardiomyopathy (HCM)
    • in idiopathic hypertrophic subaortic stenosis (IHSS) the Q waves tend to appear in the same leads in which normal "septal" Qs are seen- because the pathology is thickening of the septum
    • these "significant" Qs of IHSS are almost always accompanied by evidence of marked left ventricular hypertrophy
  50. in summary, what are the causes of Q waves, where do you see septal Q waves, what are the significant Q waves, and what causes HOCM (IHSS)
    • causes: septal, infarct, IHSS
    • septal: I, aVL, V5-V6, occasionally inferior leads
    • signifant Qs: Q>1/3 of R, Q> 1 box wide, NOT in lead III
    • HOCM (IHSS): increased "septal" Qs, evidence of LVH
  51. what can a deviation in the ST segment from baseline indicate
    • infarct or ischemia
    • pericarditis
    • electrolyte abnormality
    • ventricular strain
  52. where are ST elevation or depression usually measured
    at a point 2 boxes beyond the QRS complex
  53. when is an ST segment depression considered significant
    if the ST segment is at least one box below baseline, as measured two boxes after the end of the QRS.

    As with infarction, the location of the ischemia is reflected in the leads in which the ST depression occurs
  54. what are the etiologies of an ST depression
    • ischemia
    • hypothermia
    • hypokalemia
    • tachycardia
    • subendocardial infarct
    • reciprocal infarct
    • ventricular hypertrophy
    • BBB
    • digitalis
  55. what is an ST segment elevation usually attributed to
    impending infarct but can also be due to pericarditis or vasospastic angina
  56. in ST elevation, how is the ST segment height measured
    at a point 2 boxes after the end of the QRS complex
  57. when is an ST segment elevation considered significant
    if it exceeds 1 mm in a limb lead or 2 mm in a precordial lead
  58. what are the etiologies of an ST segment elevation
    • infarction
    • vasospastic (Prinzmetal's angina)
    • pericarditis
    • early repolarization

    • measure: 2mm beyond QRS
    • significant: 1mm limb lead
    •                  2 mm chest lead
  59. T waves are normally upright in which leads
    I, II, and V3-V6
  60. T waves are normally inverted in which lead
    aVR
  61. when will T waves usually be abnormal
    • ventricular hypertrophy
    • LBBB
    • chronic pericarditis
    • electrolyte abnormality
  62. what can cause tall, peaked T waves
    hyperkalemia if generalize, infarction if localized
  63. what are the etiologies of inverted T waves
    • evolving infart
    • chronic pericarditis
    • conduction block
    • ventricular hypertrophy
    • acute cerebral disease
  64. what causes a flattened T wave
    non-specific
  65. when would you see a large U wave
    • electrolyte abnormality (hypokalemia)
    • severe CAD
    • drug effects
  66. this type of angina is CP or discomfort that typically occurs with activity or stress. The pain usually begins slowly and gets worse over the next few minutes before going away. It quickly goes away with medication or rest, but may happen again with additional activity or stress
    stable angina
  67. this type of angina occurs without cause, lasts longer than 15-20 minutes and responds poorly to nitro
    unstable angina
  68. this type of angina is CP due to spasm of the coronary arteries. May occur in non atherosclerotic arteries and is thought to be caused by endothelial dysfunction
    variant or Prinzmentals angina
  69. this is a lack of adequate oxygen supply to the myocardial muscle tissue to meet its demand. Usually caused by inadequate blood flow to the coronary arteries
    ischemia
  70. in ischemia and infarct, what does an ST depression represent
    • subendocardial myocardial ischemia
    • not necessarily associated with injury
    • may be reversible
    • it is a dire warning sign and should be managed aggressively
    • often associated with T wave inversion
  71. this occurs when there is cellular death and tissue necrosis, and it represents a permanent loss of myocardium and subsequent loss of function
    infarct
  72. in ischemia and infarction, what does an ST elevation represent
    • acute transmural myocardial injury
    • severe and progressive
    • ST segment elevation occurs in area of necrosis
    • there can be ST elevation without actual necrosis in variant angina
  73. by the time ST elevation occurs in ischemia and infarction, what has occurred
    there has been a transmural deprivation of oxygen/blood flow from the epicardium to the endocardium
  74. what are the shapes of T wave Δs
    • may be hyperacute early (tall, peaked)
    • may be flattened
    • may invert
    • may persist for days, months or years after an infarct
  75. explain the evolution of the hyperacute MI
    • tall, peaked T wave
    • suggestive, but not diagnostic of MI
    • may proceed clinical symptoms
    • not generalized (only in leads, "looking at" MI
  76. explain with evolution of the acute MI
    • ST segment elevation
    • increased ST elevation
    • Q waves
  77. if the ST elevation is in leads II, III, and aVF, where would the ST depression be in reciprocal changes
    I, aVL, and any of the V leads

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