EKG I and II Flashcards Preview

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Flashcards in EKG I and II Deck (11):
1

Limb leads

  • Bipolar limb leads
  • Augmented limb leads
  • Precordial leads

  • Bipolar limb leads
    • Lead I: right arm -, left arm + (0)
    • Lead II: right arm -, left leg + (+60)
    • Lead III: left arm -, left leg + (+120)
  • Augmented limb leads
    • Lead aVR: right arm + (-150)
    • Lead aVL: left arm + (-30)
    • Lead aVF: left leg + (+90)
  • Precordial leads
    • Leads V1 & V2: right side
    • Leads V3 & V4: middle
    • Leads V5 & V6: left side
  • Positve (upward) deflection: signal moves toward positive electrode

2

Waves

  • P wave
  • PR interval
  • QRS complex
  • T wave
  • QT interval
  • ST segment
  • Increased signal size
  • Decreased signal size

  • P wave
    • Atrial contraction (systole)
    • Atrial tissue depolarization propagates inferiorly & leftward --> upward deflection
  • PR interval
    • Time required for the wave to pass through atrium & AV node before ventricular activation
    • Normal = 120-200ms
  • QRS complex
    • Ventricular depolarization
      • Q wave: downward component
      • R wave: upward component
      • S wave: downward component
    • Normal ≤ 100 ms
    • Incomplete bundle branch block = 100-200 ms
    • Bundle branch block > 100 ms
  • T wave
    • Repolarization of the ventricle
  • QT interval
    • Ventricular depolarization & repolarization
    • Normal < 440 ms
    • Correction: QTc = QT / √(preceding RR interval (s))
      • At HR = 60, QT = QTc
  • ​​​ST segment
    • ​Diagnoses ischemia & myocardial injury
  • Increased signal size
    • Muscular hypertrophy
  • Decreased signal size
    • Loss of functioning muscle, heart attack

3

Calibration

  • Measure
  • Normal

  • Measure
    • Rectangular square wave
      • 5 mm wide
      • 10 mm high
    • Lead II = Lead I + Lead III
    • Lead I ≈ V6
  • Normal
    • Paper speed = 25 mm/s
    • Gain setting = 10 mm/mV
    • Small box = 1mm = 40ms
    • Large box = 5mm = 200ms

4

Heart rate

  • Measure
  • Normal
  • Abnormal

  • Measure
    • 60,000ms/min / (40ms * # small boxes)
    • Large boxes: 300 - 150 - 100 - 75 - 60
    • (# QRS in 6s strip) * 10
  • Normal
    • HR = 60-100 bpm
  • Abnormal
    • HR < 60 bpmbradycardia
    • HR > 100 bpmtachycardia

5

Axis

  • Measure
  • Normal
  • Abnormal

  • Measure
    • Avg direction of electrical vector
    • Horizontal: Lead I (+ = right)
    • Vertical: Lead aVF (+ = down)
  • Normal
    • Normal: -30 to +110
    • Positive Lead I & aVF
  • Abnormal
    • -30 to -90: left axis deviation
    • +110 to +180: right axis deviation
    • +180 to =90: indeterminate axis

6

Rhythm

  • Normal
  • Abnormal

  • Normal
    • Sinus rhythm
    • HR = 60-100 bpm
    • + P wave in Lead II
  • Abnormal
    • No clear P, irregularly irregular QRSatrial fibrillation
    • Long QRS, normal HRslow ventricular (accelerated idioventricular) rhythm
    • Long QRS, high HRfast ventricular rhythm (ventricular tachycardia)

7

P wave

  • Normal
  • Abnormal

  • Normal
    • Always precede QRST
    • Always followed by QRST
  • Abnormal
    • Prolongation of consecutively conducted P before dropped QRSMobitz Type I AV (Wenkebach) block
    • Dropped QRSs w/ no PR prolongationMobitz Type II AV block
    • Regular HR but no conducted P3o AV block
    • Tall (>2.5) peaked P in II, >1.5 in V1 & V2right atrial abnormality
    • Long (>4) P in II, negative P in V1left atrial abnormality

8

QRS complex

  • Measure
  • Normal
  • Abnormal

  • Measure
    • (Small boxes containing big & small peak) * 40
  • Normal
    • QRS < 100ms
  • Abnormal
    • QRS = 100-120msincomplete BBB or conduction delay
    • QRS > 120msbundle branch block
    • Rabbit ears in V1 & V2, wide S in I, V5, & V6right (I)BBB
    • Broad/notched R & absent Q in I, V5, & V6left (I)BBB / intraventricular conduction delay
    • LAD, aR in I & aVL, rS in II, III, & aVFleft anterior fascicular (hemi)block
    • RAD, rS in I & aVL, aR in II, III, & aVFleft posterior fascicular block
    • |R| in V1 > |S| in V1right ventricular hypertrophy
    • Large |R| in V5 or V6left ventricular hypertrophy
    • Long (>1) large (25% of total QRS height) Qinfarction

9

PR interval

  • Measure
  • Normal
  • Abnormal

  • Measure
    • (Small boxes b/n P & R) * 40
  • Normal
    • PR = 120-200ms
  • Abnormal
    • PR < 120msaccelerated AV conduction (Wolf-Parkinson-White Syndrome)
    • PR > 200ms1o AV block

10

QT interval

  • Measure
  • Normal
  • Abnormal

  • Measure
    • (Small boxes b/n Q & T) * 40
    • QTc = AT / √(RR interval)
  • Normal
    • QTc < 440ms
  • Abnormal
    • QTc << 440mshypercalcaemia
    • QTc > 440mshypocalcaemia

11

ST segment & T wave

  • Abnormal

  • Abnormal
    • T inversionischemia
    • ST elevation: injury, acute infarction
      • With PR depressionpericarditis
      • With tall peaked Tearly repolarization
      • With tall narrow peaked Thyperkalemia
    • ST depression
      • ​With T inversionDigoxin therapy
      • With short T, U waveshypokalemia