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Clinical Medicine III > EKG Interpretation > Flashcards

EKG Interpretation Flashcards

1
Q

Lead Location and View of Heart

A
  • V1: 4th intercostal on right - septum view (anterior wall)
  • V2: 4th intercostal on left - septum view (anterior wall)
  • V3: directly between V2 and V4 - anterior view
  • V4: 5th intercostal midclavicular - anterior view
  • V5: level with V4 anterior axillary - lateral view
  • V6: level with V5 midaxillary - lateral view
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2
Q

Direction of EKG Spikes

A
  • upward/positive deflection - neg. to pos. direction
  • downward/negative defletion - pos. to neg. direction
  • equiphasic deflection/pos. AND neg. - between neg. and pos.
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3
Q

EKG Paper Wave Description

A
  • small box:
    • 1mm tall x 0.04sec wide
  • large box:
    • 5mm tall x 0.2sec wide
  • paper speed: 25mm/sec
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4
Q

Order and Meaning of Waves

A
  • P (upward)- atrial depolarization
  • QRS complex- ventricular depolarization and contraction
    • Q (downward)- depolarization of interventricular septum
    • R (larger upward)
    • S (downward)
  • T (modest upward)- ventricular repolarization
  • U (small/nonobserved upward)- recovery of Perkinje fibers
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5
Q

Intervals vs. Segments

A

invertval - contains a wave

segment - section with no wave

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6
Q

Pathologic Q Wave

A

>.04sec (1 small block) wide

>25% of height of R wave

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7
Q

J point

A

level of ST segment compared to PQ segment

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8
Q

EKG Reading Scheme

(what you need to read)

A
  • Rate:
    • 300, 150, 100, 75, 60, 50…
    • strip is 10sec - count # beats x 6
  • Rhythm:
    • P-QRS coupling present and constant
    • QRS complexes occurring regularly
  • Waves: present and normal
  • Axis
  • Intervals:
    • PR interval
    • QRS interval
    • QT interval
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9
Q

What is the QRS Axis

A

summation vector of where the heart’s electrical current

is spending most of its time (avg direction of electrical activity)

normal = -30 to +90

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10
Q

On what is the axis charted

A

Einthoven’s Triangle / Hexaxial System

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11
Q

Causes of Axis Deviation

A
  • left axis deviation (-30 to -90)- left ventricular hypertrophy
  • right axis deviation (+90 to 180)- MI (tissue death) in left ventricle
  • extreme right axis deviation (-90 to 180)- “no mans land”
    • could be extreme right or left
    • typically a congenital anomaly
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12
Q

2 Steps to Determining Axis

A
  1. QRS complex in I and aVF:
    • +/+ = normal
    • +/- = POSSIBLE left axis (0 to -30 is normal)
      • Look at Lead II:
        • (+) = normal
        • (-) = left axis
    • -/+ = right axis
    • -/- = extreme right axis
  2. Look for equiphasic lead in 1st 6 leads
    • axis will be at right angle to equiphasic lead
    • will point to quadrant determined by step 1
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13
Q

Why a bundle branch block (BBB) occurs

A

block in propogation of AV signal

ventricles normally contract simultaneously, but this interrupted

see split in QRS complex as a result

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14
Q

Right BBB

A
  • “rabbit ears” (RSR’) in V1 and V2
  • prominent S wave in 1 and aVL

d/t lungs

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15
Q

Left BBB

A
  • “rabbit ears” (RR’) in V5 and V6
  • broad R waves in 1, aVL, V6

d/t ischemic heart failure, HTN

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16
Q

Role of T-wave in BBB

A

  • want T wave to be inverted with BBB (downward)
  • elevated T wave may be an infarction
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17
Q

Hemiblocks (Fascicular Block)

A
  • Anterior hemiblock
    • left axis deviation > -45’ with no explanation
    • small q in 1, aVL
    • small r in II, III, aVF
  • Posterior hemiblock
    • right axis deviation > +120’ with no explanation
    • small r in 1, aVL
    • small q in II, III, aVF
18
Q

Bifascicular Blocks

A
  • RBBB + anterior fascicular block
  • RBBB + posterior fascicular block
19
Q

Complete Heart Block (3rd degree)

A

All 3 Fascicles blocked - no coupling

(atria no longer talking to ventricles - irregular rhythms)

look for P without QRS periodically

20
Q

Chamber Enlargement - Right Atrium

A

P-wave large (>3mm) and pointed particularly in inferior leads

21
Q

Chamber Enlargement - Left Atrium

A

Wide, notched P wave (>.12sec) particularly in inferior leads

22
Q

Chamber Enlargement - Right Ventricle

A
  • axis moves to right (spending more time here)
  • J point lowered (ST depression)
  • inverted T-wave
23
Q

Chamber Enlargement - Left Ventricle

A
  • amplified S and R waves
  • (S-wave in V1) + (greater of R-wave in V5 or V6) > 35mm
    • then check lead II to see if it’s negative
24
Q

First Degree Block

A

prolonged PR interval

(0.1 - 0.2sec)

25
Q

Second Degree: Mobitz Type 1 (Wenckebach)

A

short PR -> longer PR -> even longer PR -> dropped QRS

26
Q

Second Degree Block: Mobitz Type II

A

P-wave then dropped QRS (no P-wave lengthening)

DANGEROUS!

27
Q

Third Degree (Complete) Block

A

No P to QRS Coupling

(often requires pacemaker)

28
Q

Potassium

A

Potassium (K+) “lives under the T-wave”

  • Increased potassium - elevated T-wave
  • Decreased potassium - lowered T-wave and U-wave created
29
Q

Calcium

A

Ca++ determines time of repolarization

  • Low Ca++ = prolonged QT interval (longer to repolarize)
  • High Ca++ = shortened QT interval
30
Q

EKG Changes d/t MI

A
  • ischemia- ST depression with or without T-wave inversion
  • injury- ST elevation with or without loss of R wave
  • infarction- DEEP Q waves
31
Q

Timing of EKG Changes with Acute Occlusion

A
  • pathologic Q waves: hours to days
  • ST segments: minutes to hours
  • T-waves:
    • Hyperacute T-waves in minutes
    • T-wave inversion in hours
32
Q

Location of Ischemia per EKG

A
  • inferior:
    • 2, 3, aVF
    • right coronary and circumflex
  • lateral
    • 1, aVL, V5, V6
    • left circumflex
  • septal
    • V1, V2
    • LAD
  • anterior
    • V3, V4
    • LAD
33
Q

“Fooler” EKG

A

“Humped” ST elevation (possible ventricular aneurism)

34
Q

Digoxin Effect

A

inverted T-wave in lateral leads

“moustache affect”

35
Q

“knife-like” chest pain eased with bending over

ST elevation in I and II and “all over”

A

Pericarditis

36
Q

“Slurring” of QRS - Delta wave

followed by tachycardia in later EKG

A

Wolff-Parkinson-White Syndrome

IMPORTANT!

37
Q

Wolff-Parkinson-White

Orthodromic

A

impulse flows up accessory path to atria - atria overstimulated tachycardia

38
Q

Wolff-Parkinson-White

Antidromic

A

impulse flows down accessory path

39
Q

Accessory Path through AV Node

A

Lown-Ganong-Levine (LGL) Syndrome

  • short PR segment
  • no delta wave d/t accessory path
40
Q

Posterior Wall MI

A
  1. ST depression in V1 - V4 (septal and anterior)
  2. R/S wave ratio greater than 1 in V1 or V2
41
Q

Right Ventricular MI

A
  1. ST elevation in V1 (only lead that looks directly at right ventricle)
  2. ST elevation in III > II (b/c III is more rightward facing than II)

Clinical Medicine III (3 decks)

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