ECG/EKG Analysis

Calibration

 * paper speed is normally 25mm/second
 * therefore each 1mm box in the x axis = 0.04sec
 * a 1mV test pulse is normally over 10 mm
 * therefore each 1mm box in the y axis = 0.1 mV

Rhythm

 * P wave upright in I, II, AVF
 * PR interval > 0.12
 * P wave for every QRS
 * QRS for every P wave

Rate

 * 300,150,100,75, 60, 50 rule
 * If rhythm is not normal count the number of QRS complexes in 25 big boxes (5 seconds) and multiply by 12
 * (an alternative method is to count the number of QRS complexes in a 10 second duration and multiply by 6)
 * tachycardia >100bpm
 * bradycardia <60bpm

Axis

 * QRS upright in I and aVF
 * If not upright in aVF look @ II
 * If upright then axis is normal
 * If not then there is left axis deviation

Intervals

 * PR 0.12-0.20 (3-5 squares)
 * QRS < 0.10 (2.5 square)
 * QT <0.44 (11 squares)

Atrial enlargement

 * Right atrium - lead II - p wave wave's initial component is enlarged, taller 2.5mm
 * Left atrium - Lead V1 - p wave downward deflection of terminal component

Ventricular hypertrophy

 * Right ventrical - tall R waves in V1 and V2, deep S in V6
 * Left ventrical - tall R wave in V6, deep S in V1, plus one of
 * R in V5/6 > 26mm
 * S in V1 or 2 + R in V5 or V6 > 35 mm
 * R+S in any chest lead > 45mm


 * R in aVL > 11mm
 * R in I > 15mm

Bundle Branch Blocks
note: normally depolarization of the ventricular septum is stimulated by a branch of the left bundle

incomplete block: QRS 0.10-0.12 (2.5-3 squares) complete block: QRS > 0.12 (3)

RBBB

 * R' in V1
 * S in V6

LBBB

 * absent normal R in V1 and Q in V6 (initial depolarization directed to LV)
 * terminal R' in V6 and downward deflection in V1

LAFB

 * Q wave in I, aVL
 * initial R wave in II, III, aVF

LPFB

 * Q in II, III, aVF
 * initial R wave in I, aVL

Q waves

 * may be normal in V6 and aVL
 * pathologic > 0.04, depth >25% QRS height

Inferior: II, III, aVF    RCA Anteroseptal: V1-V2  LAD Anteroapical: V3-V4   LAD (distal) Aterolateral: V5-V6, I, aVL   CFx Posterior: V1-V2 (tall R, no Q)  RCA

MI

 * ST elevation - returns to baseline in days
 * T wave inversion - weeks to months
 * Q wave - persists
 * if ST remains elevated - fibrotic scar (ventricular anurysm) developed

Pericarditis

 * diffuse ST elevation
 * PR depression

Hyperkalemia

 * tall "peaked" T waves
 * flat p
 * wide QRS

Hypokalemia

 * U wave
 * ST depression
 * flat T

Hypercalcemia

 * decreased QT interval

Hypocalcemia

 * increased QT interval

External link

 * EKG Reference Guide - Arrhythmia lessons, drills and tracings
 * EKG Academy – free EKG lectures, drills and quizzes