Axis / BBB / LVH / Ischemia
I, aVL, V5 & V6
Lateral Left Coronary Circumflex & Obtuse marginal
Left circumflex artery feeds:
Lateral & posterior walls of left ventricle.
T wave inversion
Normal in V1 & III
LVH
(STEP 1) Refer to leads V1 & V2: Measure and select the deepest ventricular depolarization of the 2 views. Measure from the isoelectric line down to the tip of the deepest QS complex. (STEP 2) Refer to leads V5 & V6: Measure and select the tallest ventricular depolarization of the 2 views. Measure from the isoelectric line up to the tip of the tallest "R" wave. Count the number of millimeters (small boxes). (STEP 3) Add the 2 numbers together. If it adds up to 35mm or more, clinically you must suspect left ventricular hypertrophy.
Axis
1. Look at 1 & AVF to determine general axis then locate the most biphasic lead. 2. Look for the lead perpendicular to this one. 3. If the QRS is predominantly positive, the axis will be located in its direction; if the QRS is predominantly negative, it will be located on the opposite direction. 4. Review the 2 leads on either side of the perpendicular lead. Whichever one has a bigger QRS pulls the axis toward that lead. *Normal Axis: -30 degrees to +100 degrees *Right Axis Deviation: +100 degrees to ±180 degrees *Extreme Right Axis Deviation: ±180 degrees to -90 degrees *Left Axis Deviation: -90 degrees to -30 degree
Pathological Q wave
>0.04 mm or 1/3rd R-wave. Infarction when seen with ST elevation.
ST segment elevation
>1 mm or >2 mm elevation in septal leads. Present in two or more contiguous leads. Measure at J point.
V3 & V4
Anterior Left Coronary Anterior Descending and Diagonal arteries
Left Coronary Artery (LCA) feeds:
Anterior & septal walls of left ventricle. Bundle of HIS. Both bundle branches.
MI & LBBB (V1)
Cannot call it an MI
Bifasicular block (Posterior):
Down, Any, Up & RBBB (Any LBBB)
Right Axis & Posterior hemiblock
Down, Any, Up (90* to 180*)
Extreme Right Axis
Down, Down, Down (>180*)
VT vs. SVT
I, II, III down and V1 up. Concordance up or down in V1 - V6. Negative V6.
Right Coronary Artery (RCA) feeds:
Inferior left ventricle which turns into posterior descending coronary artery right ventricle. SA & AV nodes Left bundle branch
II, III, aVF
Inferior wall of left ventricle Right Coronary Artery Marginal branch
V1 & V2
Septum Left Coronary Septal branch
Right Atrial Enlargement (RAE)
Tall peaked P-wave >2.5 mm
Bifasicular block (Anterior):
Up, Down, Down & RBBB (Any LBBB)
Pathological Left Axis & Anterior hemiblock
Up, Down, Down (-40* to -90*)
Physiological Left Axis
Up, Up or Bi, Down (0* to -40*)
Normal Axis
Up, Up, Up (0* to 90*)
BBB
V1 QRS wider than 0.12 Starting at the "J" point go one small box back into the QRS (moving to the left). If the energy is below the isoelectric line, this is a left BBB. If the energy of the depolarization is above the isoelectric line, this is a right BBB. Turn signal: down is left, up is right.
Left Atrial Enlargement (LAE)
Widened notched P-wave >120 ms