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