QRS duration |
≥0.12
sec |
Intrinsicoid deflection |
>0.05 sec in lead V6 |
Common pattern
|
Loss of q wave and wide slurred R in I, aVL, and V6 rS
or QS in V1 ST depression and T wave inversion in leftward leads; ST
elevation and upright T waves in right precordial leads |
These
changes reflect relentlessly leftward vectorial forces. V1 morphology
depends on initial leftward or rarely rightward forces. ST and T
vectors are usually 180º discordant to the QRS vector. |
Variant pattern
|
Terminal S wave in V6 but not usually in I. |
Mean
electrical axis superior and to the left (about -55º). |
ST
depression and T wave inversion in leftward leads; ST elevation and
upright T waves in right precordial leads |
These
changes reflect superior and posterior displacement of loop with a
terminal, often rightward, conduction delay. ST and T vectors are
discordant to the QRS vector. |