The HEART acronym provides the following steps to help insure that all aspects of the 12-lead are carefully examined and that no stone is left unturned.
H = Hypertrophy – apply the *criteria of LVH (please note some authors utilize slightly different criteria; for clarity, we will use the following below.)
As follows: LVH present if…. S + R > 35 mm where…
S = Tallest S-wave of V1, V2, V3
R = Tallest R-wave of V4, V5, V6
and/or°
R-wave > 12 mm Lead avL
*applicable only if age > 35 years
PEARL: The criteria above does not apply in the presence of LBBB, LAFB or WPW.
E = Extent of Intervals – measure the intervals PR, |QRS|, QT
NORMAL Ranges as follows:
- PR = 0.12 – 0.20 sec
- |QRS| ≤ 0.10 sec
- QT < 1/2 of RR (if not tachy or brady)
A = Axis – Calculate the frontal electrical axis
The axis is normal if———Leads I and avF are positive
Consider LAFB if axis ≤ – 45 degrees (more negative than – 45°)
Left Axis if: Lead I positive and Lead avF negative
R = QRS- ST Analysis – look for significant Q-waves, transition zone, ST-elevation, ST-depression,R-wave progression
Normal if:
- No significant Q-waves
- No ST segment changes
- Transition zone occurs between (V2, V3, V4) inclusive
- R-wave progression normal
T = T-wave – look at all T-waves in search of ischemia/infarction
All T-waves are upright(except maybe in Leads V1, avL, avF or III)
If otherwise inverted, consider ischemia
Consider Hyperacute if: tall, peaked broad-based, symmetrical
Now click “MARK COMPLETE” or “NEXT”.