A left posterior-inferior hemiblock can be identified based on changes in the electrocardiogram.
Right axis deviation in frontal plane: often > 110° (others use > 90°)
QRS interval: <= 100 msec (may be greater if right bundle branch block present)
Lead aVL: small initial r wave and large S wave
Lead aVF: small q wave and large R wave, late intrinsicoid deflection
Lead I: small r wave and large S wave
Leads II and III: small q wave and large R wave
Exclusions (can produce similar changes in the ECG):
(1) chronic lung disease
(2) right ventricular hypertrophy
(3) large left lateral wall myocardial infarct
(4) asthenic body habitus
