- Normally, QRS upright in leads I and AVF; 0-90^; - Note: the mean QRS Vector and Ventricular Hypertrophy Can't be accurately calculated in presence of B.B.B. * LEFT AXIS Deviation: -30 to -90 degrees; - QRS pos in I & neg in AVF - S wave > R wave in lead II; - Consider: IsoElectric Vectors: - LVH - Lft Ant Hemiblock ( < -45^, I AVR - LBBB III | II - anterior infarction | - nl variation; AVF ________|________ AVF - Endocardial cushion defect | - Ostium Primum Def II | III AVR | AVL I Cardiac Axis: RIGHT AXIS Deviation: Normal: QRS upright in leads I and AVF; 0-90^; Note: the mean QRS Vector and Ventricular Hypertrophy Can't be accurately calculated in the presence of B.B.B. Right Axis Deviation: +90 to +180; - QRS neg in I & pos in AVF - QRS in lead III > QRS in lead I; - Consider: IsoElectric Vectors: - RVH - Rt BBB I AVR - COPD III | - Acute PE | - Nl variation; AVF ________|________ AVF - Lat. MI | - Inf. MI II | III - A.S.D. AVR | AVL - Tetralogy of Fallot I - Sinus Venous Defect - Ventricular Septal Defect - Ebstein's Anomaly
Original Text by Clifford R. Wheeless, III, MD.