Right axis deviation
![The hexaxial reference system is a diagram that is used to determine the heart's electrical axis in the frontal plane.](/Images/godic/202502/07/Hexaxial_reference_system.svg5223.png")
![A very slight right axis deviation, possibly due to height and not a posterior block, approximately 110° from lead I+. One can tell the rough angle by which lead is isoelectric (or biphasic); in this case lead I is most biphasic and thus we know the axis is roughly perpendicular to this lead. However, the downstroke of lead I is slightly larger than the upstroke so we know it is slightly more than 90°.](/Images/godic/202502/07/MyRADekg5223.jpg")
Right axis deviation (RAD) is a heart condition wherein the electrical conduction of the heart has an electrical axis greater than +90° (or sometimes greater than +105°) on a 12-lead ECG. When the axis is extremely deviated to the right (i.e. between 180 degrees and -90 degrees) the condition may be termed extreme right axis deviation or northwest deviation).