Right axis deviation
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 North West deviation.
RAD can be indicative of increased workload of the right ventricle, i.e. right ventricular hypertrophy. Examples include COPD, pulmonary arterial hypertension, or large pulmonary embolism. In the latter, for example, a clot in the pulmonary arteries requires more work of the right ventricle to push blood past it.
Alternatively, RAD can be reflective of loss of muscle power of the left ventricle, such as in left sided myocardial infarction.
Conduction abnormalities can also cause RAD, left posterior fascicular block being an example of this.
Finally, anatomy can be the source of RAD. For instance, slight RAD is relatively common in tall, slim individuals, as the apex of the heart generally becomes more vertically aligned. Furthermore, RAD can be seen in individuals with Situs Inversus, a rare medical condition where the visceral organs are flipped across a vertical axis.