Dextrocardia

Dextrocardia is an extremely rare diagnosis and the main differential diagnosis is limb lead reversal. The effects of dextrocardia should be divided by the limb leads and precordial leads. All of the changes will be negated if the chest leads are placed on the right side of the chest mirrored to the typical left placement and if the limb leads are reversed. This should be done (and marked on the EKG) to accurately assess the patient's EKG. Dextrocardia is sometimes confused with RA/LA limb lead reversal, but patients with RA/LA limb lead reversal will not have the precordial changes seen in dextrocardia.

Limb Lead Changes

• right axis deviation

• positive QRS complexes in aVR

• completely inverted lead I (P, QRS, and T waves) as it is the opposite direction as the right chest

The inverted P waves in lead II are one of the two times where these are still normal sinus rhythm (with the other being limb lead reversal). The all positive QRS complexes in aVR are almost always produced by either limb lead reversal or dextrocardia.

Precordial Changes

• absent R wave progression (all QRS complexes negative-in other words, dominant S waves throughout)

The absent R wave progression is sometimes called reverse R wave progression as the QRS complex evolution is the opposite of a normal EKG). Because of the inverted QRS complexes, there are commonly associated ST-T changes that are not necessarily indicative of ischemia.

Example

Further Reading:

https://litfl.com/dextrocardia-ecg-library/