Limb lead reversal usually occurs due to the technical error of reversing the right and left arm electrodes and has become more common as non-experienced personnel replace ECG technicians. It is usually a change from a previous tracing and the precordial V leads exhibit normal R wave progression. It is the most common noticeable frontal lead error since the right arm and left arm leads are usually connected together and the right and left leg electrodes can be switched without affecting the recorded ECG. When every tracing from an ECG machine exhibits this pattern it can be due to mislabeled ECG leads.

Dextrocardia can usually be distinguished by noting that the precordial V leads do not have a normal R wave transition and by recording right sided chest leads which should be a mirror image of the normal left sided leads.

Repeat the ECG after checking previous ECGs from the patient, the ECG machine and proper lead placement. If this does not explain the finding then check the precordial leads for normal R wave progression. If the R waves do not progress normally, then record the right-sided precordial leads. If dextrocardia is confirmed, correlation with the chest x-ray is the next step. An echocardiogram should be considered to evaluate the patient for congenital heart disease. The patient should be evaluated for bronchiectasis and sinusitis that along with situs inversus form the triad of the familial disorder known as Kartagener's syndrome. Chronic antibiotic therapy may be required as well as genetic counseling.