Dextrocardia

Dextrocardia, (from Latin dexter, meaning "right," and Greek Kardia, meaning "heart") refers to a condition in which the heart is on the right side of the mediastinum. With dextrocardia situs inversus, the heart is a mirror image of its normal position. dextrocardia situs totalis all visceral organs are mirrored. So, if you see a ECG and it looks as if your leads are all reversed, consider that maybe the heart is.

Dextrocardia is a rare condition and occurs in approximately 1 in 12,000 people.

Dextrocardia of embryonic arrest

Is a form of dextrocardia, the heart is simply placed further right in the thorax than is normal, this can be commonly associated with severe defects of the heart and related abnormalities including pulmonary hypoplasia.

Causes of Dextrocardia:

- Kartagener syndrome: Also known as Primary ciliary dyskinesia (PCD). A rare ciliopathic, autosomal recessive genetic disorder that causes defects in the action of cilia lining of the respiratory tract, this is characterized by enlarged bronchial tubes, chronic sinusitis in the lower and upper sinuses, Eustachian tube, middle ear.

- Marden-Walker Syndrome: A rare genetic disorder characterized by blepharophimosis, joint contractures and fixed facial expression.

- Campomelia Cumming type: A rare syndrome characterized by limb and multiple abdominal organ abnormalities. The disorder results in death before birth or soon after.

ECG Features of Dextrocardia 

* Right axis deviation (RAD)

* Positive QRS complexes (with upright P and T waves) in aVR

* Lead I: inversion of all complexes, aka ‘global negativity’ (inverted P wave, negative QRS, inverted T wave)

* Absent R-wave progression in the chest leads (dominant S waves throughout)

Diagram above shows left-sided ECG recorded of a patient with Situs inversus dextrocardia 

Click ECG to enlarge

Differential Diagnosis of Suspected Dextrocardia

Accidental reversal of the left and right arm electrodes may produce a similar picture to dextrocardia in the limb leads (but with normal appearances in the precordial leads).

Diagnosis

This done with either a chest x-ray or 12-lead ECG. .

The chest X-ray below is not reversed, this is a patient with dextrocardia situs inversus showing the cardiac apex facing the right.

Click X-ray to enlarge

Suggested correct lead placement for dextrocardia

ECG study card for dextrocardia

Click study card to enlarge

Things to consider if your patient has dextrocardia and needs pacing/cardioversion or is in cardiac arrest and you have a shockable rhythm.

When defibrillating or pacing the patient with dextrocardia, its is suggested that you place the pads opposite of normal showed in the diagram below. It is suggested that traditional pad placement should be mirrored to the right chest. Anterior/posterior placement should be just right of the mediastinum. 

Artwork by Jason Winter

Click study card to enlarge

REFERENCES:

1) http://circ.ahajournals.org/content/91/5/1602.full

2) http://medicmadness.com/2010/05/dextrocardia-and-proper-lead-placement/

3) http://europepmc.org/articles/PMC2564044

4) http://www.wikidoc.org/index.php/Dextrocardia_electrocardiogram

5) http://www.emtcity.com/topic/14811-modifying-paddles-placement-dextrocardia/

6) https://www.researchgate.net/publication/8478385

7) http://emj.bmj.com/content/23/2/147.abstract

8) http://ecgguru.com/ecg/dextrocardia

9) https://en.wikipedia.org/wiki/Marden%E2%80%93Walker_syndrome

10) https://en.wikipedia.org/wiki/Primary_ciliary_dyskinesia