Dextrocardia

IMAGE OF THE WEEK 2015

IMAGE 03 - 1 JUNE 2015

DEXTROCARDIA WITH SITUS INVERSUS

Figure 1a: PA x-ray of a middle aged female patient with dextrocardia and two pulmonary shadows on the left lung field. (Click on image to enlarge)

Figure 1b: CT coronal section of the same patient showing the heart with the apex in the right chest and liver on the left side indicating the presence of dextrocardia with situs inversus. (Click on image to enlarge)

Definitions:

Dextrocardia is a congenital defect in which the apex of the heart is situated on the right side of the body (Wikipedia (en.wikipedia.org/wiki/Dextrocardia) with normal anatomical arrangements of the heart chambers, a perfect mirrored inversion of the normal left heart. Incidence of dextrocardia is about 1 in 12000 population.

Situs Inversus (also called situs transversus or oppositus) is a congenital condition in which the major visceral organs are reversed or mirrored from their normal positions (Wikipedia (en.wikipedia.org/wiki/Situs_inversus). Incidence of situs inversus is about 0.01% of the population, or about 1 in 10,000 population.

Dextrocardia with Situs Inversus is a rare congenital condition in which all the normal anatomical organ arrangements are inverse from right to left. Hence a patient with dextrocardia with situs inversus will have the heart in the right chest with the position of the heart chambers as well as visceral organs like the liver and spleen all reversed (situs inversus) from left to right (heart and spleen – Figure 1 and 2) and right to left (Figure 2b).

Figure 2a: Transverse section of the CT scan of the thorax of the same patient at the level of the cardiac chambers showing normal anatomical arrangements of the cardiac chambers. (Click on image to enlarge)

Figure 2b: Transverse section of the CT scan of the abdomen of the same patient at the level of the liver showing the inverse mirrored image of situs inversus with the liver on the left and spleen and stomach on the right. (Click on image to enlarge)

Dextrocardia with situs inversus is rare and is transmitted by autosomal recessive gene. During fetal development, the primitive loop in the embryo moves into the reverse direction from its normal position, resulting in displacement of the internal organs. Both genders are equally affected.

Clinical Significance

Individuals with dextrocardia with situs inversus can live a normal life without symptoms or disability. Clinical significance is associated with knowing the condition and getting a proper ECG readings by placing the leads on the right chest, a mirror reflection of the normal left side chest leads. Similarly this applies to cardiopulmonary resuscitation in which case the cardiac compression should be placed more effectively towards the right side and also the pads for DC cardioversion should be placed with the apex pad towards the right and sternal pad towards the left side of the sternum.

In the presence of Situs inversus totalis, abdominal symptoms can be confusing since the stomach is on the right and liver is on the left. Hence epigastric symptoms may reflect hepatic pathology such as cholecystitis and right hypocondrium symptoms may be related to the stomach, in this case, common condition like gastritis may have symptoms on the right. Similarly with the appendix on the left, appendicitis may present with left iliac fossa pain.

Images and text contributed by

Mr William Chong, Thoracic Unit, Department of Surgeryy,RIPAS Hospital.