Situs Inversus

At a glance

Congenital condition caused by malrotation of viscera in utero. Can be classified further into situs inversus with dextrocardia or situs inversus with levocardia. The classification is independent of the cardiac apical position. The association of situs inversus and ciliary dyskinesia is known as the ☞Kartagener Syndrome.

History

First described by Marco Severino an Italian anatomist and Matthew Baillie, a Scottish Pathologist in the 16th century.

Incidence

Overall frequency estimated 1:10,000 of the population. Patients have a normal life expectancy. In the rare instance of cardiac anomalies, the life expectancy is determined by the heart condition and not the presence of a situs inversus. The male:female ratio is 1:1.

Genetic inheritance

Autosomal recessive inheritance and congenital anomalies.

Pathophysiology

Unknown. Abnormal rotation of the viscera in utero results in the orientation of the lungs and abdominal organs being reversed. Dextrocardia may or may not be present. The occurrence of situs inversus viscerum with levocardia is associated with severe congenital heart disease.

Diagnosis

Radiological and echographic demonstration of abnormal orientation of organs with or without dextrocardia.

Clinical aspects

Situs inversus may remain asymptomatic throughout life, with little impact on cardiorespiratory function. Situs inversus is a feature of Kartagener Syndrome, Asplenia Syndrome, and Polysplenia Syndrome. Clinical features of these medical conditions may therefore be present. Congenital heart disease described with situs inversus includes ventricular septal defect, atrial septal defect, transposition of the great arteries, and conotruncal malformations.

Precautions before anesthesia

Examine for features of Kartagener Syndrome (increased risk of pneumonia and perioperative respiratory embarrassment). Consider chest radiograph. Full cardiac evaluation, including history, examination, ECG, and echocardiography if congenital heart disease is present. Verify correct positioning of central venous catheters and endotracheal double lumen tubes.

Anesthetic considerations

Anesthetic technique dictated by presence or absence of cardiac disease. If part of Kartagener Syndrome, a technique to maximize ability to clear secretions and early use of physiotherapy postoperatively should be considered.

Pharmacological implications

There are no known specific implications with this condition.

Other conditions to be considered

• Situs Ambiguous or Heterotaxy Syndrome: When the situs orientation cannot be determined, the patient has situs ambiguous or heterotaxy. The liver may be midline, the spleen absent or multiple, the axial morphology unclear, and the bowel malrotated. Two primary subtypes include: Right Isomerism or Asplenia Syndrome, and Left Isomerism or Polysplenia Syndrome.

• ☞Kartagener Syndrome: This medical condition is characterized by the association of a situs inversus and ciliary dyskinesia. Genetically transmitted polymalformative syndrome characterized by bronchiectasis, ...