IS Case 377: Situs inversus with dextrocardia (situs inversus totalis)
2009 URMC Imaging Sciences
Publication Date: 2010-03-02
History
Patient is a one-week-old infant with complex congenital cardiac disease. Exam was requested to evaluate lungs for pulmonary edema.
Findings
The cardiothymic silhouette is on the right. The stomach bubble is on the right. There is a paucity of bowel gas in the left upper quadrant. These findings are compatible with situs inversus. Additionally, there are 13 rib pairs.
Diagnosis
Situs inversus with dextrocardia (situs inversus totalis)
Discussion
The 'normal' position of the heart is referred to as levocardia, which refers to the cardiac apex lying to the left of the spine. Dextrocardia is the term used when the cardiac apex lies to the right of the spine, and is considered a cardiac malposition. These terms do not account for the orientation of the cardiac chambers. Congenital cyanotic heart disease is frequent with dextrocardia. There are other types of cardiac malpositions as well; when faced with any of these it is important to determine the position of the abdominal organs.
The normal position of the viscera is referred to as situs solitus, which refers to the liver on the right and the stomach on the left. If this is reversed, it is called situs inversus. Situs inversus occurs more commonly with dextrocardia than levocardia, and the combination is associated with a 3-5% incidence of congenital heart disease. About 80% of these patients have a right-sided aortic notch.
Diagnosis can be made with radiography; it is important to note the position of the heart, stomach and liver on neonates suspected of having situs inversus. Early diagnosis occurs if the patient has congenital cyanotic heart disease. If this is not the case, patients can be undiagnosed until later in life, and often diagnosis is made incidentally when the patient presents for evaluation of an unrelated condition.
In the case of this patient, initial radiograph showed dextrocardia which was suspected as heart sounds were on the right. In the OR, patient was found to have dextrocardia with right-sided arch, tricuspid atresia type IIC, and interrupted aortic arch type B. Situs inversus was also discovered, as suggested by initial radiograph. Situs inversus with dextrocardia is also known as situs inversus totalis, or the mirror image of normal.
References
- Donnelly LF. Pediatric Imaging: The Fundamentals. Saunders, 2009:66-7.
- Brant WE, Helms CA (editors). Fundamentals of Diagnostic Radiology, 3rd ed., Lippincott Williams Wilkins, 2006: 1272-4.
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