Right isomerism is?
Right isomerism is Asplenia.
Types of situs inversus
a. Situs inversus can be classified further into situs inversus with levocardia or situs inversus with dextrocardia.
b. The classification of situs is independent of the cardiac apical position.
c. Isolated dextrocardia is also termed situs solitus with dextrocardia.
d. The cardiac apex points to the right, but the viscera are otherwise in their usual positions.
e. Situs inversus with dextrocardia is also termed situs inversus totalis because the cardiac position, as well as the atrial chambers and abdominal viscera, is a mirror image of the normal anatomy.
f. When situs cannot be determined, the patient has situs ambiguous or heterotaxy.
g. In these patients, the liver may be midline, the spleen absent or multiple, the atrial morphology unclear, and the bowel malrotated. Often, normally unilateral structures are duplicated or absent.
The 2 primary subtypes of situs ambiguous include
a. Right isomerism, or asplenia syndrome, and
b. Left isomerism, or polysplenia syndrome.
a. In classic right isomerism, or asplenia, bilateral right-sidedness occurs.
i. These patients have bilateral right atria, a centrally located liver, and an absent spleen, and both lungs have 3 lobes.
ii. The descending aorta and inferior vena cava are on the same side of the spine.
iii. In left isomerism, or polysplenia, bilateral left-sidedness occurs. These patients have bilateral left atria and multiple spleens, and both lungs have 2 lobes.
iv. Interruption of the inferior vena cava with azygous or hemiazygous continuation is often present.
b. The features of situs ambiguous
i. The features of situs ambiguous are inconsistent; therefore, situs ambiguous cases are challenging and require thorough evaluation of the viscera.
ii. The location and relationships of the following should be reviewed carefully: abdominal viscera, hepatic veins, superior vena cava, inferior vena cava, coronary sinus, pulmonary veins, cardiac atria, atrioventricular connections and valves, cardiac ventricles, position of the cardiac apex, and aortic arch and great vessels.
Other features of situs inversus
a. Situs inversus occurs more commonly with dextrocardia. A 3-5% incidence of congenital heart disease is observed in situs inversus with dextrocardia, usually with transposition of the great vessels. Of these patients, 80% have a right-sided aortic arch. Situs inversus with levocardia is rare, and it is almost always associated with congenital heart disease.
b. Kartagener syndrome is typified by bronchiectasis, sinusitis, and situs inversus and affects 20% of patients with situs inversus; however, only 50% of patients with Kartagener syndrome have situs inversus.
c. The recognition of situs inversus is important for preventing surgical mishaps that result from the failure to recognize reversed anatomy or an atypical history. For example, in a patient with situs inversus, cholecystitis typically causes left upper quadrant pain, and appendicitis causes left lower quadrant pain. If surgery is planned on the basis of radiographic findings in a patient with situs inversus, the surgeon should pay careful attention to image labeling to avoid errors such as a right thoracotomy for a left lung nodule.