This therapy battles infection by both gram-positive and gram-negative bacteria. Right-atrial and left-atrial isomerism and associated pulmonary issues are treated in a series of steps based on the severity of symptoms. Isomeric patients are first treated by inserting a shunt that will move incoming blood through the pulmonary circuit. The Fontan procedure routes blood through the patient's single ventricle, to the lungs, and into systemic circulation. This process is favorable in patients aged 2 to 5 years old. About 20–30% of patients will require a heart transplant. Left-atrial isomeric patients have less severe complications, as they typically have 2 functional ventricles. In this case, they can undergo biventricular repair to form 2 separate ventricles and functional associated valves. Prognosis Prognosis for patients with situs ambiguus is quite varied, owed to the spectrum of clinical manifestations. Infants who experience severe cyanosis at birth may die within hours of delivery if medical intervention is not immediate. Alternatively, longevity of neonates with mild cardiac lesions is unaffected. Ten percent of patients born with right atrial isomerism die by the age of 5 without intervention. Improvements in therapies has increased the 5-year survival to 30–74% for right atrial isomeric patients and 65–84% for left atrial isomeric patients based on the cause of their disease. Research There have been vast amounts of research on the clinical features, racial disparities, and physiological mechanisms of heterotaxy syndrome dating back to 1973. Mishra et al. published a review in November 2015 describing current knowledge of cardiac and non-cardiac abnormalities associated with situs ambiguus. The author stresses the importance of genetic testing prior to deciding a prognosis for affected patients. She also proposes prenatal screening and evaluation in cases at risk for development of situs ambiguus. Recent studies have shown higher rates of heterotaxy syndrome among Hispanic infants of Mexican descent, as well as female infants of non-Hispanic black and white mothers. Additional studies must be done to clarify the mechanisms behind racial disparities in heterotaxy syndrome. Individuals of Asian descent show a higher prevalence of heterotaxy syndrome in general than members of the Western world. The National Birth Defects Prevention study (October 2014) attempted to link clinical presentations of situs ambiguus to demographics in an epidemiological study. This proved a difficult task due to the vast differences in presentation of this disorder. However, the authors are hopeful that finding a link can help inform clinical decision-making, predictive analyses,