Prenatal Imaging of Congenital Fetal Anomalies: A Case Series

Abstract

Hypoplastic left heart syndrome (HLHS) comprises 2 to 3 percent of all congenital heart disease. HLHS is uniformly lethal if left untreated; however, there is currently an estimated 70 percent 5-year survival rate for infants who undergo surgical correction. The hypoplastic left heart syndrome encompasses a spectrum of cardiac malformations that are characterized by significant underdevelopment of the components of the left heart and the aorta, including the left ventricular cavity and mass. Its main anatomical characteristics include mitral stenosis or atresia, aortic stenosis or atresia, and hypoplasia of left ventricle. The apex of the heart is usually formed by the right ventricle. The right ventricle is the single functional ventricle maintaining fetal circulation in these patients.After births, due to decreased pulmonary vascular resistance and closure of the ductus arteriosus, infants with HLHS develop a constellation of symptoms that include cyanosis, dyspnea, heart failure, hypoxemia and acidosis. Surgery is the only effective treatment. Unfortunately, even when treated, this disease is associated with significant morbidity including an increased risk of thrombotic complications, decrease in exercise tolerance, and neuro-developmental impairment. Continuous intravenous prostaglandin E1 is used to maintain a PDA to allow adequate systemic perfusion. Nitrogen may be used in some centers to decrease inspired oxygen which increases pulmonary arterial resistance. This therapy encourages systemic rather than pulmonary blood flow and enhances systemic perfusion. Double outlet right ventricle (DORV) is a type of ventriculoarterial connection in which both the aorta and pulmonary artery arise entirely or predominantly from the right ventricle (RV). The only outlet from the left ventricle (LV) is a ventricular septal defect (VSD). DORV is usually associated with concordant atrioventricular connections with the right atrium draining into the RV and the left atrium draining into the LV. DORV is almost always associated with a VSD and occasionally with an atrial septal defect. Transposition of great arteries is characterized by both the outflows being parallel to each other at the origin. On color Doppler, they show similar color flows, indicating that the direction of flow in both the great vessels is same. Most atrial septal defects involve either the septum primum or septum secundum. Primum atrial septal defect is the simplest form of the atrioventricular septal defect. Secundum atrial septal defect which is the commonest are usually isolated septal defects, but may be related to other cardiac anomalies like mitral, tricuspid, pulmonary or aortic atresia and are occasionally found as part of syndromes like Holt-Oram syndrome.