Increasing isolated right heart chambers in second trimester ultrasound: always a warning sign?

Aumento isolado das câmaras cardíacas no ultrassom de segundo trimestre de gestação: sempre um sinal de alerta? Congenital heart disease (CHD) is one of the leading causes of birth defects and occurs in approximately 1 in every 100 live births [1]. This condition has been attracting the attention of the medical community in terms of screening and diagnosis of CHDs. Because of the constant movement of the fetus during ultrasound examinations and the small size of the heart, it is challenging to obtaining good quality images and performs accurate analysis of intracardiac structures and outflow tracts. The increasing ability of medical professionals allied to recent technological advances, from the development of sector transducers with real-time imaging to two-dimensional studies and color mapping of blood flow to the advent of three-dimensional (3D) technology, has enabled new perspectives for earlier and more accurate diagnoses. Despite these medical advancements, analysis of the enlargement of the right cardiac chamber of the fetus remains a major challenge for sonographers and echocardiographers. In the normal fetal heart, physiological enlargement of the right atrium and a simultaneous increase in the right ventricle can be observed. Moreover, the right atrium is the only cardiac chamber that receives the entire cardiac output [2]. This situation demands special attention and caution when determining the boundaries between physiological and pathological processes, particularly when evaluating aortic coarctation, which can be erroneously considered as normal. Since 1988, the enlargement of the right cardiac chambers has drawn attention from specialists in fetal cardiology. Allan et al. [3] conducted a prospective study involving approximately 2000 pregnant women, and enlargement of the right ventricle and pulmonary artery were found in 24 fetuses. Coarctation or interruption of the aorta was clinically suspected in 18 of these fetuses and confirmed in 10. Five cases of aortic coarctation were not detected by fetal echocardiography but were confirmed postnatally [3]. Starting in 2001, Hornung et al. [4] studied 43 fetuses with right ventricular enlargement over a 5-year period and verified that this condition had both cardiac and noncardiac origins. Fifteen patients presented enlargements of cardiac origin, 14 of which were caused by structural abnormalities; one patient had tachycardia. These structural abnormalities primarily included coarctation of the aorta (N=4) and ventricular septal defects (VSD; N=4). Nine patients with enlargement had associated extracardiac malformations, particularly chromosomal disorders, and 19 others had associated enlargement of the right ventricle without intra-or extracardiac anomalies [4]. …