Isn't It Time for the Cardiac Sweep to Span From the Stomach to the Left Brachiocephalic Vein?

Contemporary guidelines for evaluating the fetal heart, such as The American Institute of Ultrasound in Medicine,1 The International Society of Ultrasound in Obstetrics and Gynecology,2 American Society of Echocardiography,3 and American Heart Association,4 require reporting a 5 standard view approach: 4-chamber, left and right ventricular outflow tracts, 3-vessel trachea view, and sagittal aortic and ductal arches using both real-time grayscale, and color Doppler techniques. These may be accessed through a sweep commencing at the stomach and ending at the level of the 3-vessel and trachea view. None of the above guidelines recommend assessing the upper mediastinum at the level of left brachiocephalic vein (LBCV—innominate vein). Over a decade ago, Sinkovskaya et al established the nomogram for the LBCV, described its normal and anomalous course and its role in the detection of venous anomalies.5, 6 Since then, numerous publications have highlighted the importance of assessing the BCV in the diagnosis of abnormalities of the venous collecting system.5-10 The prevalence of various congenital venous malformations is reported at 1.35%.11 Of those, 48.9% are cardinal vein disorders which include persistent left superior vena cava (PLSVC), absent LBCV, left inferior vena cava (IVC), and interrupted IVC with azygous continuation to superior (SVC). Total anomalous pulmonary venous return (TAPVR) accounts for only 0.07% of all venous anomalies.11 Although the incidence of TAPVR is quite rare, fetuses with TAPVR exhibit the worst outcomes, especially if undiagnosed prenatally, since prenatal detection remains challenging. Despite the various sonographic markers proposed for fetal TAPVR, prenatal diagnosis of isolated TAPVR remains difficult. Reported prenatal detection rates vary depending on the study and year of publication: 1–10%,12, 13 0–50%,14 and 6.7%.15 In addition, associated cardiac defects are reported in up to 57.1% of fetuses with TAPVR and 41.3% of fetuses with cardinal vein anomalies.11 In the absence of a single sonographic sign for the diagnosis of fetal TAPVR, a systematic and sequential approach is crucial to improve the prenatal detection and diagnosis of TAPVR.16 Normal anatomy and abnormal findings of the LBCV can be demonstrated by grayscale and color Doppler during the fetal cardiac examination. The LBCV passes horizontally through the upper mediastinum, anterior and superior to the aortic arch, and posterior to the thymus.9 It can be evaluated by sweeping cephalad from the level of the 3-vessel trachea view to the level of the upper mediastinum with the thymus visualized. Established normative values for LBCV allow for accurate size assessment.6, 17, 18 Congenital anomalies of the brachiocephalic veins are exceedingly rare, accounting for 0.2–1% of all congenital cardiovascular anomalies. Absent, dilated, double, or abnormal courses of LBCV may point toward compensatory changes of other veins and indicate the presence of associated cardiac and extra cardiac anomalies or genetic conditions.6, 7, 13, 19-21 Table 1 represents the various types of LBCV abnormalities and the associated anomalous conditions. Depends on the associated anomaly. Warrants detailed evaluation No associated anomalies in only in 12.5% cases5, 19 Can be associated with heterotaxy syndromes (40%), Left ventricular outflow tract obstruction, aortic coarctation, and conotruncal anomalies Trisomy 21, 18, and others are reported in 9% with PLSVC19 With dilatation of the LBCV, the likelihood of pulmonary venous return anomalies or arteriovenous malformations increases. Researchers and specialists in fetal cardiology have stressed the importance of evaluating the LBCV in improving the prenatal detection rates of venous anomalies. In 2012, Sinkovskaya et al suggested incorporating it into the fetal echocardiographic evaluation. Based on the above, we are recommending that when the current international guidelines pertaining to the evaluation of the fetal heart are revised, the cardiac sweep, which currently extends from the stomach to the 3-vessel trachea view, be expanded to the level of the LBCV in both grayscale and color Doppler. In Videos 1 and 2, sweeps 1 and 2 represent examples of extended sweeps from the stomach to left BCV in grayscale and color. Extending the cardiac sweep to span the area from the fetal stomach to the LBCV will not result in any significant increase to the total examination time. In fact, it may potentially expedite accurate completion of the cardiac examination without the need to obtain additional views. This is especially applicable to cases where there may be a suspected anomaly or the need to confirm questionable sonographic findings pertaining to the venous system. This may also be of potential utility to enable a comprehensive cardiac evaluation particularly with the current increasing need for remote sonographic readings by various specialists. Ultimately, it may enhance the prenatal detection rates of some of the most critical, yet challenging anomalies, and will translate into improved neonatal outcomes. We would like to express our profound gratitude to the Gottesfeld-Hohler Memorial Foundation for the Beryl Benacerraf Fellowship as this manuscript was a result of author collaboration made possible by this fund.