Diagnosis Advances in the field of noninvasive cardiac imaging have markedly improved the rate of detection of anomalies of systemic venous return Echocardiography remains the initial modality of investigation As highlighted previously, most of the systemic venous anomalies can be detected in this fashion However, evaluation by echocardiography is limited by the windows available for interrogation Such interrogation is particularly limited in detecting anomalies located in the peripheral portions of the systemic veins In addition, echocardiographic assessment of the coronary sinus remains suboptimal Not uncommonly, the diagnosis remains obscure despite detailed echocardiographic evaluation This is particularly the case with anomalous drainage as opposed to anomalous connection, since echocardiographic diagnosis depends upon direct visualization of an anomalous connection, which is not always possible Saline Contrast Echocardiography Unlike simple echocardiography, use of the saline contrast echocardiogram depends on analysis of the sequence of appearance of microbubbles in the different cardiac chambers following an injection of agitated saline Multiple injections from different limbs are necessary for complete diagnosis, and to achieve the full diagnostic potential of the technique.27,28,90,91 On this basis, we have recently proposed an algorithm for diagnostic evaluation of suspected anomalous drainage of systemic veins (Fig 27.21) In our experience, saline contrast echocardiography is safe, inexpensive, and easy to perform In most instances, a carefully performed and logically interpreted saline contrast echocardiogram can clarify the anomalous drainage of caval veins (Fig 27.22) However, the diagnostic utility for anomalies of coronary sinus and anomalies of the course of caval veins is limited FIG 27.21 Algorithm showing the sequence of events from suspicion of anomalies of systemic venous connection to their diagnosis, emphasizing the role of saline contrast echocardiography ASD, Atrial septal defect; AVM, arteriovenous malformation; CHD, congestive heart disease; CXR, chest x-ray; ECG, electrocardiogram; Hb, hemoglobin; ICV, Inferior caval vein; LA, left atrium; LSCV, left superior caval vein; LV, left ventricle; RA, right atrium; RSCV, right superior caval vein; RV, right ventricle; SCV, superior caval vein (Modified from Gupta SK, Juneja R, Anderson RH, et al Clarifying the anatomy and physiology of totally anomalous systemic venous connection Ann Pediatr Cardiol 2017;10:269–277.) FIG 27.22 Sequence of saline contrast echocardiography performed in a child with a persistent left superior caval vein connecting and draining directly to the left atrium (LA) The injection of agitated saline is from the left antecubital vein (A) Microbubbles are seen to be limited to the LA (B– C) The bubbles subsequently appear in the left ventricle (LV), and then through the left-to-right shunt in the right ventricle (RV) as they cross the ventricular septal defect (asterisk) RA, Right atrium Computed Tomographic Angiography Computed tomography provides an excellent representation of cardiac as well as extracardiac anatomy and permits diagnosis of almost all anomalies of systemic veins However, the diagnostic yield may be limited in cases with suspected functional drainage of the inferior caval vein, particularly if the contrast is injected from an arm vein The rapid acquisition of high resolution images permits prompt diagnosis even in sick children Although modern scanners have mechanisms to reduce exposure to radiation, this remains a concern Therefore computed tomography should only be performed if the benefits achieved outweigh the risks of exposure to radiation Cardiac Magnetic Resonance Imaging This technique permits the diagnosis of all anomalies of the systemic veins without any risk of radiation However, such imaging is time consuming and therefore is not suitable for sick children Four-dimensional flow imaging with magnetic resonance imaging, by providing information about flow patterns, is more suited if anomalous drainage of systemic veins is being evaluated Although not evaluated systematically, precise detection of flow patterns is expected to provide useful information related to the connection and drainage of systemic veins.92,93 Catheter Angiography Cardiac catheterization is preferable in cases where assessment of both hemodynamic and morphologic changes is necessary.28 However, unlike computed tomography and magnetic resonance imaging, selective injections are required in each systemic vein to confirm the diagnosis Also, like computed tomography, radiation remains a problem