Comment

Totally anomalous pulmonary venous connections according to the site of drainage are classified into supracardiac, cardiac, infracardiac, and mixed variants. More pertinent to clinical management is the obstructed as opposed to unobstructed nature of the drainage. Whilst the infracardiac variant is almost always obstructed subsequent to closure of the venous duct, the supracardiac variant is often unobstructed, since the ascending vertical vein usually traverses the mediastinum anterior to the vascular structures. Obstruction, when present, is usually the consequence of passage of the vertical vein between the left pulmonary artery and the left main bronchus – the so-called “haemodynamic vise.” In our case, the vertical vein was anterior to the left pulmonary artery, but was compressed by a persistent arterial duct. To the best of our knowledge, such an occurrence has been described previously but once. ^{Reference Muneuchi, Takenaka, Ochiai and Joo1} These variants are pertinent to the developmental origin of the vertical vein. In the past, the vein has been interpreted by some as a remnant of the left superior caval vein. Such a channel, however, would not be found between the left pulmonary artery and the arterial duct. It is much more plausible to interpret the vessels as representing pulmonary-to-systemic collateral channels. This case also illustrates the utility of cross-sectional imaging in recognising unusual anatomical features in CHDs as these variations cannot be identified by echocardiogram alone.