Anatomy of a wrong diagnosis: false Sinus Venosus Atrial Septal Defect

Transthoracic echocardiography has high sensitivity to detect secundum-type atrial septal defects(ASDs) and up to 100% for defects of the interatrial foramen primum, while its diagnostic usefulness for more uncommon causes of shunting at the atrial level is considerably less [1,2]. In particular, diagnostic images of the sinus venosus atrial septal defect (SVD) usually are not obtainable in most adults [1].In contrast to clinical examination or transthoracic echocardiography, transesophageal echocardiography (TEE) provides a sure way to make the diagnosis of SVD; on the other hand this abnormality is more complex than that seen with the secundum ASDs, and inexperienced operators may fail to recognize the defect. TEE is a highly accurate means to diagnose SVD, especially when performed by experienced operators [3].In front of a high reported sensitivity for SVD diagnosis, specificity is difficult to assess, due to possible underreporting of diagnostic errors.The following case report is to date the first in medical literature to describe a false positive diagnosis of SVD, even if probably it is not such a rare mistake, particularly in the setting of modified heart anatomy.A 30-year-old woman presented for evaluation of multiple syncopal spells. She had been in her usual state of health until four months earlier when first syncopal episode presented; since then she has had five similar episodes. She was not using any type of medication; five years earlier she gave birth to a healthy baby, following an uncomplicated pregnancy. She described her syncopal episodes as typical for true syncope: episodes were 1) transient, 2) self-limited 3) leading to falling, 4) the onset was relatively rapid with spontaneous recovery.ECG pattern was suggestive for right ventricle enlargement and strain (Fig 1).Echocardiogram showed: massive dilatation of both the right atrium and the right ventricle, with a high estimated systolic pulmonary artery pressure = 75 mmHg. There was no clear e