Transcatheter intervention on the pulmonary vein often requires performing transseptal puncture, which is a risky procedure. We describe a rare association of a partially unroofed coronary sinus with pulmonary vein stenosis causing desaturation in a young infant where the presence of the unroofed coronary sinus allowed for a novel interventional approach to the stenotic left pulmonary vein, avoiding the high risk of transseptal puncture.

An unusual combination of three types of interatrial communications – coronary sinus defect, primum defect, and secundum defect – occurring together in a 3-year-old child is presented.

Unroofed coronary sinus syndrome complicated by coronary sinus orifice atresia is a rare congenital anomaly. There are two alternate exits for coronary venous return: unroofed coronary sinus and persistent left superior caval vein. The coronary venous direction could be bidirectional depending on the pressure balance between the left atrium and the systemic vein. This anomaly has the risk of heart failure, paradoxical embolism, and cyanosis.

We report a case of unroofed coronary sinus not associated with the persistent left superior vena cava. Definite diagnosis of the unroofed coronary sinus was obtained by trans-oesophageal echocardiography, which revealed the unroofed portion with left-to-right shunt. Real-time three-dimensional trans-oesophageal echocardiography could show the whole pictures of the defect, which was useful information for surgical repair.

Objectives: We describe the structure of, and suggest an etiology for, the interatrial communication which can occur through the mouth of the coronary sinus. Based on the study of human embryos, we propose that the defect is best explained by dissolution of the wall of the coronary sinus adjacent to the left atrium, permitting shunting between the atriums through the right atrial orifice of the sinus. Background: An interatrial communication across the mouth of the coronary sinus defect was first described in 1965 by Raghib and colleagues, its existence being predicated on the basis of incomplete formation of the left “atriovenous fold”. Their hypothesis implies that the coronary sinus never develops, and thus the atrial septum itself is incomplete. Methods: We have studied the development of the coronary sinus in a series of human embryos. Based on this work, we present the anatomical findings in 6 specimens with varying degrees of dissolution of the walls of the coronary sinus, and ten specimens with isomerism of the right atrial appendages, in which the sinus has never been formed. Results: The coronary sinus defect is not a hole within the atrial septum, but a communication between the atriums through the mouth of the sinus. There was a range of defects in our series of specimens with usual atrial arrangement, extending from complete absence of the walls which normally separate the coronary sinus from the left atrium, to small fenestrations between this vessel and the left atrial cavity. In the hearts with isomerism of the right atrial appendages, however, we never observed an orifice of the coronary sinus. Thus, a coronary sinus defect cannot exist in this setting. Conclusions: Our findings indicate that the defect requires initial formation of the walls of the coronary sinus, but with subsequent dissolution of the wall adjacent to the left atrium. This produces a communication between the atriums through the mouth of the sinus.

Reported is a case with a rare association of divided left atrium, supramitral stenosing ring of the left atrium, connection of the left superior caval vein to the roof of the left atrium, unroofed coronary sinus with an interatrial communication at the mouth of the unroofed sinus and ventricular septal defect. The need for a complete echocardiographic examination in the presence of pulmonary venous obstruction is emphasized. Surgery was successful in spite of significant preoperative pulmonary hypertension.

In a young infant with divided left atrium, unroofed coronary sinus syndrome, and persistent left superior caval vein, the pulmonary venous blood was successfully routed, after atrial septectomy, to the mitral valve by constructing a baffle using the partially detached diaphragm which had initially separated the pulmonary venous and vestibular components of the left atrium. The baffle was augmented with a patch of untreated autologous pericardium.

A 14-year-old female patient underwent surgical treatment of multiple atrial septal defects associated with unroofed coronary sinus and pulmonary valvar stenosis. One of the defects was that of the superior oval fossa and the other a large ellipsoidal defect positioned inferior to the inferior rim of the oval fossa. The patient underwent primary closure of the defects with a favorable result. To the best of our knowledge, this is the first surgical experience of an unusual atrial septal defect or the vestibular defect.