You are in: eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiothoracic Surgery Atrial Septal Defect, Unroofed Coronary Sinus: Surgical PerspectiveArticle Last Updated: Jun 19, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Samuel Weinstein, MD, Associate Professor, Albert Einstein College of Medicine; Director, Department of Pediatric Cardiothoracic Surgery, The Children's Hospital at Montefiore Samuel Weinstein is a member of the following medical societies: American College of Surgeons, American Heart Association, American Medical Association, Ohio State Medical Association, and Society of Thoracic Surgeons Coauthor(s): Robert E Michler, MD, Karl P Klassen Chair and Professor of Surgery, Ohio State University; Chief, Division of Cardiothoracic Surgery and Thoracic Transplantation, Montefiore Medical Center; Suzanne Courtwright, MS, CPNP, Pediatric Nurse Practitioner, Department of Cardiothoracic Surgery, Division of Pediatric and Adult Congenital Heart Disease, Montefiore Medical Center Editors: Daniel S Schwartz, MD, FACS, Clinical Assistant Professor of Cardiothoracic Surgery, New York University School of Medicine; Consulting Staff, Department of Surgery, Division of Thoracic Surgery, North Shore University Hospital/Long Island Jewish Medical Center; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; John Myers, MD, Director, Pediatric and Congenital Cardiovascular Surgery, Departments of Surgery and Pediatrics, Professor, Penn State Children's Hospital, Milton S Hershey Medical Center; Daniel Rauch, MD, FAAP, Director, Pediatric Hospitalist Program, Associate Professor, Department of Pediatrics, New York University School of Medicine; John Kupferschmid, MD, Director of Congenital Heart Surgery, Department of Surgery, Methodist Children's Hospital at San Antonio Author and Editor Disclosure Synonyms and related keywords: atrial septal defect, unroofed coronary sinus, ASD, coronary sinus atrial septal defect, coronary sinus ASD, persistent left superior vena cava, persistent LSVC, left superior vena cava, LSVC, left SVC, right superior vena cava, RSVC, right anterior cardinal vein, left anterior cardinal vein, coronary sinus, unroofed coronary sinus atrial septal defect, unroofed coronary sinus ASD INTRODUCTIONSection 2 of 12
  Coronary sinus atrial septal defects (ASDs) are rare and usually associated with other forms of congenital heart disease, usually heterotaxy syndromes. They are also frequently associated with a persistent left superior vena cava (LSVC), which is the most common anomaly of systemic venous drainage (Ramos, 2005). ProblemSymptomatology stems from right-to-left shunting, the amount of which is related to the size of the defect and the presence or absence of a persistent LSVC draining into or through it. The presence of a persistent LSVC also creates risk for brain abscess and cerebral emboli (Troost, 2006). Undiagnosed, this defect may leave behind a significant residual right-to-left shunting flowing surgical repair of other associated defects (Watanabe, 2004). EtiologyCoronary sinus ASDs are usually associated with other forms of congenital heart disease (eg, heterotaxy syndromes) or persistent LSVC. Persistent LSVC occurs in 0.1-0.5% of the general population, with 8% draining into the left atrium. Unroofed coronary sinus ASD is seen in 75% of patients with an LSVC that drains into the left atrium and is usually associated with other forms of congenital heart disease and heterotaxy syndromes (Ramos, 2005). PathophysiologyIn normal fetal development, the paired anterior cardinal veins drain the upper body and extremities of the fetus and become connected by an oblique vessel. During the 8-week period of embryological development, a communication forms between the veins, which becomes the innominate vein. The distal end of the left anterior cardinal vein degenerates, and the remaining right anterior cardinal vein ultimately becomes the right superior vena cava (RSVC). The distal end of the left anterior cardinal vein drains into the coronary sinus before it degenerates; this explains the drainage pattern of a persistent LSVC into the coronary sinus. Failure of the distal left anterior cardinal vein to degenerate is possible with or without degeneration of the right cardinal veins (Ramos, 2005). A persistent LSVC can be the sole drainage of systemic venous blood in the upper extremities and the head, or it may exist in conjunction with an RSVC. With dual superior vena cavae (SVCs), a bridging innominate vein is often not present. ClinicalPatients usually present with symptoms related to their concomitant defects. Unroofed coronary sinus ASD is difficult to diagnose based on clinical signs and symptoms alone and should be suspected in a patient with an LSVC and a history of brain abscess or cerebral emboli or in a patient with a left-to-right interarterial shunt with unexplained arterial oxygen desaturation. Suspect a brain abscess or a cerebral embolism whenever an LSVC is seen on an echocardiograph. Coronary sinus ASDs have been reported to occur with several other congenital heart defects, such as canal defects (Alexi-Meskishvili, 1999), cor triatriatum (van Son, 1999), pulmonary atresia or stenosis, abnormal ventriculoarterial connection (Miraldi, 2002), tetralogy of Fallot, and anomalous pulmonary venous return (Takahashi, 2005). INDICATIONSSection 3 of 12
As in other ASDs, indications for surgery include symptoms of ASD physiology (eg, left-to-right shunting), right heart volume overload, and risk of cerebral embolism. Indications for surgical repair include complications from right-to-left shunting, including cerebral emboli and brain abscesses (Troost, 2006). RELEVANT ANATOMYSection 4 of 12
The LSVC enters the pericardium anterior to the left pulmonary artery. It then runs posterior to enter the left atrium and drain through the coronary sinus to the right atrium. When the wall between the coronary sinus tube and left atrium fails to form (which is thought to be caused by a maldevelopment of the arteriosinus fold) the systemic venous blood drains directly into the left atrium. This fenestration into the left atrium usually occurs between the left atrial appendage and the left upper pulmonary vein (Drinkwater, 1996). When this fold is missing, the defect is called an unroofed coronary sinus or unroofed coronary sinus ASD. CONTRAINDICATIONSSection 5 of 12
Surgery is contraindicated in the presence of major genetic abnormalities. WORKUPSection 6 of 12
Imaging Studies
TREATMENTSection 7 of 12
Surgical therapyThe goals of surgical therapy include the separation of systemic venous drainage from pulmonary venous drainage, completion of the atrial septum, and management of the LSVC, if present. This lesion can be repaired with systemic venous cannulation of LSVC, RSVC, and IVC; right atriotomy and cardiac arrest; or with circulatory arrest if the patient is an infant or neonate. Intraoperative detailsRepair of a coronary sinus ASD without a LSVC can be accomplished with a roofing procedure (Takahashi, 2005). After cardiac arrest and right atriotomy, the defect is examined through the atrial septum. If the atrial septum is intact, the fossa ovalis is incised for exposure. When the tissues are redundant, the defect can be closed primarily. A cannula or obturator may be introduced into the coronary sinus toward the left atrium to stent the area while a roof of pericardial tissue is created (de Leval, 1994). The patch runs from a location between the left atrial (LA) appendage and upper pulmonary veins, continues inferiorly toward the mitral valve, and terminates near the right atrium and right atrial orifice of the coronary sinus. Bites are placed superficially toward the right side of the atrium to avoid injury to conduction tissue (de Leval, 1994). The atrial septum is then repaired primarily or with a patch. If an LSVC is present, the repair can be performed in a similar manner, or with an intraatrial baffle to help avoid narrowing of pulmonary veins or obstruction of the mitral valve (de Leval, 1994; Mainwairing, 1998; Ootaki, 2003). After cardiac arrest and right atriotomy, the atrial septum is first incised for exposure if the ASD is small or nonexistent. A patch of pericardium serves as a baffle, separating the orifice of the left SVC from the pulmonary veins. This allows the pulmonary venous blood to drain toward the mitral valve, while the systemic venous blood drains directly to the right atrium. When a common atrium is present or when a coronary sinus is absent, landmarks for the conduction system are not available to the surgeon (de Leval, 1994). To remedy this and avoid the area of conduction, de Leval has described placement of the sutures along the base of the septal leaflet of the tricuspid valve and then out onto the right atrial wall beyond the tricuspid valve annulus. In each case, the left SVC is addressed on its own merits. If it is small and a bridging innominate vein is present, the left SVC can be ligated. Others have recommended ligation when the occlusion pressure is less than 16 mm Hg (Ootaki, 2003). If it is large and is the sole source of venous drainage for the upper extremities and head, an intraatrial baffle can be considered. Still, others have described extracardial techniques, ie, reimplantation of the LSVC into the right atrium (Shumacker et al, 1967, in de Leval, 1994) or RSVC (van Son, 1998). Postoperative detailsAn LSVC to the left atrium with absence of the coronary sinus and with a low-lying ASD is known as Raghib syndrome. Physiologically, this is similar to an unroofed coronary sinus ASD with an LSVC and common atrium. This syndrome should be suspected whenever an inferior type sinus venosus ASD is present with a LSVC. Simple closure of the ASD results in arterial desaturation. ASD repair and LSVC ligation can be performed, or, in more complex situations, excision of the atrial septum with an intraatrial baffle can be preformed (Mainwairing, 1998). Follow-upFor excellent patient education resources, visit eMedicine's Heart Center. Also, see eMedicine's patient education articles Ventricular Septal Defect and Tetralogy of Fallot. COMPLICATIONSSection 8 of 12
Complications are similar to other atrial level repairs. Risks of residual left-to-right shunting and risk of heart block or sinus node dysfunction are most commonly encountered. However, these ASDs are usually seen with other lesions, which may have more severe complications that take precedence. OUTCOME AND PROGNOSISSection 9 of 12
Outcome and prognosis for an isolated coronary sinus ASD are excellent, but the more serious lesions that can be associated may alter the overall outcome for a patient. FUTURE AND CONTROVERSIESSection 10 of 12
Results of surgical repair are closely related to the complexity of the associated lesions also being operated on. An unroofed coronary sinus should be suspected whenever an LSVC is encountered on echocardiogram. Failure to repair these defects results in excessive blood return to the heart and a residual right-to-left shunt. Debate on this topic is negligible because this ASD is a very rare lesion—most centers may see 1 or 2 a year. A minimally invasive approach could be discussed, but these ASDs are observed in children who usually have other more complex problems; thus, a minimally invasive approach would often not apply. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Atrial Septal Defect, Unroofed Coronary Sinus: Surgical Perspective excerpt Article Last Updated: Jun 19, 2006 | ||||||||||||||||||||||||||||
