Ann Thorac Surg 2008;86:1999. doi:10.1016/j.athoracsur.2008.01.037
© 2008 The Society of Thoracic Surgeons
Images in Cardiothoracic Surgery
Cor Triatriatum Associated with ASD and Common Atrium in 7-Month-Old With Tachypnea and Failure to Thrive
Michael K. McLean, MD*,a,
Grace C. Kung, MDb,
Anastasios Polimenakos, MDa,
Winfield J. Wells, MDa,
Brian L. Reemtsen, MDa
a Department of Cardiothoracic Surgery, Children's Hospital of Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, California
b Department of Pediatric Cardiology, Children's Hospital of Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, California
* Address correspondence to Dr McLean, Department of Cardiothoracic Surgery, University of Southern California, 1520 San Pablo St, Suite 4300, Los Angeles, CA 90033-4612 (Email: mmclean{at}surgery.usc.edu).
A 7-month-old child without significant past medical history was presented to her primary care physician with progressive symptoms of tachypnea and failure to thrive. A transthoracic echocardiogram revealed an atrial septal defect measuring 26 mm essentially creating a common atrium. Also observed was an interruption of the inferior vena cava with azygous continuation. Operative intervention was scheduled. Of note, the patient's twin sister underwent repair of an atrioventricular septal defect as an infant.
The intraoperative transesophageal echocardiogram is shown in Figure 1
(* = redundant fenestrated membrane), and the transesophageal echocardiogram apical 4-chamber view is shown in Figure 2
(left atrium [LA], left ventricle [LV], mitral valve [MV], right atrium [RA], right ventricle [RV], arrow = redundant fenestrated membrane), which again revealed essentially a common atrium. In addition, there was a redundant membrane superior to the mitral valve resulting in a two-chambered left atrium without obstruction, consistent with cor triatriatum sinister.
The atrial septal defect was approached through a standard right atriotomy after institution of cardiopulmonary bypass. The redundant fenestrated left atrial membrane was identified. Consistent with the intraoperative transesophageal echocardiographic findings, this fenestrated membrane was observed to be proximal (superior) to the mitral valve with insertion to the remnant of primum septum as seen in Figure 2. The pulmonary veins were noted to empty into the proximal atrial chamber, whereas the ostium of the left atrial appendage was distal to THE insertion of the membrane as demonstrated in Figure 3
(arrow = redundant fenestrated membrane above the mitral valve; left atrial appendage [LAA]).
On inspection, the membrane was found to be fibrinous tissue reminiscent of valvular tissue. The membrane was completely excised from its attachments, followed by patch closure of the atrial septal defect with autologous pericardium. The postoperative transesophageal echocardiography showed no valvular insufficiency or residual atrial septal defect.
Cor triatriatum represents less than 0.1% of all congenital cardiac malformations. In its most common form, cor triatriatum sinister, the left atrium is divided into a proximal and distal chamber, with a membrane partitioning the left atrium, with attachment to the atrial septum. We believe that no other description of cor triatriatum with common atrium in the pediatric population has been published. The anatomy of this patient was unique due to both the lack of atrial septum and the site of attachment of the membrane. This membrane fits the definition of cor triatriatum, with the membrane inserting above the annulus of the mitral valve and extending superior to the ostium of the left atrial appendage. When grossly viewing the membrane intraoperatively, we initially believed that the membrane was a supra-mitral ring, until the extent of the attachments was elucidated. Interestingly, this membrane was not clearly defined and was interrogated on two prior transthoracic echocardiograms, but as noted in Figures 2 and 3, the membrane was clearly visible in the intraoperative transesophageal echocardiography. In retrospect, this finding was indeed present on the preoperative transthoracic echocardiogram, but it was not obvious to the referring cardiologist. Without intraoperative transesophageal echocardiogram modality, we would have most likely missed this cor triatriatum membrane, which would have likely led to an increased mid-term and long-term risk for development of left ventricular inflow obstruction.
