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Interact CardioVasc Thorac Surg 2005;4:285-286. doi:10.1510/icvts.2005.109512 © 2005 European Association of Cardio-Thoracic Surgery
A diagnostic challenge – an unusual right atrial mass, 12 years following atrial septal defect surgery
a Department of Cardiac Surgery, Toronto General Hospital, Ontario, Canada M5G 2C4 Received 21 March 2005; received in revised form 16 May 2005; accepted 16 May 2005
*Corresponding author: Dr Jain Bhaskara Pillai, 17 Paxford Close, Vicars Lane, Benton, Newcastle upon Tyne NE7 7PA, UK. Tel.: +44-0191-266-5472; fax: +44-0191-213-1968.
A young girl presented with a right atrial mass, 12 years following ostium secundum atrial septal defect surgery. The unusual pathology and the various diagnostic considerations for an atrial mass are discussed.
Key Words: Right atrial mass; Cardiac myxoma; Atrial septal defect
A 21-year-old woman presented with a five-year history of atypical chest pain. She had undergone surgical closure of an asymptomatic, 8 mm secundum atrial septal defect by primary suture at the age of nine years. Clinical examination was unremarkable. She was in sinus rhythm. A transesophageal echocardiogram (Fig. 1a) revealed a 1.8 cmx1.0 cm lobulated, highly mobile, echogenic mass in the right atrium. A prominent eustachian valve and a Chiari network were present. MRI confirmed a mass attached to the posterolateral right atrial wall distal to the inflow of the superior vena cava and anterior to the sinus venosus portion of the atrial septum. The heterogenous ‘salt and pepper’ MRI appearance suggested an atrial myxoma.
On cardiopulmonary bypass, the mass was excised completely (Fig. 1b). It did not look like a myxoma. It was attached to the right atrial wall with a short narrow stalk. It seemed to arise from the site of an old suture piercing into the atrial wall at that site. The suture was most likely that placed for holding the temporary atrial pacemaker wires at the original operation. The postoperative course was essentially uneventful. Histopathology is described in Fig. 2.
Most atrial septal defects are now electively closed in early childhood to prevent late onset complications. In a 25 years' reoperation-rate review, Monroe had a 0.013% incidence for ASD [1]. Here, the preoperative features suggestive of a myxoma were the MRI picture, the female sex and the long duration elapsed since initial surgery. However, the absence of any myxoma cell, unexpectedly, excluded this diagnosis. A more detailed review reveals the atypical features in our case against this knee-jerk diagnosis. A mass in the atrium commonly results from thrombus, infections with vegetations, and tumors. Primary cardiac tumors occur in 0.2 to 0.3% of all individuals; nearly 50% of which are myxomas. The usual sporadic variety occurs in the third and sixth decades of life and preferentially in women. Seventy-five percent of myxomas occur in the left atrium and only about 20% in the right atrium. Seventy-five percent originate from the interatrial septum at the inferior border of the fossa ovalis. Right atrial myxomas tend to have a broader base of attachment and are also more calcified. The origin of the myxoma cell is debated [2]. This predilection for the fossa ovalis is important and was explained by the clustering of the ‘Prichard structures’ here. These are multipotent subendocardial mesenchymal cells; embryonic remnants capable of differentiating into different cell lines, explaining the occurrence of bone, cartilage, etc. in myxomas. Heavy calcification is reported in about 10% of myxomas. Rarely, the myxoma cells may almost be completely replaced or mummified, termed a cardiac ‘lithomyxoma’ [3]. A wide spectrum of other cardiac tumors, as well as thrombus are known to calcify. In our case, the location away from the fossa ovalis, its small size, and the much younger age group were atypical. We found only one report of a myxoma developing after ASD repair [4]. It developed after 4 years on the atrial septum between the orifices of the coronary sinus and inferior vena cava. The suture line was uninvolved. We found three reports of the co-association of a myxoma with an ASD resulting in symptomatic right to left shunting in adults [5]. An anecdotal report described an atrial myxoma at the site of a trans-septal puncture for percutaneous balloon dilatation of the mitral valve. They concluded that some atrial myxomas might be reactive to trauma rather than neoplastic in origin [6]. There are few reports of atrial thrombus following atrial septal defect surgery. This has been described with primary suture and the patch closure techniques. This was usually within six months of surgery and usually arose from the repair site. However, a thrombus has been described occurring as a thin, stalked mobile mass on the free wall of the right atrium near the inferior vena cava, and was attributed to endocardial damage [7]. The main pre-operative feature against a thrombus in our case was its remote timing, its site away from the surgical secundum site and the presence of sinus rhythm. Prominent right atrial anatomy can sometimes be mis-interpreted. Such a ‘pseudomass’ include Prominent cristae terminalis, lipomatous hypertrophy of the septum [8], eustachian valve mimicking a cystic mass, and the persistent embryologic right sinus venosus valve known as the Chiari network. Werner found the Chiari network in 2–3% of normal hearts and is more often associated with the orifice of the IVC [9]. The prominent anatomical structures did not confuse the issue in our case.
In this case, after review of all the available pre and postoperative information, we conclude that the suture material served as an inflammatory focus, subsequent thrombus formation with eventual dystrophic calcification and ossification. One should be guided by a systematic approach in such an atypical case.
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Abstract
1. Clinical presentation
