Abstract
Cor triatriatum sinister is a rare congenital cardiac anomaly. It consists of a fibro-muscular membrane that separates the left atrium into two chambers resulting in a tri-atrial heart. It is often found in association with other structural cardiac anomalies. The “acquired” form is extremely rare and only anecdotal reports are found in literature. We describe a case of acquired cor triatriatum following surgical repair of coronary sinus type of total anomalous pulmonary venous connection (TAPVC), which presented 11 years after initial repair of TAPVC.
Keywords: Acquired cor triatriatum, TAPVC late complication, LA membrane
Introduction
Classic cor triatriatum, or cor triatriatum sinister, is a rare congenital cardiac anomaly in which a fibro-muscular membrane separates the common pulmonary chamber from the true left atrium with one or more, usually restrictive, communications in the membrane. When it occurs in the right atrium, it is known as cor triatriatum dexter. It represents 0.1% of all congenital cardiac malformations at autopsy with a male-to-female ratio of 1:1, and it is commonly associated with other cardiovascular malformations (up to 84% in some series) [1]. In classic cor triatriatum, the membrane divides the atrium into an upper chamber receiving the pulmonary veins and a lower chamber related to the left atrial appendage and mitral valve. Symptoms occur when restriction of flow through the membrane causes congestion of the pulmonary vascular bed. The degree of restriction dictates the age of presentation and the severity of symptoms. Diagnosis can be missed if the restriction is mild or absent. A restrictive membrane may result in pulmonary venous hypertension progressing to congestive heart failure. The most widely accepted current theory about the embryogenesis of cor triatriatum sinister relates to incomplete absorption of the common pulmonary vein into the left atrium [2]. Diagnosis is usually established by two-dimensional trans-thoracic and trans-esophageal echocardiography. Computed tomography or magnetic resonance imaging can be used in selected cases. Cardiac catheterization may be indicated in the presence of associated cardiac lesions. Anatomic variants include a pulmonary venous chamber that receives part of the pulmonary veins and communicates with the left atrium, and a pulmonary venous chamber receiving all or part of the pulmonary veins that does not connect to the left atrium. Congenital pulmonary vein stenosis is a rare association with cor triatriatum [2]. Variable types of subtotal cor triatriatum may be noted, with only the right or left pulmonary veins draining into the upper chamber.
Case report
An 11-year-old boy presented to our clinic with history of recent onset dyspnea on exertion of grade III/IV (the New York Heart Association (NYHA) classification). He had undergone surgery for coronary sinus–type total anomalous pulmonary venous connection (TAPVC) at the age of 3 months elsewhere. Electrocardiogram showed sinus rhythm. Echocardiography showed a membrane in the left atrium between pulmonary veins and mitral valve with a very small fenestration in it with peak/mean gradient of 21/10 mm of Hg (Fig. 1). There was severe pulmonary hypertension with a mean pressure of 70 mm of Hg. The patient was taken up for excision of this membrane and relief of pulmonary venous hypertension. Surgery involved aorto-bicaval cardiopulmonary bypass under moderate hypothermia and antegrade cold del Nido cardioplegia. Right atrium was opened after cardioplegic arrest. The previous atrial septal defect patch was incised. Exploration of the left atrium revealed a thick, fibro-muscular membrane of 2–3 mm thickness, located inferior to the pulmonary vein openings and left atrial appendage and communicating with the mitral valve through a 6- to 8-mm aperture (Fig. 2). The membrane was about 5 mm above the mitral valve annulus. It was found to be closely related to the previous suture line in the left atrium following reendothelialization of the cutback edges of the coronary sinus. The orifices of the pulmonary veins were not involved. The membrane was excised completely after which the opening easily admitted a Hegar dilator of required mitral valve size. Raw areas in the left atrium following excision of the membrane were reendothelialized with 5-0 polypropylene running suture. The atrial septal defect was closed with a patch of bovine pericardium (Synkroscaff ™). The rest of the operation was completed in standard fashion. Trans-esophageal echocardiogram (TEE) after coming off bypass showed no gradients across the mitral valve and no residual membrane in the left atrium (Fig. 1). He had an uneventful postoperative course in the hospital.
Fig. 1.
Echocardiography before and after resection of membrane. a, b Before resection of membrane. c, d After resection of membrane
Fig. 2.
Intraoperative image of “cor” being excised
Comment
Darling’s classification, first introduced in 1957, is the most commonly used system for TAPVC classification. TAPVC is classified into four categories according to the sites where the abnormal connection occurs.
The entrance of the pulmonary blood flow into the systemic venous system is cranial to the right atrium. This accounts for 45–55% of TAPVC cases, in which the confluent vessel usually empties into the innominate vein or the right or left superior vena cava (SVC) [3]. Type II: Cardiac type, which is diagnosed when the pulmonary veins converge on a confluent vessel and then horizontally connect to the right atrium through the coronary sinus (CS) or at the posterior wall of the right atrium. Approximately 20–30% of TAPVC patients exhibit the cardiac type. Type III: infracardiac type. The pulmonary veins conjoin and form a vertical vessel that travels caudally into the portal vein or its branches such as the ductus venosus, hepatic vein, and inferior vena cava (IVC). This type accounts for 13–25% of cases. Type IV: Mixed type. Less than 10% patients belong to this subtype, in which the right and left pulmonary tributaries drain at two or more different levels [3].
Supra-cardiac and infracardiac TAPVC repair can lead to the cor triatriatum if the size or even the lie of the anastomosis is not proper. The size of the anastomosis should be at least the size of the mitral valve. The lie of the anastomosis is also important to prevent twisting of the anastomosis. Anastomosis can be small if TAPVC at superior vena cava-right atrium junction is closed with patch only, instead of chamber and left atrium roof anastomosis. In coronary sinus TAPVC, inadequate cutback or Cooley’s technique [4] without adequate opening in roof of coronary sinus can lead to development of cor triatriatum.
Reports of hypertrophied atrial tissue following orthotopic cardiac transplantation are found in literature [5, 6]. There is a report of a membrane in the left atrium developing after surgery for infective endocarditis of the aortic valve with ring abscess treated by valve replacement and a report after TAPVC repair [7, 8]. Recently it has been reported after the Fontan operation [9]. It is thought the membrane develops secondary to hypertrophied atrial tissue, presence of suture lines in the left atrium, or torsion of the atrium. We feel that incomplete cut-back of the coronary sinus into the left atrium and leaving a residual gradient in the left atrium following coronary sinus–type TAPVC repair can be a substrate for acquired cor triatriatum. It is important to note that a wide anastomosis at the time of primary surgery is of utmost importance to prevent complications of an acquired cor triatriatum. Intraoperative sizing of the anastomosis to that of the mitral valve for the body surface area can be an effective method to alleviate this problem. Redo surgical correction is necessary, if this problem arises and relief of symptoms, if present, is immediate.
Funding
None.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Ethics approval
Ethical approval was waived by the local Ethics Committee in view of the retrospective nature of the study and all the procedures being performed were part of the routine care.
Consent for manuscript publication
Yes.
Informed consent
Yes.
Footnotes
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