Introduction

Cor triatriatum sinister is a rare congenital defect in which the left atrium is divided by a fibromuscular membrane into two distinct chambers[₁]. Divided left atrium or Cor Triatriatum, is a congenital cardiac malformation having low incidence during paediatric age, ranging between 0.1 - 0.4%. Its appearance in adulthood is even more exceptional and often inadvertently discovered[₂]. It is usual for patients to present in infancy and early childhood, although some cases remain undetected until adult life. As a consequence of trans-membrane flow obstruction, the clinical features often mimic mitral stenosis. At present, the reasons for late presentation are poorly understood[₃]. Severity of the disease depends on the size of the opening on the membrane[₄].

Case Presentation

Our case was a 55 years old man and he was examined at an other institution for dyspnea and increasing fatigue. He was in New York Heart Association (NYHA) functional class III at presentation.He was evaluated by clinical,hematological,electrocardiographical and echocardiographical examination preoperatively. Transthoracic echocardiography(TTE) showed mild mitral regurgitation. Diameter of left atrium(57mm) and left ventricle(54/37mm)were widened.Left ventricular EF was 50%. Echocardiographic score was found to be 9. Other valves’ functions were normal. Because he was middle-aged, coronary arteriography(CAG) and cardiac catheterization were performed. CAG showed significant stenotic lesions in LAD and CxOM1 branch. It confirmed mild mitral regurgitation(Figures 1&2).

Figure 1

Figure 1

Figure 2

Figure 2

He underwent operation. He was operated under endotracheal general anesthesia and in supine position.Following a median sternotomy,pericardium was opened longitudinally.. After heparinization, extra-corporeal circulation was established between the venae cavae and the ascending aorta. A cross clamp was placed on aorta and by antegrade intermittant isothermic blood cardioplegia from aortic root,cardiac arrest was established.Hypothermia was moderate (28ºc).A vent was placed via the right superior pulmonary vein. First of all, a distal anastomosis of autogenous saphenous graft to OM1 branch was performed (Figure 3).

Figure 3

Figure 3

LIMA to LAD anastomosis was postponed in order to avoid retractions. Then, left atriotomy was performed. There was an anatomical structure observed, which constitutes a stenosis without any annulus and possesses no chordae and papillary muscles. This structure was thought to be cor triatriatum sinister (Figure 4).

Figure 4

Figure 4

This structure was dilated and a mitral valve was searched for. It was identified that native valve was intact. Upon this, the orifice of the cor triatriatum was dilated and calcified segments were resected. (Figure 5&6).

Figure 5

Figure 5

Figure 6

Figure 6

Native mitral valve was competent and normal anterior and posterior leaflet structures and subvalvular apparatus were normal. Coaptation tests with saline test showed that coaptation was optimal (Figure 7).

Figure 7

Figure 7

Left atriotomy was closed, and LIMA-LAD anastomosis was completed (Figure 8).

Figure 8

Figure 8

The post-operative course was uneventful with successful anatomical correction. Postoperatively a recent echocardiogram shows absence of residual obstruction or shunt and good status of the left cardiac chambers.

Discussion

Cor triatriatum is a rare congenital cardiac anomaly in which the left atrium is divided into proximal (dorsal or upper) and distal (ventral or lower) chambers by a fibromuscular septum. The upper chamber receives the pulmonary veins and the lower chamber contains the atrial appendage and the mitral valve. The 2 chambers communicate through a defect in the membrane[₅]. Cor-triatriatum sinister is being diagnosed with increasing frequency in adults due to improvements in diagnostic imaging[₆].

When cor triatriatum is the only abnormality, the clinical findings are also similar to mitral stenosis with development of pulmonary hypertension and subsequent right ventricular hypertrophy and atrial enlargement[₅]. The incidence of atrial fibrillation and mitral regurgitation was found to rise with advancing age[₆].

In the study of Gheissari et al.,twelve patients with cor triatriatum sinistrum were treated over a 28-year period. Associated cardiac anomalies included persistent left superior vena cava, atrial septal defects, coarctation of the aorta, and total anomalous pulmonary venous drainage[₇].

In the study of Nagatsu; twenty-one patients (age 35 days to 39 years) with cor triatriatum were treated surgically over a 17 year period at his institute. He presented a clinical classification of cor triatriatum as follows: type I is the classical form with intact atrial septum, type IIa has an ASD between an accessory and a right atrial chambers, type IIb has an ASD between a right and a true left atrial chambers, and type IIc is a complexed form that has both communications of IIa's and IIb's. Transaccessory chamber approach for type I and IIb as the first choice provided ample exposure for complete excision of the obstructing membrane[₈].

Clinical findings and cardiac catheterization do not provide sufficient data for the correct diagnosis. From a review of the experience of Arvay et al.; it is concluded that echocardiography is superior to angiography for diagnosing cor triatriatum[₄].

In coclusion; cor triatriatum sinistrum, a rare congenital cardiac anomaly, can be diagnosed by echocardiography. Cor triatriatum can be corrected surgically with a low mortality and excellent late results if an early preoperative diagnosis has been made[₄].