Cor triatriatum sinister with severe obstruction: a rare presentation in an adult

Abstract

Cor triatriatum sinister is a rare congenital anomaly usually presenting in infancy or childhood. Most cases reported in adulthood have minimal obstruction. A case of critically obstructed cor triatriatum sinister presenting for the first time in adulthood is described here. The characteristic ECG, radiological and echocardiographic findings of this rare anomaly are demonstrated in this case report. The clinical features closely mimic mitral stenosis. The clues to differentiate cor triatriatum from other causes of left ventricular inflow obstruction are described.

Background

Cor triatriatum sinister is a rare congenital cardiac anomaly with a 0.1% prevalence of cases of congenital heart disease.¹ The left atrium is partitioned by a fibromuscular membrane into a proximal chamber receiving pulmonary veins, and a distal chamber having a left atrial appendage and mitral valve.² Symptomatic cor triatriatum is usually diagnosed in infancy or childhood and has high mortality. Critically obstructed cases diagnosed in adults are very rare. This case report describes the clinical and imaging evaluation of an adult case of cor triatriatum sinister.

Case presentation

A 26-year-old woman was referred for cardiac evaluation with suspected mitral stenosis. She had had dyspnoea on exertion and recurrent episodes of paroxysmal nocturnal dyspnoea for 2 years. There was no history of rheumatic fever. On examination, she had regular low volume pulse and arm blood pressure of 110/80 mm Hg. There was no cardiomegaly. Left parasternal heave and palpable second heart sound were present on palpation. There was conspicuous absence of loud first heart sound and opening snap. Second heart sound was closely split with a loud pulmonary component. A low-pitched continuous murmur was heard at the apex, which was louder during expiration. The diastolic component was louder than systolic component.

Investigations

Twelve-lead ECG showed sinus rhythm, right axis deviation and right ventricular hypertrophy (figure 1). There was no left atrial enlargement. Chest radiograph showed a normal cardiothoracic ratio. The main pulmonary artery segment was dilated. The lung fields showed pulmonary venous congestion with a diffuse ground-glass appearance. There was no left atrial dilation in chest X-ray (figure 2). Transthoracic echocardiogram revealed the partitioning membrane in the left atrium, which was bulging towards the mitral valve (figure 3). The proximal chamber, which receives the pulmonary veins, was dilated whereas the distal left atrium proper, which carries the appendage, was not. Transoesophageal echocardiography (TEE) clearly demonstrated the characteristics of the membrane and continuous gradient (figure 4). There was a very narrow fenestration (diameter of 5 mm) in the membrane, with a continuous turbulent jet towards the mitral valve (video 1). The mitral valve was normal. Continuous wave Doppler evaluation showed a continuous gradient across the membrane. The diastolic gradient was higher than systolic gradient. The membrane was bulging towards the mitral valve during diastole as well as systole (video 2). The typical movement away from the mitral valve during systole described that, classically, in cor triatriatum was absent in this case, probably due to the high gradient throughout the cardiac cycle. There was mild tricuspid regurgitation with a peak gradient of 46 mm Hg.

Figure 1.

Twelve-lead ECG showing right axis deviation and right ventricular hypertrophy.

Figure 2.

Chest radiograph posterioranterior view showing pulmonary venous congestion without left atrial enlargement.

Figure 3.

Transthoracic echocardiogramimages showing the membrane in parasternal long axis view in diastole (A) and systole (B), apical four-chamber view (C) and continuous wave Doppler showing continuous gradient (D).

Figure 4.

Transoesophageal echocardiographyimages showing the membrane (A), proximal chamber with pulmonary vein (red colour flow) and distal chamber with left atrial appendage (B), continuous flow through the fenestration (C) and continuous wave Doppler gradient (D).

Video 1.

Download video file ^{(4.6MB, mp4)}

DOI: 10.1136/bcr-2016-215718.video01

Transoesophageal echocardiography image showing continuous turbulent flow through fenestration.

Video 2.

Download video file ^{(9MB, mp4)}

DOI: 10.1136/bcr-2016-215718.video02

Transoesophageal echocardiography image showing movement of membrane during systole and diastole.

Differential diagnosis

The important differential diagnoses in an adult patient with pulmonary venous congestion are mitral inflow obstruction and left ventricular failure. Symptoms of cor triatriatum are similar to those of rheumatic mitral stenosis. The typical findings of a loud first heart sound and opening snap differentiate this from cor triatriatum. Cor triatriatum typically has a diastolic murmur that mimics mitral stenosis. In our case, presence of a continuous murmur at the apex made the clinical diagnosis easy. Absence of left atrial enlargement in ECG and pulmonary congestion in the absence of left atrial dilation in chest radiograph differentiate this condition from mitral stenosis. Other causes of left ventricle inflow obstruction, such as supramitral ring, parachute mitral valve, etc, should be considered in the differential diagnosis. Echocardiography can easily differentiate these conditions. In cases of supramitral ring, the left atrial appendage belongs to the proximal chamber and the mitral valve is often deformed. Parachute mitral valve has a single eccentric papillary muscle.

Treatment

The patient was initially treated with diuretics and β-blockers. Digoxin was not given as she was in sinus rhythm. She underwent resection of the membrane through midline sternotomy under cardiopulmonary bypass. The postoperative period was uneventful.

Outcome and follow-up

The patient has been on asymptomatic follow-up for the past 6 months. She is not on any medication.

Discussion

Cor triatriatum usually involves the left atrium (cor triatriatum sinister) and rarely the right atrium (cor triatriatum Dexter). It occurs as an isolated lesion or in association with other congenital defects such as ostium secundum atrial septal defect and anomalous pulmonary venous return.³ The detailed pathological description was first described by Church in 1868, and the name ‘cor triatriatum’ was coined by Borst in 1905. Loeffler proposed a classification scheme based on number and size of fenestrations, in 1949.⁴ Group 1 with no opening, group 2 with one or more small openings and group 3 with one large opening. Group 1 and 2 usually present in infancy or childhood and are highly symptomatic. Group 3 may present during adulthood. In this case report, a group 2 patient with critical obstruction of the membrane presenting for the first time in adulthood is described. Several theories are proposed for the embryological pathogenesis of this rare disease. The ‘malincorporation’ theory states that the common pulmonary vein did not normally incorporate into the left atrium.⁴ The malseptation theory suggests that the membrane is an abnormal growth of the septum primum.⁵ Diagnosis is usually established by echocardiography, which delineates the characteristics of the membrane and associated lesions.^{6 7} TEE and three-dimensional echocardiography are very useful tools for evaluation of this condition.^{8 9} Other imaging modalities include multislice CT and MRI.^{10 11} Surgical treatment is indicated in symptomatic children and adults with significant obstruction.

Learning points.

• Cor triatriatum sinister with severe obstruction presenting for the first time in adulthood is very rare.

• Absence of loud first heart sound and opening snap distinguishes it from mitral stenosis, which is the immediate differential diagnosis.

• Pulmonary congestion in chest radiograph in the absence of left atrial enlargement is characteristic of this anomaly.

• Demonstration of typical continuous gradient by Doppler helps in establishing diagnosis.