Large Left Atrial Myxoma Causing Mitral Valve Obstruction: A Rare Cause of Syncope.

Cardiac myxoma is the most frequent benign tumors of heart. A 37-year-old woman dropped during the second prostration in prayer and decreased his mental state, with no prior history of syncope. On cardiac examination, there was an early diastolic sound that was compatible with a tumor plop. A transthoracic echocardiogram was performed which showed the presence of a pediculated mass in the left atrium, with an appearance suggestive of atrial myxoma. Atrial Myxoma can appear with non-specific symptoms. The best diagnostic method for myxoma is echocardiography that has a high sensitivity.

INTRODUCTION

Myxoma is the most common benign cardiac primary tumors, accounting about 50% of cardiac tumors and is more prevalent among females.[1] Because of different size of myxomas and their location in the different chambers of heart, patients with atrial myxoma usually present with cardiovascular symptoms such as heart failure and pulmonary hypertension, secondary to mitral valve obstruction. Constitutional symptoms of atrial myxoma include weight loss, fatigue, fever, clubbing, anemia, orthopnea, and acute pulmonary edema.[2] On the other hand, myxomas may cause life-threatening cardiac symptoms, e.g., syncope, requiring emergency surgery.[3] Two-dimensional echocardiography is the primary diagnostic imaging, not only as a complement to conventional echocardiography in the assessment of left atrial myxomas but also as a method of differentiating such masses from extra-cardiac tumors compressing the atrium. Echocardiography is a helpful method that can determine the tumor size, shape, and mobility.[2] Here, we report a case of left atrial myxoma presented with syncope.

CASE REPORT

A 37-year-old woman was referred to our emergency department of our hospital. She dropped during the second prostration in prayer and decreased her mental state, with no prior history of syncope, shortness of breath, or chest pain. She had no significant past medical history, but she had a positive family history of early cardiovascular disease. At presentation, the patient was afebrile and had normal vital signs (heart rate 80 bpm, blood pressure 110/70 mmHg, oxygen saturation 97% while breathing room air) and jugular venous pressure (JVP) was normal.

A 12-lead electrocardiogram revealed normal sinus rhythm with nonspecific minor ST-T abnormalities. On cardiac examination, S1 was accentuated and S2 was normal. There was an early diastolic sound that was compatible with a tumor plop.

A transthoracic echocardiogram (TTE) was performed which showed the presence of a pediculated mass in the left atrium, with an appearance suggestive of atrial myxoma, that was prolapsed through the mitral valve towards the left ventricle by changing patient's position [Figure 1a–c].

Figure 1

(a-c) Transthoracic echocardiography: Chambers view showing a large mobile left atrial mass prolapsing through mitral valve

The patient was referred for urgent surgery. The intraoperative findings included a mass, and histopathology confirmed an atrial myxoma. She recovered without major complication and was discharged. At 2-year follow-up, she remains with excellent cardiac function.

DISCUSSION

Myxoma is the most common primary benign cardiac tumor. Despite the fact that they can be discovered unexpectedly in asymptomatic patients, myxomas usually present with nonspecific signs and symptoms.[4] Depending on myxomas locations and their association with the heart structures, they can provide symptoms. Tumors that origins from the left atrium, especially if mobile and large, may result in symptoms similar to mitral stenosis due to obstruction of atrio-ventricular blood flow. These symptoms include: Exertional dyspnea, paroxysmal nocturnal dyspnea, orthopnea, fatigue, and syncope. In our patient, the cardiac auscultation may also mimic mitral valve stenosis. The tumor plop of myxoma is a protodiastolic murmur that is heard 80 to 150 ms after S2. Tumor plop may be mistaken for an opening snap, and tumor obstruction of the valve leads to a diastolic murmur.[5] The central nervous system (CNS) symptoms usually call for computed tomography (CT) or magnetic resonance imaging (MRI) scan of the brain to exclude embolization or an aneurysm formation, which is sometimes associated with myxomas. It has been suggested as prudent to perform MRI scan of the brain in all cardiac myxoma cases to exclude central nervous system (CNS) manifestations.[6]

In our patient, transthoracic echocardiography reported a mobile and pedunculated mass in the left atrium, which was attached to the interatrial septum. The mass prolapsed into the left ventricle across the mitral valve, resulting in a mitral valve obstruction. Recently, the diagnosis of cardiac tumors has improved enormously, and echocardiography has become a choice screening tool for cardiac tumors.[7] Myxoma often has heterogeneous echogenicity occasional calcifications. The location of the myxoma in the left atrium and its origination from the atrial septum are chief clues for the diagnosis. These clues enable cardiologists to differentiate myxoma from other cardiac masses.[8] Thus, it is very important to recognize the location of the tumor during echocardiography.[9] As reported in other studies, echocardiography is also valuable for the detection of atypical left atrial tumors. TTE is usually sufficient to make the diagnosis, but if the results are suboptimal, transesophageal echocardiogram (TEE) should be employed.[9]

In conclusion, echocardiography is likely to be a valuable diagnostic tool in patients who have had a cardiac mass. Besides, it also offers the cardiologist and cardiovascular surgeon the chance of more accurate pre- and intra-operative assessment of cardiac masses.