Discussion
Myxomas are benign growths in the heart. When in the LA, they are usually attached to the fossa ovalis region (83%). They may also be found in the right atrium (12.7%), both atriums (1.3%) or more rarely in the left or right ventricles. (1.7% and 0.6%, respectively) (1)(3)(4).
Cardiac myxomas are observed in approximately 0.5-1 cases per 1 million people per year. (5) Atrial myxomas occur predominantly in females between the ages of 40 and 60, with a women-to-men ratio of 2.05:1. (6)
There are two types of cardiac myxomas: typical and atypical. Typical cardiac myxomas are the most common. They usually grow in the LA and attach to the interatrial septum, typically forming sessile or pedunculated masses with smooth or papillary surfaces. (7). Myxomas may also be inherited in the Carney complex11The Carney Complex is a rare, autosomal dominant, multiple endocrine neoplasia and lentiginosis syndrome, caused in most patients by defects in thePRKAR1A gene, which encodes the regulatory subunit type 1α of protein kinase A. Characterized by abnormal cutaneous and mucosal pigmentation, myxomas predominantly of the heart, skin, and breast, endocrine neoplasms, psammomatous melanotic schwannomas (PMS), breast ductal adenomas, osteochondromas, and other non-endocrine tumors. (8) due to mutations of the PRKAR1A gene. (5)
Myxomas present with a classic triad: obstructive symptoms, embolic signs and symptoms and constitutional or systemic manifestations (4)(8). A study from the National Heart Center of Singapore (NHCS) observed no significant differences in gender, body size, tumor size, hemoglobin counts, blood cell or platelet counts between symptomatic and asymptomatic groups. They also found that the most common symptoms are dyspnea, ischemic stroke and palpitations. (8)
Diagnosis is difficult in atypical presentations due to echocardiographic limitations such as lack of tissue characterization and a restricted field of view (3), therefore, definitive diagnosis of a myxoma should be made following surgical removal of the tumor and subsequent histopathological assessment, where characteristic stellate or globular cells may be observed. (8)
Cardiac myxomas are most commonly diagnosed through TTE or transesophageal echocardiography (TEE). Additional diagnostic tools are useful, like electrocardiography, chest computed tomography (CT) and chest or heart magnetic resonance imaging (MRI). There are no specific blood tests for this condition. (5)
TTE is useful for determining a myxoma’s location, size, shape, attachment, mobility and hemodynamic impact. Characteristically, cardiac myxomas are found as a mobile pedunculated mass attached to the endocardial surface, usually in the interatrial septum, ranging in size from 3 to 4 cm in diameter. They are attached by a broad or narrow based stalk, frequently without involvement of adjacent structures. An homogenous or heterogenous aspect may be found depending on the presence of hemorrhage, calcification and surface thrombi. Distinctively, these heart tumors are mobile, which makes them prone to prolapsing into the left ventricle through the atrioventricular valves during diastole. TEE is also useful in these instances, improving spatial resolution and allowing for a better visualization of implantation and extension to adjacent veins (3)(5)(10). Our patient’s case provides an excellent example of typical echocardiographic findings in patients with this clinical entity.
Typical LA myxomas may cause obstructive complications, such as mitral valve obstruction or regurgitation, left-sided heart failure and secondary pulmonary hypertension. The most common symptom referred by patients is exertion dyspnea, followed closely by orthopnea. Furthermore, myxomas present with a high risk of systemic embolization, resulting in TIA, CVA, hemiplegia, loss of vision, chest pain and dyspnea. A wide number of patients (approximately 3.2% to 46.4%) with cardiac myxomas are asymptomatic, which toughens the clinical diagnosis, thus highlighting the need for imaging techniques like TTE, TEE, CT or MRI. These studies are also important for the characterization of the mass and subsequent surgical removal, which is the only definitive treatment for this condition. (5)
LA myxomas are the most common cardiac tumors, and as such, they should be the first clinical suspicion when a heart mass is observed through an imaging study. Moreover, the first step towards diagnosis should always be TTE. Our study suggests the usefulness of transillumination echocardiography for the assessment of tumor morphology, for it resembles macroscopic pathologic findings post-surgically and may be useful for surgical planning. However, more evidence is needed on the significance of this matter.