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.