A matter of the heart

A 60-year-old woman was admitted to the hospital because of a 1-year history of progressively worsening dyspnea on exertion. Chest auscultation revealed a loud first heart sound (S₁), but no murmurs or extra heart sounds were audible. A transthoracic echocardiogram showed a 2.9 x 2.1-cm left atrial mass extending from the interatrial septum and prolapsing into the left ventricle through the mitral valve (Figure 1). Coronary arteriography showed normal coronary arteries and no vascularization of the mass. The levo phase of a pulmonary angiogram showed a well-demarcated, mobile filling defect in the left atrium (Figure 2). The patient underwent successful surgical excision of the mass (Figure 3).

Figure 1. Echocardiography (apical

4-chamber view) showing the atrial

mass.

Figure 2. Pulmonary angiogram

showing a well-demarcated, mobile

filling defect in the left atrium.

Diagnosis

Left atrial myxoma measuring 3.1 x 1.6 x 2.3 cm.

Figure 3. Postoperative

echocardiography.

Points to remember

Myxomas are neoplasms of endocardial origin that usually develop in the atrium, with about 75% originating in the left atrium and 15% to 20% occurring in the right atrium. Most myxomas arise from the inter-atrial septum at the border of the fossa ovalis. Only 6% to 8% of myxomas are detected in the ventricles. Multiple tumors and atypical locations are more frequently observed in cases of familial myxoma. Patients generally present with at least one of the classic triad of symptoms, which include embolism, intracardiac obstruction, and constitutional symptoms. Physical examination findings include systolic murmurs, diastolic murmurs, or both; a loud S₁ may be caused by the late onset of mitral valve closure resulting from increased left atrial pressure or prolapse of the tumor through the mitral valve orifice. In some cases, an early diastolic sound (≈100 msec after S₂), termed a tumor plop, can be identified. It is thought to be produced as the tumor strikes the endocardial wall or when its excursion is abruptly halted and its stalk tenses. The treatment of choice for myxomas is surgical excision.