Pulmonary valve and pulmonary artery myxomas.

To the Editor,

Myxomas arising from the pulmonary valve and pulmonary artery are very rare. The mechanisms of these myxomas remain unknown; however, it is supposed that they arise in situ or from a dislodgement of myxomas from remote sites (1). Eck reported the first case of pulmonary valve myxoma in a premature neonate in 1935 (2). Later in 1955, Blodorn (2) reported an autopsied case of myxomas involving both the pulmonary valve and pulmonary artery (2). Until present, only two decades of such cases have been reported worldwide. The myxoma could be found at any age, from neonate to very aged patients, with a slight male predominance.

The myxomas located near the pulmonary valve may influence opening and closing of the valve leading to valvular stenosis and (or) insufficiency. As some patients were asymptomatic, the myxomas were discovered by incidental findings during routine examinations, whereas majority presented with circulatory or institutional symptoms. Physical examinations, electrocardiography, and chest X-ray films might not offer specific diagnostic evidences.

Myxomas may be misdiagnosed as pulmonary valve stenosis, pulmonary artery embolism, or pulmonary valve vegetation and lead to an inappropriate therapy, such as anticoagulation or thrombolysis (3). Transthoracic or transesophageal echocardiography and cardiac computed tomography are reliable diagnostic means. Computed tomography could clearly show the location, size, and mobility of the myxoma as well as the relation between myxoma and cardiac system. The feature of pulmonary artery myxoma in cardiac magnetic resonance imaging was reported to be a hypointense mass (4). A moving mass on echocardiography or a filling defect on computed tomography could be helpful in establishing the diagnosis. However, the final diagnosis relied on pathological investigations.

In spite of the benign nature of myxomas, they may inevitably cause valvular dysfunction and secondary pulmonary hypertension and have a significant propensity to embolize the pulmonary artery (1). Pulmonary artery and pulmonary valve myxomas have the common features of right heart system, such as predilections of right ventricular obstruction, right-sided valve insufficiencies, and pulmonary embolism; however, their special characteristic is a smaller size. Pulmonary myxomas could occur isolated or in association with other congenital heart defects or acquired disorders. There were more myxomas arising from the pulmonary valve than from the pulmonary artery or from pulmonary valve and pulmonary artery. Most pulmonary valve myxomas arose from the valve leaflets, and most pulmonary artery myxomas arose from the main pulmonary artery. Because of potential hazards and occasional misdiagnosis, the patients endow an early surgical treatment upon diagnosis (5). Most patients warranted a surgical resection of the myxoma under standard cardiopulmonary bypass, while some patients were operated under normothermic cardiopulmonary bypass or deep hypothermic circulatory arrest. Concurrent procedures to myxoma resection, such as pulmonary valve repair or replacement, or right ventricular outflow tract reconstruction should be performed simultaneously. An early surgical treatment is warranted upon diagnosis because of potential hemodynamic disturbances and predilection of embolization. Most patients have a good prognosis following surgical treatment.