Cardiac myxoma

Cardiac myxomas are the most common type of primary tumor of the heart. They are usually benign and arise from primary connective tissue. Most cardiac myxomas arise sporadically; however, 10% are hereditary (following an autosomal dominant pattern). Even though they may develop in any chamber of the heart, most (∼ 75 %) cardiac myxomas arise in the left atrium, usually from the interatrial septum, while the rest occur in the right atrium (ventricular myxomas are rare). Clinical features are primarily caused by obstruction of the blood flow through the heart and include dyspnea on exertion, palpitations, syncope, weight loss, or even sudden death. Rarely, life-threatening conditions (e.g., stroke) may result from an embolization from the myxoma. Typical examination findings include abnormal heart sounds, such as a rumbling diastolic murmur over the apex or a characteristic “tumor plop.” The diagnosis is not easily established clinically because of the nonspecific nature of symptoms. Echocardiography is the diagnostic procedure of choice. Surgical resection of the tumor is the curative treatment of choice. The prognosis is usually favorable, but tumors can recur after inadequate resection.

• Most common primary cardiac neoplasm in adults (usually benign)
• Most common location: left atrium (∼ 75% of all cases) ^[1]
• Sex: ♀ > ♂ (3:1)
• Peak incidence: 40–60 years ^[2]

Adult hearts are left with myxed feelings.

Epidemiological data refers to the US, unless otherwise specified.

• The exact etiology is unknown.
• Most cases are sporadic.
• Familial inheritance:
  • ∼ 10% of all cases
  • Autosomal dominant inheritance
  • Carney syndrome

• General
  • Production of IL-6 by tumor causes constitutional symptoms (e.g., weight loss, fever, pallor)
  • Digital clubbing
• Clinical features caused directly by the tumor
  • Symptoms caused by obstruction
    • Dyspnea on exertion, paroxysmal nocturnal dyspnea, and/or orthopnea
    • Dizziness or syncope (patients commonly have a history of multiple syncopes)
    • Palpitations
    • Auscultatory findings
      • Low pitched, middiastolic rumbling murmur over the apex (similar to mitral stenosis)
      • Early diastolic murmur: “plop” sound related to movement of the tumor
      • Potentially, an additional heart sound (audible just after S2)
      • These sounds may change when the patient changes position (improve lying down, worsen upright)
    • Valve damage may result in mitral regurgitation.
    • See “Symptoms of left heart failure” and “Symptoms of right heart failure.”
  • Symptoms due to embolization
    • CNS: transient ischemic attack, stroke, or seizure
    • Abdomen: visceral infarction or hemorrhage
    • Lungs: pulmonary embolization
    • Distant recurrence

Because of the nonspecific nature of the cardiac symptoms, the diagnosis is often only established much later in the course of the disease.

• Echocardiography: diagnostic test of choice
  • The tumor appears as a pedunculated, heterogeneous, mobile mass, usually present in the left atrium (the valve may appear as an obstructing ball). ^[3]
  • Helps assess tumor location, size, attachment, and mobility
• Other tests: CT and MRI scans help better visualize the intracardiac mass.

• Microscopic appearance ^[4]
  • Scattered mesenchymal cells within mucoid, gelatinous material
  • Surrounded by glycosaminoglycans
  • Produce VEGF
• Macroscopic appearance: often pedunculated, gelatinous consistency

• Secondary (metastatic) cardiac tumors
  • ∼ 20–30 times more common than primary cardiac tumors
  • Most common primary cancers: melanoma, lung cancer, and breast cancer
• Lipoma: usually an incidental finding
• Rhabdomyoma
  • A type of hamartoma
  • Most common primary cardiac tumor in children
  • Associated with tuberous sclerosis

The differential diagnoses listed here are not exhaustive.

• The only definitive treatment of cardiac myxoma is immediate surgical resection. ^[5]
• Medical intervention may be required for the treatment of associated conditions like arrhythmias, heart failure, or embolism.

Recurrence may occur in cases of incomplete excision of the tumor, growth from a second focus, or intracardiac implantation from the primary tumor.