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AUTHOR AND EDITOR INFORMATION
Section 1 of 10  
Author: Gyanendra K Sharma, MD, FACP, FACC, Associate Professor, Department of Medicine, Section of Cardiology, Medical College of Georgia
Gyanendra K Sharma is a member of the following medical societies: American College of Physicians, American Society of Echocardiography, Society for Cardiovascular Magnetic Resonance, and Society of Cardiovascular Computed Tomography
Coauthor(s):
L Michael Prisant, MD, FACC, Director of Hypertension Unit, Professor, Department of Internal Medicine, Medical College of Georgia
Editors: Robert E Fowles, MD, Clinical Professor of Medicine, University of Utah College of Medicine; Consulting Staff, LDS Hospital; Director and Consulting Staff, Department of Cardiology, Salt Lake Clinic; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Steven J Compton, MD, FACC, FACP, Director of Cardiac Electrophysiology, Alaska Heart Institute, Providence and Alaska Regional Hospitals; Amer Suleman, MD, Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital; Marschall S Runge, MD, PhD, Marion Covington Distinguished Professor of Medicine, Vice Dean for Clinical Affairs, Chairman, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine
Author and Editor Disclosure
Synonyms and related keywords:
atrial myxoma, cardiac tumors, heart tumors, familial myxoma syndrome, primary cardiac neoplasms, polypoid mass, myxomatosis, Carney syndrome, NAME syndrome, LAMB syndrome, myxoid neurofibroma, tumor embolism, atrial fibrillation, vascular endothelial growth factor, angiogenesis, tumor growth
Background
Atrial myxomas are the most common primary heart tumors. Because of nonspecific symptoms, early diagnosis may be a challenge. Left atrial myxoma may or may not produce characteristic findings on auscultation. Two-dimensional echocardiography is the diagnostic procedure of choice. Most atrial myxomas are benign and can be removed by surgical resection.
Pathophysiology
Myxomas account for 40-50% of primary cardiac tumors. Approximately 90% are solitary and pedunculated, and 75-85% occur in the left atrial cavity. Up to 25% of cases are found in the right atrium. Most cases are sporadic. Approximately 10% are familial and are transmitted in an autosomal dominant mode. Multiple tumors occur in approximately 50% of familial cases and are more frequently located in the ventricle (13% vs 2% in sporadic cases). Myxomas are polypoid, round, or oval. They are gelatinous with a smooth or lobulated surface and usually are white, yellowish, or brown. The most common site of attachment is at the border of the fossa ovalis in the left atrium, although myxomas can also originate from the posterior atrial wall, the anterior atrial wall, or the atrial appendage. The mobility of the tumor depends upon the extent of attachment to the interatrial septum and the length of the stalk. Although atrial myxomas are typically benign, local recurrence due to inadequate resection or malignant change has been reported. Occasionally, atrial myxomas recur at a distant site because of intravascular tumor embolization. The risk of recurrence is higher in the familial myxoma syndrome. Symptoms are produced by mechanical interference with cardiac function or embolization. Being intravascular and friable, myxomas account for most cases of tumor embolism. Embolism occurs in about 30-40% of patients. The site of embolism is dependent upon the location (left or right atrium) and the presence of an intracardiac shunt. Jong-Won Ha and associates reported a more frequent occurrence of systemic embolism in polypoid tumors as compared to round (58% vs 0%). Also, polypoid tumors more frequently prolapse into the ventricle. Prolapse of a tumor through the mitral or tricuspid valve may result in the destruction of the annulus or valve leaflets. In one study, 19% of the patients had atrial fibrillation associated with large atrial myxoma. Left atrial myxomas produce symptoms when they reach about 70 g. Right atrial myxomas grow to approximately twice this size before becoming symptomatic. Tumors vary widely in size, ranging from 1-15 cm in diameter. Rate of growth is not exactly known. In one case report, right atrial myxoma had a growth rate of 1.36 x 0.03 cm/month. Myxomas have been demonstrated to produce numerous growth factors and cytokines, including vascular endothelial growth factor, resulting in angiogenesis and tumor growth and an increased expression of the inflammatory cytokine, interleukin-6.
Frequency
United States
Based upon the data of 22 large autopsy series, the prevalence of primary cardiac tumors is approximately 0.02% (200 tumors per million autopsies). About 75% of primary tumors are benign, and 50% of benign tumors are myxomas, resulting in 75 cases of myxoma per million autopsies.
International
Surgical incidence in the Republic of Ireland from 1977-1991 was 0.50 atrial myxomas per million population per year.
Mortality/Morbidity
- Sudden death may occur in 15% patients with atrial myxoma. Death is typically caused by coronary or systemic embolization or by obstruction of blood flow at the mitral or tricuspid valve.
- Morbidity is related to symptoms produced by tumor embolism, heart failure, mechanical valvular obstruction, and various constitutional symptoms.
Sex
- Approximately 75% of sporadic myxomas occur in females.
- Female sex predominance is less pronounced in familial atrial myxomas.
Age
- Myxomas have been reported in patients aged 3-83 years.
- The mean age for sporadic cases is 56 years.
- The mean age for familial cases is 25 years.
History
Symptoms range from nonspecific and constitutional to sudden cardiac death. In about 20% of cases, myxoma may be asymptomatic and discovered as an incidental finding. Signs and symptoms of mitral stenosis, endocarditis, mitral regurgitation, and collagen vascular disease can simulate those of atrial myxoma. A high index of suspicion aids in diagnosis.
- Symptoms of left-sided heart failure
- Dyspnea on exertion (75%) that may progress to orthopnea, paroxysmal nocturnal dyspnea, and pulmonary edema is observed.
- Symptoms are caused by obstruction at the mitral valve orifice. Valve damage may result in mitral regurgitation.
- Symptoms of right-sided heart failure
- Patients experience fatigue and peripheral edema.
- Abdominal distension due to ascites is rare; however, it is more common in slowly growing right-sided tumors.
- These symptoms are also observed in the later stage of progressive heart failure associated with left atrial myxomas.
- Severe dizziness/syncope
- This is experienced by approximately 20% of patients.
- The most frequent cause in patients with left atrial myxomas is obstruction of the mitral valve.
- Symptoms may change as the patient changes positions.
- Symptoms related to embolization
- Systemic or pulmonary embolization may occur from left- or right-sided tumors.
- Left-sided symptoms are produced from the infarction or hemorrhage of viscera.
- Embolization to the central nervous system may result in transient ischemic attack, stroke, or seizure. In a recent analysis of 113 cases of atrial myxoma with neurologic presentation, 83% of patients presented with ischemic stroke, most often in multiple sites (43%). Twelve percent of patients presented with seizures. In a retrospective review of 74 patients with atrial myxoma, 12% had neurologic manifestations.1 Cerebral infarction was present in 89% of the cases and most myxomas (89%) demonstrated a mobile component on transesophageal echocardiography. Other complications include myxoma-induced cerebral aneurysm and myxomatous metastasis that can mimic vasculitis or endocarditis.
- Involvement of the retinal arteries may result in vision loss.
- Systemic embolization that causes occlusion of any artery, including coronary, aortic, renal, visceral, or peripheral, may result in infarction or ischemia of the corresponding organ.
- On the right side, embolization results in pulmonary embolism and infarction.
- Multiple, recurrent small emboli may result in pulmonary hypertension and cor pulmonale.
- Presence of an intracardiac shunt (atrial septal defect or patent foramen ovale) may result in a paradoxical embolism.
- Constitutional symptoms that include fever, weight loss, arthralgias, and Raynaud phenomenon are observed in 50% of patients. These symptoms may be related to overproduction of interleukin-6.
- Hemoptysis due to pulmonary edema or infarction is observed in up to 15% of patients.
- Chest pain is infrequent. If it occurs, it may be due to coronary embolization.
Physical
- Jugular venous pressure may be elevated, and a prominent A wave may be present.
- A loud S1 is caused by a delay in mitral valve closure due to the prolapse of the tumor into the mitral valve orifice (mimicking mitral stenosis).
- P2 may be delayed. Its intensity may be normal or increased, depending on the presence of pulmonary hypertension.
- In many cases, an early diastolic sound, called a tumor plop, is heard. This sound is produced by the impact of the tumor against the endocardial wall or when its excursion is halted.
- An S3 or S4 may be audible.
- A diastolic atrial rumble may be heard if the tumor is obstructing the mitral valve.
- If there is valve damage from the tumor, mitral regurgitation may cause a systolic murmur at the apex.
- A right atrial tumor may cause a diastolic rumble or holosystolic murmur due to tricuspid regurgitation.
- General examination may reveal fever, cyanosis, digital clubbing, rash, or petechiae.
- Patients with familial myxoma may have a variety of features called syndrome myxoma or Carney syndrome, as follows:
- Myxomas in breast, skin, thyroid gland, or neural tissue
- Spotty pigmentation such as lentigines (ie, flat brown discoloration of skin), pigmented nevi, or both
- Endocrine hyperactivity such as Cushing syndrome
- Other described syndromes associated with atrial myxomas include the following:
- NAME syndrome features nevi, atrial myxoma, myxoid neurofibroma, and ephelides (ie, freckles [tanned macules found on the skin]).
- LAMB syndrome features lentigines, atrial myxoma, and blue nevi.
Causes
- Most cases of atrial myxoma are sporadic, and the exact etiology is unknown.
- Familial atrial myxomas have an autosomal dominant transmission.
- Carney syndrome is genetically heterogenous and is caused by a defect in more than one gene. Abnormalities in the short arm of chromosome 2 (Carney) and chromosome 12 (Ki-ras oncogene) have been described. In a recent case report, a frame shift mutation was found in exon 2 in the causative gene of Carney complex, protein kinase A regulatory subunit 1 alpha (PRKAR 1A).
Mitral Regurgitation
Mitral Stenosis
Pulmonary Embolism
Pulmonary Hypertension, Primary
Tricuspid Regurgitation
Tricuspid Stenosis
Other Problems to be Considered
Carcinoid heart disease
Cerebrovascular accident
Collagen vascular disease
Left atrial thrombus
Lab Studies
- Lab studies are nonspecific and nondiagnostic. If present, abnormalities may include the following:
- Elevated erythrocyte sedimentation rate (ESR) and elevated C-reactive protein and serum gamma globulin levels
- Leukocytosis
- Anemia may be normochromic or hypochromic. Hemolytic anemia may occur because of the mechanical destruction of erythrocytes by the tumor.
- Serum interleukin-6 levels may be raised and can be used as a marker of recurrence.
Imaging Studies
- Chest radiography
- Abnormal cardiac silhouette, mimicking mitral stenosis
- Unusual intracardiac tumor calcification
- Pulmonary edema
- Echocardiography
- Although transesophageal echocardiography is more sensitive, 2-dimensional echocardiography is usually adequate for diagnosis.
- Tumor location, size, attachment, and mobility can be assessed with this technique.
- Because tumors may be in multiple locations, all 4 chambers should be visualized.
- An atrial myxoma must be differentiated from a left atrial thrombus. The thrombus is usually situated in the posterior portion of the atrium and has a layered appearance. Presence of a stalk and mobility favors atrial myxoma.
- Doppler echocardiography can show the hemodynamic consequences of atrial myxoma. The findings are consistent with mitral stenosis or regurgitation.
- Transesophageal echocardiography
- Better specificity and 100% sensitivity compared to transthoracic echocardiography
- Good resolution of both atria and the atrial septum
- Better visualization of anatomic details of the tumor and stalk
- Reveals smaller (1-3 mm in diameter) vegetations or tumors
- Visualizes atrial appendages
- Detects shunting
- Advisable for myxoma syndrome - Multiple less common sites
- MRI
- MRI provides useful information about size, shape, and surface characteristics on T1-weighted images. Cine MR gradient echo (GRE) images can demonstrate the mobility of a tumor. Point of attachment is best visualized by MRI with a postsurgical correlation of 83%. In a small series, MRI was superior to CT scan, which showed only 30% correlation for the site of attachment.
- Information about tissue composition can be used to differentiate a tumor and a thrombus.
Other Tests
- If petechiae are present, a skin biopsy may reveal the presence of elongated or spindle-shaped, myxomatous, endothelial-like cells with round or oval nuclei and prominent nucleoli.
- Electrocardiography may show left atrial enlargement, atrial fibrillation, atrial flutter, or conduction disturbances.
Procedures
- Cardiac catheterization
- Preoperative cardiac catheterization and angiocardiography are used in selected patients in whom noninvasive evaluation is inadequate.
- Cardiac catheterization is usually performed to exclude coexistent coronary artery disease in patients older than 40 years.
- Atrial myxoma appears as an intracardiac filling defect on angiography. This was the pre-echocardiography method of diagnosis.
Histologic Findings
Histologic studies are characterized by the presence of lipidic cells embedded in a vascular myxoid stroma.
- The cells are polygonal to stellate in shape with scant eosinophilic cytoplasm.
- Tumor necrosis is present in approximately 8% of patients; calcification is present in 10-20%.
- A variable degree of hemorrhage may be present, and mitoses are typically absent.
- In a series of 37 cases, 74% of tumors showed immunohistochemical expression of interleukin-6 while 17% had abnormal DNA content.
Medical Care
- Generally, evaluation can be performed on an outpatient basis.
- A patient with embolic stroke requires hospitalization.
- No known medical treatment exists for atrial myxoma.
- Drug therapy is used only for complications such as congestive heart failure or cardiac arrhythmias.
Surgical Care
- Operative resection of the myxoma is the treatment of choice.
- The surgery is safe, with an early postoperative mortality of 2.2%. Some authorities believe resection should be performed immediately after the diagnosis is made.
- Because of the risk of tumor fragmentation and embolization, vigorous palpation or manipulation should be performed only after cardioplegia.
- Surgery for sporadic atrial myxoma is usually curative. Long-term prognosis is excellent. In a series of 112 patients, only 4 deaths occurred over a median follow-up of 3 years.
- The recurrence rate is 1-5%. Recurrence after 4 years is uncommon.
- The recurrence rate of familial patients is 20%.
- Recurrence is usually attributed to incomplete excision of the tumor, growth from a second focus, or intracardiac implantation from the primary tumor.
- Wider resection of the stalk attachment to the endocardium may reduce the burden of pretumorous cells.
- A cloth patch or parietal pericardium is used to close the surgical defect.
- Pretumorous cells around the stalk should be destroyed by laser photocoagulation. This obviates the need for a wide surgical resection.
- To fully visualize both sides of the heart, some surgeons recommend a biatrial approach.
- Damaged valves may require annuloplasty or prosthetic replacement.
- Biannual echocardiograms are useful for early detection of recurrent tumors.
- Endoscopic cardiac tumor resection: Deshpande et al have reported 27 cases (23 myxomas) of endoscopic cardiac tumor resection using the port access approach. Follow-up did not show any residual or recurrent tumor. This is an alternate approach that has cosmetic appeal and was appreciated by 92 of the patients.2
Consultations
If myxoma is suspected, a cardiologist should be consulted and a cardiothoracic surgical consultation will be required for consideration of resection.
Diet
No special diet is required.
Activity
Patients may engage in activities as tolerated.
Complications
- Congestive heart failure
- Sudden death
- Cardiac arrhythmias
- Infection
- Embolization
Medical/Legal Pitfalls
- Failure to recognize associated valvular damage
- Failure to differentiate an atrial thrombus from myxoma
- Failure to suggest screening of family members in the case of familial myxoma syndrome
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Atrial Myxoma excerpt Article Last Updated: Dec 17, 2007
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