Cardiac Case Study: June 2007
An Uncommon Problem: Atrial Myxoma
By Jake Green, MD, Cardiology Fellow, Emory University School of Medicine
Primary cardiac tumors are extremely rare, having an estimated incidence of only 0.1%. Metastatic involvement of the heart is greater than 20 times more common than primary tumors. More than 75% of primary cardiac tumors are benign, and the majority of these are atrial myxomas.
Approximately 80% of myxomas arise in the left atrium, often impairing blood flow through the mitral valve. In time, they may lead to pulmonary hypertension, heart failure and/or peripheral embolism. Right atrialmyxomas behave like tricuspid stenosis with symptoms of right heart failure and pulmonary embolism. Regardless of location, typical symptoms are shortness of breath, dizziness, syncope and palpitations. About 30% of patients also have constitutional symptoms (weight loss, fever, fatigue), attributable to cytokine and growth factor secretion by the tumor.
Both the rarity of benign cardiac tumors and the frequently nonspecific symptoms make diagnosis a challenge and necessitate a high index of suspicion, as illustrated in this case report.
A 76-year-old man saw his primary care physician for nocturia and urinary frequency. His medications included lisinopril 20 mg once daily for hypertension, gemfibrozil 600 mg twice daily for hypertriglyceridemia and glyburide 2.5 mg once daily for diabetes. A routine electrocardiogram (ECG) identified left bundle-branch block (LBBB). Doxazosin was prescribed for benign prostatic hypertrophy, which he discontinued after a month because of dizziness.
Four months later, he presented to an urgent care center complaining of lightheadedness upon standing. He had no other symptoms, but he had been doing yard work in the heat for the past few days. Examination and laboratory tests were unrevealing. An ECG demonstrated a left atrial abnormality, LBBB and normal sinus rhythm. Positional changes in blood pressure and pulse were noted as 132/71 mmHg and 85/min while seated and 124/75 mmHg and 94/min on standing.
A diagnosis of orthostasis was made, and he was instructed to decrease lisinopril to 5 mg a day and follow up with his primary care physician.
Having decreased his lisinopril dosage as instructed and remaining well hydrated, he visited his primary care physician the following week. His orthostatic symptoms had continued and his blood pressure remained in the range of 130/80. Doppler ultrasound of the carotids was unremarkable, so his physician ordered 24-hour Holter monitoring, which demonstrated benign findings of occasional premature ventricular contractions, rare premature atrial contractions and no AV dissociation or block.
Transthoracic echocardiogram (echo) identified a mass in the left atrium. A transesophageal echo better defined a pedunculated left atrial mass attached to the interatrial septum. The patient subsequently underwent preoperative cardiac catheterization in consideration of resection of the mass. The catheterization revealed no obstructive coronary disease but was remarkable for vascular sinusoidal contrast filling of the mass with injection of the right coronary artery. The patient was admitted for resection.
On microscopic examination of the surgically resected tumor, the composition was typical of a myxoma. Soft, gelatinous, polypoid tissue was admixed with hemorrhagic material. The tumor surface was covered by endothelium, and the base attachment was firm and fibrous.
Prompt surgical resection of atrialmyxoma reduces the risk of embolization, cardiovascular complications and sudden death, and generally is recommended. Recurrences are rare and probably are due primarily to incomplete removal of the tumor.
Overall operative and immediate postoperative mortality has been reported in the range of 2%-8% at experienced centers. The causes of death are very heterogeneous, with no predominating reported etiology. Low cardiac output with multiorgan failure, sepsis related to preoperative infections, cerebral tumor embolization and mitral ring rupture (in an infant) are among the reported causes of early mortality in some series. Early postoperative morbidity frequently includes atrialtachyarrhythmias and less frequently (<5%) involves varying degrees of heart block, pericardial effusions, disturbed wound healing, bleeding, stroke, respiratory insufficiency and infection and ileus. The distribution of these perioperative complications is generally in keeping with those seen with other cardiac operations.
Benign myxomas, which account for 75% of all primary cardiac tumors, originate from multipotentmesenchymal cells capable of neural and endothelial differentiation. The majority of tumors are pedunculated and gelatinous, sometimes growing to a diameter of 15 cm. Although typically sporadic, some cases are familial (Carney syndrome) and have been linked to at least two genes. Transmission is autosomal dominant and affects women more frequently than men.
As demonstrated in this case, diagnosis may require a high index of suspicion as symptoms may be vague and suggestive physical exam findings may be absent. Heart sounds frequently are normal and the classic tumor “plop” is not always heard. Abnormal laboratory values (anemia and elevated erythrocyte sedimentation rate, C-reactive protein and globulin levels) are nonspecific, as are ECG findings. Fortunately, frequent symptoms such as dyspnea, palpitations or neurologic events often prompt cardiac imaging with echocardiography, which yields a diagnosis.
This case report demonstrates the need for detailed exploration of vague, possibly cardiac-related symptoms and, when indicated, aggressive treatment.
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