Right Atrial Myxoma

Case Study: Right Atrial Myxoma

Introduction:

Atrial myxomas are the most common primary heart tumours. 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. They affect the left side of the heart most often and are suggested when a patient develops fatigue, syncope, or arrhythmia. Approximately 18% of myxomas involve the right side of the heart. These tumours often go undiagnosed for long periods and are most often considered when searching for a cause of recurrent pulmonary thromboembolism. . We report on a patient who presented with nonspecific abdominal complaints, shortness of breath and a clotting disorder secondary to a large right atrial myxoma.

Case Report:

This 17 year old boy presented to us with 2 months history of abdominal pain, shortness of breath and intermittent fever. His clinical examination revealed that he did have tachycardia, signs of right sided heart failure with bilateral pleural effusions. An EKG displayed low voltage with right atrial enlargement, and an echocardiogram showed a large echogenic mass extending from right atrium to right ventricle. View Figure 1. Pulmonary artery pressures and the pulmonary valve were normal but the tricuspid valve was obscured due to a large mass. There was also thrombus in the inferior vena cava. View Figure 2. Left sided chambers and valves were normal. The patient went under open heart excision of tumour, with repair of the tricuspid valve and atrial septum. A biopsy revealed diagnosis of atrial myxoma.

The patient’s haemoglobin level was 11.0 g/dL, total WBC count 15,600/mm, and platelet count 49,000/mm. His prothrombin time was prolonged to 15.4 s, and partial thromboplastin time increased to 24 s (international normalized ratio, 1.6). His fibrinogen level was decreased to 186 mg/dL. D-dimer assay was positive at 3.2 µg/mL, and the ratio of fibrin split products was found to be > 40. The analysis of blood gas levels with the patient breathing room air revealed the following: PaO2, 63 mm Hg; PaCO2, 23.2 mm Hg; and calculated bicarbonate level, 18.8 mEq/L.

A dynamic CT scan of the chest also demonstrated bilateral effusions as well as a small pericardial effusion. The major arteries were free of thrombi, and the scan was interpreted as negative for pulmonary emboli. On close inspection of the helical CT scan, a mass was discerned in the right atrium and right ventricle.

On non-invasive vascular imaging of the right upper extremity, a fairly extensive deep venous thrombosis was visible. It involved the internal jugular, subclavian, and axillary veins. These vessels were distended and were filled with echogenic material, which was consistent with thrombi.

Figure 1: an apical 4 chamber view with thrombus extending from RA to RV

Figure 1: an apical 4 chamber view with thrombus extending from RA to RV

Figure 2: a subcostal long axis view of the IVC entering the RA

Figure 2: a subcostal long axis view of the IVC entering the RA

Discussion:

Myxoma formation is three times more commonly seen in the left atrium compared to the right. A ventricular location is very unusual. Most commonly, it occurs in the left atrium. Patients have ranged in age from 11 to 79 years (mean, 48 years) with the majority of patients being between 30 and 60 years old at the time of diagnosis. The surgical incidence was 0.5 atrial myxomas per 1 million population per year in the Republic of Ireland. Only 20% of these will involve the right atrium. Most cases are sporadic. Approximately 10% are familial and are transmitted in an autosomal dominant mode. Multiple tumours occur in approximately 50% of familial cases and are more frequently located in the ventricle (13% vs. 2% in sporadic cases).

Myxomas take a polypoid, round, or oval shape and are gelatinous with a smooth or lobulated surface. 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 tumour 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 tumour embolisation. The risk of recurrence is higher in the familial myxoma syndrome.

Symptoms are produced by mechanical interference with cardiac function or embolisation. Being intravascular and friable, myxomas account for most cases of tumour 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 tumours as compared to round (58% vs. 0%). Also, polypoid tumours more frequently prolapse into the ventricle. Prolapse of a tumour 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. Tumours 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.

Removal of a right atrial myxoma is important not only for preventing possible obstruction of the tricuspid orifice, eliminating pulmonary emboli, and maintaining systolic function, but also for restoring biventricular diastolic function.1 Surgical excision gives excellent short-term and long-term results that lead to an eventual cure of nonfamilial myxomas. The crucial aspects of surgery are measures taken for the prevention of intraoperative embolisms, en bloc excision of the tumour with a wide cuff of normal tissue, and the inspection of all four chambers in order to avoid missing tumour emboli or the occasional multicentric lesion. Clinical follow-up for at least 10 years may be needed to rule out recurrence or metastasis.

The clinical manifestations of atrial myxoma vary from no symptoms and no clinical signs to various manifestations of chronic or acute congestive heart failure, syncope, and arrhythmia, as well as vascular evidence of tumour embolisation.

Sudden death may occur in 15% patients with atrial myxoma. Death is typically caused by coronary or systemic embolisation or by obstruction of blood flow at the mitral or tricuspid valve. Morbidity is related to symptoms produced by tumour embolism, heart failure, mechanical valvular obstruction, and various constitutional symptoms.

References:

  1. Jardine, DL, Lamont, DL (1997) Right atrial myxoma mistaken for recurrent pulmonary thromboembolism. Heart 78,512-514.
  2. Bitner, M, Jaszewski, R, Wojtasik, L, et al (1998) Unusual course of right atrial myxoma, masked by acute abdominal pain and complicated by pulmonary embolus. Scand Cardiovasc J 32,371-373
  3. Lijoi, A, Scoti, P, Faveto, C, et al (1993) Surgical management of intracardiac myxomas: a 16 year experience. Tex Heart Inst J 20,231-234.
  4. Lee VH, Connolly HM, Brown RD Jr. Central nervous system manifestations of cardiac myxoma. Arch Neurol. Aug 2007; 64(8):1115-20.
  5. Acebo E, Val-Bernal JF, Gomez-Roman JJ, Revuelta JM. Clinicopathologic study and DNA analysis of 37 cardiac myxomas: a 28-year experience. Chest. May 2003; 123(5):1379-85.
  6. Silaruks, SS, Kiatchoosakul, S, Tatsanavivat, P, et al (1999) Atrial myxoma: a review of clinical experience at Srinagarind Hospital. J Med Assoc Thai 82,107-114
  7. Bhan, A, Mehrotra, P, Choudhary, SK, et al (1998) Surgical experience with intracardiac myxomas: long-term follow-up. Ann Thorac Surg 66,810-813

 

Author:

Dr Mohammad Nasir & Dr Sajid Dhakam
Cardiologists
Aga Khan University Hospital
Pakistan

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