Ann Thorac Surg 2000;70:2156-2158
© 2000 The Society of Thoracic Surgeons
Case report
Surgical resection of an intracardiac rhabdomyoma
Hartmuth B. Bittner, MD, PhDa,
Ajeet D. Sharma, MDa,
Kevin P. Landolfo, MDa
a Division of Cardiothoracic Surgery, Duke University Medical Center, Durham, North Carolina, USA
Accepted for publication February 11, 2000.
Address reprint requests to Dr Bittner, Division of Cardiovascular and Thoracic Surgery, University of Minnesota, Box 207 Mayo, 420 Delaware St SE, Minneapolis, MN 55455
e-mail: bittn006{at}tc.umn.edu
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Abstract
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There are only a few previous reports of intracardiac rhabdomyomas causing ventricular arrhythmias and near syncope. In this report we describe the successful surgical resection of an intracardiac rhabdomyoma using cardiopulmonary bypass, blood cardioplegia, and hypothermia. Preoperative evaluation consisting of echocardiography, computed tomography (CT), magnet resonance imaging (MRI), and positron emission tomography (PET) strongly suggested the presence of a symptomatic primary cardiac tumor projecting from the interventricular septum into the right ventricle.
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Introduction
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Primary cardiac tumors are a rare entity with an incidence of 0.02% [1]. Only one fourth of all cardiac tumors are malignant. The modern era of diagnosis began with the development of angiography, which, in 1952, allowed Goldberg to diagnose a left atrial lesion. In the same year the first intracardiac tumor resection was performed by Bahnson using bicaval occlusion technique. A cardiac tumor was first demonstrated by echocardiography in 1959, and subsequently cardiac echography became the cornerstone for the diagnosis of cardiac tumors.
A 35-year-old man was referred to Duke University Medical Center in March 1999 with the diagnosis of a right ventricular mass. The patient was in excellent health until several weeks before admission when he started to experience episodes of palpitations and mild epigastric pain occurring at different times. On the day of admission, the patient experienced a near syncopal episode that occurred while rising from his chair. He was subsequently admitted to the emergency room and diagnosed with frequent premature ventricular contractions and nonsustained episodes of ventricular tachycardia as well as cardiomegaly.
A transesophageal echocardiogram (TEE) revealed a moderately reduced left ventricular function with an ejection fraction of about 30%, mild left ventricular dilatation, as well as a spherical, homogeneous mass of about 1.5 cm diameter in the right ventricle attached to the interventricular septum (Fig 1). Further evaluation was performed including a chest computed tomography (CT) scan, which confirmed the echocardiographic findings (Fig 2). Whole body positron emission tomography (PET) tumor scanning was negative for metastatic lesions, and magnetic resonance imaging (MRI), chest and abdominal CT revealed no additional abnormal findings. Selective coronary angiography also showed neovascularization of the tumor (Fig 3).
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Fig 1. Transesophageal two-dimensional four-chamber echocardiogram showing a spherical, homogeneous mass of about 1.5 cm diameter in the right ventricle attached at the interventricular septum.
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Fig 2. Chest computed tomography showing excellent tissue discrimination of a 2.2 cm x 2 cm soft tissue right ventricular mass that abuts and may be contiguous with the interventricular septum, and represents a primary cardiac tumor.
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Fig 3. Selective coronary angiography and left coronary injections revealing neovascularization of the tumor (arrows).
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It was concluded that the patient had a solitary cardiac lesion consistent with a primary cardiac tumor. The patient was subsequently taken to the operating room where the tumor was resected through a median sternotomy under cardiopulmonary bypass (CPB) with mild hypothermic cardiac arrest and bicaval cannulation technique [2]. The tumor was approached through the right atrium, which was generously opened and a brownish broad-based 2 x 2 cm right ventricular septum lesion was visualized through the tricuspid valve. The tumor was excised through the incompetent tricuspid valve. The resection defect in the interventricular septum was closed with a glutaraldehyde prepared autologous pericardial patch using a running 5–0 monofilament suture. Temporary pacing wires were used until the patient recovered normal sinus rhythm on postoperative day 2.
The patient was weaned off CPB without difficulties and postprocedural TEE did not show any residual masses or ventricular septum defects. After the operation the patient had a successful resolution of his arrhythmias and did not require antiarrhythmic medication. Pathologic examination revealed a pedunculated tumor composed of striated muscle cells predominantly with round to oval slightly irregular nuclei with variable cytoplasmatic clearing typical of "spider cells." This microscopic examination is consistent with rhabdomyoma. There were areas of increased cellularity and nuclear pleomorphism but no other criteria for a diagnosis of cardiac rhabdomyosarcoma. This tumor represents a congenital rhabdomyoma that has acquired atypical histopathologic features over the years.
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Comment
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A diagnosis of an intracardiac primary tumor causing malignant arrhythmias was made preoperatively. Right ventricular tumors can present with right-side heart failure, right ventricular outflow obstruction, tumor embolization, and pulmonary hypertension [3]. A secondary cardiac tumor, although 30 times more common than primary cardiac lesions, was ruled out using chest, abdomen, and pelvis CT, MRI, and PET scanning. MRI is a particularly good imaging technique for determining whether there is extracavitary involvement of the tumor and whether the tumor originates in an intracavitary location. Cardiac catherization revealed neovascularization with septal feeding branches off the left anterior descending coronary artery (Fig 3). Intraoperative TEE evaluation is a valuable tool and assisted in planning the surgical approach. Owing to the deep infiltration of the tumor and the right ventricular location and especially the neovascularization, an occurrence of a primary malignant cardiac tumor was assumed. Historically, most primary malignant cardiac tumors are sarcomas, which generally affect adults [4]. Because these tumors are highly aggressive with local invasion and early metastases, resection is considered a palliative measure and the goal is to relieve symptoms [5]. Therefore a surgical approach and management was decided.
A complete excision with a 1-mm margin was successfully accomplished through the tricuspid valve. Temporary pacing wires were applied and the likelihood of placing a permanent pacer was considered relatively high given the broad-based ventricular septum location and its vicinity to the conducting system. The final pathologic report identified the lesion as a rhabdomyoma, which is the most common cardiac tumor in infants and children and usually presents with tachyarrhythmias [2]. The tumors can also extend within a cavity and obstruct the cardiac chamber or respective valve orifice. The lesions are well circumscribed from the surrounding myocardium but are not encapsulated. Microscopically, classic spider cells are found. Whether a partial regression occurred in this patient, a hallmark feature of rhabdomyomas, is uncertain but cellular features of a congenital rhabdomyoma were discovered in this 35-year-old patient.
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References
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Reynen K. Frequency of primary tumors of the heart. Am J Cardiol 1996;77:107.[Medline]
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Murphy M.C., Sweeney M.S., Putnam J.B., et al. Surgical treatment of cardiac tumors: a 25-year experience. Ann Thorac Surg 1990;49:612-618.[Abstract]
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Reece I.J., Cooley D.A., Frazier O.H., Hallman G.L., Powers P.L., Montero C.G. Cardiac tumors. Clinical spectrum and prognosis of lesions other than classical benign myxoma in 20 patients. J Thorac Cardiovasc Surg 1984;88:439-446.[Abstract]
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McAllister HA, Fenoglio JJ. Tumors of the cardiovascular system. In: Atlas of tumor pathology. Fasc 15, 2nd series. Washington, DC: Armed Forces Institute of Pathology, 1978.
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Abstract
Introduction
