Myxomata comprise 50% of all benign cardiac tumors in adults and 15% of such tumors in children. Occurrence during infancy is rare (Tables 62-2 and 62-3). A vast majority of myxomas occur sporadically and tend to be more common in women.4,21 The peak incidence is between the third and sixth decades of life, and 94% of tumors are solitary.26 Approximately 75% occur in the left atrium28 and 10 to 20% occur in the right atrium. The remaining proportion are equally distributed between the ventricles.2 The deoxyribonucleic acid (DNA) genotype of sporadic myxomas is normal in 80% of patients.27 Myxomas are unlikely to be associated with other abnormal conditions and have a low recurrence rate.4,28
Table 62-2 Benign Cardiac Neoplasms in Adults ||Download (.pdf)
Table 62-2 Benign Cardiac Neoplasms in Adults
|AV node mesothelioma||9||4|
|Granular cell tumor||3||1|
Table 62-3 Benign Cardiac Neoplasms in Children ||Download (.pdf)
Table 62-3 Benign Cardiac Neoplasms in Children
|AV node mesothelioma||1||2||3||4.0|
About 5% of myxoma patients show a familial pattern of tumor development based on autosomal dominant inheritance.29,37,38 These patients and 20% of those with sporadic myxoma have an abnormal DNA genotype chromosomal pattern.27 In contrast to the "typical" sporadic myxoma profile, familial patients are more likely to be younger, equally likely to be male or female, and more often (22%) have multicentric tumors originating from either the atrium or ventricle.30-34 Although familial myxomas have the same histology, they have a higher recurrence rate after surgical resection (21 to 67%).28,35 Approximately 20% of familial patients have associated conditions such as adrenocortical nodule hyperplasia, Sertoli cell tumors of the testes, pituitary tumors, multiple myxoid breast fibroadenomas, cutaneous myomas, and facial or labial pigmented spots.26,35 These conditions often are described as complex myxomas within the group of familial myxoma.27 A familial syndrome with autosomal X-linked inheritance characterized by primary pigmented nodular adrenocortical disease with hypercortisolism, cutaneous pigmentous lentigines, and cardiac myxoma is referred to as Carney's complex.26,35
Both biatrial and multicentric myxomas are more common in familial disease. Biatrial tumors probably arise from bidirectional growth of a tumor originating within the atrial septum.36 Atrial myxomas generally arise from the interatrial septum at the border of the fossa ovalis but can originate anywhere within the atrium, including the appendage.4 In addition, isolated reports confirm that myxomas can arise from the cardiac valves, pulmonary artery and vein, and vena cava.37,38 Right atrial myxomas are more likely to have broad-based attachments than left atrial tumors; they also are more likely to be calcified,32 and thus visible on chest radiographs. Ventricular myxomas occur more often in women and children and may be multicentric.2,39 Right ventricular tumors typically arise from the free wall, and left ventricular tumors tend to originate in the proximity of the posterior papillary muscle.
Grossly, about two-thirds of myxomas are round or oval tumors with a smooth or lobulated surface (Fig. 62-1).21 Most are polypoid, compact, pedunculated, mobile, and not likely to fragment spontaneously.2,4 Mobility depends on stalk length, the extent of attachment to the heart, and the amount of tumor collagen.4 Most are pedunculated with a short, broad base, and sessile forms are unusual.2,40 Less common villous or papillary myxomas are gelatinous and fragile and prone to fragmentation and embolization, occurring about one-third of the time.21,41 Myxomas are white, yellow, or brown in color, and are frequently covered with thrombus.2 Focal areas of hemorrhage, cyst formation, or necrosis may be seen in cut section. The average size is about 5 cm in diameter, but growth to 15 cm in diameter and larger has been reported.4 Myxomatous tumors appear to grow rapidly, but growth rates vary, and occasionally, tumor growth arrests spontaneously.4 Weights range from 8 to 175 g, with a mean between 50 and 60 g.5
Large in situ left atrial myxoma as seen from the surgeon's perspective just before removal.
Histologically, myxomas are composed of polygonal-shaped cells and capillary channels within an acid mucopolysaccharide matrix. 4 The cells appear singularly or in small clusters throughout the matrix, and mitoses are rare.42,51 The matrix also contains occasional smooth muscle cells, reticulocytes, collagen, elastin fibers, and a few blood cells. Cyst, areas of hemorrhage, and foci of extramedullary hematopoiesis are also found.35,41 Ten percent of the tumors have microscopic deposits of calcium and metastatic bone deposits, as well as sometimes glandular-like structures.35,41 The base of the tumor contains a large artery and veins that connect with the subendocardium but do not typically extend deep beyond the subendocardium.35 A coronary angiography in our own institution revealed a large feeding vessel and was suspected originally of being an angiosarcoma but on histology proved to be a typical benign myxoma. Myxomas tend to grow into the overlying cardiac cavity rather than into the surrounding myocardium. Myxomas arise from the endocardium and are considered derivative of the subendocardial multipotential mesenchymal cell.43,44,45 This accounts for the occasional presence of hematopoietic tissue and bone in these tumors. Interestingly, myxomas have developed after cardiac trauma, including repair of atrial septal defects and trans-septal puncture for percutaneous dilatation of the mitral valve.
The classic clinical presentation of a myxoma is intracardiac obstruction with congestive heart failure (67%); signs of embolization (29%); systemic or constitutional symptoms of fever (19%); weight loss or fatigue (17%); and immunologic manifestations of myalgia, weakness, and arthralgia (5%).21 Cardiac rhythm disturbances and infection occur less frequently.
Nearly all myxoma patients admit to a variety of constitutional symptoms. These complaints may be accompanied by a leukocytosis, elevated erythrocyte levels and sedimentation rate, hemolytic anemia, thrombocytopenia, and elevated C-reactive protein. Immunoelectrophoresis may reveal abnormal immunoglobulin levels with increased circulating IgG.46 The recent discovery of elevated levels of interleukin-6 in patients with myxoma has been linked to a variety of associated conditions, including lymphadenopathy, tumor metastasis, ventricular hypertrophy, and development of constitutional symptoms.39,47,48 Other less frequent complaints include Raynaud's phenomenon, arthralgias, myalgias, erythematous rash, and clubbing of the digits.4,49
Possible etiologies of such varied complaints and symptoms include tumor embolization with secondary myalgias and arthralgias and elevated immunoglobulin response.50 Circulating antibody–tumor antigen complexes with complement activation also may play a role.51 Such symptom complexes tend to resolve following surgical resection of the tumor.52
Obstruction of blood flow in the heart is the most common cause of acute presenting symptoms. The nature of these symptoms is determined by which of the chambers is involved and the size of the tumor. Myxomas in the left atrium tend to mimic mitral disease. These produce positional dyspnea and other signs and symptoms of heart failure associated with elevated left atrial and pulmonary venous pressures. Clinically, mitral stenosis often is suspected and leads to echocardiography and diagnosis of myxoma. Syncopal episodes occur in some patients and are thought to result from temporary occlusion of the mitral orifice.32,53 Right atrial myxomas can produce a clinical picture of right-sided heart failure with signs and symptoms of venous hypertension, including hepatomegaly, ascites, and dependent edema and can cause tricuspid valve stenosis by partially obstructing the orifice.32,53 If a patent foramen ovale is present, right-to-left atrial shunting may occur with central cyanosis, and paradoxical embolization has been reported.54 Large ventricular myxomas may mimic ventricular outflow obstruction. The left ventricular myxoma may produce the equivalent of subaortic or aortic valvular stenosis,54,55 whereas right ventricular myxomas can simulate right ventricular outflow track or pulmonic valve obstruction.
Systemic embolization is the second most common mode of myxomatous presentation, occurring in 30 to 40% of patients.2,4,32 Because the majority of myxomas are left-sided, approximately 50% of embolic episodes affect the central nervous system owing to both intra- and extracranial vascular obstruction. The neurologic deficits following embolization can be transient but are often permanent.56 Specific central nervous system consequences include intracranial aneurysms, seizures, hemiparesis, and brain necrosis.57–59 Retinal artery embolization with visual loss has occurred in some patients.60
Embolic myxomatous material has been found blocking iliac and femoral arteries.61–62 Other sites of tumor embolization include abdominal viscera and the renal and coronary arteries.63 Histologic examination of surgically removed peripheral myxoma that has embolized provides the diagnosis of an otherwise unsuspected tumor.32 Renal artery specimens from a nephrectomy have shown viable enlarging embolic myxoma after excision of the primary tumor. Right-sided myxomatous emboli mainly obstruct pulmonary arteries and cause pulmonary hypertension and even death from acute obstruction.4,54
Infection arising in a myxoma is a rare complication and produces a clinical picture of infectious endocarditis.64,65 Infection increases the likelihood of systemic embolization,4 and an infected myxoma warrants urgent surgical resection.
Findings at the time of clinical assessment of a patient with cardiac myxoma vary according to the size, location, and mobility of the tumor. Left atrial myxomas may produce auscultatory or clinical findings similar to mitral disease. The well-described "tumor plop" can be confused with a third heart sound,66 occurring just after the opening snap of the mitral valve created from contact between the tumor and endocardial wall.66 Left atrial myxomas that cause partial obstruction of left ventricular filling may result in elevated pulmonary vascular pressures with augmentation of the pulmonary component of the second heart sound.67
Right atrial myxomas may produce similar auscultatory findings as left atrial myxomas with the exception that they are best heard along the lower right sternal border rather than at the cardiac apex. In addition, right atrial hypertension may produce a large a wave in the jugular venous pulse and, when severe, may mimic superior vena caval syndrome.
Chest Radiograph and Electrocardiogram
The findings on chest roentgenogram may include generalized cardiomegaly, individual cardiac chamber enlargement, and pulmonary venous congestion. More specific rare findings are density within the cardiac silhouette caused by calcification within the tumor (see Fig. 62-3) occurring more often with right-sided myxomas.4
Nonspecific abnormalities such as chamber enlargement, cardiomegaly, bundle-branch blocks, and axis deviation can be found.68 Fewer than 20% of patients have atrial fibrillation.39 Evaluation of nonspecific electrocardiographic abnormalities occasionally leads to an incidental diagnosis of myxoma most electrocardiograms are not helpful in establishing a diagnosis.
Cross-sectional echocardiography is the most useful test employed for the diagnosis and evaluation of myxoma. The sensitivity of two-dimensional (2-D) echocardiography for myxoma is 100%, and this imaging technique largely has supplanted angiocardiography.69 However, coronary angiography usually is performed in myxoma patients more than 40 years of age to rule out significant coronary disease. Transesophageal echocardiography (TEE) provides the best information concerning tumor size, location, mobility, and attachment.70
Transesophageal echocardiograms detect tumors as small as 1 to 3 mm in diameter.71 Most surgeons obtain a transesophageal echocardiogram in the operating room before the operation (Fig. 62-2). We particularly evaluate the posterior left atrial wall, atrial septum, and right atrium, which often are not well displayed on transthoracic examination, to exclude the possibility of biatrial multiple tumors. Additionally, post operative TEE ensures a normal echocardiogram before leaving the operating room.
Transesophageal echocardiogram of a giant left atrial myxoma that does not appear attached to the mitral valve.
Computed Tomography and Magnetic Resonance Imaging
Although myxomas have been identified using computed tomography (CT),69,72 this modality is most useful in malignant tumors of the heart because of its ability to demonstrate myocardial invasion and tumor involvement of adjacent structures.68 Similarly, magnetic resonance imaging (MRI) has been employed in the diagnosis of myxomas and may yield a clear picture of tumor size, shape, and surface characteristics.68–72 MRI is particularly useful in detecting intracardiac and pericardial extension, invasion of malignant secondary tumors, and the evaluation of ventricular masses that occasionally turn out to be myxoma. Both CT and MRI detect tumors as small as 0.5 to 1.0 cm and provide information regarding the composition of the tumor.4 Neither CT nor MRI is needed for atrial myxomas if an adequate echocardiogram is available. The exception is the occasional right atrial myxoma that extends into one or both caval or tricuspid orifices. CT or MRI should be reserved for the situation in which the diagnosis or characterization of the tumor is unclear after complete echocardiographic evaluation.
Surgical resection is the only effective therapeutic option for patients with cardiac myxoma and should not be delayed because death from obstruction to flow within the heart or embolization may occur in as many as 8% of patients awaiting operation.73 A median sternotomy approach with ascending aortic and bicaval cannulation usually is employed. Manipulation of the heart before initiation of cardiopulmonary bypass is minimized in deference to the known friability and embolic tendency of myxomas. In the event of preoperative known cerebral embolization without hemorrhage, the tumor should be resected approximately seven days after the event to prevent further embolization and yet allow time for stabilization of the brain for cardiopulmonary bypass. For left atrial myxomas, the venae cavae are cannulated through the right atrial wall, with the inferior cannula placed close and laterally to the inferior vena cava–right atrial junction. Caval snares are always used to allow opening of the right atrium, if necessary. If extensive exposure of the left atrium is needed or a malignant left atrial tumor is suspected, we mobilize and directly cannulate the superior vena cava, which allows it to be transected if necessary for additional exposure. Body temperature is allowed to drift down, but there is no attempt to induce systemic hypothermia unless the need for reduced perfusion flow is anticipated. Modern cardioplegic techniques yield a quiet operative field and protect the myocardium from ischemic injury during aortic cross-clamping. Cardiopulmonary bypass is started, and the aorta is clamped before manipulation of the heart.
Exposure of left atrial myxomas is maximized by using several principles from mitral valve repair surgery. The surgeon desires the right side of the heart to rotate up and the left side of the heart to rotate down. Therefore, stay sutures are placed low on the pericardium on the right side, and no pericardial stay sutures are placed on the left before placing the chest retractor. This rotates the heart for optimal exposure of both the right and, particularly, the left atrium (Fig. 62-3). For left atrial tumors, the superior vena cava is mobilized extensively, as is the inferior vena cava–right atrial junction, allowing increased mobility and exposing the left atrial cavity. Left atrial myxomas can be approached by an incision through the anterior wall of the left atrium anterior to the right pulmonary veins (Fig. 62-4). This incision can be extended behind both cavae for greater exposure (Fig. 62-5). Exposure and removal of large tumors attached to the interatrial septum may be aided by a second incision parallel to the first in the right atrium. This biatrial incision allows easy removal of tumor attached to the fossa ovalis with a full-thickness Ro (margin-negative) excision at the site of attachment and easy patch closure of the atrial septum if necessary (Fig. 62-6).
Rotation of the heart with pericardial stay sutures for left atrial exposure. IVC = inferior vena cava.
Left atriotomy and exposure of myxoma.
Left atrial atriotomy posterior to the inter-atrial groove to expose the left atrial tumor.
Repair of left atrial wall after removal of myxomas.
Right atrial myxomas pose special venous cannulation problems, and intraoperative echocardiography may be beneficial. Both venae cavae may be cannulated directly. When low- or high-lying tumor pedicles preclude safe transatrial cannulation, cannulation of the jugular or femoral vein can provide venous drainage of the upper or lower body. In general, we always can cannulate the superior vena cava distal enough from the right atrium to allow adequate tumor resection, but occasionally femoral venous cannula drainage has been necessary. If the tumor is large or attached near both caval orifices, peripheral cannulation of both jugular and femoral veins may be used to initiate cardiopulmonary bypass and deep hypothermia. After the aorta is cross-clamped and the heart is arrested with antegrade cardioplegia, the right atrium may be opened widely for resection of the tumor and reconstruction of the atrium during a period of circulatory arrest if this is needed for a dry field. Resection of large or critically placed right atrial myxomas often requires careful preoperative planning, intraoperative TEE, and special extracorporeal perfusion techniques to ensure complete removal of the tumor, protection of right atrial structures, and reconstruction of the atrium. Because myxomas rarely extend deep in the endocardium, it is not necessary to resect deeply around the conduction tissue. The tricuspid valve and the right atrium, as well as the left atrium and ventricle, should be inspected carefully for multicentric tumors in patients with right atrial myxoma. Regardless of the surgical approach, the ideal resection encompasses the tumor and a portion of the cardiac wall or interatrial septum to which it is attached (Fig. 62-7). Our policy is to perform a full thickness resection whenever possible. However, partial-thickness resection of the area of tumor attachment has been performed when anatomically necessary without a noted increase in recurrence rate.74,75
Giant left atrial myxoma just before removal.
Ventricular myxomas usually are approached through the atrioventricular (AV) valve76 or by detaching the anterior portion of the AV valve for exposure and resection and reattachment after resection. Occasional small tumors in either outflow tract can be removed through the outflow valve.76 If necessary, the tumor is excised through a direct incision into the ventricle, but this is unusual and the least preferred approach. It is not necessary to remove the full thickness of the ventricular wall because no recurrences have been reported with partial-thickness excisions. As with right atrial myxoma, the presence of ventricular myxoma prompts inspection for other tumors because of the high incidence of multiple tumors.
Every care should be taken to remove the tumor without fragmentation. Following tumor removal from the field, the area should be liberally irrigated, suctioned, and inspected for loose fragments. There are rare instances of distant metastases from myxoma many years after tumor resection, and these reports raise the issue of potential intraoperative dissemination of tumor.77 Cardiotomy suction can be used during the operation, but wall suction should strictly be used during the brief time that the tumor is exposed. The low malignant potential of the vast majority of myxomas and the rarity of metastasis support the author's current policy of retaining rather than discarding blood, and we believe that most cases of metastatic implantation of myxoma represent a preoperative embolic event.
Minimally Invasive Approaches to Surgical Removal
Minimally invasive approaches are being applied with increasing frequency in all areas of cardiac surgery, and cardiac tumors are no exception. Experience is confined to benign tumors and is quite limited. Approaches have included right parasternal or partial sternotomy exposure with standard cardioplegic techniques,78 right submammary incision with femoral-femoral bypass and nonclamped ventricular fibrillation,79 and the right submammary port access method with antegrade cardioplegia and ascending aortic balloon occlusion.80 Thoracoscopic techniques have been used to aid in visualization and removal of ventricular fibroelastomas81,82 (Fig. 62-8). Myxoma removal is possible via thoracoscopy.83 Results in this limited number of selected patients have been good, but more experience and longer follow-up are needed before this can be recommended as a standard approach.
Thoracoscopic view of left atrial fibroelastoma.
Removal of atrial myxomas carries an operative mortality rate of 5% or less.21 Operative mortality is related to advanced age or disability and comorbid conditions. Excision of ventricular myxomas can carry a higher risk (approximately 10%). Our experience over the last 15 years with 85 myxomas shows no operative or hospital mortality.
Recurrence of nonfamilial sporadic myxoma is approximately 1 to 4%.4,74,75 Many large series report no recurrent tumors.74,83–86 The 20% of patients with sporadic myxoma and abnormal DNA have a recurrence rate estimated at between 12 and 40%.4 The recurrence rate is highest in patients with familial complex myxomas, all of whom exhibit DNA mutation, and this is estimated to be about 22%.4 Overall, recurrences are more common in younger patients. The disease-free interval averages about 4 years and can be as brief as 6 months.75 Most recurrent myxomas occur within the heart, in the same or different cardiac chambers, and may be multiple.19,32,87 Extra-cardiac recurrence after resection of tumor, presumably from embolization and subsequent tumor growth and local invasion, has been observed.19,87,88 The biology of the tumor, dictated by gene expression rather than histology, may be the only reliable factor predicting recurrence. DNA testing of all patients with cardiac myxoma may prove to be the best predictor of the likelihood of recurrence.89
Myxomas generally classified as "malignant" are often found on subsequent review to be sarcomas with myxoid degeneration.90 However, this issue also remains unsettled because of reports of metastatic growth of embolic myxoma fragments in the brain, arteries, soft tissue, and bones.56,88,91–97 Symptomatic lesions of possible metastatic myxoma should be excised if feasible.56,91
The extent to which patients should be subjected to long-term echocardiographic surveillance after myxoma resection is not standardized. It would seem prudent to closely follow patients who are treated initially for multicentric tumors, those whose tumors are removed from unusual locations in the heart, all tumors believed to have been incompletely resected, and all tumors found to have an abnormal DNA genotype. Patients undergoing resection of tumors thought to be myxomas but with malignant characteristics at pathologic examination should have long-term, careful follow-up.
Other Benign Cardiac Tumors
As shown in Table 62-2, myxomas comprise approximately 41% of benign cardiac tumors, with three other tumors (ie, lipoma, papillary fibroelastoma, and rhabdomyoma) together contributing a similar proportion. A number of rarely encountered tumors account for the remainder.
Lipomas are well-encapsulated tumors consisting of mature fat cells that may occur anywhere in the pericardium, subendocardium, subepicardium, and intra-atrial septum.2 They may occur at any age and have no sex predilection. Lipomas are slow growing and may attain considerable size before producing obstructive or arrhythmic symptoms. Many are asymptomatic and are discovered incidentally on routine chest roentgenogram, echocardiogram, or at surgery or autopsy.98,99 Subepicardial and parietal lipomas tend to compress the heart and may be associated with pericardial effusion. Subendocardial tumors may produce chamber obstruction. The right atrium and left ventricle are the sites affected most often. Lipomas lying within the myocardium or septum can produce arrhythmias or conduction abnormalities. Large tumors that produce severe symptoms should be resected. Smaller, asymptomatic tumors encountered unexpectedly during cardiac operation should be removed if excision can be performed without adding risk to the primary procedure. These tumors are not known to recur.
Lipomatous Hypertrophy of the Interatrial Septum
Nonencapsulated hypertrophy of the fat within the atrial septum is known as lipomatous hypertrophy.2 This abnormality is more common than cardiac lipoma and usually is encountered in elderly, obese, or female patients as an incidental finding during a variety of cardiac imaging procedures.84 Various arrhythmias and conduction disturbances have been attributed to its presence.85,100 The main difficulty is differentiating this from a cardiac neoplasm on echocardiography.101 After the demonstration of a mass by echocardiography, the typical T1 and T2 signal intensity of fat on MRI usually can establish a diagnosis.102,103 Arrhythmias and heart block are considered by some as indications for resection, but data are lacking as to the long-term benefits from resection.104
Papillary Fibroelastoma of the Heart Valves
Papillary fibroelastomas are tumors that arise characteristically from the cardiac valves or adjacent endocardium.105 These tumors are described as resembling sea anemones with frondlike projections in gross description (Fig. 62-9). The AV and semilunar valves are affected with equal frequency. It is now known that these are capable of producing obstruction of flow, particularly coronary ostial flow, and may embolize to the brain and produce stroke.106–115 They are usually asymptomatic until a critical event occurs. Papillary fibroelastomas of the cardiac valve should be resected whenever diagnosed, and valve repair rather than replacement should follow the resection of these benign tumors whenever technically feasible (Fig. 62-10). Cytomegalovirus has been recovered in these tumors, suggesting the possibility of viral induction of the tumor and chronic viral endocarditis.111
Additional enhanced view of an in-situ left atrial fibroelastoma.
Surgical removal of a papillary fibroelastoma.
Rhabdomyoma is the most frequently occurring cardiac tumor in children. It usually presents during the first few days after birth. It is thought to be a myocardial hamartoma rather than a true neoplasm.116 Although rhabdomyoma appears sporadically, it is associated strongly with tuberous sclerosis, a hereditary disorder characterized by hamartomas in various organs, epilepsy, mental deficiency, and sebaceous adenomas. Fifty percent of patients with tuberous sclerosis have rhabdomyoma, but more than 50% of patients with rhabdomyoma have or will develop tuberous sclerosis.117 More than 90% of rhabdomyomas are multiple and occur with approximately equal frequency in both ventricles.118 The atrium is involved in fewer than 30% of patients. Pathologically, these tumors are firm, gray, and nodular and tend to project into the ventricular cavity. Micrographs show myocytes of twice normal size filled with glycogen, containing hyperchromatic nuclei and eosinophilic-staining cytoplasmic granules.2,119 Scattered bundles of myofibrils can be seen within cells by electron microscopy.118
Clinical findings may mimic valvular or subvalvular stenosis. Arrhythmias, particularly ventricular tachycardia and sudden death, may be a presenting symptom.119 Atrial tumors may produce atrial arrhythmias.119 The diagnosis is made by echocardiography. Rarely, no intramyocardial tumor is found in a patient with ventricular arrhythmias, and the site of rhabdomyoma is located by electrophysiologic study.119
Early operation is recommended in patients who do not have tuberous sclerosis before 1 year of age.86 The tumor usually is removed easily in early infancy, and some can be enucleated.86 Unfortunately, symptomatic tumors often are both multiple and extensive, particularly in patients with tuberous sclerosis, who, unfortunately, have a dismal long-term outlook. In such circumstances, surgery offers little benefit.
Fibromas are the second most common benign cardiac tumor, with more than 83% occurring in children. These tumors are solitary, occur exclusively within the ventricle and the ventricular septum, and affect the sexes equally. Fewer than 100 tumors have been reported, and most are diagnosed by age 2 years. These tumors are not associated with other disease, nor are they inherited. Fibromas are nonencapsulated, firm, nodular, gray-white tumors that can become bulky. They are composed of elongated fibroblasts in broad spiral bands and whirls mixed with collagen and elastin fibers. Calcium deposits or bone may occur within the tumor and occasionally are seen on roentgenography (Figs. 62-11 and 62-12).
Left ventricular fibroma as seen from an external view of the heart.
MRI of left ventricular fibroma.
Most fibromas produce symptoms through chamber obstruction, interference with contraction, or arrhythmias. Depending on size and location, such a tumor may interfere with valve function, obstruct flow paths, or cause sudden death from conduction disturbances in up to 25% of patients.114 Intracardiac calcification on chest roentgenograms suggests the diagnosis, which is confirmed by echocardiogram.
Surgical excision is successful in some patients, particularly if the tumor is localized, does not involve vital structures, and can be enucleated.86,120–122 However, it is not always possible to remove the tumor completely, and partial removal is only palliative, although some patients have survived many years.86,121 Operative mortality may be high in infants. Most cases are in adolescents and adults.186,120,121 Successful, complete excision is curative.120,121 Children with extensive fibromas have been treated with cardiac transplantation.122,123
Mesothelioma of the AV Node
Mesothelioma of the AV node, also termed polycystic tumor, Purkinje tumor, or conduction tumor. It is a relatively small, multicystic tumor that arises in proximity to the AV node and may extend upward into the interventricular septum and downward along the bundle of His.2 Mesothelioma is associated with heart block, ventricular fibrillation,124 and sudden death. Cardiac pacing alone does not prevent subsequent ventricular fibrillation. Surgical excision has been reported.24
Cardiac pheochromocytomas arise from chromaffin cells of the sympathetic nervous system and produce excess amounts of catecholamines, particularly norepinephrine. Approximately 90% of pheochromocytomas are in the adrenal glands. Fewer than 2% arise in the chest. Only 32 cardiac pheochromocytomas had been reported by 1991.125 The tumor predominantly affects young and middle-aged adults with an equal distribution between the sexes. Approximately 60% occur in the roof of the left atrium. The remainders involve the interatrial septum or anterior surface of the heart. The tumor is reddish brown, soft, lobular, and consists of nests of chromatin cells.
The patients usually present with symptoms of uncontrolled hypertension or are found to have elevated urinary catecholamines. The tumor usually is located by scintigraphy using [I131] metaiodobenzylguanidine126 and CT or MRI.126 Cardiac catheterization with differential blood chamber sampling sometimes is necessary in addition to coronary angiography.125 After the tumor is located, it should be removed using cardiopulmonary bypass with cardioplegic arrest. Patients require preanesthetic alpha and beta blockade and careful intraoperative and immediate postoperative monitoring. Most tumors are extremely vascular, and uncontrollable operative hemorrhage has occurred.126 Resection may require removal of the atrial and/or ventricular wall or a segment of a major coronary artery.135 Explantation of the heart to allow resection of a large left atrial pheochromocytoma has been attempted.127 Transplantation has been performed for unresectable tumor and complete excision produces cure.121–123
Paragangliomas are endocrine tumors that can secrete catecholamines. As a result, their presentation is often similar to that of pheochromocytomas. When found within the thoracic cavity, they are located most often in the posterior mediastinum. Paragangliomas typically present with atypical chest pain.128,129 On echocardiography, they are often large and highly vascular tumors.130 On cardiac catheterization, they may be intimately associated with the coronary arteries (Fig. 62-13). If they involve the left atrium, the technique of cardiac autotransplantation may be used to completely resect them131 (Fig. 62-14).
Paraganglioma blush of tumor during cardiac catheterization.
MRI of left atrial paraganglioma that required an autotransplant for removal.
Hemangiomas of the heart are rare tumors (24 clinical cases reported), affect all ages, and may occur anywhere within the heart.132,133 These are vascular tumors composed of capillaries or cavernous vascular channels. Patients usually develop dyspnea, occasional arrhythmias, or signs of right-sided heart failure.134 Diagnosis is difficult, and echocardiography or cardiac catheterization can establish a diagnosis of cardiac tumor by showing an intracavity filling defect.135 CT and MRI show axial T2-weighted MRI should show a high signal mass owing to vascularity (Fig. 62-15). Coronary angiography typically shows a tumor blush and maps the blood supply to the tumor. During resection, meticulous ligation of feeding vessels is required to prevent postoperative residual arteriovenous fistulas or intracavity communications. Partial resections have produced long-term benefits.132 Tumors rarely resolve spontaneously.136
Axial T2-weighted magnetic resonance image showing high signal mass of left atrial hemangioma. (Reproduced with permission from Lo JJ, Ramsay CN, Allen JW, et al: Left atrial cardiac hemangioma associated with shortness of breath and palpitations. Ann Thorac Surg 2002; 73:979.)
Cardiac teratoma is a rare tumor that typically presents in infants and young children.137 About 80% of the tumors are benign.138 These tumors are discovered by echocardiography after a variety of symptoms lead to cardiac or mediastinal evaluation. There is little experience with surgical removal, which should be possible.
Castleman disease is a poorly understood lymphoproliferative disorder. The disease was first described by Castleman and colleagues in 1956.139 It typically presents as a solitary lesion in the mediastinum. The most common histologic type is hyaline vascular, which accounts for approximately 90% of cases and often behaves in a benign fashion. The more aggressive subgroups are the plasma and mixed-cell types, which have a more malignant behavior.140 Patients may have a localized or multicentric disease with lymph node involvement, typically in the mediastinum. These tumors typically present as well-circumscribed masses. There have been reports of Castleman disease with myocardial and coronary artery invasion or development of a coronary pseudoaneurysm.141 In these more aggressive cases, cardiac assist devices have been used as a bridge to recovery141 (Figs. 62-16 and 62-17). CT imaging of the lesions reveals atypical or target-like enhancement that corresponds to various degrees of degeneration, necrosis, and fibrosis. Technetium-99m tetrofosmin and [I123] beta-methyliodophenyl pentadecanoic acid (BMIPP) imaging may aid in the diagnosis. On BMIPP, these tumors show reduced uptake compared with the surrounding normal myocardium.142 Complete surgical resection is considered curative.143
Castleman tumor showing fistula site indicated by insertion of a coronary probe.