In general, primary tumors of the heart are rare. In autopsy studies, the overall prevalence ranges from 0.002% to 0.33%, with about 75-79% of these considered benign.[1, 2]
Although most tumors of the heart are benign, because of their malignant potential, the risks secondary to impaired cardiac function (eg, congestive heart failure, inflow/outflow tract obstruction), conduction system involvement, and/or peripheral embolism mandate prompt evaluation and definitive treatment.
It has been reported that patients with benign cardiac tumors are at increased risk of first ischemic stroke, particularly patients younger than 50 years.[3]
The most common primary cardiac tumor is a myxoma.[4] Other less common neoplastic tissue types occur; each has distinguishing characteristics that often aid in accurate preoperative diagnosis or diagnosis prior to death. A definitive diagnosis is important because some cardiac tumors can be malignant or, more commonly, can represent metastasis from a distant primary tumor.
Myxomas arise usually from the endocardium and range in size from 1-20 cm. The vast majority (86%) develop from the left atrium, with the remainder developing from the right atrium.[5] They tend to develop from the fossa ovalis but can be found arising from anywhere in the atrium. Ventricular or valvular sites are rare.
Rhabdomyomas are intramural tumors that are typically smaller and most often involve the left (80%) or right (15%) ventricles.
Fibromas most commonly involve the intraventricular septum or left ventricular free wall. Less than 10% of reported cases have atrial or great vessel involvement. Unlike myxomas, tumor embolization is uncommon. Tumor growth can displace or directly involve mitral and aortic valves and result in hemodynamically significant valvular stenosis or regurgitation.
View Image
Benign Cardiac Tumors. Large epicardial cardiac lipoma.
Symptoms are typically secondary to adverse effects on normal left ventricular geometry, filling, and ejection. Additionally, arrhythmias, particularly sudden death and abnormal atrioventricular conduction, are common because of tumor disruption of the nodal or septal conduction tissue. Benign cardiac tumors can also present without symptoms as incidental findings found on cardiac studies investigating other pathology.
The precise etiology of benign cardiac tumors is unknown.
There may be a causal association with Gorlin syndrome, as follows:
Syndrome of multiple nevoid basal-cell carcinomas, cysts and fibrosarcomas of the jaws, and skeletal abnormalities
Multiple skin abnormalities, including milia, epidermoid cysts, chalazia, and comedones
Associated with medulloblastoma, meningioma, ovarian fibroma/fibrosarcoma, cardiac fibroma, fetal rhabdomyoma, and mesenteric lymphatic or chylous cysts
Carney complex is a syndrome of myxoma, endocrine hyperfunction, and areas of skin pigmentation. Myxomas associated with this complex have a high risk of recurrence following resection.
Benign cardiac tumors are extremely rare. Of all primary cardiac tumors, 75% are histologically benign.[6] Myxomas represent approximately 75% of benign tumors, while rhabdomyomas (5-10%) and fibromas (4-6%) occur less commonly.
Sex- and age-related demographics
No known sex predilection is recognized, although the rarity of the different benign cardiac tumors prevents accurate determination of a male-to-female ratio.
Myxomas are the most common tumors in adults. However, rhabdomyoma is the most common tumor in children (second most common benign cardiac tumor overall). Fibromas are rare and typically occur in children.
The prognosis is excellent, including disease-free survival, if the tumor is completely resected.[7] Incomplete resections predispose patients to further tumor growth and recurrence of symptoms; risk is undefined.
Although unproved, concern for recurrence, similar to that for fibromas found in other parts of the body, is warranted.
Systemic embolization is the most common causes of complications. It is typically a presenting symptom in 25-50% of cases. Embolization can occur to any end organ including the brain, lower extremities, kidneys, and heart (coronary artery) with subsequent ischemia and possible infarction. Cardiac tumor should be in the differential diagnosis when evaluating any cause of embolization. Rhabdomyomas often manifest early in life with inflow/outflow obstruction (ie, heart failure) or arrhythmia and resection is typically indicated.
Despite complete resection, patients are still at risk for sudden death due to damage to the conduction system.
The role of prophylactic antiarrhythmics or implanted cardioverter/defibrillators is undefined.
Any patient with an embolic complication or signs or symptoms of inflow or outflow obstruction (ie, left or right heart failure) should have an evaluation with cardiac tumor considered in the differential diagnosis.
Heart failure
Chamber obliteration by tumor involvement or abnormal myocardial function and arrhythmias is secondary to intramyocardial tumor growth.
Tumor growth can cause signs and symptoms of left ventricular outflow tract obstruction.
Diastolic murmurs might indicate impaired valve function due to tumor compression or growth.
Palpitations
Tumor involvement of the conduction system might cause palpitations or syncopal episodes.
Sudden death
Sudden death has been reported in as many as 33% of cases.
Syncope
Syncopal episodes might be related to associated arrhythmias.
Obtain blood cultures to evaluate the possibility of endocarditis.
On electrocardiography, nonspecific changes and/or left-axis deviation might occur. Repolarization abnormalities, similar to those found in persons with myocardial infarction or ischemia, are secondary to disruption of normal conduction patterns by electrically silent tumor or localized ischemia from tumor compression.
On chest radiographs, findings are often unremarkable. Enlargement of the cardiac silhouette or mediastinal widening might be present. Focal cardiac calcifications are often suggestive and can be characteristic of a fibroma, especially in children.
Echocardiography plays a fundamental role in the evaluation of patients with embolic complications, unexplained cardiac murmurs, or signs and symptoms of heart failure.[5]
Cardiac echocardiography represents the best diagnostic test for evaluating patients with history and/or physical examination findings suggestive of valvular dysfunction or the possibility of an intracardiac mass.[1, 4, 8] The ability to distinguish tissue characteristics, location, morphology, and mobility noninvasively, quickly, and without the use of ionizing radiation makes echocardiography the ideal diagnostic modality.
Equivocal transthoracic findings typically indicate the need for a transesophageal evaluation, during which the atria and great vessels might be better imaged.
Surgical intervention is often indicated based on echocardiographic findings, without the need for additional time-consuming, costly, or invasive studies.
Once a cardiac mass is identified, magnetic resonance imaging (MRI) can be extremely beneficial in determining the extent of tumor involvement and cellular characteristics.[1, 9, 10, 11]
T1- and T2-weighted images often provide valuable clues regarding tissue characterization; spin-echo image intensities can help differentiate cardiac tumors.
Although MRI cannot definitively distinguish between benign and malignant tumors, this imaging modality may help to identify characteristics more common in malignant cardiac masses, such as larger size and more frequent demonstration of contrast first-pass perfusion and late gadolinium enhancement compared to benign masses.[10] A tissue diagnosis is required in order to determine whether tumors are benign or malignant.
Cardiac MRI (CMRI) may also be highly accurate in differentiating cardiac thrombi from tumors.[10, 12]
Several small studies have suggested that MRI might be more sensitive and specific for primary cardiac tumors than echocardiography, but no large studies have demonstrated a benefit of MRI over echocardiography.
With equivocal echocardiographic findings, MRI might help differentiate an intracavitary tumor from a thrombus or hypertrophied papillary muscle.
Computed tomography (CT) scanning is often performed during an evaluation for a possible thoracic malignancy, and findings might suggest a primary cardiac tumor.[1, 13] CT scan findings might provide clues regarding tissue characterization, with central calcification suggestive of a cardiac fibroma.
However, even with advances in electrocardiographic (ECG) gating, cardiac CT scanning often offers little diagnostic value over a thorough echocardiographic evaluation.
In patients with known intracardiac masses, ventriculography is relatively contraindicated because of the significant risk of catheter-induced tumor embolization.
In patients who possibly are at high risk for concomitant coronary disease and are undergoing surgical treatment, simple coronary angiography might be necessary.
If a mass is found as an incidental finding during angiography, take strict care to minimize disruption of the mass to avoid causing a systemic embolic complication.
Ventriculography might demonstrate filling defects suggestive of an intracavitary mass.
Myxomas are similar to pluripotent germ cells with acid mucopolysaccharide matrix. The cells appear spindle or polygonal shaped.
Microscopically, fibromas are a light-gray, complex interlacing of dense collagen with occasional fibroblasts. Cardiac fibromas are similar to fibromas found in other soft tissue locations, except for the lack of a distinct capsule. Fibromas can contain myocardial fibers, but these are believed to reflect entrapment of myoblasts during tumor growth rather than tissue invasion. Overall, growth tends to displace myocardial tissue rather than invade or destroy it.
Medical management is not indicated unless symptoms are minimal, operative risks are prohibitive, or tumor size limits adequate resection. Thus, medications are not indicated for primary treatment.
Rhabdomyomas have a high tendency to regress, therefore close follow-up with a pediatric cardiologist is needed. Indications for resection are usually for severe intracavitary obstruction.
Complete surgical resection of benign masses typically is curative.[2, 14, 15] Note the following:
Expedited treatment is recommended because the risk for embolization is high in myxoma.[8, 16] The risk for lethal arrhythmias does not drive this decision.
Resection typically involves cardiopulmonary bypass with cardiac arrest.
Cardiac autotransplantation is also a feasible technique for resection of complex left-sided cardiac tumors.[17]
Cardiac transplantation has been reported in persons with large, unresectable tumors.[18, 19]
Fibromas should be resected, if possible, due to impedance of cardiac flow, ventricular contraction abnormalities, and conduction abnormalities. Also, lethal arrhythmias are a risk in cardiac fibroma; based on this, excision should be considered, even in asymptomatic patients. See the images below.
Benign Cardiac Tumors. Resected left atrial myxoma.
Ventricular tumors should be resected to preserve ventricular function, maintain valve function, and preserve as much of the conduction system as possible.
Conventional surgical treatment uses standard median sternotomy; however, right anterolateral minithoracotomy (RALT) recently has become an alternative method.[20, 21] Dong et al compared the outcomes of 66 patients undergoing RALT (n=30) with median sternotomy (n=36) for resection of left atrial myxoma. There were no significant differences in aortic cross-clamp and cardiopulmonary bypass time, the number of blood transfusions, or postoperative complications. The total incision length was significantly shorter in the RALT group resulting in a more favorable cosmetic outcome. The length of stay in both the ICU and hospital was shorter, resulting in a lower total cost of the RALT procedure.[21] Overall that RALT procedure outperformed the standard median sternotomy, although the number of patients in the study was small.
No restrictions on activity are necessary following elective resection (other than usual postoperative restrictions during the recovery phase).
Long-term follow-up with transthoracic echocardiography is needed in all patients after tumor resection.[8] Routine transthoracic echocardiographic evaluation is recommended every 2-5 years to evaluate for recurrence. According to American Heart Association guidelines, to minimize the risk of endocarditis, instruct the following patients to take prophylactic antibiotics:
Patients with residual postoperative valvular dysfunction
Patients with implanted prosthetic valves or artificial materials (used to repair postresection myocardial defects)
Dale K Mueller, MD, Cardiovascular and Thoracic Surgeon, Cardiothoracic and Vascular Surgical Associates
Disclosure: Nothing to disclose.
Specialty Editors
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
Steven J Compton, MD, FACC, FACP, FHRS, Director of Cardiac Electrophysiology, Alaska Heart Institute, Providence and Alaska Regional Hospitals
Disclosure: Nothing to disclose.
Chief Editor
Karlheinz Peter, MD, PhD, Professor of Medicine, Monash University; Head of Centre of Thrombosis and Myocardial Infarction, Head of Division of Atherothrombosis and Vascular Biology, Associate Director, Baker Heart Research Institute; Interventional Cardiologist, The Alfred Hospital, Australia
Disclosure: Nothing to disclose.
Additional Contributors
Russell F Kelly, MD, Assistant Professor, Department of Internal Medicine, Rush Medical College; Chairman of Adult Cardiology and Director of the Fellowship Program, Cook County Hospital
Disclosure: Nothing to disclose.
Acknowledgements
The authors and editors of Medscape Drugs & Diseases gratefully acknowledge the contributions of previous authors Michael S Firstenberg, MD, and James D Thomas, MD, to the development and writing of this article.
){kind=link}
){kind=link}
){kind=link}