The Intraoperative Diagnosis of Atrial Myxoma by Transesophageal Echocardiogram

Although pathologically benign, cardiac myxomas often have serious clinical manifestations and consequences. Certain physical findings and details from a patient's history may lead the clinician to consider this entity which is often discovered after an embolic event and may be characterized by obstruction to intracardiac blood flow and various constitutional symptoms 1,2. We present a case in which the diagnosis of an atrial myxoma (AM) was made by intraoperative transesophageal echocardiography (TEE) in a patient undergoing emergent embolectomy of the left common femoral artery. The timely discovery of an AM in this patient was significant, for it prevented further delay in diagnosis and expedited definitive therapy. Case Report A 37-yr-old female was scheduled for emergent embolectomy of the left common femoral artery. Her history was remarkable for 2 wk of malaise and low-grade fever followed by the sudden onset of right-sided weakness. This weakness was accompanied by an expressive and receptive aphasia. The patient's evaluation at the time of operation included a physical examination remarkable only for the neurologic deficits previously mentioned. Examination of the heart revealed a regular rate and rhythm. No murmurs or gallops were detected. Likewise, the electrocardiogram was unremarkable. Computed tomography of the head was normal as was her spinal fluid analysis. A magnetic resonance image of the head showed signal changes consistent with an ischemic stroke in the distribution of the left middle cerebral artery. The patient was placed on systemic anticoagulants and, while awaiting further evaluation, experienced a cold and pulseless left lower extremity. She was taken to the operating room for emergent femoral artery exploration and possible embolectomy. General endotracheal anesthesia was considered more appropriate than a regional technique because of ongoing anticoagulation and because it was difficult to communicate with the patient. The patient's history and recent clinical course were highly suggestive of a possible central circulatory embolic source and intraoperative examination of the patient with the TEE was planned to rule out any intracardiac pathology. After induction of general anesthesia, an Omniplane 2-dimensional TEE probe (Model 21364A; Hewlett Packard, Andover, MA) was placed without difficulty. An initial four-chamber view of the heart revealed a large pedunculated mass near the annulus of the mitral valve Figure 1 which prolapsed into the left ventricle during diastole and was projected back into the left atrium during systole. Although the standard four-chamber view of the heart failed to provide a clear image of the pedicle attachment site, subsequent views with the imaging plane rotated to approximately 120 degrees clearly demonstrated attachment of the myxoma pedicle immediately superior to the annulus of the mitral valve Figure 2. After initial inspection of the mass, the remaining cardiac chambers and left atrial appendage were examined and noted to be free of mass or thrombus. The atrial septum was examined using color flow and was functionally intact.Figure 1: A four-chamber view of the heart, demonstrating the atrial myxoma (AM) prolapsed into the left ventricle during diastole. AS = atrial septum; AL/PL = anterior and posterior leaflets of the mitral valve.Figure 2: A long-axis view of the left ventricle, illustrating the stalk and attachment site of the myxoma immediately superior to the mitral valve annulus. AM = atrial myxoma; AA = ascending aorta; AL/PL = anterior and posterior leaflets of the mitral valve.A left femoral embolectomy was performed while a cardiologist, cardiac surgeons, and family members were consulted. After consultation, all parties agreed it was best to proceed directly to cardiopulmonary bypass and avoid further delay in treatment. At operation, a myxoma was removed from the left atrium without incident. The atrial septum was noted to be intact, and no valvular abnormalities or additional masses were present. Separation from cardiopulmonary bypass was uneventful as was the postoperative recovery. The patient was discharged from the hospital to her home on the sixth postoperative day. By that time she had experienced significant recovery with improvement of her paresis and abatement of her aphasia. Discussion The sudden onset of a large and potentially devastating stroke in this patient is characteristic of an embolic event 3. Subsequent occlusion of her common femoral artery accentuated the need for rapid identification of the source. Although transthoracic echocardiography (TTE) can be used for diagnosis in this setting, the availability of intraoperative TEE allowed prompt diagnosis of an AM without delay or further risks associated with the hemodynamic fluctuations which can occur during emergence from general endotracheal anesthesia. Several large series indicate that cardiogenic embolism is responsible for approximately 15% of ischemic strokes 4-6. Atrial fibrillation, ischemic heart disease, prosthetic valves, and rheumatic heart disease comprise 90% of all sources 3, with other less common findings, such as mitral valve prolapse, paradoxical embolism, endocarditis, and cardiac myxoma making up the remaining 10%. The age of this patient and her previous good health made several of the more common embolic sources unlikely, and pointed toward more obscure etiologies. Constitutional symptoms and signs, including fever, malaise, weight loss, and fatigue, are present in up to 90% of patients with myxomas 2,7 and also indicated the diagnosis in this patient. Primary cardiac tumors are rare, being detected in only 0.03%-0.05% of patients at autopsy 8. Myxomas constitute approximately 90% of tumors removed from the left atrium and thus Figure highlyin the differential diagnosis when a mass is detected in that location 9. Although found primarily in the left atrium, 25% of myxomas occur in the right atrium or ventricles 10. Most patients with myxomas are between 30 and 60 yr of age 11; however, the disease has been reported in individuals as young as 13 yr and as old as 80 yr 9. Most series show myxomas to be approximately twice as common in females 2,7. The triad of clinical manifestations characteristic of AM reported by Goodwin 1 includes embolization, obstruction of blood flow, and constitutional symptoms. An embolic event is the presenting symptom in 17% to 59% of patients with AM and up to 45% of these patients will sustain cerebral infarcts 2,7,10. Cerebral emboli commonly involve the middle cerebral artery, as was the case in our patient 3,7. Obstruction to blood flow, manifested by heart failure or syncope, is a common symptom occurring in 41%-79% of patients 2,7,10. Physiologically, a myxoma obstructing the left ventricular inflow tract may mimic mitral stenosis. Right-sided lesions have likewise been associated with obstruction, and have presented as cardiovascular collapse during induction of anesthesia 12. Despite many clinical reports of symptoms suggestive of blood flow obstruction, one study using Doppler ultrasound demonstrated significant pressure gradients in only one of seven patients with known left AM 13. These authors suggested that paroxysmal congestive heart failure reported in some patients may be related to the position of the patient or the degree of protrusion of the tumor inside the left ventricle. As in mitral stenosis, heart rate may also have a significant effect on the transvalvular pressure gradient in this patient population. The vast majority of patients with cardiac myxomas will have constitutional symptoms or signs, including fever, malaise, weight loss, increased erythrocyte sedimentation rate, and anemia 2,7. These resolve soon after resection of the mass and are thought to be caused by inflammatory cytokines released from tumor cells 13. The diagnosis of AM indicates the need for immediate surgical intervention to prevent death or significant morbidity resulting from new or additional tumor embolism. The perioperative mortality was zero in two recent series 2,10 with surgical removal being almost uniformly curative 14. Long-term complications or recurrences are less than 2% in most series 7,9,15. TEE, although not proven to be superior to TTE in detection of AM does offer increased resolution, and is superior to TTE for detection of other left-sided embolic foci in the atrium or atrial appendage 16. The enhanced resolution of TEE may help distinguish AM, which typically attach to the atrial septum from thrombi which are more commonly attached to the atrial appendage. Additionally, TEE does not invade the operative field and can be used successfully in patients with suboptimal anatomic windows in transthoracic studies. This case illustrates the ability of intraoperative TEE to function not only as a cardiovascular monitor but to significantly impact diagnosis, therapy, and patient outcome.