Ann Thorac Surg 2008;85:313-315. doi:10.1016/j.athoracsur.2007.07.084
© 2008 The Society of Thoracic Surgeons
Case Reports
Giant Left Atrial Ball Thrombus in a Patient With Chronic Nonvalvular Atrial Fibrillation
Jae Hoon Lee, MDa,
Shin Kwang Kang, MDd,
Cheol Whan Lee, MDb,
Jae Kwan Song, MDb,
Jung Sik Park, MDc,
Suk Jung Choo, MDa,*
a Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
b Department of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
c Department of Nephrology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
d Department of Thoracic and Cardiovascular Surgery, College of Medicine, Chungnam National University, Daejeon, Korea
Accepted for publication July 24, 2007.
* Address correspondence to Dr Choo, Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, Ulsan University School of Medicine, 388-1 Poongnap-dong Songpa-gu, Seoul, 138-736, Korea (Email: sjchoo{at}amc.seoul.kr).
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Abstract
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A 56-year-old woman with chronic nonvalvular atrial fibrillation presented with cardiac arrest during magnetic resonance imaging for back pain evaluation. Brain magnetic resonance imaging performed after cardiopulmonary resuscitation revealed multiple embolic lesions. Transesophageal echocardiography showed a large free floating thrombus ball and multiple mural thrombi in the left atrium. In light of the high-risk situation, an emergency operation was performed despite the occurrence of a fresh stroke within the previous 24 hours. The surgery was successful and the postoperative course was uneventful. The patient has been doing well since the operation on outpatient follow-up for 8 months.
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Introduction
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Most cases of left atrial thrombus ball in the literature have been reported in association with atrial fibrillation and mitral stenosis [1]. The absence of any large scale clinical analysis with only sparse case reports in the literature seems to suggest an infrequent occurrence of this condition. Nevertheless, when this is present, its importance can not be undermined as it has the potential to be fatal secondary to acute mitral valve orifice occlusion [2]. Distal embolization subsequent to fragmentation is believed to be the cause of cerebrovascular accident or potential loss of a limb [3, 4]. However, in this reported case the absence of any surface disruption in the thrombus ball seemed to suggest the distal embolization to be caused by detachment of concomitant mural thrombi. Regardless of mechanism, the diagnosis of a left atrial thrombus ball should be regarded as an urgent indication for preventive surgery.
A 56-year-old woman with chronic nonvalvular atrial fibrillation presented with cardiac arrest while undergoing magnetic resonance imaging for evaluation of back pain. Cardiac function and alert mental status were promptly restored after cardiopulmonary resuscitation, but a new acute stroke evidenced by a previously absent left-sided motor weakness was noted. Immediate brain magnetic resonance imaging and a computed tomographic scan showed multiple acute embolic infarctions in the cerebellum, left thalamus, and both occipital lobes. A subsequent transesophageal echocardiography revealed a large free-floating bouncing mass approximating 4 cm in diameter in the left atrium. The mass was noted to cause left ventricular inlet obstruction due to more than half of the mass being intermittently wedged in the mitral valve orifice (Fig 1). In addition, multiple smaller mural thrombi were detected in the left atrial appendage and adjacent wall. Given the freely mobile nature of the thrombus, its persistent obstructive hemodynamic interactions with the left atrial orifice, and the potential for an acute catastrophic event, a decision to carry out an emergency operation was made irrespective of the onset of stroke within the previous 24 hours.
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Fig 1. (A) Preoperative transesophageal echocardiography showing a huge mobile mass in the left atrium and multiple smaller mural thrombi (arrow) in the left atrial appendage. (B) The free floating mass is shown obstructing the mitral inlet and protruding into the left ventricular cavity.
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Review of the past medical records showed the patient having received only aspirin during the past 5 years for prophylactic anticoagulation of atrial fibrillation. A hemorrhagic stroke was also diagnosed at the time of initiating long-term anticoagulation therapy, along with an additional diagnosis of nonoliguric immunoglobulin A nephropathy.
An incision through the Sondegaard’s groove revealed a large, well-demarcated spherical thrombus ball lying in the left atrium. This and a few other smaller organized thrombi in and around the left atrial appendage were carefully removed (Fig 2). A moderately thickened layer of well-organized fibrin variably covering the appendage and the adjacent left atrial surface was also gently "peeled off." The left atrial appendage was then internally obliterated with a 4-0 polypropylene suture. The mitral valve was morphologically normal in appearance with no detectable valve dysfunction on a saline infusion test. After a final examination of the left atrium, surgery was concluded and the patient was taken off cardiopulmonary bypass.
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Fig 2. (A) Intraoperative photograph showing the left atrial mass to be a huge thrombus ball. (B) Shown alongside the larger mass are multiple smaller mural thrombi that were removed from the left atrial wall and appendage.
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The patient was weaned from mechanical ventilation on postoperative day 4 and was discharged on postoperative day 24 after a prolonged course of rehabilitative therapy for residual stroke symptoms. There was no postoperative occurrence of a new stroke or aggravation of the pre-existing stroke. Pathologic examination revealed the mass to be pure thrombus. The patient was followed-up at the outpatient clinic for 8 months on an oral anticoagulation regimen of aspirin and warfarin and has since been doing well with symptomatic improvement of the stroke.
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Comment
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Since the introduction of the terminology of "ball thrombus" by Wood in 1814 to describe the autopsy findings of a 15-year-old girl with rheumatic mitral stenosis and syncope, several cases of this rare condition have been reported in the literature [5, 6]. Most of these were associated with mitral valve disease (ie, usually mitral stenosis and atrial fibrillation). Left atrial ball thrombus in the absence of mitral valve disease has been reported even less frequently with most of the patients having been described as not being adequately anticoagulated for their atrial fibrillation [6, 7]. The patient in the current case had only received aspirin for anticoagulation. According to the guidelines of the Seventh American College of Chest Physicians Conference on antithrombotic therapy in atrial fibrillation, treatment with warfarin should have been instituted, especially in light of the 15-year history of hypertension comprising an increased risk of thromboembolism [7]. However, the treatment for this patient was confounded by the occurrence of cerebral hemorrhage and consequent reluctance to pursue aggressive anticoagulation with warfarin at the time of initiating long-term anticoagulation. As a result the patient was treated with aspirin only and regular outpatient follow-up.
Although it may not be possible to know the precise mechanism by which the thrombus ball was formed, it is reasonable to assume an origin from a smaller mural thrombus created secondary to chronic blood stagnation. The mass may have then gradually grown until becoming detached under its own weight. Its round and smoothened surface is probably attributed to the sculpting effect of the numerous multifaceted collisions with the atrial wall.
A description of clinical presentations in the literature varies from thromboembolism to those attributed to hemodynamic instability, such as syncope, pulmonary congestion, and sudden death, most likely due to left ventricular inlet obstruction [2, 5, 6]. In the present case, clinical manifestations included thromboembolic complications and hemodynamic instability, such as motor weakness, loss of consciousness, ventricular fibrillation, pulmonary hypertension, and congestion. Brain magnetic resonance imaging and computerized tomography showed multiple acute infarctions secondary to particulate thromboembolism. The sudden obstructive nature of the freely mobile thrombus ball interacting with the normal mitral leaflet and subvalvular apparatus may have resulted in a hemodynamic strain equivalent to severe acute uncompensated mitral stenosis. There were no arguments regarding the futility of further anticoagulation or thrombolytic therapy. Emergency surgery was considered the best treatment option at the time, but the prospect of performing cardiopulmonary bypass in the presence of a fresh stroke, as in this case, was cause for concern due to the risk of possible hemorrhagic infarction or infarct expansion due to clot lysis and reperfusion injury. Notwithstanding, the overwhelming risk of an invariably fatal embolism by the thrombus ball left little choice but to proceed with emergency surgery. Atrial fibrillation, the single most important underlying factor responsible for the current woes of this patient may have been effectively treated by the maze procedure. However, the surgery was performed under an emergency situation after a freshly occurring stroke and recent cardiac arrest with acute cardiac decompensation evidenced by new onset pulmonary hypertension, pulmonary edema, and cardiac dysfunction. Under the circumstances, all considerations weighed in favor of a bare essentials approach to minimize cardiopulmonary bypass and ischemic time. Furthermore, the thrombotic materials were removed in their entirety and the left atrial appendage was internally obliterated in an effort to lesson the possibility of a future recurrence as much as possible.
Aspirin alone and regular echocardiographic follow-up has been shown to be inadequate as an effective long-term anticoagulation strategy. In cases such as this, in which full anticoagulation with warfarin is either contraindicated or believed to be in the best interest of the patient to withhold for whatever reasons, the maze procedure should be considered as a first-line therapeutic option, even in the absence of a definite mitral pathology. Furthermore, with increasing availability of ever ingenious and safer surgical options to manage atrial fibrillation, a more aggressive approach to the treatment of atrial fibrillation is all the more warranted to reduce the risks of long-term complications and death.
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References
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- Lie TJ, Entman ML. "Hole-in-one" sudden death: mitral stenosis and left atrial ball thrombus Am Heart J 1976;91:798-804.[Medline]
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- Wrisley D, Lee I, Parker F, Brownlee W, Ismail M. Recurrent systemic embolization from left atrial ball thrombus: the case of early surgical intervention NY State J Med 1990;9:74-75.
- Yoshida K, Fujii G, Suzuki S, Shimomura T, Miyahara K, Matsuura A. A report of a surgical case of left atrial free floating ball thrombus in the absence of mitral valve disease Ann Thorac Cardiovasc Surg 2002;8:316-318.[Medline]
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- Singer DE, Albers GW, Dalen JE, Go AS, Halperin JL, Manning WJ. Antithrombotic therapy in atrial fibrillation: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy Chest 2004;126(Suppl 3):429S-456S.[Medline]
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Abstract
Introduction
