A case of returning left atrial free-floating thrombus in a patient with mitral prosthesis and multiple emboli is described.

A case of returning left atrial free-floating thrombus in a patient with mitral prosthesis and multiple emboli is described. Transthoracic echocardiography failed to point out to the first ball thrombus, whereas transesophageal echocardiography prov highly useful the one and the other in diagnosis and in indicating the left atrial appendage as the source of the thrombi. (Chest 1994; 106:303-04)

Left atrial free-floating thrombus is rare and may cause fatal systemic emboli or mitral valve orifice occlusion, ofttimes resulting in sudden death.(1) Thus, early diagnosis is paramount and common evidence points to prompt surgical removal of the thrombus as the therapy of choice in the majority of cases.(2) We describe the first case reported in the literature, to our knowledge, of recurring free-floating thrombus in the left atrium.

CASE REPORT

A 51-year-old woman who had a Starr-Edwards prosthesis placed in the mitral position 13 years previously was admitted to the hospital because of chest pain of 20 min duration. She had long-standing atrial fibrillation and had been maintained in succession a regimen of adequate anticoagulation. She had stomached two transient cerebral ischemic attacks 9 and 2 years earlier, respectively.

Physical examination disclosed normal prosthetic hardy with no anomalies. An ECG revealed 1-mm ST portion depression in leads II, III, and AVF, and atrial fibrillation with an average ventricular rate of 100 beats/min. Catheterization showed no prosthesis dysfunction or coronary disease, and the ejection fraction was 49 percent

Two-dimensional echocardiogram revealed dilation of the left atrium (81 mm) with no prosthesis dysfunction; left atrial thrombus was not finded Transesophageal echocardiogram disclosed the existence of a 29X22-mm free-floating thrombus in the left atrium (Fig 1) that had not been ascertained on transthoracic echocardiogram. The thrombus occasionally quiescenceed on the surface of the prosthesis, being then propell backwards into the left atrium by means of closure of the prosthesis. Spontaneous contrast was observ in the left atrial appendage. Immediate surgery was performed, and a smooth-surfaced left atrial 27X22-mm free-floating thrombus was remov The Starr mitral prosthesis was replaced according to a Bjork-Sorin mitral prosthesis.

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The postoperative period was normal. Eight days postsurgery a transesophageal echocardiographic contemplation was performed and showed normal prosthesis function and the appearance of a thrombus inside the left atrial appendage (Fig 2); no released thrombus was seen in the left atrium. Three month postsurgery the patient was asymptomatic and receiving adequate anticoagulant treatment. Transesophageal contemplation was performed and revealed a renewed floating thrombus moving freely around the left atrium, and no thrombi were observ in the left atrial appendage. Surgery was performed to displace the thrombus from the left atrium, and this thrombus was construct to have the same dimensions and features as the former. The left appendage, exempt of thrombi, was closed along since it was suspected of being the source of the free-floating thrombus. Transesophageal echocardiogram was repeated at 6 and 18 month after the other operation and no thrombi were observ in the left atrium upon either occasion.

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DISCUSSION

The current case is remarkable for the following reasons. First, the diagnosis could be established barely by transesophageal echocardiography. Although the greater value of transesophageal compared with transthoracic echocardiography has been established for several exemplars of cardiac masses, this superiority had not been documented for free-floating thrombus in the left atrium. Since the released thrombus is of low density and prevail upons in a circular fashion,(3) it is more easily detectable by the agency of this technique. Second, to our knowledge, this is the first reported case of intermittent free-floating thrombus formation after surgery for removal of the initial ball thrombus.

Free-floating thrombi are idea to originate as mural thrombi, usually forward the interatrial septum but rarely in the left atrial appendage.(4)(5) However, it is public practice to ligate left atrial appendage routinely during mitral surgery when atrial thrombosis is build In fact, the rationale for of that kind practice is well illustrated in the quick in emergencies case, where ligation had not been done upon the first procedure. Observation of the left appendage thrombus through transesophageal echocardiography following first surgery and the succeeding finding of a thrombus-free left appendage and a floating ball thrombus in the left atrium during the following reflection suggested that this thrombus had originated in the left appendage. Transesophageal echocardiography was essential to display this previously undocumented sequence of marked occurrences which allows us to hypothesize as to mechanism of recurrence

ACKNOWLEDGEMENT: We are indebted to G Permanyer-Miralda and C O'Hara for careful and critical review of the manuscript.

REFERENCES

(1)Wrisley D Giambartolomei A, lee-side I, Brownlee W. Left atrial ball thrombus: review of clinical and echocardiographic manifestations with suggestions for management. Am Heart J 1991; 121:1784-90

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