Abbreviation: LA= Left atrium, MS= Mitral stenosis , AR= Aortic regurgitation, MR= Mitral regurgitation, PASP= Pulmonary artery systolic pressure, AF= Atrial fibrillation, TEE= Transesophageal echocardiography OPD= out patients department.

Introduction

Nearly every fifth MS patient presents with thrombus in the LA. Most thrombi are located in the LA appendage, but atrial appendage thrombus can also extend to the LA cavity (¹). LA thrombus without mitral disease is rare (²). The diagnosis of a LA thrombus should be regarded as an urgent indication for preventive surgery (³). TEE is the easiest way to detect LA thrombus when located ^{in the LA appendage and should be carried out before percutaneous mitral valvuloplasty or surgery (4). The differential diagnosis of clots and myxomas in the LA is mostly based on echocardiography (5). Infection of intracardiac thrombi is extremely rare and is generally reported in ventricular clots or aneurysms following myocardial infarction (5). Mitral valve replacement is the only treatment for severe degenerated calcified valve with organised thrombus.}

Case Presentation

A 35 year- old woman presented with complains of fever, shortness ^{of breath, palpitation and facial puffiness. She had longstanding MS and AF and was classified as NYHA-III. She never had any episode of embolism or syncope and was not on any oral anticoagulants. Her ECG showed an AF rhythm, Echocardiography revealed dilated LA with a large thrombus (Figure-1), PASP of 95mmHg, severe MS (Figure-2), mild MR, mild AR and an ejection fraction of 55%. Laboratory data was normal except for leukocytosis (28000/mm3) and elevated erythrocyte sedimentation rate of 52mm/1h. Chest x-ray revealed cardiomegaly with dilated LA.}

Figure 1

Figure -1 Transthoracic echocardiogram showing a large thrombus in the LA cavity with dilated LA.

Broad-spectrum antibiotics were started due to high suspicion of sepsis and blood cultures were done which showed the presence of E. coli. An urgent operation (open heart surgery) with mitral valve replacement was performed general anesthesia.

Figure 2

Figure -2 Thickened and calcified mitral valve with severe MS (valve area of 0.7 cm).

Preoperatively right radial artery was cannulated and fixed. A triple lumen central venous line was inserted into the right internal jugular vein. Other basic monitoring was done and

General anesthesia was given. Following median sternotomy, pericardium was open longitudinally. After heparinisation, extra-corporeal circulation was established between superior vena cava and ascending aorta.

Figure 3

Figure -3 Thrombus in the LA cavity.

Cross clamp was placed on aorta, antegrade cold blood cardioplegia given via aortic root, heart arrested cooled to 30⁰C. Standard left atriotomy was made, immediately after opening LA a large red color mass popped out through the incision (Figure3).

Figure 4

Figure -4 Manual removal of thrombus from LA

On examination the thrombus was found to be organized, occupying the whole LA and LA appendix. Thrombus was removed in toto and there was foul smell from LA and thrombus. (Figure-4-5)

Figure 5

Figure -5 Showing clean LA appendix after removal of thrombus.

On inspection, Mitral valve was found to be grossly deformed and commissures were fused with evidence of severe MS. There was fish mouth narrowing mitral valve orifice with gross sub valvular deformity.

Figure 6

Figure -6 Size of thrombus outside the cardiac cavity.

Mitral valve was replace with prosthetic valve after preserving the chordea and LA appendix was ligated externally.

The patient had an uneventful recovery. She required inotropic support during weaning from cardiopulmonary bypass and early postoperative period. Her postoperative trans-thoracic echocardiogram showed good ventricular contractility with no residual thrombus in the left atrium.

Figure 7

Figure -7 Weight of removed thrombus is 200gram.

There was dramatic improvement in the clinical status of patient in post operative period. Fever subsided, blood culture became sterile, PASP reduced to 50mmHg and she was reclassified as NYHA-I. She was discharge on 15^th post operative day. Two OPD follow-ups showed absolutely normal cardiac function.

Discussion

Infection of intracardiac thrombus is very rare, with only 10 previously reported cases associated with myocardial infarction. (^7–16). Thrombus is generally hypovascular tissue, so ingress of antibiotics and immune system antibodies via vasculature is thought to be poor. Thus, prompt surgical resection of the infected thrombus should be performed, followed by prolonged administration of antibiotics. (⁶) Anticoagulant therapy in patients with mitral valve disease and atrial fibrillation should be applied according to the currently available guidelines and standards in order to avoid analogous paradigms in the future. (⁵) Mitral valvesubstitution should be considered in patients with mitral valve disease presenting with thromboembolic complications.

Surgery should be considered as the treatment of choice in cases of organized left atrial thrombus and suspected tumor or infected mass. (⁵) Infection of cardiac mural thrombus has a high mortality because of the difficulty of diagnosis. The patients in 6 of the previously reported 10 cases died without accurate diagnosis of the infected thrombus. (^{7–10, 12, 15})

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 (¹⁷). It gradually enlarges and forms projecting mass that remains attached to the atrial wall by a pedicle (¹⁸).During thrombus development and subsequent morphologic changes, it is very likely that the patient may experience transient embolisms or strokes(¹⁸,¹⁹). Distal embolization subsequent to fragmentation is believed to be the cause of cerebrovascular accident or potential loss of a limb (¹⁷, ²⁰).

In conclusion, we present here the case describing an infected arial thrombus with mitral disease treated successfully with surgical resection. To the best of our knowledge this is the third report of an infected LA thrombus which was successfully removed followed by mitral valve replacement.