Calcified amorphous tumor of mitral annulus treated by simple aspiration

Abstract

A 49-year-old woman on hemodialysis was diagnosed with severe aortic stenosis and a growing calcified amorphous tumor in the mitral annulus. Because of the anatomical location, we did not resect the whole tumor, while aortic valve replacement was performed instead aspirated the tumor deposit. However, 3 weeks later, a mobile mass attached to the atrial wall was found with echocardiography. We removed the mass and folded the wall of the tumor inside to prevent calcified amorphous tumor recurrence.

Introduction

Calcified amorphous tumor (CAT) is a non-neoplastic cardiac mass composed of calcification on a background of amorphous fibrous material. CAT was first described in 1997 by Reynolds et al. ¹ Despite the scarcity of case reports, most have insisted on the importance of complete excision of the tumor. In this case report, we describe the treatment of cardiac tumor by simple aspiration of its contents.

Case report

A 49-year-old woman was diagnosed with progressive aortic stenosis and mitral annulus calcification. She was on hemodialysis since 6 years because of end-stage chronic kidney disease following pregnancy-induced hypertension. During a year of following the patient by echocardiography, a high echoic mass in the posterior side of the mitral valve annulus was observed to rapidly grow up to a size of 25 × 27 mm² (Figure 1). The mass was diagnosed as CAT by computer tomography and magnetic resonance imaging. The CAT was identified to neighboring the left circumflex artery (LCX) and epicardium of posterior wall of left ventricle. The mitral valve had mild regurgitation, and its valve area was 1.52 cm² measured by a cardiac catheter. Concurrently, the aortic valve area was 0.60 cm² and surgical replacement was required. Laboratory assays did not reveal any elevated inflammatory markers. She had no history of malignancy or rheumatic disorder.

Figure 1.

Echocardiography showing a high echoic mass in the mitral valve annulus.

Elective surgery of aortic valve replacement and aspiration of CAT was performed. First, the aortic valve was removed, and the annulus was decalcified using The Cavitron Ultrasonic Surgical Aspirator (CUSA). We then checked the mitral valve via conventional left atriotomy. Mobility of the posterior leaflet was slightly limited by annulus calcification; however, the valve opening was sufficiently spared and regurgitation was not detected intraoperatively. Thus, the mitral valve was saved untouched. We made a small slit on the tumor wall in left atrium and carefully aspirated its paste-like content by a sucker device (Figure 2). After flushing the empty space with saline, we closed the slit using a continuous suture of 4-0 polypropylene. We completed the aortic valve replacement using an On-X Aortic Valve 19-mm (On-X Life Technologies, Austin, TX, USA). Aortic clamping time was 113 minutes, cardiopulmonary bypass time was 144 minutes, and operative time was 255 minutes.

Figure 2.

Paste-like content* coming out through the slit by compressing the mitral valve annulus.

Histological examination revealed that the paste-like content of the tumor was eosinophilic homogenous calcification, with the tumor wall comprising collagenous fibrous tissues and inflammatory cells (Figure 3). These findings firmly supported the diagnosis of CAT.

Figure 3.

(a) The tumor wall consists of collagenous fibrous tissues and inflammatory cells. (b)The content of the tumor is eosinophilic granular calcification without cells.

Three weeks following the first operation, a swinging mass in the left atrium was found by echocardiography. An urgent second operation was performed to prevent secondary embolism. Resternotomy was done successfully, and we chose the transseptal approach this time. To prevent reoccurrence, we made an inverting suture to fold the intima of the tumor inside and then dragged the wall of the left atrial appendage to cover the suture line. Aortic clamping time was 62 minutes, cardiopulmonary bypass time was 132 minutes, and operative time was 267 minutes.

The postoperative echocardiography showed the mitral valve area was 2.72 cm², pressure gradient was 15.8 mmHg and mild regurgitation was unchanged. The prosthetic valve in the aortic position had no paravalvular leakage and was 1.63 cm² in area. The patient was discharged on 16th days after second operation without complication. Since 1 year from the last operation, the patient is alive and well, with no evidence of the recurrence of the tumor or progression of mitral valve disease.

Discussion

CATs are rare non-neoplastic cardiac masses composed of amorphous calcified material. When they are reported, they are often found within mitral annular calcifications, particularly in patients who are on long-term hemodialysis.^2,3 On echocardiography, images of CAT appear like other cardiac lesions, such as fibroelastoma, myxoma, or marantic vegetation. ⁴

Treatment of CAT requires complete surgical excision. In this case, the tumor was neighboring the epicardium of the left ventricle and the LCX. Complete excision of the tumor requires following repair of the left ventricular wall and a bypass grafting to the distal part of the LCX. Those procedures have a risk of the left ventricular rupture and severe myocardial ischemia. Cardiac CAT might recur after incomplete resection; therefore, careful follow-up with cardiac echography or other imaging studies is required. ⁵

Here, we reported a case of a cardiac tumor found in patients undergoing hemodialysis. If the growing calcified tumor is found in the left side of the heart, complete surgical excision should be immediately considered to prevent stroke or other systemic embolism. However, simple aspiration might be an alternative treatment in cases where the anatomical location of the tumor is suitable.