Male patient, 70 years of age, white, agricultural worker, with no remarkable pathological history. He presented with fever, vomiting and dehydration, interpreted as bacterial bronchopneumonia, for which he was treated with antimicrobials. Two weeks later, he complained of general malaise, malaise and dizziness. He was re-evaluated and a second-degree atrioventricular block was detected, so the heart rate was regulated with a transient pacemaker (PM), to later implant the permanent generator. The referred symptoms worsened and dyspnoea appeared. A transthoracic echocardiographic (TTE) study detected an intracardiac mass and he was referred to our centre. Physical examination revealed a diminished vesicular murmur towards the lung bases, with wheezing, and a diastolic murmur towards the tip that appeared to change with changes in the patient's position. The baseline electrocardiogram showed a rhythm of MP to 80 beats per minute, and the chest X-ray showed a small left pleural effusion with pulmonary oedema. There was anaemia and mild leukocytosis with a predominance of polymorphonuclear cells. Transesophageal echocardiography (TEE) showed the tumour mass attached to the anterior mitral leaflet on its atrial side, which prolapsed into the left ventricle (LV) in diastole, producing a peak transvalvular mitral diastolic gradient of 20 mmHg, and a mean of 10 mmHg, with a left ventricular ejection fraction (LVEF) of 60.5%. Coronary angiography showed no significant coronary lesions, and the patient was prepared for urgent surgery.

In the operating theatre, after longitudinal median sternotomy, arterial and venous cannulation for extracorporeal circulation (ECC), right atriotomy, aortic clamping and anoxic arrest with isothermal haematic cardioplegia, the interatrial septum (AIS) was opened with extension to the roof of the left atrium (LA). This exposed a yellowish-brown oval tumour mass, approximately 8 cm in diameter, with an implantation base extending into the mitral annulus involving its anterior leaflet and causing loss of mitral annulus integrity. The tumour was completely resected next to the mitral leaflet and a Sorin/Carbomedics Standard 25 mm bi-disc mechanical prosthesis was implanted. The procedure was completed in a conventional manner, without difficulties, using 87 minutes of aortic clamping and 120 minutes of cardiopulmonary bypass. He was extubated 2 hours after arrival at the Surgical Intensive Care Unit, transferred to the conventional ward on the second day, and discharged on the sixth postoperative day. At three months follow-up the patient was asymptomatic, in sinus rhythm (inhibited PM) and TTE showed a left LA free of tumour masses, a normofunctioning mechanical prosthesis, with a transvalvular gradient of 12 mmHg and LVEF of 58%.
