Left atrial dissection after a supra-annular mitral valve replacement for endocarditis

We report the case of a 66-year-old female patient suffering from acute heart failure due to severe aortic and mitral stenosis. She underwent a combined mitral and aortic valve replacement with bioprosthetic valves (respectively 29-mm Epic St Jude Medical and 21-mm Trifecta GT St Jude Medical) on October 7th, 2021 and was discharged after a 10-day hospitalization.

4 weeks later, she was admitted to hospital for asthenia and fever. A paroxystic third-degree atrioventricular block was diagnosed on the electrocardiogram and blood cultures were positive to Enterococcus faecalis. Transthoracic echocardiography (TTE) confirmed the presence of a double supracentimetric endocarditis on the two prosthetic valves with an aortic root abscess. CT-scan did not find any sign of septic embolism. She received an antibiotherapy with Ceftriaxone and Amoxicillin.

The patient underwent a replacement of the aortic and mitral prosthetic valves and the implantation of a leadless pacemaker on November, 07th 2021.

Surgical examination confirmed the diagnosis of large vegetations of the two prosthetic valves and a massive destruction of the mitral annulus. The two prosthetic valves were replaced. A 21-mm Edwards Magna Ease valve was placed in aortic position. Nevertheless, because of the extensive deterioration of the mitral annulus, the 31-mm Edwards Magna Ease valve was inserted in supra-annular mitral position. Immediate post-operative transoesophageal echocardiography (TOE) was satisfying, with a good function of the new prosthetic valves. She was weaned from mechanical ventilation the next day.

The postoperative course was marked by an acute kidney injury needing continuous renal replacement therapy. One week after the surgery, she developed a severe hypoxemic respiratory failure due to a pulmonary oedema needing mechanical ventilation.

The TOE revealed a LA wall dissection and the creation of a new atrium cavity interpreted as a FA behind the LA posterior wall, squeezing the left atrium at every systole (Figs. 1, 2). The two new prosthetic valves were functional and unscathed without intra- nor para-valvular regurgitation. A severe left-ventricular regurgitant jet filled the FA pushing the LA posterior wall through the LA, probably causing pulmonary veins obstruction (Fig. 1). No shunts were detected by the bubble test and the aortic wall and the interatrial septum were normal.

Fig. 1figure 1

Left atrial dissection visualized in transesophageal echocardiography. a, b, d Mid-oesophageal 4-chamber view, the false aneurysm is squeezing the left atrium in systole (a, b), and drained in the left ventricle in diastole (d). c Mid-oesophageal 4-chamber view with colour-doppler illustrating the para-valvular leakage. e, f mid-oesophageal 4-chamber view in systole (f) and diastole (e). FA: false aneurysm, LA: left atrium, LV: left ventricle, RA: right atrium

Fig. 2figure 2

Transgastric transoesophageal echocardiography views; the false aneurysm is developed behind the prosthetic mitral valve and the left atrium. FA: false aneurysm, PAV: prosthetic aortic valve, PMV: prosthetic mitral valve

Contrast-enhanced synchronized cardiac CT-scan (128-slice) was realized to perform a 3D reconstruction imaging to guide a potential surgery. It confirmed a FA measuring 65 × 40 x 30 mm behind the LA with a mass effect on it, communicating with the left ventricle outflow tract through a 23-mm defect, close to the mitral prosthetic valve (Fig. 3). Pulmonary veins were correctly inserted in the right atrium.

Fig. 3figure 3

Cardiac CT-scan and 3D-reconstruction. The false aneurysm measures 65 × 40 × 30 mm, behind the prosthetic mitral valve and the left atrium. FA: false aneurysm, LA: left atrium, LV: left ventricle, PAV: prosthetic aortic valve, PMV: prosthetic mitral valve

Unfortunately, weaning from mechanical ventilation was unsuccessful. Considering the high risk of a third surgery, the impossibility of a percutaneous treatment facing a very large collar and false aneurysm and the worsening of the clinical course, a palliative care support was collegially decided and the patient finally died.

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