Description
The patient was a 40-year-old female with rheumatic mitral valve disease and longstanding severe mitral stenosis. She reported significant fatigue and NYHA class II dyspnea. She had undergone successful percutaneous balloon commissuroplasty four years prior to this presentation. Routine serial transthoracic echocardiograms (TTEs) indicated progression of her disease. She had no other significant medical history. Preoperative coronary angiography revealed normal coronary arteries. The patient was scheduled for an outpatient mitral valve replacement via midline sternotomy.
During the operation, the mitral valve was exposed through the interatrial groove. The anterior leaflet was resected and annular calcifications were debrided. The posterior leaflet was tacked to the posterior annulus to maintain annulopapillary muscle continuity. The annulus was sized for a 25/33 mm On-X MMV. Interrupted 2-0 pledgeted sutures were used to sew the ring and after tying all the sutures, the valve appeared to be well-seated. With the prosthesis positioned in the anti-anatomical orientation, gentle probing of the occluders revealed restricted opening. Their excursion appeared to be limited by remnants of native tissue protruding below the level of the posterior annulus. A decision was made to rotate the valve within its sewing ring into an anatomic orientation. Both testing with the leaflet probe and initial transesophageal echocardiogram (TEE) images obtained while weaning from cardiopulmonary bypass (CBP) showed that the MMV was closing and opening well. However, a repeat TEE done at the time of chest closure suggested that while the anterior leaflet continued to move normally, the motion of the posterior leaflet was now restricted, causing an incomplete closure (Fig.1; Supplementary Video 1). The mean transvalvular pressure gradient was still 2 mmHg and there was no regurgitant flow. At that point, the patient was already decannulated. Therefore, we elected to validate our suspicion using cinefluoroscopy. Findings on cinefluoroscopy confirmed limited excursion of the posterior leaflet (Fig.2; Supplementary Video 2) and the decision was made to reinstitute CPB for valve repositioning.
On surgical re-inspection, the infra-annular tissue previously protruding was no longer visible. It is likely that it became tucked under the housing of the prosthesis with repeated ventricular filling and expansion. This allowed us to rotate the prosthesis back to an anti-anatomical orientation. Intraoperative TEE was reassuring and showed normal movement of both occluders. The patient was discharged from hospital after seven days. At the 3-month follow-up, she had made a good recovery and an outpatient TTE showed normal MMV function with low gradients.