Intermittent opening of a mitral valve tilting disc prosthesis 23 years after implantation caused by circumferential pannus
A 58 year old woman was admitted with a short history of presyncope and orthopnoea. Mitral valve (MV) replacement with a 29 mm Bjork-Shiley tilting disc prosthesis had been performed 23 years earlier. Transthoracic echocardiogram showed the mitral prosthesis was well seated but appeared to open on alternate cardiac cycles only. M mode examination of the aortic valve revealed cyclical variation of the ejection time and transmitral Doppler showed antegrade flow through the valve on alternate cardiac cycles only (below left, arrows mark intermittent absence of transmitral flow). Transoesophageal echo showed no evidence of thrombus or vegetation. At left and right heart catheterisation, the pulmonary wedge pressure (PCW) showed cyclical variation, rising to a crescendo every second cycle before MV opening. Simultaneous PCW and left ventricle (LV) pressure monitoring revealed a peak MV gradient of 24 mm Hg, falling to 2 mm Hg during opening (below right). Correspondingly, LV and aortic pressure traces showed an alternating rise and fall, which was exaggerated by deep inspiration.
The patient was referred for urgent valve surgery. At operation no evidence of strut fracture, thrombus or vegetation was found. On the ventricular aspect a florid pannus was seen, spanning 360° of the valve impinging on the free margin of the disc. During ventricular systole the valve closed normally, but during diastole would only open when atrial pressure reached a level sufficient to overcome the frictional resistance imparted by the pannus. The valve was replaced with a 25 mm Sorin bileaflet valve and she was discharged without complication.