Discussion
To the best of our knowledge, this is the first report describing a group of patients in whom transcatheter prosthetic MV implantation utilizing the transapical method was accomplished for a severely degenerated MV prosthesis or severe native MV stenosis status post a surgically inserted mitral annuloplasty ring with co-existing thrombus in the LAA and/or LA body. In a prior publication comparing surgical versus transcatheter MV in prosthetic MV patients, two patients with thrombus in the LA were listed in a table, but there was no further mention and no other details were provided in the published manuscript.12 Since fluoroscopy does not visualize intracardiac thrombi, use of both 2D and 3DTEE was essential in finding the location and other attributes of the thrombi such as their size and extent in our patients and guiding the transcatheter procedure such that there was no contact with the thrombus at any time. Although in all our patients, the procedure could be successfully performed avoiding any disruption of the thrombus, it may be difficult to avoid it if the thrombus involved the prosthetic valve or was very close to it or was closely related to other anatomic landmarks normally used during the procedure such as the left upper pulmonary vein. However, in all our patients, the thrombus did not involve any of these sites by both 2D and 3DTEE further ensuring a successful outcome without any complications.
3DTEE provided incremental value over 2DTEE in more comprehensively assessing both the LAA and LA body for the presence and exact sites of location of thrombus, its size, shape and mobility characteristics as well as thrombus volume which is a superior parameter of size than thrombus area measured by planimetry.9,13,14 These findings helped the operator in carefully guiding the guide wire and the prosthesis deployment system as they traversed through the degenerated bioprosthetic MV/native stenotic MV and annuloplasty ring into the left atrium bypassing the thrombus. In all our patients, 3DTEE, unlike 2DTEE, also facilitated en face view of the degenerated bioprosthetic MV leaflets which permitted accurate measurement of the orifice area by planimetry.15 In addition, color Doppler en face views of vena contracta of the mitral regurgitant jet facilitated measurement of vena contracta areas permitting more accurate assessment of regurgitation severity.16 3DTEE also provided increased confidence level during deployment of the MV prosthesis. Another additive value of 3DTEE was the ability to ensure the absence of any residual valvular or paraprosthetic MR following the procedure with a greater degree of certainty than using 2DTEE alone since the prosthesis could be viewed in multiple projections.