Minimally Invasive Direct Transcatheter Aortic Valve Replacement in Mitral Annular Calcification Implantation for Heavy Annular Calcification

The patient is an 80-year-old woman with severe mitral valve regurgitation and moderate-severe mitral valve stenosis who was evaluated for mitral valve replacement.  The patient had a mitraclip procedure performed two years prior and her mitral regurgitation had recurred. Her symptoms included fatigue and dyspnea on exertion.  She had prior coronary stents and her imaging studies demonstrated heavy mitral annular calcification (MAC), more prominent posteriorly and at the commissures.

Given her age, severe MAC, and the small annular sizel, the patient was felt to not be a good candidate for an operation for the resection of the calcium bar, so an alternative approach was seeked. After counseling the patient on an off-label balloon expandable transcatheter aortic valve in MAC, and after obtaining prior authorization and institutional approval for the procedure, the patient consented to this approach. The patient was offered a right minithoracotomy mitral valve operation. 

The operation was successful, with a 130 minute crossclamp. Twenty minutes of this time was spent constructing the composite TAVR valve felt/bovine pericardial composite on the back table. The patient was extubated six hours after arrival to the intensive care unit and had a 2-day stay in intensive care.  She had an uneventful recovery and was discharged on postoperative day seven. Her echocardiogram prior to discharge showed no residual mitral regurgitation and mean gradient of 2 mm Hg across the valve. 

Discussion

Mitral valve replacement in severe mitral annular calcification represents a risky endeavor. The concern for AV-groove disruption is ever present. Removal of the calcium bar with patch reinforcement of the posterior annulus is not a simple technique. This technique carries a palpable risk for life-threatening complication, even with the most experienced surgeons. Newer techniques have been proposed to address severe MAC, and in six years, the use of a transcatheter aortic valve in the mitral position with different modifications has gain traction (1, 2, 3). The operation has been performed via sternotomy (4) and via a minimally invasive approach (1). 

Different modifications to the transcatheter balloon expandable valve have been described, but perhaps the most consistent is the suturing of the felt strip on the atrial side of the valve accompanied by a pericardial doughnut shaped washer. The rationale behind these two modifications is to minimize the risk for paravalvular leak and prevent valve migration.

A word of caution is warranted when performing this operation, and it is to factor in the time that it takes to construct the modifications on the back table. Sizing the valve using a balloon early on after resecting the anterior leaflet allows a second surgeon to perform the modification while the primary surgeon applies the annular sutures.

Direct implantation of a transcatheter aortic valve of a balloon expandable type in severe mitral annular calcification is safe and effective. It can be performed via sternotomy and minimally invasive approaches, such as right minithoracotomy. 

References

1. Baumgarten H, Squiers JJ, Brinkman WT, DiMaio JM, Gopal A, Mack MJ, et al. Implantation of transcatheter aortic prosthesis in 3 patients with mitral annular calcification. Ann Thorac Surg. 2016;102(5):e433-e435.
2. Praz F, Khalique OK, Lee R, Veeragandham R, Russell H, Guerrero M, et al. Transatrial implantation of a transcatheter heart valve for severe mitral annular calcification. J Thorac Cardiovasc Surg. 2018 Jul;156(1):132-142.
3. Astarci P, Glineur D, De Kerchove L, El Khoury G. Transcatheter valve used in a bailout technique during complicated open mitral valve surgery. Interact Cardiovasc Thorac Surg. 2013 Oct;17(4):745-747.
4. Lee R, Borchelt B, George I. Hybrid surgical mitral valve replacement with a transcatheter valve in the setting of mitral annular calcification. CTSNet. March 2018. doi:10.25373/ctsnet.5999933.

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