A sixty-four-year-old woman (body mass index, 20.34 kg/m2) underwent aortic root enlargement and placement of a 21-mm Regent mechanical aortic valve (St. Jude Medical, Saint Paul, MN) twelve years ago in an outside institution. She presented to our center with lightheadedness and fatigue after minimal exertion. A transesophageal echocardiogram (TEE) showed severe aortic stenosis with mean 43 mmHg and peak 79 mmHg transvalvular gradients. Peak aortic valve jet velocity measured 5 m/s. The mechanical valve’s posterior disc appeared immobile. Left ventricular ejection fraction was 55%, with no other valvular lesions. Preoperative heart catheterization showed normal coronary arteries. Her Society of Thoracic Surgeons Predicted Risk of Operative Mortality score was 4.7% for a planned redo aortic valve replacement. The patient opted for a bioprosthetic aortic valve. The patient also had a moderately enlarged mid-ascending aorta (~4.0–4.3 cm) and elected to have it replaced concurrently, rather than face the prospect of a potential third open-heart operation.
Preparation and exposition
The patient underwent full resternotomy and cardiopulmonary bypass with axillary artery cannulation (Video 1). During her previous surgery, her aortic annulus had been too small to accommodate the 21-mm mechanical aortic valve; thus, the neo-noncoronary sinus had been reconstructed with a Dacron patch down to the anterior leaflet of the mitral valve, as part of a Nicks technique for aortic root enlargement. The existing mechanical prosthesis was excised after extensive pannus removal, and 4-0 polypropylene pledgetted sutures were placed to approximate tissue planes adjacent to the annulus.
The annulus was unable to accommodate the sizers for several commercially available 21-mm bioprosthetic valves, yet a 19-mm valve would create a patient-prosthesis mismatch. We therefore elected to place a balloon-expandable transcatheter aortic replacement (TAVR) valve as a bailout option. A 23-mm Sapien 3 valve (Edwards Lifesciences, Irvine, CA, USA) was deployed under direct vision with careful balloon inflation and was determined to be positioned satisfactorily (Video 1).
The ascending aorta and the proximal transverse arch were replaced with a 26-mm Dacron graft during a short period of moderate hypothermic (25 °C) circulatory arrest. The proximal anastomosis was performed by using a running 4-0 polypropylene suture between the Dacron graft and the aorta distal to the new TAVR valve.
Completion and clinical course
The immediate postoperative TEE revealed a well-positioned aortic valve, no paravalvular leak, and a mean transvalvular gradient of 4 mmHg. The postoperative course was notable for complete atrioventricular block—unsurprising, given the extensive-but-necessary debridement of the aortic annulus—that necessitated dual-chamber permanent pacemaker implantation (PPI). The patient was discharged on postoperative day twelve.
The patient was symptom free at the three-month postoperative follow up. Her echocardiogram showed a dimensionless valve index of 0.5, consistent with normal prosthetic aortic valve function without stenosis.
We present a bailout direct-vision, open transcatheter valve replacement for patient-prosthesis mismatch in a woman with a previous mechanical aortic valve replacement and aortic root enlargement. When we encountered a small aortic annulus during surgery, we used a hybrid approach in which we surgically deployed a TAVR valve under direct vision.
Although conventional aortic valve replacement is standard treatment for patients with prosthetic aortic valve stenosis (1,2), reoperation for failure of the prosthetic valve with previous aortic root enlargement remains challenging (3). Increasingly, valve-in-valve TAVR is an option for patients needing bioprosthetic valve replacement (4). Both TAVR valve insertion under direct vision during open-heart surgery when a hostile aortic root is present (5) and transcatheter mitral valve replacement for extensive mitral annular calcification (6) have been documented, but not for prosthetic mechanical aortic valve replacement in the presence of previous aortic root enlargement.
In this case, the stiffness and small caliber of the sinotubular junction precluded the placement of appropriate bioprosthetic or mechanical aortic replacement valves, given the risk for prosthesis-patient mismatch. We considered aortic root replacement; however, potential distortion of the patch extension into the mitral valve, which could damage its competency, and the desire to limit myocardial ischemia time and avoid coronary artery dissection obliged us to find an alternative approach (7). We also thought that direct insertion of a TAVR valve would reduce the risk for annular disruption and allow slight oversizing of the prosthesis (in this case, a 23-mm Sapien 3). Furthermore, insights from the Placement of Aortic Transcatheter Valve (PARTNER, Edward LifeSciences. Irvine, CA) trial (8) indicate that TAVR procedures have lower mean gradients compared with bioprosthetic surgical aortic valve replacement (SAVR) in women, which made the direct implantation of a TAVR valve an attractive option for this patient. A rapid-deployment, sutureless aortic valve bioprosthesis might also have been considered as an alternative; however, we believed that even the three guiding sutures would be problematic in this case, because of the frail aortic tissue alongside the left ventricle.
Other investigators (9) have shown that adding concomitant aortic replacement to an elective cardiac procedure does not significantly increase the risk for in-hospital mortality or stroke.
Although PPI was almost unavoidable in this case, placing the TAVR valve under direct vision during open surgery may have conferred unique benefits. The membranous septum length anatomically represents the distance between the aortic annulus and the bundle of His and is inversely correlated with the risk for conduction system abnormalities after TAVR (10). Deploying the device with direct visualization of the annulus and membranous septum transition could reduce the risk for needing a pacemaker. Nonetheless, the separation along the tissue planes adjacent to the annulus made our case challenging, and it is likely that any aortic valve replacement in this patient would have necessitated PPI.
In complex aortic valve surgical reoperation, direct insertion of a TAVR valve may be feasible option for avoiding the risks of prosthesis-patient mismatch or complete root replacement by combining the effectiveness of both TAVR and SAVR as a bailout strategy. As surgeons continue to become facile with TAVR and patients with previous TAVR increasingly require surgery, creative hybrid applications of both SAVR and TAVR for complex scenarios will be increasingly necessary in the future.
Jeanie F. Woodruff, BS, ELS, contributed to the editing of the manuscript.
Conflicts of Interest: JSC participates in clinical studies with and/or consults for Terumo Aortic, Medtronic, W.L. Gore & Associates, CytoSorbents, and Abbott Laboratories and receives royalties and grant support from Terumo. OP participates in clinical trials with and/or consults for Terumo Aortic and W.L. Gore & Associates None of the other authors has any potential conflict of interest with regard to the work described in this manuscript.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
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