Early and midterm outcomes of a bentall operation using an all-biological valved BioConduit™

It was a prospective observational study, without control-group, carried out from 2017 to 2020 in our tertiary centre.

All consecutive patients undergoing a Bentall procedure with the BioIntegral™ Surgical BioConduit™ No-React® in our institution (n = 91) were prospectively included during the study period. All patient data were collected from hospitals’ medical records. Cohort patients underwent an aortic root replacement with an all-biological graft in cases of complex endocarditis or redo surgeries, cases of patients who were not candidates for an autograft procedure but a mechanical graft was not indicated and in elderly patients with degenerative aortic root disease.

The study is conformed to the principles outlined in the Declaration of Helsinki. According to French law on ethics, patients were informed that their codified data would be used for the study. The patient also provided informed written consent for the publication of the study data. The Institutional Review Board of the Rangueil University Hospital of Toulouse, France, approved the study protocol and the publication of data (number RnlPH 2022-50) on the 7th of April 2022.

All interventions were performed by four senior surgeons. All patients were operated through median sternotomy. Standard cardiopulmonary bypass, aortic cross-clamp and anterograde and retrograde cold blood potassium-enriched cardioplegia were used in all patients. When an aortic arch replacement was performed, moderate hypothermic circulatory arrest and selective antegrade cerebral perfusion through the right axillary artery were associated. After aortic cross-clamping, the aortic valve, the aortic root and the ascending aorta were excised, followed by aortic annulus decalcification when required. The coronary ostia were isolated with their buttons. After sizing of the aortic annulus, the prosthesis was chosen, with a trend in oversizing. The all-biological stentless valved bioconduit is designed to offer similar hemodynamics as the native aortic valve and theoretically aimed to insure a larger post-operative effective orifice area (EOA). The conduits’ No-React® treatment aims to reduce the grafts’ related infections and calcifications as well as to prevent remodeling and graft aneurysmal dilatation [5‐7]. As the traditional glutaraldehyde preserved biological valves tend to calcify, the No-React® detoxification process promises to eliminate residual glutaraldehyde and to ensure stable tissue cross-linking, resulting in less or no calcification or tissue deterioration in the animal model [5, 6]. A variety of BioConduit™ sizes between 21 to 29 mm were implanted. The trend of oversizing refers to choosing a conduit one-size oversized following the manufacturer’s recommendations, to achieve greater effective surface areas, avoiding mismatch [7]. Depending on operator preferences, two types of implantation techniques were used, either multiple single, interrupted, non-everting, reinforced U-stiches to implant the composite graft in supra-annular position (n = 33, 36%) or everting stitches to implant the prosthesis in intra-annular position (n = 58, 64%). Then, 2 holes were made in the tubular graft and both coronary ostia were reimplanted by running sutures (Prolene 6–0). Fibrin glue was used in most cases to reinforce sutures.

A post-operative transthoracic echocardiographic (TTE) assessment was performed before hospital discharge: 2D TTE standard views were obtained using a standard ultrasound system using a 1–5 MHz probe (VIVID S70, GE Healthcare). A new TTE assessment was conducted at 1 year, using the same system. EOA was calculated by the continuity equation method. Aortic annulus diameter was measured at mid-systole, from the parasternal long-axis view, at the level of the prosthetic annulus, in a zoomed mode, from inner-edge to inner-edge. The velocity–time integral of blood flow was measured in the left ventricular outflow track by pulsed doppler. Mean transaortic gradient and maximal velocity were evaluated by transprosthetic continuous wave doppler. The doppler velocity index was calculated as the ratio of the proximal peak flow velocity in the LVOT to the transprothetic peak flow velocity. All examinations were interpreted blindly on a dedicated workstation (EchoPac 204 GE Healthcare) by two operators. In addition, during the follow-up, in case of bioprosthetic valve failure (BVF), a TEE and a cardiac CT were performed.

The endpoints used were those proposed by the Valve Academic Research Consortium 3 (VARC3).

Continuous variables were expressed as means ± standard deviation or as medians with interquartile ranges (IQR) when not normally distributed. Nominal variables were expressed as numbers and percentages. The association between the mean values of continuous variables was assessed using the Mann–Whitney rank sum test. Nominal variables were investigated by the χ² test or the Fisher exact test when appropriate. The software XLSTATS v2019.1 (Addinsoft, Paris, FR) was used for statistical analysis.

This study included 91 patients, mostly men (74%) with a mean age at intervention of 70 ± 10 years. Preoperative patient’s characteristics are reported in Table 1. Most patients had an ascending aortic aneurysm (n = 65, 72%). There were 22 cases of redo procedures (24%). Sixteen procedures were performed on an emergency basis (18%), including 10 cases of type A acute aortic dissection (11%), 12 cases of severe prosthetic endocarditis (13%) and 1 complex of native aorto-mitral endocarditis. Forty-four patients underwent combined interventions (48%): coronary artery bypass graft in 22 cases (24%), mitral valve repair or replacement in 5 (6%) and aortic arch or hemiarch replacement in 14 (15.3%) cases.

Among the 83 patients discharged from hospital, 9 were lost to follow-up (10%). Median follow-up was 4 years.

The periprocedural mortality rate was 8% (n = 8). Among them, 3 patients with a pre-operative severe left ventricular dysfunction died shortly after the procedure from low cardiac output and multiorgan failure syndrome, 2 patients operated for complicated infective endocarditis on previous Bentall prosthesis died in the first 24 h from refractory septic vasoplegic syndrome, 2 patients operated for acute type A aortic dissection died either from massive hemorrhagic stroke or acute right ventricular failure in the first week after surgery and 1 patient experienced acute respiratory distress syndrome.

Early mortality rate was 2%. Among the 83 patients discharged from hospital, 2 died in the first year, both of them experiencing graft proximal anastomosis partial detachment at 9 and 10 months, respectively. Both were reoperated, but died from hemorrhagic stroke or massive intraoperative bleeding, respectively.

Midterm mortality rate was 4% (3 patients). One 62 years-old male, who had already undergone two Bentall procedures presented a recurrent bacterial graft endocarditis at 18 months after discharge. He was referred to surgery and died in the operating room from uncontrolled bleeding. One 83 years-old patient died from respiratory distress related to a severe form of Covid-19 pneumonia. The third, 72 years-old male died from metastatic pulmonary adenocarcinoma.

Five patients experienced infective endocarditis (6.8%) at a median of 1 year and 4 months. One patient was treated surgically and the other 5, medically.

There weren’t observed any more cases of hemodynamic dysfunction or AV disruptions until follow up was closed.

Regarding early and midterm results, we observed a total of 14 patients presenting a BVF during follow-up (17%). A re-intervention was performed in 8 cases (10%). Three patients had a valve-in-valve TAVR for severe HVD. Five patients had open redo surgery: three cases of partial proximal anastomosis detachment, one case of graft endocarditis with valvular involvement and one severe HVD. Among them, 3 patients died related to the procedure.

Regarding etiologies of BVF, 6 patients experienced infective endocarditis (8%), 3 patients had partial proximal anastomosis detachment (4%) and the other 4 patients had severe irreversible HVD (5.5%). All patients with endocarditis underwent TTE and TEE which were abnormal in two cases, highlighting valve involvement (aortic vegetations (n = 2), aortomitral abscess (n = 1) and pseudoaneurysm (n = 1)). Endocarditis patients also underwent a CT scan which showed in all cases a proximal collection around the biological graft with peripheral contrast diffusion, without signs of a pseudoaneurysm. PET combined with CT (PET/CT) was also performed in four cases, showing an abnormal intense uptake on the graft collection and/or the valvular prosthesis. Regarding the pathogens involved, there were 2 cases of staphylococcus involvement (aureus and epidermidis), 1 with Enterobacter Aerogenes, 1 with E. coli, another case a streptococcus oralis infection and lastly, 1 with negative blood cultures.

For all patients with HVD, thrombosis was ruled out by CT, and endocarditis by Duke criteria. SVD was eliminated by TEE and CT. Of note, none of these patients had regurgitation. Regarding NSVD, a patients-prosthesis mismatch did not appear to be involved, as postoperative indexed EOA was not associated with the occurrence of HVD at 1 year. Finally, for all patients with HVD, imaging found a 3–4 mm, circumferential, hyperechogenic ring, located at the level of the prosthetic aortic annulus and at the graft’s proximal anastomosis towards its’ ventricular side, near the pledgets. In these patients, on CT and TEE, there was no structural prosthetic abnormality (neither fibrosis, calcification, leaflet tear and wear, hypo-attenuated leaflet thickening nor thrombosis). Moreover, we have randomly reviewed patients’ echocardiographic exams concluding that the circumferential structure is a common finding in patients being implanted with this type of biological graft. Indeed, 29 patients had a reduction of their aortic annulus size at 1 year (39%). We identified this annular structure in the per-operatory setting, during the reintervention for a failing bioprosthesis (Fig. 1).