Perspective. Reoperative Bentall: choice of conduits

Abstract

The Bentall procedure represents the gold standard in the treatment of patients requiring aortic root replacement. The most common indications for redo Bentall are structural degeneration or graft infection. Redo aortic root replacement can be performed with low perioperative morbidity and death. The choice of the best conduit is still up for debate but is mandatory to guarantee the best and most durable option for the patient. New options are available to reduce mortality in older or fragile patients and can modify the conduit choice.

Since the first description in 1968 of the composite conduit technique for replacement of the aortic valve and the ascending aorta by Bentall et al. [1], this procedure has become a generally accepted surgical technique for the treatment of sinus aneurysms with aortic insufficiency. Several modifications have been proposed to the original procedure to reduce the risks of associated complications [2, 3].

A variety of conduits are available for Bentall procedure: homografts, biological and mechanical composite grafts. Over time, some of these prostheses could fail due to infection/endocarditis, thrombosis, or structural degeneration and may necessitate excision. Indications for redo Bentall procedure can be simply classified into three major categories: aortic, infective, and valvular indications.

Irrespective of the indications, Bentall reoperations are technically challenging and have been associated with perioperative mortality rates of up to 18% in some series. Advanced age and endocarditis are identified as risk factors for death [4–8].

In a recent meta-analysis of 7609 patients, the linearized occurrence rates of late reoperation on the aortic root (including valve reoperation) was 0.46 (0.36–0.59) [9]. In 2011, Desai et al. [10] described a series of 986 patients with root replacement procedures, including 391 porcine bio-roots and 515 composite mechanical conduits. Freedom from reoperation was similar between groups during the follow-up period. Reoperations in patients with bio-roots occurred for leaflet calcification and stenosis in one patient and aortic insufficiency from a leaflet tear in one patient. There were no other known cases of moderate or worse prosthetic bio-root stenosis or insufficiency. Thromboembolism and endocarditis rates were also similar. Overall, minor and major bleeding events tended to be more common among mechanical root patients.

What is the best conduit in redo Bentall is still up for debate because none of the conduits are free from complications. Indications for surgery (infective or degenerative disease) and fragility of the patient could play a key role in the conduit choice.

Garrido-Olivares et al. [11] presented their series of prosthetic root explant in 84 patients: Operative mortality was 6% and Kaplan–Meier estimates for survival at 5, 10, and 12 years were 82.5 ± 4.7, 72.5 ± 6.4, and 65.0 ± 7.6%, respectively. In their experience, the most common type of re-implanted prosthesis was mechanical. Recently some studies have examined outcomes after redo aortic valve operations [12, 13] and Bentall reoperations [14, 15] reporting acceptable outcomes. The current results demonstrate that reoperative replacement of the aortic root with coronary artery reimplantation after initial aortic root replacement can be performed safely with a low operative mortality. However, there are limited studies examining the outcomes of redo Bentall replacement with a prosthetic graft [11, 16–20].

All studies agree on the careful surgical planning and operative technique that are important technical keys to the success of this operation. Preoperative imaging provides important information regarding the proximity of the ascending aorta to the sternum with a possible femoral arteries cannulation. In high-risk patients, femoro-femoral bypass is instituted before opening the sternum. Coronary artery mobilization can be challenging in aortic root reoperations, especially with homografts because of the high calcification burden.

Based on our experience and on the cited literature, we think that the conduit choice should be related to the following:

• Patient age;

• Life expectancy;

• Possibility to remove “en bloc” the diseased aortic graft (especially inprevious homograft operations).

Some studies reported the replacement with homograft in redo Bentall for infective disease as the best option. Infectious complications after a redo Bentall procedure are severe and not well documented [21]. Most published studies focus on conduit infection in general, but only few studies report specific outcomes after redo Bentall procedure [21–25].

In 2011 El-Hamamsy et al. [16] reported their experience in 82 patients undergoing reoperative aortic root replacement with coronary reimplantation after first-time total aortic root replacement using homografts. Thirty-day mortality was 2.4%. Most reoperations in this series were for homograft aortic root degeneration, which is often associated with heavy calcification of the aortic wall or cusps. They concluded that using newer generation stentless xenografts, the technical challenge of reoperation after aortic root replacement might be further decreased, than with homografts, because of lower rates of root calcification.

New strategies for redo failed homograft valve can be made simpler by using a sutureless aortic stentless valve. In this case, a correct sizing of the valve is critical to minimize paravalvular leakage, and this should be performed with trans-esophageal echocardiography and intraoperative sizing. Anyway, the rule for infective endocarditis is that all infected tissues must be excised, regardless of the conduit choice [26].

Although implantation of a new valve into a failed prosthetic composite root without redoing the coronary buttons is an attractive option [27], we believe porcine bio-root or homograft tissue is nonviable and often not a good recipient for a new prosthesis in a redo Bentall operation. In that case, sutures should be placed through both the prosthetic annulus and native annular tissue to avoid late paravalvular leaks or dehiscence. Jassar et al. [20] in 2015 presented the largest series of prosthetic aortic root explants with a full aortic root replacement reported in the literature. In contrast with El-Hamamsy, mechanical composite grafts were used in 74 patients (62%) and this was the most common prosthetic type in the degenerative (64%) and in the infection subgroups (57%). Overall mortality was 5% in the redo group (p 0.43). They conclude that to minimize any future reinterventions, a mechanical composite prosthesis remains their conduit of choice in suitable and willing younger patients. In degenerative disease, the use of mechanical valve prosthesis is associated with a decreased hazard of reoperation on the aortic root. The vast majority of Bentall procedures involve replacement of the aortic root with a mechanical valved conduit which provides a durable solution but requires life-long anticoagulation associated with well-known increased bleeding risk [9].

In agreement with Jassar et al. [20], our preferred biologic valved conduit in redo Bentall operation has shifted from stentless bio-roots or homografts toward pericardial composite grafts (Dacron [DuPont, Wilmington, DE] graft with stented pericardial valve). In fact pericardial composite grafts may be suitable for future aortic valve replacement without reimplanting the coronary buttons. Furthermore, pericardial composite roots are also more suitable to a future transcatheter valve-in-root procedure due to the structural support provided by the stent and easier visualization of the valve by fluoroscopy. Based on this sophistry that one or two transcatheter “valve-in-valve” replacements could be performed, we are pushed toward this appealing option to try to keep the patient alive up to 80–90 years old [28]. Unfortunately, patients undergoing reoperative Bentall are frequently young [20] and we think they deserve a durable repair which is probably better achieved with a mechanical conduit. In addition, most of them require an adjunct procedure at the time of aortic root replacement, like aortic arch or mitral valve intervention. These needs cannot be met by the current transcatheter valve therapies. Moreover, there are some concerns regarding coronary coverage by deploying transcatheter aortic valve replacement valves in bio-roots due to obstruction by leaflet tissue.

In conclusion, mortality and morbidity of Bentall reoperation can be effectively diminished by the integrated use of different innovative strategies including transcatheter or sutureless valve operation and conventional perioperative management including imaging, appropriate use of Cardio-pulmonary bypass (CPB), sometimes started before resternotomy, optimal myocardial protection strategy, and pharmacologic adjuvant therapy. A biologic prosthetic conduit or a homograft is chosen on surgeon preference for technical reasons, but we do not necessarily favor biologic valved conduits just because of the presence of infection or for the new appealing options. Redo Bentall in elective patients should be considered curative and justified by the expected survival benefit. There are no problems to perform a second operation in terms of outcomes, but we should avoid the third one. Mechanical conduit should be preferred in young patients and that probably represents the best option, even for endocarditis redo. If the patient is over 60 years old or with only 15–20 years of life expectancy, a bio-root will be the conduit of choice.

Compliance with ethical standards

Conflict of interest

Mariscalco G declares that he received support from Vascutek, an aortic prosthesis manufacturer, to attend scientific meetings. Serraino GF, Zanobini M, Beghi C, Maselli D, Bashir M, and Mastroroberto P declare that they have no conflict of interest.

Ethical approval

For this type of study, formal consent is not required.

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent

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