Many surgical techniques we perform are carried out almost automatically, with an assumption of correctness. Since it’s not always feasible to question the underlying scientific basis (and it likely doesn’t exist for everything), habits are formed through imitation and learning from peers. While a surgical profession like ours involves a significant amount of practical learning, the distinction between merely “tailors” stitching structures together and “physicians who operate” lies in the scientific basis of much of what we do.

In cases where such a scientific foundation doesn’t exist, we must create and disseminate it. This approach inspired the British team in today’s article to investigate the mechanical properties of BioGlue® when used for repairing the aortic wall in type A dissection, by creating a neomedia on which the Dacron conduit anastomoses could be performed. Many of us have performed this practice, adopting it more through craft than study. Notably, the product has certification for this use, in addition to being an anastomotic sealant. This adoption is driven more by craft than by study, given the extensive collection of studies delving into the so-called “black legend” surrounding this sealant. The presence of glutaraldehyde, which denatures bovine albumin to form the characteristic “caramel” layer, has led to accusations of polypropylene suture rupture, tissue necrosis, regional inflammation, and other complications resulting in pseudoaneurysms. Numerous reports also document embolization of gelatin fragments, either from accidental application into the circulatory stream or after using it in reconstructing the aortic wall, with resulting re-dissections.

Regarding pseudoaneurysm formation, a previous blog post analyzed BioGlue®’s potential role. However, none of the studies proved conclusive enough to warrant the removal of FDA and CE markings, with a usage history extending over 50 years in aortic dissection contexts.

The authors developed a porcine aorta model in which 42 tissue samples were dissected into two layers through the tunica media, replicating pathological conditions. A layer of product was applied, keeping the two layers of dissected aorta pressed together for two minutes, as per the manufacturer’s instructions. Groups were created with varying levels of pressure maintained on both layers after adhesive application, alongside a group with no applied pressure. Twenty-eight non-dissected aorta samples served as comparative controls.

Adhesive function was assessed using a T-Peel test, a standard method for evaluating the mechanical properties of adhesives across industries. The addition of BioGlue® with some degree of pressure (particularly when applied using Borst clamps specifically designed for this purpose) showed greater wall resistance compared to cases with no pressure application. In fact, compared to the non-dissected controls, the wall resistance of BioGlue® applied with pressure was similar to that of a healthy aorta. Conversely, when no pressure was applied, the wall resistance was significantly lower than that of the non-dissected controls.

Histological analyses, including optical and electron microscopy, and cell culture tests were conducted to assess cellular viability in the context of BioGlue®. Microscopy confirmed the differentiation between tissue and adhesive layers, suggesting no penetration of the product into the tissue. While no tissue or cellular damage was observed, a reduction in smooth muscle cell growth in the tunica media was noted in BioGlue-exposed environments compared to non-dissected controls.

The authors concluded that the application of the T-Peel test methodology is novel in evaluating the properties of various surgical adhesives. This study confirms the efficacy of BioGlue® in reconstructing the dissected aortic wall. However, it also emphasizes that achieving this effect requires maintaining pressure for at least two minutes.

COMMENTARY:

This study reminds us not to take anything for granted. BioGlue® is effective in aortic wall repair, but only when used correctly. Excessive product application, spilling into the intraluminal space, failure to wait for the two-minute setting time, and, as newly highlighted, maintaining continuous pressure—preferably using Borst clamps—seem to be the usage guidelines for this indication. In cardiovascular surgery practice, especially in intraoperative scenarios like circulatory arrest, these guidelines may not always be strictly followed, which can undermine the intended effect and, ultimately, be harmful. Indeed, the apparent uniformity in its application may mask diverse usage practices that could explain inconsistent results and many reported adverse events.

In summary, this is an elegant study with inherent limitations of in vitro analyses. However, its lesson transcends a mere call to use any product or device correctly. It shows that varying outcomes can arise from heterogeneous practices and a lack of scientific rigor in seemingly simple acts like applying a surgical adhesive. This study encourages us to keep researching and questioning every technical step we take, especially if it doesn’t yield satisfactory results. After all, chance, myths, tradition, “this is how it’s always been done,” “we do it this way here,” or “I was taught to do it this way” have no place in modern surgery.

REFERENCE:
Zientara A, Tseng YT, Salmasi YM, Quarto C, Stock U. How to test adhesive strength: a biomechanical testing for aortic glue used in type A dissection repair. Eur J Cardiothorac Surg. 2023 Oct 4;64(4). doi: 10.1093/ejcts/ezad270.