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Ann Thorac Surg 1999;68:1312-1313
© 1999 The Society of Thoracic Surgeons
a Department Cardio-Vasculaire, L’Institut Mutualiste Montsouris, 42, Boulevard Jourdan, Paris France, 75014
Invited commentary
The experimental study reported by Tanaka and coworkers draws our attention to the most important question of using a safe, simple, fast way of reinforcing the aortic tissues during repair of an acute aortic dissection. By proposing an apparently efficacious and easy-to-use new adhesive adjunct, the authors bring an interesting renewal to the idea of sticking the dissected layers together and, thus, avoiding the tedious and time-consuming use of Teflon felt before securing a vascular prosthesis.
Since vascular and cardiac surgery have existed, surgeons have faced technical difficulties due to the poor quality of the tissues, the unsafe sutures, and, therefore, the consequent hemorrhages. In order to reduce those deleterious difficulties, they have imagined and developed a great number of technical artifacts and procedures. Among these, the idea of using adhesives and sealants appeared in the early 1950s and rapidly resulted in numerous experimental studies.
A great variety of products have been tested. Among those, polyacrylates, rubber latex, epoxy resines, formaldehyde resines, acetate and alcoholic polyvinyles, carboxylic polymers etc, have demonstrated a more or less adhesive power. But none of them has demonstrated the necessary qualities to be used in a biological environment.
Because the tissues contain a great quantity of polypeptidic chains, it seemed logical to test products with a similar structure as adhesive agents.
In the early 1960s, Braunwald, Gay, and Tatooles demonstrated that a solution of gelatin and resorcinol polymerized with 37% formaldehyde allowed efficacious and stable adhesion. They concluded that this biologic cement had a tensile strength much higher than that of other adhesives available at that time. However, despite the statement that "because of its ability to bond tissue rapidly, even in presence of moisture, [the GRF glue] shows promise as a surgical adhesive and hemostatic agent in selected application," and in the absence of local and general toxicity, the product had had almost no clinical application during more than a decade.
In 1976, we discovered the product by accident. We, like many others, were facing at that time the operative difficulties of surgery of acute dissection. The idea of using such a sealant to reinforce the weak tissues and achieve immediate blood tightness of the sutures appeared logical.
Since then, we have always employed the GRF glue as an adjunct to reinforce the dissected tissues at the suture sites in order to perform a safe and blood-tight prosthetic replacement of the aortic portion at risk. No attempt was made to obliterate the false channel with the glue. This would have proved technically uncertain and unrealistic.
Rapidly, during the early 1980s, the use of the GRF glue during surgery of acute dissection of the aorta became very popular and was considered as a routine procedure in Europe, the Middle East, South America, Asia, etc, but the product was not available in the United States, because of local regulations. Indeed, although many published experiences with the GRF glue in surgery of acute aortic dissection have proved that this adjunct is very useful in providing excellent solidity and hemostasis of the suture sites, a question remains unsolved yet: Is the use of GRF glue totally safe?
The presence of formaldehyde which is known to be toxic on living tissues, may be of concern. Indeed, a few publications have reported adverse side effects of the product.
Through careful reading of the papers reporting complications, it appears to us that the technique of using the glue may have played an important role in causing most of those complications. In particular, the use of a too-important quantity of the hardener (ie, the mixture of formaldehyde and glutaraldehyde) may be held responsible for most of the deleterious complications observed.
A very small quantity of formaldehyde is sufficient to polymerize the gelatine. We estimate that one to three droplets of the hardener are sufficient to polymerize 1 mL of gelatin. If those proportions are respected, the risk of toxicity due to direct contact is quite reduced. It seems also important that the formaldehyde-glutaraldehyde mixture be putinto the gelatin-resorcinol mixture, and not applied on its surface in order to avoid direct contact with the surrounding living tissues.
Besides, the rate of complications associated with the use of the GRF glue is indeed extremely small in comparison with the number of acute dissections in which the adjunct has been employed. The individual risk for a patient of experiencing such a complication is therefore almost inexistant.
Last, but not least, the risks of occurrence of side effects and the possible consequences of those side effects must be compared with the beneficial effects of the product in such a catastrophic disease.
But, whatever the drawbacks of the products, the idea of gluing has made its way. The present popularity and the increasing use of glues in cardiovascular surgery have pressed the industry and the surgical community to searching for improved products that could be more efficacious, less or nontoxic, and could be available in all countries.
One of the earliest researches was an attempt to eliminate formaldehyde from the composition of the GRF glue and to replace it with glutaraldehyde alone or glyoxal. Those attempts were unsuccessful, as the reduction of toxicity was associated with a parallel reduction in bonding of the monomers and, so, in the efficacy of the product.
In the late 1970s, the fibrin glue was developed in Austria. This fibrin sealant is a biological adhesive similar to the fibrin monomer produced by the physiological coagulation cascade.
Unlike the GRF glue, the fibrin sealant has been mainly used as an hemostatic agent since its introduction. Its fields of application are numerous and various, and concern almost every surgical specialty and, inside each specialty, a great number of techniques. Personally, for more than a decade we have been using this adjunct with great liberality during aortic replacement procedures of any type. In particular, we apply or spray the glue systematically on the aortic and coronary anastomoses after complete replacement of the aortic root. The fibrin glue, on the other hand, has had very little development in use as a tissue or suture reinforcer in aortic or cardiac surgery.
Recently, at least two new adhesives have been proposed to the surgical community for use as tissue reinforcers during vascular and cardiac surgery. Advaseal is one of those. Most of those products mimic the action of the GRF glue or the fibrin sealant. Through the reported experimental studies, they seem more efficacious and perhaps safer. But, further studies and, in particular, long-term clinical experiences are necessary to confirm these preliminary animals experiments.
The legitimate desire of surgeons to reduce intraoperative and postoperative bleeding by achieving stronger and tighter sutures is largely fulfilled by the use of biological glues.
The reported experiences with the GRF biological glue, which now extend in some cases over more than 20 years, have demonstrated that the use of this adjunct has resulted in easier and safer surgical procedures.
Similarly, the side use of fibrin glue as an hemostatic agent is frequent and various surgical circumstances proves that this adjunct now belongs to the routine tools available to achieve good, safe, and durable surgical hemostasis. Those products represent obviously, and beyond any doubt, major progress in dealing with difficult surgical procedures.
Nevertheless, the present introduction or the development in the near future of new products with a better efficacy and/or a reduced toxicity will certainly widen the use of such adjuncts in cardiovascular procedures and allow the surgical community to achieve safer and simpler procedures. As stated recently by Browdie and Berstein, "we would encourage interested surgeons to undertake further investigations in this area. As, ... such investigations are valuable in developing a better understanding of these materials and their applications."
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