The foremost commandment for successful myocardial revascularization surgery is complete revascularization. However, following simple Socratic logic, if we only have four theoretical arterial grafts (considering both radial arteries), and if certain patients present contraindications for their use, achieving quality surgery without saphenous vein grafts becomes challenging. In my opinion, an average of over three grafts per procedure is typical in a revascularization service, with four or more grafts often required for multi-vessel disease, warranting systematic treatment of the right territory if its caliber and development are favorable, even in the presence of chronic occlusion.

Except in rare cases, these axioms make the use of saphenous vein grafts predominant in daily practice, originally popularized by Favaloro, who standardized the procedure with this graft. Indeed, some teams still consider more conservative approaches, using a single arterial graft per procedure, which further increases reliance on saphenous vein grafts.

This review evaluates aspects related to maintaining the quality and patency of saphenous vein grafts. It is essential to consider that, despite intraoperative hemodynamic results, various technical factors dependent on the graft itself may affect mid- and long-term patency, regardless of anastomotic quality or the condition of the target vessel.

COMMANDMENTS

• Verify Function of All Grafts: This applies to all grafts used in revascularization surgery, as it is an essential quality standard today. A graft’s future function cannot be guaranteed if intraoperative failure occurs, defined as a flow of <15-20 cc/min and/or a pulsatility index >3-3.5 (>5 for the right coronary territory). Multiple measurements should be taken after constructing the anastomoses, during extracorporeal circulation, and before reversing heparinization. However, the definitive measurement should be considered the one taken with protamine administered, prior to sternal closure, and with a mean arterial pressure >70 mmHg (systolic >100 mmHg). The characteristics of the measurement should be contextualized according to the vessel, territory, and graft used, even if showing signs of apparent normal function. A reverse flow value of <3% should be considered acceptable; if exceeded, competitive flow may be suspected, either due to a lack of significance in the proximal lesion of the grafted vessel or because of the supply of that territory from other grafts or vessels, grafted or not. This phenomenon can occur even with parameters of normal graft function but may also have implications for patency. In arterial grafts, this can manifest as a “string phenomenon” due to vasospasm, and in venous grafts, it can lead to intimal hyperplasia and accelerated atherosclerosis. If graft dysfunction or an unexpected result is evident, the entire course of the graft should be reviewed, ensuring proper geometry, verifying the quality of the anastomosis performed, and ultimately, using additional tools like epiaortic/epicardial ultrasound if necessary. With adequate training, patterns of graft injury and issues at anastomosis sites can be identified that might explain the observed results. The combination of both systems can result in a change in strategy or the need for a revision in 10-25% of cases.
• Removing Perivascular Tissue Results in an Incomplete Graft: This is one of the aspects that the selected study emphasizes the most. Using skeletonized grafts has been proposed as a technique that facilitates their use, primarily by preventing technical errors due to interference from the adventitia during branch control or anastomosis construction. Favaloro already advised, “care should be taken to dissect only the vein, avoiding the adventitia surrounding it as much as possible.” However, handling skeletonized grafts (both venous and arterial) also prevents damage during extraction and maintains autoregulation, partly through nervous/paracrine pathways (due to endothelium-independent factors such as nitric oxide and prostaglandins), and above all, nutritional supply via the vasa vasorum. It has been noted that using skeletonized arterial grafts may provide more length and limit spastic tendencies by having a larger caliber. However, the biology of venous grafts differs; as spasticity and limited caliber are not common issues, losing a structure that maintains the graft’s integrity and contains the forces from its arterialization could lead to poorer long-term results. The study refers to “the sixth layer” of the graft, and consequently, using it without perivascular fat is like using an incomplete graft. Studies have shown that graft atherosclerosis accelerates if the vasa vasorum are lost, reducing the graft to a mere conduit without a nourishing capillary network. Moreover, interesting aspects studied by the group behind the study highlight reduced meta-inflammatory or chronic inflammation phenomena in the perigraft fat (of both mammary artery and saphenous vein) compared to the epicardium of coronary vessels. This favors the graft’s biology and the release of intraluminal factors that counteract the progression of disease in the native bed. Like any technical variation, there are trade-offs. In the case of venous grafts, extraction with adipose tissue can lead to more anastomotic errors due to adventitia interference, as well as higher degrees of injury to the saphenous nerve. For the mammary artery, there is a known increased frequency of mediastinitis, which is why bilateral pedicled use is not recommended. Pedicling provides a shorter graft length, particularly for arterial grafts, but also protects against kinking along the course.
• Graft Extraction, Minimal Handling: The group responsible for the study, as well as clinical guidelines, advocate for a “no-touch” strategy, which includes several aspects: the aforementioned pedicling, performing anastomoses without touching the coronary or graft endothelium with instruments, and minimizing contact during needle steps. This also involves minimizing the size of the suture and needle used, as well as branch control with minimal vessel interference. In fact, branch control should be executed with proximal and distal clips or ligatures, followed by cold cutting. Practices involving electrocautery only transmit current into the vessel, creating thermal injury that could potentially lead to degeneration in the future.
• Prohibit Graft Distension: A common practice is venous graft distension to check the watertightness of branch control and to increase the caliber. Although this might provide a more manageable graft and even a potentially better immediate hemodynamic outcome, it causes significant wall damage by disrupting the vein’s layers and creating gaps in the tunica media and elastic layers, promoting inflammatory cell infiltration, intimal hyperplasia, and the atherosclerotic process. The graft should be verified using an intraluminal flush without distal occlusion, as it will already experience pressurization when connected to the arterial territory, though this pressure will still be more controlled compared to what we can impose manually.
• Patency Over Aesthetics: In this regard, the authors of the study are highly critical of endoscopic graft extraction. They acknowledge a higher rate of wound complications with open extraction; however, the current techniques and systems used subject the graft to trauma that will affect its future patency. Branch control by direct coagulation has already been argued against, as has excessive skeletonization or pulling that even leads to endothelial disruption. They describe experiences with prototypes and modifications to the technique using currently marketed systems to preserve periadventitial fat or perform branch control with bipolar electrocautery (which causes much more localized damage). However, a recommendation cannot be offered that supports the one currently in clinical guidelines, which are clearly influenced by economic interests and where the quality of the obtained grafts should be valued, even if it means a more conspicuous wound that affects the patient’s prognosis.
• Exostents Delay Intimal Hyperplasia: In this section, the authors provide a brief review of the role of exostents, particularly VEST, as supports for saphenous vein grafts. Their use is intended for skeletonized grafts. They describe experiences from the five published studies (VEST I-IV and CTSN VEST), although there are other analogous experiences published by other authors, with even identical clinical trial methodologies. In this regard, our group recently published a meta-analysis that aggregates the evidence, finding no differences in clinical events or patency, but significant differences in terms of saphenous vein graft degeneration, specifically luminal irregularity due to intimal hyperplasia. This phenomenon is the main factor in adverse remodeling of grafts, beginning a few months after anastomosis construction and being the primary factor in long-term failure. It is caused by shear forces that lead to subendothelial proliferation of fibro-inflammatory tissue, similar to atherosclerosis. Counteracting these forces with external support, either through periadventitial tissue or synthetic mesh, could help minimize them and prolong graft durability. However, one of the main limitations is that the VEST studies have follow-ups that are still insufficient to determine long-term benefits in terms of patency from this better luminal regularity.
• Graft Geometry Is as Important as Anastomosis Quality: Graft construction does not end with extraction and good anastomosis quality. Often, graft failure occurs due to kinking along the course, a phenomenon known as geometry. This must take into account the graft’s route along the surface of the heart and its relation to the grafted vessel, since non-laminar flows, like side-to-side “diamond” anastomosis configurations, can lead to focal intimal hyperplasia and ultimately revascularization failure. Moreover, it is essential to consider that graft configuration changes with the sternal retractor versus during the working opening, making it advisable to perform measurements with the retractor closed. This is a common personal practice to ensure there is no modification of graft configuration. However, the results obtained should be similar to the “official” measurement previously described, which should be taken as close to the distal anastomosis as possible. Another factor to consider is that grafts must have sufficient length since, in the short term, they undergo another remodeling phenomenon: dilation. This affects arterial grafts, but especially saphenous vein grafts, and in this case is due to transmural forces. Dilation, like with stents, leads to longitudinal shortening, and graft geometry that was initially adequate may later result in anastomosis distortion or altered relations with epicardial structures. This effect may be more pronounced in sequential anastomoses, particularly at the distal level. The major issue with this aspect is the inability to predict this phenomenon’s occurrence, which can only be mitigated by ensuring adequate graft length and preventing kinks along the route.
• Endothelial Protection: Flushing and Storage: When avoiding graft distension, we mentioned intraluminal flushing, but with what? Heparinized saline is commonly used; however, this product is highly toxic to the endothelium, causing damage and denudation, effectively turning the graft into a “zombie conduit.” Using blood for intraluminal flushing has been proposed as a solution, under the assumption that blood contains buffering factors and would be physiologically more suitable. The only advantage of blood is its color, which makes it easier to verify branch or anastomosis integrity. However, stagnant blood, especially in contact with plastic or metal surfaces, exhibits high levels of platelet and leukocyte activation, which affect the graft if stored until use. The most appropriate approach seems to be using non-blood buffered solutions with osmotic characteristics similar to plasma. Various products have been suggested, such as classic papaverine (too acidic, which is why it was not recommended for intraluminal use, usually mixed with whole blood, despite its drawbacks) or the Hong-Kong or He solution (verapamil + nitroglycerin buffered at pH 7.4). The big promise lies in Duragraft®, which, although still lacking solid clinical evidence, has demonstrated excellent results in vitro as an excellent endothelial preservative, both for flushing (with blood staining) and for storage.
• Four Spans of Graft, Not All Can Be the Same: A common practice is using the saphenous vein “as it comes,” obtaining sufficient length depending on the number of grafts planned. The presence of visible varicosities should lead to excluding the graft, but it’s not uncommon to tolerate irregularities or even varicose nodes in graft configuration. While repair techniques are described, these should be limited to scenarios with no other alternatives; it is far preferable to select suitable graft segments, as they will be the ones that help avoid ischemic events for the patient in the future. Preoperative graft evaluation is also an uncommon practice that can be conducted via ultrasound, giving a clearer idea of the surgical strategy. This practice reduces wound morbidity from unnecessary open approaches or helps predict the presence of significant branches in cutaneous bridge or endoscopic approaches.
• One Vessel, One Graft Standard: Despite the versatility of saphenous vein grafts and their almost infinite use possibilities, each more creative than the last—sequential grafts, composite grafts, extension of internal mammary artery grafts—it should be emphasized that “fun” does not align with science: available evidence encompasses only saphenous vein grafts used as single grafts with two anastomoses, one proximal to the aorta and one distal to the native vessel. This is quite different from arterial grafts, for which clinical trials themselves accept more varied configurations. Therefore, if the patency of these grafts is inferior in their best configurations, these kinds of “exotic” approaches should be minimized except in scenarios where the limitation of graft availability prevents offering complete revascularization.

COMMENTARY:

The saphenous vein graft, though often disparaged and underestimated, remains relevant 60 years later. Its versatility and easy availability have led to both mistreatment and inconsiderate use in equal measure. While the internal mammary arteries have been considered the Holy Grail and the radial artery the perpetual candidate as a secondary graft, it seemed that almost anything was acceptable for the poor saphenous vein. New concepts and the dismissal of outdated ones seem necessary as we continue to refine one of the oldest techniques in both general surgical treatments and, specifically, cardiac surgery. We must stop thinking of the saphenous vein as mere “spaghetti” and give it the respect it deserves: that of a coronary revascularization graft, with its own biology, indications, and “instructions” for use.

REFERENCE:

Mikami T, Dashwood MR, Kawaharada N, Furuhashi M. An Obligatory Role of Perivascular Adipose Tissue in Improved Saphenous Vein Graft Patency in Coronary Artery Bypass Grafting. Circ J. 2024 May 24;88(6):845-852. doi: 10.1253/circj.CJ-23-0581.